//! The authoring editor: a `Splicer` that knows how its format is SPELLED.
//!
//! ── The two layers ─────────────────────────────────────────────────────────
//! `Splicer` (`ast/splicer.zig`) is the engine: byte spans in, reparse,
//! rollback, undo. It is language-agnostic by construction and imports no
//! language module — hand it a `parse_fn` and it will edit djot, Markdown or
//! XML with the same code. What it cannot do is decide that bold is spelled
//! `**` here and `*` there.
//!
//! `Editor` is that decision, and nothing else: `Splicer` + a `*const Syntax`.
//! It hosts the gestures a caret editor actually performs — Cmd-B, H1, quote,
//! link — each of which is "consult the table, build the bytes, hand the
//! Splicer one span". The Splicer's invariant survives intact, because `Editor`
//! depends only on the `Syntax` INTERFACE and still names no format: it never
//! learns whether the table it was handed came from djot or Markdown.
//! `format.zig`'s registry is what binds the two.
//!
//! ── Why this exists ────────────────────────────────────────────────────────
//! All of this lived in `c_abi.zig`. Not by design — it accreted there because
//! the C ABI was the first (and only) caller with a caret to serve, and the
//! layer it needed didn't exist. The cost was steep: the knowledge that
//! `mailto:a@b.dev` is a `url` in Markdown but an `email` in djot could only be
//! reached through an `extern` function, could only be tested through a
//! `TwigEditor*` handle and a `TwigStatus` code, and could not be reached by
//! `twig edit` at all.
//!
//! So the C ABI's `TwigEditor` was never `Splicer` — it was always this type,
//! `{ editor, format }`, assembled by hand at the boundary. That is why this
//! module took the `Editor` name and the engine underneath was renamed to what
//! it always was: `TwigEditor` maps to `*Editor`, 1:1, and the ABI's job is
//! back to marshalling.
//!
//! ── Errors ─────────────────────────────────────────────────────────────────
//! Typed, so the ABI's mapping is mechanical and every other caller gets to
//! `switch` on something real. `error.UnsupportedFormat` is uniformly "the
//! `Syntax` table has a `null` where this gesture needed a spelling" — never a
//! hand-written per-format arm. See `syntax.zig`.
const std = @import("std");
const Allocator = std.mem.Allocator;
const Writer = std.Io.Writer;
const AST = @import("ast.zig");
const Document = @import("../document.zig");
const Span = @import("../span.zig");
const locate = @import("locate.zig");
const table_edit = @import("table_edit.zig");
const syntax_mod = @import("../syntax.zig");
pub const Splicer = @import("splicer.zig").Splicer;
/// Used by the free functions below; the public vocabularies all hang off
/// `Editor` itself (`Editor.InlineKind`, `Editor.Error`, ...).
const Syntax = syntax_mod.Syntax;
const ContainerSpelling = syntax_mod.ContainerSpelling;
/// The renderers' types, unwrapped from their optional fields — what a gesture
/// holds once it has dispatched on presence.
const RenderTextFn = @typeInfo(@FieldType(Syntax, "renderText")).optional.child;
const attrs_writer = @import("../attrs_writer.zig");
const RenderBlockFn = @typeInfo(@FieldType(Syntax, "renderBlock")).optional.child;
/// The node `setBlock`'s render path builds for a `BlockKind`.
fn blockNodeKind(kind: syntax_mod.BlockKind, level: u32) AST.Node.Kind {
return switch (kind) {
.paragraph => .para,
.heading => .{ .heading = .{ .level = level } },
};
}
/// The node an `InlineKind`/`ContainerKind` parses back as. The vocabularies
/// are named for their kinds, so this is a rename, not a mapping — and it fails
/// to compile rather than silently mis-mapping if one drifts.
///
/// It yields an `AST.KindRef` rather than a bare tag because seven of the eight
/// `InlineKind`s are now `InlineMark` family members sharing the `inline_mark`
/// tag; only `verbatim` (a text leaf, not a paired wrapper) is still a tag of
/// its own. The `@hasField` split is resolved at comptime, so a vocabulary
/// entry that matches NEITHER a mark nor a kind tag is still a compile error.
fn kindRef(kind: anytype) AST.KindRef {
return switch (kind) {
inline else => |k| if (@hasField(AST.InlineMark, @tagName(k)))
.{ .mark = @field(AST.InlineMark, @tagName(k)) }
else if (@hasField(AST.TextLeafKind, @tagName(k)))
.{ .text_leaf = @field(AST.TextLeafKind, @tagName(k)) }
else
.{ .tag = @field(Splicer.KindTag, @tagName(k)) },
};
}
/// `kindRef` for a vocabulary that is always a plain tag (`ContainerKind`) —
/// asserts that at comptime rather than leaving the caller to unwrap.
fn kindTag(kind: anytype) Splicer.KindTag {
return switch (kindRef(kind)) {
.tag => |t| t,
.text_leaf => unreachable,
.mark => unreachable,
.markup_leaf => unreachable,
// `kindRef` never mints one: it maps a gesture vocabulary, and no
// gesture names a container by name.
.container_named => unreachable,
};
}
/// Room for the widest marker/indent a list can produce (`999. ` and friends).
const container_indent = " " ** 24;
pub const Editor = struct {
/// The kind vocabularies, re-exported so a caller needs only this type:
/// `twig.Editor.InlineKind`. (The `Syntax` type itself is `twig.Syntax`.)
pub const InlineKind = syntax_mod.InlineKind;
pub const BlockKind = syntax_mod.BlockKind;
pub const ContainerKind = syntax_mod.ContainerKind;
pub const Error = error{
/// `start > end`, or a range reaching past the source.
InvalidRange,
/// A heading level outside 1-6.
InvalidLevel,
/// A destination this format cannot hold (one containing a newline).
InvalidDestination,
/// An info string this format's code fence cannot hold — one carrying a
/// line end, the fence byte itself, or (where the format ends its info
/// string at whitespace) a space.
InvalidLanguage,
/// A colour name outside `Syntax.MarkColors.colors` — a colour this
/// format has no spelling for, which is not one an editor may write:
/// the bytes would be content, not a colour.
InvalidColor,
/// A label this format cannot hold. For a footnote: empty, or carrying
/// a line end or a reference bracket. For a directive: carrying a line
/// end or a square bracket, either of which closes the `[…]` the label
/// is written in. An EMPTY directive label is legitimate — `::name[]`
/// — and is a different document from no label at all, which is
/// spelled by passing `null`.
InvalidLabel,
/// A table shape no pipe format spells: zero columns, or zero body rows
/// under the header.
InvalidShape,
/// A directive name outside the grammar every format reads one back
/// by: an ASCII letter followed by letters, digits, `-` and `_`. A
/// name is the whole identity of the node being written — there is no
/// `::` without one — and it is written where a delimiter would
/// otherwise be, so anything outside that alphabet reparses as
/// something else. See `checkDirectiveName`.
InvalidName,
/// An attribute no format reads back as one: a key outside the grammar
/// they share (an ASCII letter or `_`, then letters, digits, `-`, `_`
/// and `:`), a BARE key with no value (djot's `{…}` has no spelling
/// for one, so it would come back as text), or a value carrying a
/// line end or a double quote. See `checkAttr`.
InvalidAttribute,
/// A formula this format cannot hold: printed on its own, the math
/// the gesture asked for does not come back holding exactly these
/// bytes. Markdown's `$` refuses an empty formula, one opening or
/// closing on a space, and one holding a `$`; djot's run takes almost
/// anything. See `insertInlineMath`.
InvalidFormula,
/// A destination that names the block being moved: `moveBlock`'s `to`
/// inside the block, or at the boundary the block already sits on —
/// a move that would change nothing, refused rather than reported as
/// a change with no bytes in it.
InvalidArgument,
/// The `Syntax` table has no spelling for this gesture in this format.
UnsupportedFormat,
/// No block covers the offset/range this gesture needs one for.
NoBlock,
/// The target node has no editable span/interior, or the gesture would
/// corrupt something it refuses to touch.
NotEditable,
/// The edit produced a document that no longer parses; it was rolled
/// back and nothing changed.
EditConflict,
} || Allocator.Error;
splicer: Splicer,
/// This format's spelling. Borrowed — `format.zig`'s registry entries are
/// static, so it outlives any editor.
syntax: *const Syntax,
/// `parse_ctx`/`parse_fn` are the Splicer's contract (see its doc comment);
/// `syntax` is the table every gesture below consults. Pair them from
/// `format.zig`'s registry rather than by hand — an entry's `parseToAst` and
/// `syntax` are two halves of one language, and crossing them would spell
/// djot into a Markdown document.
pub fn init(
allocator: Allocator,
source_bytes: []const u8,
parse_ctx: *const anyopaque,
parse_fn: Splicer.ParseFn,
syntax: *const Syntax,
) !Editor {
return .{
.splicer = try Splicer.init(allocator, source_bytes, parse_ctx, parse_fn),
.syntax = syntax,
};
}
pub fn deinit(self: *Editor) void {
self.splicer.deinit();
}
pub fn sourceBytes(self: *const Editor) []const u8 {
return self.splicer.sourceBytes();
}
pub fn astView(self: *const Editor) *const AST {
return self.splicer.astView();
}
pub fn lastChange(self: *const Editor) ?Splicer.Change {
return self.splicer.last_change;
}
/// Validate a caller-supplied byte range. `Splicer.replaceAtSpan` ASSERTS on
/// a bad range — fine for internal callers, but a range from a C caller or a
/// stale caret is untrusted input, so it is checked into an error here,
/// once, before any gesture can reach the assert.
fn checkRange(self: *const Editor, start: usize, end: usize) Error!void {
if (start > end or end > self.sourceBytes().len) return error.InvalidRange;
}
/// Splice rebuilt source in over `[start, end)`. Every gesture ends here.
fn commitSplice(self: *Editor, start: usize, end: usize, text: []const u8) Error!void {
return self.commitSpliceChecked(start, end, text, null);
}
/// `commitSplice`, kept only if `check` accepts the reparse. A rejected
/// reparse is `error.NotEditable`: the bytes parsed, and meant something
/// other than what the gesture wrote, at this place in this document.
fn commitSpliceChecked(self: *Editor, start: usize, end: usize, text: []const u8, check: ?Splicer.Check) Error!void {
self.splicer.replaceAtSpanChecked(Span.init(start, end), text, check) catch |err| switch (err) {
error.OutOfMemory => return error.OutOfMemory,
error.Rejected => return error.NotEditable,
// Anything else is the parser rejecting the edited document; the
// splicer has already rolled it back.
else => return error.EditConflict,
};
}
// ── Capability ─────────────────────────────────────────────────────────
/// One gesture, named with whatever kind it takes — the question
/// `supports` answers, in the same vocabulary the gesture itself is called
/// with. A payload here exists exactly where the gesture has a `kind`
/// parameter, so a caller that can spell the call can spell the query.
///
/// Every gesture `Editor` has appears here, because every gesture now has a
/// FORMAT-level gate. Nine of them didn't:
///
/// * The seven TABLE gestures rebuilt a table by writing pipe syntax from
/// literals in `table_edit.zig`. HTML's parser lowers `<table>` to the
/// same `table`/`row`/`cell` nodes a pipe table produces, so the grid
/// extracted cleanly and the pipes were spliced over the elements —
/// which reparses as a paragraph, so not even `EditConflict` fired. They
/// read `Syntax.table_spelling` now.
/// * `splitBlock`'s plain-text arm separated the halves with a blank line,
/// which means "two blocks" only where blank lines separate blocks. In
/// HTML it is insignificant whitespace inside the `<p>`: one paragraph
/// in, one paragraph out, success reported. It reads
/// `Syntax.block_separator` now, and `assertCoherent` pins the other two
/// spellings it may need (a heading marker, a code fence) non-null
/// alongside it, so the answer below stays a total one rather than a
/// property of the caret.
/// * `renumberOrderedLists` rewrote `N.`/`N)` markers textually, which
/// finds nothing in an HTML `<ol>` and reports a successful no-op. It
/// gates on the ordered-list container spelling now.
///
/// The table gestures get one variant EACH rather than one shared
/// `table_edit`, which is the granularity the task and code-block families
/// already use: they share a gate, and a toolbar still grays out seven
/// buttons.
pub const Gesture = union(enum) {
wrap_range: InlineKind,
toggle_inline: InlineKind,
set_mark_color,
set_block,
toggle_block_container: ContainerKind,
insert_thematic_break,
toggle_code_block,
set_code_language,
toggle_task_item,
set_task_checked,
toggle_task_checked,
insert_link,
insert_image,
insert_footnote,
insert_literal,
insert_line_break,
split_block,
join_blocks,
renumber_ordered_lists,
table_insert_row,
table_delete_row,
table_insert_column,
table_delete_column,
table_set_alignment,
table_move_row,
table_move_column,
insert_table,
insert_directive,
set_block_attrs,
wrap_range_attrs,
set_node_attrs,
move_block,
insert_inline_math,
insert_display_math,
};
/// Whether `syntax` can spell `gesture` — the toolbar's gray-out question,
/// asked WITHOUT a document, so a caller can build its UI before it has one.
///
/// This is the format half of the answer and only that half. `true` means
/// the gesture will not fail with `error.UnsupportedFormat`; it says
/// nothing about the caret, so a supported gesture can still report
/// `NoBlock`, `NotEditable` or `EditConflict` at the position it is
/// actually run. Gray out on `false`; do not assume `true` means the call
/// will succeed.
///
/// Distinct from BOTH neighbouring questions, which are easy to reach for
/// and wrong here:
///
/// * `Syntax.authorable()` is "is there a door in" — true for HTML,
/// while a task box, a footnote and every table edit over it are
/// still unsupported. A toolbar enabled on that predicate has buttons
/// that fail.
/// * `diagnostics.zig`'s `fidelity` is "what survives a CONVERSION to this
/// target", which is a different table with genuinely different answers
/// (a smart-quote container is unauthorable in djot yet round-trips
/// there perfectly). Use that one for a save-as warning, this one for
/// an enabled/disabled button.
///
/// Static — it takes the table rather than an editor — because the whole
/// point is to answer before an `Editor` exists. `format.zig`'s `syntaxFor`
/// gets you the table from a `Format`.
pub fn supports(syntax: *const Syntax, gesture: Gesture) bool {
return switch (gesture) {
// The two inline gestures share one gate, and it is
// `authorableDelimsFor` rather than `delimsFor`: a spelling the
// serializer may emit but a gesture must not mint (Markdown's
// `==mark==`) is unsupported HERE while still being written on
// conversion. That asymmetry is `Delims.authorable`'s reason to
// exist, so the query has to ask the same way the gesture does.
.wrap_range, .toggle_inline => |k| syntax.authorableDelimsFor(kindRef(k)) != null,
// A separate gate from `.toggle_inline = .mark`, and a strictly
// narrower one: Markdown authors a highlight under
// `ParseOptions.highlight` and can only COLOUR one under
// `highlight_colors` on top, so a toolbar grays the palette while
// the highlight button stays live. `assertCoherent` pins the
// implication (a palette implies an authorable mark), not the
// converse.
.set_mark_color => syntax.mark_colors != null,
// Either path: a marker alphabet to write, or a fragment renderer
// to print a fresh node through. Each of these gestures prefers
// the alphabet and falls back to the renderer, in that order —
// see `setBlock`, which set the pattern — so a format that has an
// alphabet keeps its byte-preserving path and a format with none
// (HTML's tag pairs, AsciiDoc's `dest[text]` link) prints the node.
.set_block => syntax.heading_marker != null or syntax.renderBlock != null,
.toggle_block_container => |k| syntax.container_spelling.get(k) != null or syntax.renderBlock != null,
.insert_thematic_break => syntax.thematic_break != null,
.toggle_code_block, .set_code_language => syntax.code_fence != null or syntax.renderBlock != null,
.toggle_task_item, .set_task_checked, .toggle_task_checked => syntax.task_marker != null,
.insert_link => syntax.link_text_escapes != null or syntax.renderBlock != null,
// Both halves, as `insertImage` checks them. `assertCoherent` pins
// them null-together, so this can't disagree with `.insert_link` —
// it is written out anyway so the query reads as the gesture does.
.insert_image => (syntax.link_text_escapes != null and syntax.link_dest_escapes != null) or syntax.renderBlock != null,
.insert_footnote => syntax.footnote != null,
.insert_literal => syntax.renderText != null,
.insert_line_break => syntax.cell_line_break != null,
// A total answer only because `assertCoherent` pins a heading marker
// and a code fence non-null wherever a block separator is: those are
// the two spellings `splitBlock` reaches for once it knows which
// block the caret is in, and without that invariant this row would
// be true while the gesture reported unsupported in a fence.
.split_block => syntax.block_separator != null,
// A WIDER gate than the split's, and the pair is the clearest case
// in this switch for why each gesture reads its own field: a join
// writes a line break INSIDE a block, which HTML spells (a newline
// in a `<p>` is whitespace, and the reparse gives back the one
// paragraph the gesture claims) while it spells no blank-line
// block separator at all. Nothing else the gesture needs comes
// from the table — a heading's marker, the container prefix and
// the closing markup it carries are all read out of the document —
// so this row needs no `assertCoherent` implication behind it.
.join_blocks => syntax.line_join != null,
.renumber_ordered_lists => spellsOrderedMarkers(syntax),
.table_insert_row,
.table_delete_row,
.table_insert_column,
.table_delete_column,
.table_set_alignment,
.table_move_row,
.table_move_column,
.insert_table,
=> syntax.table_spelling != null,
// Both halves, and neither implies the other here: the renderer is
// how the bytes are written, and the claim is whether the parser
// hands them back as the container they were. `assertCoherent`
// pins the first onto the second, so this cannot answer true with
// nothing to print through.
.insert_directive => syntax.names_leaf_containers and syntax.renderBlock != null,
// The same two halves: a shape the attributes come back in, and
// the renderer that prints them. `assertCoherent` pins the second
// onto the first, as for the directive.
.set_block_attrs => syntax.block_attrs != null and syntax.renderBlock != null,
.wrap_range_attrs => syntax.inline_attrs and syntax.renderBlock != null,
// One half only: the run is written by a fixed algorithm
// (`attrs_writer.writeHtmlAttrs`) into a span the parser recorded,
// so no renderer is consulted and none has to be present.
.set_node_attrs => syntax.node_attrs != null,
// A block moves as its LINES, re-prefixed for the container it
// lands in, and every prefix is read off the document — so what
// the table has to say is only how two blocks are kept apart: a
// blank line where `block_separator` states one, or nothing
// where a block is a delimited fragment of its own (HTML's tag
// pairs, which `renderBlock` is the sign of). A parse-only table
// has neither, which is what makes XML unsupported: it has no
// blocks for a caret to name.
.move_block => syntax.block_separator != null or syntax.renderBlock != null,
// Both halves, as the gesture checks them: a formula the parser
// reads back, and the renderer that prints it. `assertCoherent`
// pins the second onto the first, as for the directive.
.insert_inline_math => syntax.authorableDelimsFor(.{ .text_leaf = .inline_math }) != null and syntax.renderBlock != null,
.insert_display_math => syntax.authorableDelimsFor(.{ .text_leaf = .display_math }) != null and syntax.renderBlock != null,
};
}
/// Whether this format spells an ordered list item as a NUMBERED LINE
/// MARKER — the one question `renumberOrderedLists` needs answered, and the
/// expression it and `supports` share so the two cannot drift.
///
/// The renumber pass rewrites the numeric run of a `N.` / `N)` marker in the
/// source. That is a gesture about a marker, so a spelling is not enough: a
/// format could spell an ordered list some other way (`ContainerSpelling`
/// admits a fixed `marker`), and rewriting digits in it would find none and
/// call the no-op a success — which is precisely what an HTML `<ol>` did
/// before this gate, where there is no container spelling at all.
fn spellsOrderedMarkers(syntax: *const Syntax) bool {
const sp = syntax.container_spelling.get(.ordered_list) orelse return false;
return sp.numbered;
}
// ── Inline marks ───────────────────────────────────────────────────────
/// Wrap `[start, end)` in `kind`'s delimiters — the unconditional half of
/// the inline toolbar (always adds a mark). One pair per block the range
/// touches; see `applyInline`.
pub fn wrapRange(self: *Editor, span: Span, kind: InlineKind) Error!void {
return self.applyInline(span, kind, .wrap);
}
/// Toggle `kind` over `[start, end)`: strip the mark where the range already
/// IS a node of `kind` — covers its whole interior and reaches no further
/// than its delimiters, looking through a mark of another kind that is
/// nothing but it (`Splicer.inlineNodeCovering`) — else wrap it — a rich
/// editor's Cmd-B. One decision per block the range touches; see
/// `applyInline`.
pub fn toggleInline(self: *Editor, span: Span, kind: InlineKind) Error!void {
return self.applyInline(span, kind, .toggle);
}
/// Whether the gesture may REMOVE a mark it finds, or only ever adds one —
/// the single difference between `toggleInline` and `wrapRange`, which
/// otherwise cut the range up and reassemble it identically.
const InlineMode = enum { wrap, toggle };
/// One replacement inside the assembled region: `span` goes, and either
/// `interior` takes its place (a mark being removed) or `span`'s own bytes
/// come back wrapped in delimiters (a mark being added).
///
/// `interior` aliases the pre-edit source, so an `Edit` is valid only until
/// the splice that consumes it.
const Edit = struct { span: Span, interior: ?[]const u8 };
/// Both inline gestures, in one pass: cut `span` at its block boundaries,
/// decide per piece, and splice the lot once.
///
/// ── Why per block ──────────────────────────────────────────────────────
/// A selection is a byte range; a mark is not. Wrapping the range whole put
/// the opening delimiter in one block and the closing one in the next
/// (`**one two\n\nthree four**`), which reparses perfectly well as two
/// paragraphs carrying four literal asterisks — so nothing failed, and the
/// document simply did not gain the mark the gesture reported writing.
/// `locate.inlineHostPieces` is where the boundaries come from; the bytes
/// between the pieces (the blank line, the next block's `- ` or `> `) are
/// copied through untouched, so what comes out is `**one two**` and
/// `**three four**` and a document that still says what it said.
///
/// This is what every rich editor does with a multi-block selection, and it
/// is also what makes the SECOND press work: each piece is decided on its
/// own, so pressing Cmd-B again over the same selection finds a mark around
/// each piece and removes both, instead of nesting a second pair around the
/// first.
///
/// ── Why still ONE splice ───────────────────────────────────────────────
/// Every gesture here is one `commitSplice`, and that is not a stylistic
/// preference: a splice is a reparse, an undo step, and a `Splicer.Change`
/// the host re-anchors its caret against. N pieces spliced separately would
/// be N reparses, N undo steps to press Cmd-Z through, and N changes whose
/// offsets each invalidate the next piece's span. So the pieces are decided
/// against ONE document state, assembled into one buffer, and written once
/// — the same shape `renumberOrderedLists` uses over a whole list.
///
/// The region that buffer covers is the selection UNION every mark being
/// removed, because a removal takes its delimiters with it and those sit
/// outside a selection of the mark's interior (see `Splicer.inlineStrip`).
/// That is why nothing can be written until every piece has been asked.
///
/// `error.NotEditable` when the range holds no inline host at all — a
/// selection inside a code block, where `**` would be two asterisks of
/// someone's program rather than a mark. A code SPAN is the same asterisks
/// at a smaller scale, and a piece that cuts into one is widened to the
/// whole of it (`locate.widenOverVerbatim`), so the mark closes around the
/// backticks. A zero-width range is exempt from the whole business: it
/// crosses no boundary, and inserting an empty pair for the caret to type
/// between is a gesture in its own right.
fn applyInline(self: *Editor, span: Span, kind: InlineKind, mode: InlineMode) Error!void {
try self.checkRange(span.start, span.end);
const d = self.syntax.authorableDelimsFor(kindRef(kind)) orelse return error.UnsupportedFormat;
const allocator = self.splicer.allocator;
var pieces: std.ArrayList(Span) = .empty;
defer pieces.deinit(allocator);
if (span.len() == 0) {
// A caret spans no block, and clipping it to a host would find a
// zero-width share and drop it — losing "open a pair here".
try pieces.append(allocator, span);
} else {
try locate.inlineHostPieces(allocator, &self.splicer.doc, span, &pieces);
if (pieces.items.len == 0) return error.NotEditable;
// A piece that cuts into a code span widens to the whole of it:
// `**` inside the backticks is two asterisks of code, so the
// mark closes around the code instead — `` **`word`** `` from a
// selection of `word`, which the next press takes off again.
for (pieces.items) |*p| locate.widenOverVerbatim(&self.splicer.doc, p);
}
// Decide everything first: a removal expands its piece to the whole
// mark, so the region being spliced is not known until the last piece
// has answered.
var edits: std.ArrayList(Edit) = .empty;
defer edits.deinit(allocator);
var region = span;
for (pieces.items) |p| {
// A piece widened over a code span reaches past the selection.
region.start = @min(region.start, p.start);
region.end = @max(region.end, p.end);
const strip = if (mode == .toggle)
self.splicer.inlineStrip(p, kindRef(kind), d.open, d.close) catch
return error.NotEditable
else
null;
if (strip) |s| {
region.start = @min(region.start, s.span.start);
region.end = @max(region.end, s.span.end);
try edits.append(allocator, .{ .span = s.span, .interior = s.interior });
} else {
try edits.append(allocator, .{ .span = p, .interior = null });
}
}
const src = self.sourceBytes();
var out: std.ArrayList(u8) = .empty;
defer out.deinit(allocator);
var cursor = region.start;
for (edits.items) |e| {
// Ascending and disjoint by construction — one piece per host, and
// hosts do not overlap — but a removal grows its piece leftward, so
// refuse rather than slice backwards if that ever stops holding.
if (e.span.start < cursor) return error.EditConflict;
try out.appendSlice(allocator, src[cursor..e.span.start]);
if (e.interior) |interior| {
try out.appendSlice(allocator, interior);
} else {
try out.appendSlice(allocator, d.open);
try out.appendSlice(allocator, src[e.span.start..e.span.end]);
try out.appendSlice(allocator, d.close);
}
cursor = e.span.end;
}
try out.appendSlice(allocator, src[cursor..region.end]);
return self.commitSplice(region.start, region.end, out.items);
}
/// Set — or clear — the COLOUR of the `mark` the caret at `offset` is in:
/// the second half of an authorable highlight, and the only gesture that
/// writes a mark's colour rather than its delimiters.
///
/// `color` is a name from `Syntax.MarkColors.colors` (`"red"`), or `null`
/// to leave the highlight uncoloured. Setting one on a mark that has none
/// inserts the prefix, setting one on a mark that has another REPLACES it,
/// and clearing removes it — so the gesture is total over the palette plus
/// "no colour", the way a colour picker asks it.
///
/// ── Why this is not part of `toggleInline` ─────────────────────────────
/// A colour is a property of a mark that already exists, and every gesture
/// here is one splice: giving the toggle a colour parameter would make
/// "highlight this" and "recolour that" the same call with two different
/// answers to "what if there is no mark?". Authoring a coloured highlight
/// from scratch is the two gestures in order — `toggleInline(.mark)`, then
/// this at any offset inside the new mark, which is `start + open.len` for
/// a range wrapped at `start`.
///
/// ── What "the prefix" is ───────────────────────────────────────────────
/// The bytes between the mark's opening delimiter and its content span,
/// read from the SOURCE rather than from the node's attributes. That keeps
/// the edit honest about what it is overwriting: a mark whose interior
/// starts right after its opener has no prefix to replace, one whose
/// interior starts later has exactly those bytes, and anything there that
/// the palette does not spell is `error.NotEditable` rather than a splice
/// that eats a character of the author's text.
///
/// An existing prefix keeps its own SPACING — `==🔴text==` recolours tight,
/// `==🔴 text==` recolours spaced — because that is spelling the author
/// chose and the parser preserves. A prefix being written for the first
/// time gets `MarkColors.space`.
///
/// `error.UnsupportedFormat` where the format (or the parse config behind
/// this editor — see `format.zig`'s `syntaxForConfig`) spells no colour,
/// `error.InvalidColor` for a name outside the palette, `error.NotEditable`
/// when the caret is not inside a mark. Clearing a colour a mark does not
/// have is a no-op that reports success.
pub fn setMarkColor(self: *Editor, offset: usize, color: ?[]const u8) Error!void {
const mc = self.syntax.mark_colors orelse return error.UnsupportedFormat;
// The mark's own delimiters, which the prefix sits behind. Pinned
// non-null beside `mark_colors` by `Syntax.assertCoherent`.
const d = self.syntax.delimsFor(.{ .mark = .mark }).?;
const new_prefix: ?[]const u8 = if (color) |name|
(mc.prefixFor(name) orelse return error.InvalidColor)
else
null;
const src = self.sourceBytes();
if (offset > src.len) return error.InvalidRange;
const doc = &self.splicer.doc;
const allocator = self.splicer.allocator;
var chain: std.ArrayList(AST.Node.Id) = .empty;
defer chain.deinit(allocator);
try locate.caretChain(allocator, doc, offset, &chain);
// The innermost `mark`, so a highlight nested in emphasis (or in
// another mark) recolours the one the caret is actually in.
var found: ?AST.Node.Id = null;
var i = chain.items.len;
while (i > 0) {
i -= 1;
const kind = doc.ast.nodes[chain.items[i]].kind;
if (kind == .inline_mark and kind.inline_mark == .mark) {
found = chain.items[i];
break;
}
}
const id = found orelse return error.NotEditable;
const node_span = doc.span(id);
const cs = doc.contentSpan(id) orelse return error.NotEditable;
const prefix_start = node_span.start + d.open.len;
if (prefix_start > cs.start or cs.start > src.len) return error.NotEditable;
// What is there now, and whether this editor recognizes it. A prefix it
// cannot read is text as far as it knows, and text is not ours to
// overwrite.
const existing = src[prefix_start..cs.start];
var spaced = false;
if (existing.len > 0) {
const c = mc.prefixAt(existing) orelse return error.NotEditable;
const rest = existing[c.prefix.len..];
if (std.mem.eql(u8, rest, mc.space)) {
spaced = true;
} else if (rest.len != 0) return error.NotEditable;
}
const prefix = new_prefix orelse
// Clearing: the prefix goes, and the space it absorbed goes with it
// — it was part of the spelling, not of the text.
return if (existing.len == 0) {} else self.commitSplice(prefix_start, cs.start, "");
// A first colour is written spaced; a replacement keeps the spacing the
// source already had.
const write_space = if (existing.len == 0) true else spaced;
const buf = try allocator.alloc(u8, prefix.len + if (write_space) mc.space.len else 0);
defer allocator.free(buf);
@memcpy(buf[0..prefix.len], prefix);
if (write_space) @memcpy(buf[prefix.len..], mc.space);
return self.commitSplice(prefix_start, cs.start, buf);
}
// ── Block kind ─────────────────────────────────────────────────────────
/// Convert the block at `offset` to `kind` (a `level`-N heading, or a
/// paragraph) by rewriting its leading marker while keeping its inline
/// content verbatim — the block half of the toolbar (H1 / Body).
///
/// ON A BLANK LINE this OPENS the block instead of converting one, so
/// "H2, then type" works from an empty line the way it works from a full
/// one. There is no node there to rewrite — no format spells an empty
/// paragraph, which is the same gap `splitBlock` documents — so a caller
/// that could only convert an existing block had to spell `#` itself, and
/// spell it per format. See `openBlockOnBlankLine`.
///
/// TWO SPELLINGS, tried in this order. Where the format has a
/// `heading_marker` the block's leading marker is rewritten and its inline
/// bytes are kept verbatim — a `*em*` stays `*em*`. Where it has none but
/// carries a `renderBlock`, there is no marker to rewrite (HTML's heading is
/// a tag PAIR, level in both ends), so the block's inline children are put
/// under a fresh node of the requested kind and the format prints it — the
/// same tree, re-spelled, which is why a marker is preferred when there is
/// one. A format with neither is `error.UnsupportedFormat`.
pub fn setBlock(self: *Editor, offset: usize, kind: BlockKind, level: u32) Error!void {
if (self.syntax.heading_marker) |marker| return self.setBlockByMarker(offset, kind, level, marker);
if (self.syntax.renderBlock) |render| return self.setBlockByRender(offset, kind, level, render);
return error.UnsupportedFormat;
}
/// `setBlock` over a format with a leading heading marker: rewrite it.
fn setBlockByMarker(self: *Editor, offset: usize, kind: BlockKind, level: u32, marker: u8) Error!void {
if (kind == .heading and (level < 1 or level > 6)) return error.InvalidLevel;
const src = self.sourceBytes();
if (offset > src.len) return error.InvalidRange;
const block = locate.innermostBlock(&self.splicer.doc, offset) orelse
return self.openBlockOnBlankLine(offset, kind, level, marker);
const cs = self.splicer.doc.contentSpan(block) orelse return error.NotEditable;
const content = src[cs.start..cs.end];
// Rewrite [the block's own marker, end-of-text): the leading marker
// (a heading) or nothing (a paragraph), plus the text — but NOT any
// trailing newline the block span includes (Djot blocks do), so we don't
// fuse with the next block. Rebuilding from `content_span` also
// collapses a setext heading's underline line away for free.
//
// Not from the block span's start: Markdown's span for a block in a
// quote begins at the `> ` its line carries, which is the quote's and
// not the block's to lose. The rewrite starts at the content, or at a
// marker in front of it on the same line.
const block_span = self.splicer.doc.span(block);
var start = cs.start;
if (self.splicer.doc.markerSpan(block)) |m| {
if (m.end <= cs.start and m.start >= locate.lineStartAt(src, cs.start)) start = m.start;
}
var end = block_span.end;
if (end > block_span.start and src[end - 1] == '\n') end -= 1;
if (end > block_span.start and src[end - 1] == '\r') end -= 1;
const allocator = self.splicer.allocator;
const prefix_len: usize = if (kind == .heading) level + 1 else 0; // marker*level + " "
const buf = try allocator.alloc(u8, prefix_len + content.len);
defer allocator.free(buf);
if (kind == .heading) {
@memset(buf[0..level], marker);
buf[level] = ' ';
}
@memcpy(buf[prefix_len..], content);
return self.commitSplice(start, end, buf);
}
/// `setBlock` over a format with no leading marker but a fragment
/// renderer: BUILD the block and let the format print it.
///
/// The block's inline children are cloned under a new `heading`/`para`
/// node — its attributes ride along, so `<p class="lead">` becomes
/// `<h2 class="lead">` — and the rendered fragment replaces the block's
/// whole span. The renderer's trailing line end is dropped because a block
/// span excludes its own; the reparse is the backstop, as everywhere.
fn setBlockByRender(
self: *Editor,
offset: usize,
kind: BlockKind,
level: u32,
render: RenderBlockFn,
) Error!void {
if (kind == .heading and (level < 1 or level > 6)) return error.InvalidLevel;
const src = self.sourceBytes();
if (offset > src.len) return error.InvalidRange;
const doc = &self.splicer.doc;
const block = locate.innermostBlock(doc, offset) orelse
return self.openBlockByRender(offset, kind, level, render);
const allocator = self.splicer.allocator;
var b = AST.Builder.init(allocator);
defer b.deinit();
var kids: std.ArrayList(AST.Node.Id) = .empty;
defer kids.deinit(allocator);
var child = doc.ast.nodes[block].first_child;
while (child) |c| : (child = doc.ast.nodes[c].next_sibling) {
try kids.append(allocator, try b.graftSubtree(&doc.ast, c));
}
const root = try b.addContainer(blockNodeKind(kind, level), kids.items);
if (doc.ast.nodes[block].attrs) |ai| try b.setAttrs(root, doc.ast.attrs[ai]);
const block_span = doc.span(block);
return self.spliceRendered(&b, root, render, block_span.start, block_span.end);
}
/// `setBlockByRender` on a BLANK LINE: open an EMPTY block of the requested
/// kind there. The same guard as `openBlockOnBlankLine` — a blank line
/// interior to a leaf (a code body, a table) is `error.NotEditable`, and
/// `.paragraph` is a no-op — but no quote markers to carry and no blank
/// separation to write: a format that spells a heading as a fragment does
/// not read line prefixes, so the fragment stands wherever it is spliced.
fn openBlockByRender(
self: *Editor,
offset: usize,
kind: BlockKind,
level: u32,
render: RenderBlockFn,
) Error!void {
const line = try self.blankLineBetweenBlocks(offset);
if (kind == .paragraph) return;
var b = AST.Builder.init(self.splicer.allocator);
defer b.deinit();
const root = try b.addContainer(blockNodeKind(kind, level), &.{});
return self.spliceRendered(&b, root, render, line.start, line.end);
}
/// Print `root` of `b` through `render` and splice it over `[start, end)`,
/// minus the line end a block renderer writes after its block — the span
/// being replaced excludes its own.
fn spliceRendered(
self: *Editor,
b: *const AST.Builder,
root: AST.Node.Id,
render: RenderBlockFn,
start: usize,
end: usize,
) Error!void {
const view = b.view(root);
var out: Writer.Allocating = .init(self.splicer.allocator);
defer out.deinit();
try renderNode(self.splicer.allocator, render, &view, root, &out.writer);
const rendered = std.mem.trimEnd(u8, out.written(), "\r\n");
return self.commitSplice(start, end, rendered);
}
/// One node through `render`, with the renderer's errors folded into the
/// editor's: a refusal to print is a content refusal, not a format one,
/// since the renderer exists.
fn renderNode(allocator: Allocator, render: RenderBlockFn, ast: *const AST, id: AST.Node.Id, out: *Writer) Error!void {
render(allocator, ast, id, out) catch |err| switch (err) {
error.OutOfMemory, error.WriteFailed => return error.OutOfMemory,
else => return error.NotEditable,
};
}
/// The line the caret is on, when it is a BLANK line lying BETWEEN a
/// container's children — the place `setBlock` may open a block. The span
/// is the whole line body, trailing spaces included, so a splice over it
/// takes them along. `error.NotEditable` for a line with content, or for a
/// blank line INTERIOR to a leaf; `openBlockOnBlankLine` below makes the
/// same two tests, with a line prefix in the way, and says why
/// `locate.isBlockParent` is the hinge.
fn blankLineBetweenBlocks(self: *const Editor, offset: usize) Error!Span {
const src = self.sourceBytes();
const doc = &self.splicer.doc;
const line_start = locate.lineStartAt(src, offset);
const body = locate.lineBody(src[line_start..locate.lineEndAt(src, offset)]);
if (!locate.isBlankLine(body)) return error.NotEditable;
if (locate.lineOwningBlock(doc, offset)) |lb| {
if (!locate.isBlockParent(doc.ast.nodes[lb.block].kind)) return error.NotEditable;
}
return Span.init(line_start, line_start + body.len);
}
/// `setBlock` where there is no block to convert: the caret sits on a BLANK
/// LINE, so the marker is OPENED rather than rewritten.
///
/// The line's own quote markers are kept and the heading marker written
/// after them, so an H2 asked for on a quote's blank line lands inside the
/// quote rather than ending it. They are re-emitted with a SPACE after the
/// last `>` even when the blank line carries none, because a blank quoted
/// line is spelled `>` and `>#` is not a quoted heading in both formats:
/// Markdown reads it as one, djot reads the whole line as a paragraph. The
/// space is what makes one spelling work in both, the same argument
/// `Syntax.thematic_break` makes for blank-separating a rule.
///
/// It is BLANK-SEPARATED from whatever precedes it, and that is load-bearing
/// rather than cosmetic: djot does not let a heading interrupt a paragraph,
/// so a `## ` written on the line directly under one is read there as the
/// paragraph's own text — the document gains no heading and the marker shows
/// up as literal `##`. Markdown reads the same bytes as a heading. Emitting
/// the blank when the line above is non-blank is what makes one spelling
/// work in both, the same argument `insertThematicBreak` makes for a rule
/// and `Syntax.thematic_break` records for `---`.
///
/// The blank carries the line's quote markers, minus the space after them —
/// a quote's blank line is spelled `>` — so a heading opened on a quote's
/// blank line stays inside the quote instead of ending it.
///
/// `error.NotEditable` when the blank line is INTERIOR to a block rather
/// than between blocks — a blank line in a fenced code block, or in a table.
/// `locate.isBlockParent` is the hinge: a line owned by a container (the
/// document, a quote, a list item) is a gap between that container's
/// children and a block may open there, while a line owned by anything else
/// is inside a leaf whose bytes mean something already. Writing `## ` into a
/// code body would add no heading and corrupt the listing.
///
/// `.paragraph` is a NO-OP rather than an error: a blank line already holds
/// no block marker, so the state the caller asked for is the state it is in.
fn openBlockOnBlankLine(
self: *Editor,
offset: usize,
kind: BlockKind,
level: u32,
marker: u8,
) Error!void {
const src = self.sourceBytes();
const doc = &self.splicer.doc;
const line_start = locate.lineStartAt(src, offset);
const body = locate.lineBody(src[line_start..locate.lineEndAt(src, offset)]);
// Past the line's own quote markers; what remains must be blank, or this
// is a line with content that simply isn't a `para`/`heading` — a fence
// line, a table row — and there is nothing here to open.
var i: usize = 0;
while (skipQuoteMarker(body, i)) |j| i = j;
if (!locate.isBlankLine(body[i..])) return error.NotEditable;
// Interior to a leaf (a code block's body, a table) rather than between
// a container's children. `innermostBlock` reports `null` for both, and
// only this tells them apart.
if (locate.lineOwningBlock(doc, offset)) |lb| {
if (!locate.isBlockParent(doc.ast.nodes[lb.block].kind)) return error.NotEditable;
}
if (kind == .paragraph) return;
const allocator = self.splicer.allocator;
var out: std.ArrayList(u8) = .empty;
defer out.deinit(allocator);
// The line's quote markers, re-emitted with the space djot needs after
// the last `>` even when the blank line carries none.
const prefix = body[0..i];
const needs_space = i > 0 and body[i - 1] == '>';
// A blank line above, when the previous line has content — see above for
// why that is correctness rather than tidiness. Inside a quote the blank
// carries the marker WITHOUT its trailing space, which is how a quote
// spells a blank line.
if (precedingLineHasContent(src, line_start)) {
try out.appendSlice(allocator, std.mem.trimEnd(u8, prefix, " "));
try out.append(allocator, '\n');
}
try out.appendSlice(allocator, prefix);
if (needs_space) try out.append(allocator, ' ');
try out.appendNTimes(allocator, marker, level);
try out.append(allocator, ' ');
// The whole line body, so a blank line's trailing spaces go with it.
return self.commitSplice(line_start, line_start + body.len, out.items);
}
// ── Block containers (quote / lists) ───────────────────────────────────
// `setBlock` rewrites the leading marker of ONE block at one offset. A block
// container is a different animal: it prefixes EVERY line of a possibly
// multi-block range, it nests, and a list numbers its items — so it gets its
// own gesture rather than another `BlockKind`. Everything below is line
// surgery over the covered blocks, spliced in one shot.
/// Toggle a block container over the blocks `[start, end)` covers.
///
/// The already-in-container test walks the AST ancestors of `start` for a
/// container of `kind`, and the toggle turns OFF only when the range covers
/// every block that container holds — otherwise it turns ON, which is what
/// makes a partial selection inside a quote nest (`> >`) instead of dragging
/// the container's uncovered siblings out with it. Toggling a list kind
/// while inside the other list kind converts in place rather than nesting.
///
/// ON A BLANK LINE this OPENS an empty container instead of wrapping one,
/// `setBlock`'s rule for the same position — see `openContainerOnBlankLine`.
///
/// TWO SPELLINGS, in `setBlock`'s order. Where the format has a
/// `ContainerSpelling` every line of the range is prefixed and the covered
/// bytes are kept verbatim. Where it has none but carries a `renderBlock`,
/// the container is a wrapping pair (`<blockquote>`, `<ul>` with an `<li>`
/// per item) and the covered blocks are put under a fresh node the format
/// prints — see `toggleBlockContainerByRender`. A format with neither is
/// `error.UnsupportedFormat`.
pub fn toggleBlockContainer(self: *Editor, span: Span, kind: ContainerKind) Error!void {
try self.checkRange(span.start, span.end);
const sp = self.syntax.container_spelling.get(kind) orelse {
if (self.syntax.renderBlock) |render| return self.toggleBlockContainerByRender(span, kind, render);
return error.UnsupportedFormat;
};
const allocator = self.splicer.allocator;
const src = self.sourceBytes();
const ast = self.astView();
const blocks = coveredBlocks(allocator, &self.splicer.doc, span.start, span.end) catch |err| switch (err) {
error.OutOfMemory => return error.OutOfMemory,
// Nothing to wrap: the caret is on a BLANK LINE, where the gesture
// opens an empty container rather than failing.
else => return self.openContainerOnBlankLine(span.start, kind, sp),
};
defer allocator.free(blocks.chain);
const region_start = locate.lineStartAt(src, self.splicer.doc.span(blocks.first).start);
const region_end = locate.lineEndAt(src, self.splicer.doc.span(blocks.last).end -| 1);
var out: std.ArrayList(u8) = .empty;
defer out.deinit(allocator);
// The toggle-off / convert / nest decision, all from the ancestor chain.
if (locate.innermostOfKind(&self.splicer.doc, blocks.chain, kindTag(kind))) |target| {
if (containerFullyCovered(&self.splicer.doc, target, region_start, region_end)) {
const t = self.splicer.doc.span(target);
// The container's own lines, not the range's: its span can reach
// past the last covered block (a quote's trailing `>` line).
const splice_start = locate.lineStartAt(src, t.start);
const splice_end = locate.lineEndAt(src, t.end -| 1);
switch (kind) {
.block_quote => try buildQuoteStrip(
allocator,
src,
splice_start,
splice_end,
quoteDepthAbove(ast, blocks.chain, target),
&out,
),
.bullet_list, .ordered_list => try buildListRewrite(
allocator,
src,
&self.splicer.doc,
target,
splice_start,
splice_end,
null,
&out,
),
}
return self.commitSplice(splice_start, splice_end, out.items);
}
}
if (kind == .bullet_list or kind == .ordered_list) {
const other: Splicer.KindTag = if (kind == .bullet_list) .ordered_list else .bullet_list;
if (locate.innermostOfKind(&self.splicer.doc, blocks.chain, other)) |target| {
if (containerFullyCovered(&self.splicer.doc, target, region_start, region_end)) {
const t = self.splicer.doc.span(target);
const splice_start = locate.lineStartAt(src, t.start);
const splice_end = locate.lineEndAt(src, t.end -| 1);
try buildListRewrite(allocator, src, &self.splicer.doc, target, splice_start, splice_end, sp, &out);
return self.commitSplice(splice_start, splice_end, out.items);
}
}
}
try buildContainerAdd(allocator, src, &self.splicer.doc, blocks, region_start, region_end, sp, &out);
return self.commitSplice(region_start, region_end, out.items);
}
/// `toggleBlockContainer` where there is no block to wrap: the caret sits on
/// a BLANK LINE, so the container's marker is OPENED on it and the author
/// types into it — "bullet, then type", which is how a list most often
/// starts.
///
/// The twin of `openBlockOnBlankLine`, and it has to be: `setBlock` opening
/// `# ` on a blank line while the quote and list gestures answered
/// `error.NoBlock` meant a toolbar's H1 button worked on an empty line and
/// its Quote / Bulleted / Numbered buttons were silent no-ops beside it.
/// Everything that function reasons about applies unchanged here, so the
/// shape is deliberately the same one:
///
/// The line's own quote markers are kept and the container's marker written
/// after them, so a bullet asked for on a quote's blank line lands inside
/// the quote rather than ending it — re-emitted with a space after the last
/// `>` even when the blank line carries none, since a blank quoted line is
/// spelled `>` and `>-` is not a quoted bullet.
///
/// It is BLANK-SEPARATED from whatever precedes it, and here that is
/// load-bearing in BOTH formats rather than djot alone: an empty list item
/// cannot interrupt a paragraph, so `- ` written on the line directly under
/// one is read as that paragraph's own text and the document gains no list
/// at all. (`> ` can interrupt, so a quote would survive without the blank —
/// it gets one anyway, because a rule that holds for one of three buttons is
/// a rule nobody can remember.)
///
/// One thing `openBlockOnBlankLine` needs and this does NOT: a guard against
/// the blank line being INTERIOR to a leaf (a fenced code block's body, a
/// table). That function is reached whenever `locate.innermostBlock` finds
/// nothing, and that is a narrow question — `para`/`heading`, all `setBlock`
/// rewrites markers for — so a code block's interior lands there and has to
/// be turned away. This is reached only when `coveredBlocks` finds nothing,
/// and that is a broad one: a caret anywhere inside a code block resolves to
/// the code block, which the gesture then wraps whole (`- ```…` over every
/// line, listing intact). By the time control arrives here the offset is in
/// no leaf at all, so there is nothing left to refuse.
///
/// It TOGGLES, which is the whole gesture's name and not a bonus: a line
/// already holding an empty container of `kind` and nothing else has that
/// marker taken back off, because the press that made it has to un-make it.
/// Without this, Quote pressed twice on a blank line nested `> > ` and
/// Bulleted pressed twice failed outright — a button that cannot be
/// un-pressed until the author types something into it. An empty marker of
/// the OTHER list kind is CONVERTED, matching what the non-empty path does
/// for a real list.
///
/// `error.NotEditable` when the line is neither blank nor exactly one empty
/// marker — content in no block, which no container edit fits.
fn openContainerOnBlankLine(self: *Editor, offset: usize, kind: ContainerKind, sp: ContainerSpelling) Error!void {
const src = self.sourceBytes();
if (offset > src.len) return error.InvalidRange;
const line_start = locate.lineStartAt(src, offset);
const body = locate.lineBody(src[line_start..locate.lineEndAt(src, offset)]);
// The line's quote markers, and where the INNERMOST one began — the one
// a Quote press takes back off.
var quotes_end: usize = 0;
var last_quote: usize = 0;
while (skipQuoteMarker(body, quotes_end)) |j| {
last_quote = quotes_end;
quotes_end = j;
}
const marker = listMarkerAt(body, quotes_end);
const empty_list = if (marker) |m| locate.isBlankLine(body[m.end..]) else false;
const blank = locate.isBlankLine(body[quotes_end..]);
if (!blank and !empty_list) return error.NotEditable;
// `keep` is the prefix that survives the edit, `write` what follows it.
// An empty `write` is the toggle-off direction.
var keep: usize = if (empty_list) marker.?.start else quotes_end;
var num_buf: [24]u8 = undefined;
const write: []const u8 = if (kind == .block_quote) blk: {
// A quote's own marker is what `skipQuoteMarker` has already eaten,
// so "an empty quote" is a line that is blank once they are all
// gone. Drop the innermost rather than nesting a second.
if (blank and quotes_end > 0) {
keep = last_quote;
break :blk "";
}
break :blk sp.marker;
} else if (empty_list and isOrderedMarker(body[marker.?.start]) == sp.numbered)
""
else
listMarker(sp, 1, &num_buf);
const allocator = self.splicer.allocator;
var out: std.ArrayList(u8) = .empty;
defer out.deinit(allocator);
// A blank line above, when the previous line has content — see above for
// why that is correctness rather than tidiness. Only when OPENING on a
// blank line: rewriting a marker that is already there needs no
// separation it does not already have, and adding one would make an
// enclosing list loose.
if (write.len > 0 and blank and precedingLineHasContent(src, line_start)) {
try out.appendSlice(allocator, std.mem.trimEnd(u8, body[0..keep], " "));
try out.append(allocator, '\n');
}
try out.appendSlice(allocator, body[0..keep]);
// The space djot needs after the last `>` even when the blank line
// carries none: `>-` is not a quoted bullet in either format.
if (write.len > 0 and keep > 0 and body[keep - 1] == '>') try out.append(allocator, ' ');
try out.appendSlice(allocator, write);
// Toggling off can leave the prefix's own trailing space stranded on an
// otherwise empty line; a quote's blank line is spelled `>`.
const tidy = if (write.len == 0) std.mem.trimEnd(u8, out.items, " ") else out.items;
// The whole line body, so a blank line's trailing spaces go with it.
return self.commitSplice(line_start, line_start + body.len, tidy);
}
/// `toggleBlockContainer` over a format with no line prefix but a
/// fragment renderer: BUILD the container and let the format print it.
///
/// The same three decisions as the marker path, taken from the tree
/// rather than from lines — there are no lines to reason about in
/// `<ul><li>a</li><li>b</li></ul>`, and the parser has already said what
/// nests in what:
///
/// * TOGGLE OFF when the range reaches every block a container of `kind`
/// holds (`coversContainer`): the container's children — for a list,
/// each item's children — are printed in its place. The blocks print
/// from the document's own tree, so a paragraph that was a tight
/// item's elided `<p>` comes out as a `<p>` again.
/// * CONVERT when the range covers the OTHER list kind whole: its items
/// are grafted under a fresh list of the requested kind, tightness
/// kept, numbering start dropped.
/// * WRAP otherwise: the covered blocks go under a `block_quote`, or one
/// `list_item` each under a list — TIGHT when every block is a
/// paragraph, which is the list the marker path's `- a\n- b` parses
/// to. A partial selection inside a container nests, as it does there.
///
/// The splice replaces the covered blocks' own spans (toggle-off and
/// convert: the container's), minus the line end a block span may carry
/// after its closing tag, so the fragment lands where the blocks were and
/// the line structure around them is untouched.
fn toggleBlockContainerByRender(
self: *Editor,
span: Span,
kind: ContainerKind,
render: RenderBlockFn,
) Error!void {
const allocator = self.splicer.allocator;
const src = self.sourceBytes();
const doc = &self.splicer.doc;
const ast = self.astView();
const blocks = coveredBlocks(allocator, doc, span.start, span.end) catch |err| switch (err) {
error.OutOfMemory => return error.OutOfMemory,
// Nothing to wrap: a blank line, or an empty container — see there.
else => return self.openContainerByRender(span.start, kind, render),
};
defer allocator.free(blocks.chain);
if (locate.innermostOfKind(doc, blocks.chain, kindTag(kind))) |target| {
if (coversContainer(ast, target, blocks)) return self.unwrapContainer(target, render);
}
if (kind != .block_quote) {
const other: Splicer.KindTag = if (kind == .bullet_list) .ordered_list else .bullet_list;
if (locate.innermostOfKind(doc, blocks.chain, other)) |target| {
if (coversContainer(ast, target, blocks)) {
var b = AST.Builder.init(allocator);
defer b.deinit();
var items: std.ArrayList(AST.Node.Id) = .empty;
defer items.deinit(allocator);
var item = ast.nodes[target].first_child;
while (item) |i| : (item = ast.nodes[i].next_sibling) {
try items.append(allocator, try b.graftSubtree(ast, i));
}
const tight = switch (ast.nodes[target].kind) {
.bullet_list => |v| v.tight,
.ordered_list => |v| v.tight,
else => unreachable,
};
const root = try b.addContainer(containerNodeKind(kind, tight), items.items);
if (ast.nodes[target].attrs) |ai| try b.setAttrs(root, ast.attrs[ai]);
const t = doc.span(target);
return self.spliceRendered(&b, root, render, t.start, blockSpanEnd(src, t));
}
}
}
var b = AST.Builder.init(allocator);
defer b.deinit();
var kids: std.ArrayList(AST.Node.Id) = .empty;
defer kids.deinit(allocator);
var all_paras = true;
var cur: ?AST.Node.Id = blocks.first;
while (cur) |c| : (cur = if (c == blocks.last) null else ast.nodes[c].next_sibling) {
if (ast.nodes[c].kind != .para) all_paras = false;
const block = try b.graftSubtree(ast, c);
try kids.append(allocator, if (kind == .block_quote) block else try b.addContainer(.list_item, &.{block}));
}
const root = try b.addContainer(containerNodeKind(kind, all_paras), kids.items);
const first = doc.span(blocks.first);
const last = doc.span(blocks.last);
return self.spliceRendered(&b, root, render, first.start, blockSpanEnd(src, last));
}
/// `toggleBlockContainerByRender` where `coveredBlocks` found nothing: the
/// caret is on a BLANK LINE between blocks, or inside an EMPTY container.
///
/// On a blank line an empty container of `kind` is OPENED — over an empty
/// paragraph, because that is the shape a wrapped paragraph has, so the
/// press that made it un-makes it through the ordinary toggle-off above
/// and the author has a block to type into. `blankLineBetweenBlocks` makes
/// `openBlockByRender`'s guard: a blank line interior to a leaf is
/// `error.NotEditable`.
///
/// Inside an empty container of `kind` — `<blockquote></blockquote>`, or
/// an `<li></li>` that is the only item of a list of `kind`, neither of
/// which this gesture writes but both of which a document may hold — the
/// container is REMOVED, which is what a toggle owes the press that finds
/// it. Anything else the caret can be in with no block around it is
/// `error.NotEditable`.
fn openContainerByRender(self: *Editor, offset: usize, kind: ContainerKind, render: RenderBlockFn) Error!void {
const src = self.sourceBytes();
if (offset > src.len) return error.InvalidRange;
const allocator = self.splicer.allocator;
const doc = &self.splicer.doc;
const ast = self.astView();
var chain: std.ArrayList(AST.Node.Id) = .empty;
defer chain.deinit(allocator);
try locate.ancestorChain(allocator, doc, offset, &chain);
if (emptyContainerOf(ast, chain.items, kind)) |empty| {
const t = doc.span(empty);
return self.commitSplice(t.start, blockSpanEnd(src, t), "");
}
const line = try self.blankLineBetweenBlocks(offset);
var b = AST.Builder.init(allocator);
defer b.deinit();
const para = try b.addContainer(.para, &.{});
const root = switch (kind) {
.block_quote => try b.addContainer(.block_quote, &.{para}),
// Loose, so the empty paragraph is printed as a `<p>` the author can
// type into rather than elided to nothing.
.bullet_list, .ordered_list => try b.addContainer(
containerNodeKind(kind, false),
&.{try b.addContainer(.list_item, &.{para})},
),
};
return self.spliceRendered(&b, root, render, line.start, line.end);
}
/// Print `target`'s blocks — for a list, each item's blocks — from the
/// document's own tree and splice them over the container: the render
/// path's toggle-off.
fn unwrapContainer(self: *Editor, target: AST.Node.Id, render: RenderBlockFn) Error!void {
const allocator = self.splicer.allocator;
const src = self.sourceBytes();
const doc = &self.splicer.doc;
const ast = self.astView();
var out: Writer.Allocating = .init(allocator);
defer out.deinit();
const is_list = std.meta.activeTag(ast.nodes[target].kind) != .block_quote;
var child = ast.nodes[target].first_child;
while (child) |c| : (child = ast.nodes[c].next_sibling) {
if (is_list) {
var block = ast.nodes[c].first_child;
while (block) |bl| : (block = ast.nodes[bl].next_sibling) {
try renderNode(allocator, render, ast, bl, &out.writer);
}
} else {
try renderNode(allocator, render, ast, c, &out.writer);
}
}
const t = doc.span(target);
return self.commitSplice(t.start, blockSpanEnd(src, t), std.mem.trimEnd(u8, out.written(), "\r\n"));
}
/// Renumber the ordered list at `offset` so its markers run `1, 2, 3, …`,
/// with each nesting level restarting at 1 — the numbering a caret editor
/// keeps as items are inserted, deleted, and nested, where a plain splice
/// leaves the source numbers stale (`1. 2. 2. 3.`). A no-op that returns
/// `error.NoBlock` when `offset` is not inside an ordered list.
///
/// Which lines ARE items comes from the tree; only their LEVEL comes from
/// indentation. The level is one left-to-right pass with a small stack of
/// (indent column → next number), so a sub-list restarts and its parent
/// resumes where it left off — indentation, because a nested list's depth is
/// what the marker's column says it is, in both formats and at any width.
/// But whether a `N.`-looking line is an item at all is a question only the
/// parser can answer: Djot does not let a list marker interrupt a paragraph,
/// so in `1. a\n 2. b` the second line is not a nested item but literal
/// text inside item `a`'s paragraph — and a purely textual pass rewrote the
/// author's own digit there. Markdown reads the same bytes as a sub-list.
///
/// Only the numeric run of a `N.` / `N)` marker is rewritten; its delimiter,
/// spacing, indentation, and every other (bullet, prose, continuation, blank)
/// line are copied byte-for-byte.
///
/// `error.UnsupportedFormat` where the format doesn't spell an ordered item
/// as a numbered line marker (see `spellsOrderedMarkers`). An HTML `<ol>`
/// parses into the same `ordered_list`/`list_item` nodes a Markdown one
/// does, so the pass used to run over it, find no `N.` to rewrite, and
/// report the silent no-op as a success.
pub fn renumberOrderedLists(self: *Editor, offset: usize) Error!void {
if (!spellsOrderedMarkers(self.syntax)) return error.UnsupportedFormat;
const src = self.sourceBytes();
if (offset > src.len) return error.InvalidRange;
const ast = self.astView();
const allocator = self.splicer.allocator;
// The OUTERMOST ordered list on the descent to `offset`: renumber the
// whole nest under it in one pass so its levels stay consistent.
var chain: std.ArrayList(AST.Node.Id) = .empty;
defer chain.deinit(allocator);
locate.ancestorChain(allocator, &self.splicer.doc, offset, &chain) catch
return error.OutOfMemory;
var outer: ?AST.Node.Id = null;
for (chain.items) |id| {
if (std.meta.activeTag(ast.nodes[id].kind) == .ordered_list) {
outer = id;
break;
}
}
const list = outer orelse return error.NoBlock;
const region_start = locate.lineStartAt(src, self.splicer.doc.span(list).start);
const region_end = locate.lineEndAt(src, self.splicer.doc.span(list).end -| 1);
// The line each item in the region OPENS on, ascending. An item's span
// may start at its marker (Markdown) or at its text (Djot), but either
// way it starts on the marker's own line, so the line start identifies it.
var item_lines: std.ArrayList(usize) = .empty;
defer item_lines.deinit(allocator);
for (ast.nodes, 0..) |n, i| {
switch (std.meta.activeTag(n.kind)) {
.list_item, .task_list_item => {},
else => continue,
}
const start = self.splicer.doc.span(@intCast(i)).start;
if (start < region_start or start >= region_end) continue;
try item_lines.append(allocator, locate.lineStartAt(src, start));
}
std.mem.sort(usize, item_lines.items, {}, std.sort.asc(usize));
var out: std.ArrayList(u8) = .empty;
defer out.deinit(allocator);
try buildRenumber(allocator, src, region_start, region_end, item_lines.items, &out);
// Identical bytes: don't spend an edit (and an undo step) on a no-op.
if (std.mem.eql(u8, out.items, src[region_start..region_end])) return;
return self.commitSplice(region_start, region_end, out.items);
}
// ── Thematic break ───────────────────────────────────────────────────────
/// Insert a thematic break — a horizontal rule — as its own block, on the
/// line after the block `offset` sits in.
///
/// Decisions:
/// * It goes AFTER the caret's block rather than AT the caret. A rule is a
/// block, not an inline, so there is no spelling for one in the middle of
/// a paragraph; splitting the paragraph in two would be a different
/// gesture the caller didn't ask for.
/// * It is BLANK-SEPARATED from its neighbours unconditionally, and that is
/// load-bearing rather than cosmetic: Markdown reads `---` on the line
/// directly under a paragraph as a setext `<h2>` underline, so a rule
/// written flush against its predecessor silently becomes a heading and
/// eats it. The blank above is what makes one spelling safe in both
/// formats. Neither blank is added where the line is already one — the
/// one below so repeating the gesture doesn't accumulate them, the one
/// above so a caret ON a blank line between two blocks gets a rule with
/// one blank each side rather than two above (`a\n\n|\nb` used to give
/// `a\n\n\n---\n\nb`). A blank line is a separator, and one is all a
/// separator is; the gesture writes what is missing and nothing more.
/// * It inherits the caret block's QUOTE PREFIX, so a rule inside a quote
/// stays inside it (`> a` gains `>` and `> * * *`, not a rule that ends
/// the quote). Only quote markers are reproduced — a list item's indent
/// is not — so a rule requested inside a list lands at column zero after
/// the caret's ITEM, which SPLITS the list in two with the rule between.
/// That is a real document rather than a corrupted one (nothing is
/// swallowed and no item loses its marker), and it is the honest reading
/// of a rule at column zero, so it is allowed rather than refused.
/// * "The caret's block" is `locate.lineOwningBlock`, NOT
/// `locate.innermostBlock`. The latter only knows `para`/`heading`, so a
/// caret in a CODE BLOCK or a TABLE looked to it like no block at all,
/// and the fallback below put the rule at the caret's own line end —
/// inside the fence (where `---` is text, so the document gained no rule
/// and the code body was corrupted), or between a table's header and its
/// delimiter row (which stops it being a table). Losing a node is a
/// failure worth refusing over; here it needn't be refused, because the
/// rule that governs every other case already says where it goes —
/// AFTER the caret's block, the fence and the table included.
///
/// `error.UnsupportedFormat` when the format has no thematic break. There is
/// no `error.NoBlock`: an empty document is a legitimate place for a rule, and
/// with no block to sit after it goes at the caret's line — ON that line
/// when it is blank, since a blank line is where a block goes, after it
/// otherwise.
pub fn insertThematicBreak(self: *Editor, offset: usize) Error!void {
const rule = self.syntax.thematic_break orelse return error.UnsupportedFormat;
const src = self.sourceBytes();
if (offset > src.len) return error.InvalidRange;
const allocator = self.splicer.allocator;
const line = try std.mem.concat(allocator, u8, &.{ rule, "\n" });
defer allocator.free(line);
return self.insertBlockAfter(offset, line);
}
/// Insert a fresh table — one header row, `rows` body rows, `cols` columns,
/// every cell empty — as its own block after the block `offset` sits in.
///
/// The placement is `insertThematicBreak`'s, decision for decision: after
/// the caret's block rather than at the caret, blank-separated on both
/// sides, carrying a quote's prefix on every line and landing at column
/// zero after a list item. The blank above is load-bearing here for the
/// same reason it is for the rule: GFM lets a table's header row be read
/// out of the paragraph it follows, so a table written flush under prose
/// can take the paragraph's last line as its header.
///
/// The bytes are the format's own `TableSpelling`, emitted by
/// `table_edit.emit` over a `table_edit.blank` grid — the same path every
/// table edit re-spells through, so a table this mints is one those edits
/// can read back. The header row is not optional, because neither pipe
/// format has a table without one; `error.InvalidShape` for zero columns
/// or zero body rows, the shape `tableDeleteRow` and `tableDeleteColumn`
/// refuse to leave behind. `error.UnsupportedFormat` where the format has
/// no table spelling, before anything is read.
pub fn insertTable(self: *Editor, offset: usize, rows: usize, cols: usize) Error!void {
const spelling = self.syntax.table_spelling orelse return error.UnsupportedFormat;
if (offset > self.sourceBytes().len) return error.InvalidRange;
if (rows == 0 or cols == 0) return error.InvalidShape;
const allocator = self.splicer.allocator;
var grid = table_edit.blank(allocator, cols, rows) catch |e| return mapTableErr(e);
defer grid.deinit();
const bytes = table_edit.emit(allocator, &grid, spelling) catch |e| return mapTableErr(e);
defer allocator.free(bytes);
return self.insertBlockAfter(offset, bytes);
}
/// Insert a LEAF DIRECTIVE — Markdown's `::name[label]{attrs}` — as its own
/// block after the block `offset` sits in.
///
/// What a name MEANS is the host application's, not twig's: this writes a
/// named `container` with `form = .block_leaf` and asks the format to
/// spell it. A rich-text editor's page break is `insertDirective(off,
/// "page-break", null, &.{})`, and the same call with `"embed"` and a
/// `src` is an embed — twig has no vocabulary of directive names and reads
/// none back.
///
/// The placement is `insertThematicBreak`'s, decision for decision, shared
/// with it and `insertTable` as `insertBlockAfter`: after the caret's
/// block rather than at the caret, blank-separated on both sides, a
/// quote's prefix on every line — djot's two-line fence included — and
/// column zero after a list item.
///
/// The bytes are the format's own, through the FRAGMENT RENDERER: the node
/// is built with `AST.Builder`, `label` becomes its single inline child
/// (which is what the `[label]` brackets print from), `attrs` are set on
/// it, and `Syntax.renderBlock` spells the result. So the spelling is the
/// serializer's — `::name` in Markdown, an empty `::: name` fence in djot,
/// `<name></name>` in HTML — and stays that way when a serializer's does.
///
/// Gated on `Syntax.names_leaf_containers`, which is the narrower question
/// than "can this format print one": every format with a renderer prints
/// SOMETHING for a named leaf, and the gate asks whether the parser hands
/// that back as a container carrying the name. In Markdown the answer is
/// the parse config's — `::name` is a paragraph of colons without
/// `ParseOptions.directives` — so an editor over a document parsed without
/// the extension gets `error.UnsupportedFormat` here, exactly as
/// `setMarkColor` does without `highlight_colors`.
///
/// `error.InvalidName` for a name outside `checkDirectiveName`'s grammar —
/// an ASCII letter then letters, digits, `-` and `_` — which is checked
/// here rather than per format because a name is written where a delimiter
/// would otherwise be, and anything else reparses as something other than
/// the container it was meant to be. `error.InvalidLabel` for a label
/// carrying a line end or a square bracket, either of which closes the
/// `[…]` early. `error.InvalidRange` for an `offset` past the source.
/// There is no `error.NoBlock` — an empty document is a legitimate place
/// for one, as it is for a rule.
pub fn insertDirective(
self: *Editor,
offset: usize,
name: []const u8,
label: ?[]const u8,
attrs: []const AST.KeyVal,
) Error!void {
if (!self.syntax.names_leaf_containers) return error.UnsupportedFormat;
// `assertCoherent` pins this non-null wherever the claim above is
// made, so the `orelse` is the compiler's requirement rather than a
// second gate; `supports` states both halves for the same reason.
const render = self.syntax.renderBlock orelse return error.UnsupportedFormat;
if (offset > self.sourceBytes().len) return error.InvalidRange;
try checkDirectiveName(name);
// A label is written inside `[…]`, so a bracket closes it early and
// the tail becomes ordinary text beside the directive — the same
// reasoning `insertFootnote` applies to its own reference brackets.
if (label) |l| {
if (std.mem.indexOfAny(u8, l, "\r\n[]") != null) return error.InvalidLabel;
}
const allocator = self.splicer.allocator;
var b = AST.Builder.init(allocator);
defer b.deinit();
// A label is the container's INLINE CHILDREN, which is where every
// serializer looks for it: Markdown prints `[` … `]` around them and
// writes nothing at all when there are none, so "no label" is an
// absent child rather than an empty one.
var child: [1]AST.Node.Id = undefined;
var children: []const AST.Node.Id = child[0..0];
if (label) |l| {
child[0] = try b.addLeaf(.{ .str = l });
children = child[0..1];
}
const root = try b.addContainer(
.{ .container = .{ .name = name, .form = .block_leaf } },
children,
);
if (attrs.len != 0) try b.setAttrs(root, .{ .entries = attrs });
const view = b.view(root);
var out: Writer.Allocating = .init(allocator);
defer out.deinit();
try renderNode(allocator, render, &view, root, &out.writer);
// No trim here, unlike `spliceRendered`: `insertBlockAfter`
// re-terminates every line itself and trims the renderer's trailing
// newline on the way in.
return self.insertBlockAfter(offset, out.written());
}
/// Write `body` — one or more `\n`-terminated lines — as a block of its
/// own after the block `offset` sits in: the shared placement behind
/// `insertThematicBreak`, `insertTable`, `insertDirective` and
/// `insertDisplayMath`, whose doc comments own the reasoning for each
/// decision made here.
fn insertBlockAfter(self: *Editor, offset: usize, body: []const u8) Error!void {
var out: std.ArrayList(u8) = .empty;
defer out.deinit(self.splicer.allocator);
const pos = try self.blockAfter(offset, body, &out);
return self.commitSplice(pos, pos, out.items);
}
/// `insertBlockAfter`'s bytes without the splice: fills `out` with what
/// goes in and answers where it goes.
fn blockAfter(self: *Editor, offset: usize, body: []const u8, out: *std.ArrayList(u8)) Error!usize {
const src = self.sourceBytes();
const allocator = self.splicer.allocator;
const block = if (locate.lineOwningBlock(&self.splicer.doc, offset)) |lb| lb.block else null;
// With no block to sit after, the caret's own line is the anchor: a
// BLANK one is a separator the block can take the place of — written at
// its start, the blank becomes the separator below — where writing after
// it would step past a blank only to add another above.
const line_start = locate.lineStartAt(src, offset);
const on_blank = block == null and
locate.isBlankLine(locate.lineBody(src[line_start..locate.lineEndAt(src, offset)]));
const pos = if (on_blank)
line_start
else
locate.lineEndAt(src, if (block) |b| self.splicer.doc.span(b).end -| 1 else offset);
const prefix = if (block) |b| containerPrefix(src, self.splicer.doc.span(b).start) else "";
// A quote's blank line carries its marker but not the space after it —
// the same rule `ContainerSpelling.blank` states for the toggle.
const blank = std.mem.trimEnd(u8, prefix, " ");
if (pos > 0) {
// An unterminated last line is ended first, or the "blank" written
// next is not a blank line but that line's own newline, and the
// block lands flush under the paragraph — `a\n---\n`, the setext
// heading the blank exists to prevent.
if (src[pos - 1] != '\n') try out.append(allocator, '\n');
// The blank above, unless the line above already is one — the
// mirror of the rule below.
const above = src[locate.lineStartAt(src, pos - 1)..pos];
if (!locate.isBlankLine(locate.lineBody(above))) {
try out.appendSlice(allocator, blank);
try out.append(allocator, '\n');
}
}
// Every line of the block takes the prefix, not just its first: a
// quote's marker is on each line it covers.
var lines = std.mem.splitScalar(u8, std.mem.trimEnd(u8, body, "\n"), '\n');
while (lines.next()) |l| {
try out.appendSlice(allocator, prefix);
try out.appendSlice(allocator, l);
try out.append(allocator, '\n');
}
if (pos < src.len and !locate.isBlankLine(locate.lineBody(src[pos..locate.lineEndAt(src, pos)]))) {
try out.appendSlice(allocator, blank);
try out.append(allocator, '\n');
}
return pos;
}
// ── Block attributes ───────────────────────────────────────────────────
/// Replace the attribute set of the block `offset` sits in — a paragraph
/// or heading, the block `setBlock` rewrites — with `attrs`. REPLACE, not
/// merge: a caller reads the node's attributes, edits the list and passes
/// it back whole, which is the contract `Builder.setAttrs` and the C ABI's
/// `twig_builder_set_attrs` already have, and an empty list clears them.
///
/// What a key MEANS is the host's, not twig's — this is `insertDirective`'s
/// rule applied to a block's presentation: a rich-text editor's centred
/// paragraph is `setBlockAttrs(off, &.{.{ .key = "class", .value =
/// "center" }})`, and twig spells the pair and interprets neither half.
/// See `docs/proposals/presentation-as-attributes.md`.
///
/// THREE SPELLINGS, chosen by `Syntax.block_attrs` and the table's fields:
///
/// * `native` with an `attr_spelling` — djot: the format spells a
/// block's attributes on the line BEFORE it, and the document recorded
/// where (`Document.attrsSpan`). That line is rewritten, inserted with
/// the block's own quote prefix, or removed, and the block's bytes are
/// not touched. The alphabet path, preferred for the reason `setBlock`
/// prefers a marker.
/// * `native` otherwise — HTML's tag, AsciiDoc's `[…]` line: the block
/// is rebuilt with the new set and printed through `renderBlock`, as
/// `setBlockByRender` prints a heading, so its bytes are re-spelled by
/// the format.
/// * `wrapped` — Markdown under `html_elements`: the block is printed
/// inside a container the format spells as `<div …>` around it. When
/// the block is already the SOLE CHILD of such a wrapper, the wrapper's
/// attributes are replaced instead of a second one nesting, and an
/// empty set unwraps it — the rule `insertLink` applies to a link
/// covering the range, for the same reason.
///
/// `error.UnsupportedFormat` where the table makes no claim, before
/// anything is read. `error.NoBlock` when no paragraph or heading holds
/// `offset`; `error.InvalidRange` for an offset past the source;
/// `error.InvalidAttribute` for a key or value no format reads back (see
/// `checkAttr`). `error.NotEditable` where the alphabet path cannot place
/// the line — a block that starts on a list item's marker line — or where
/// the document's attributes came from more than one `{…}` block and no
/// single span describes them, and where the wrap path would need a list
/// item's continuation indent it cannot reproduce.
pub fn setBlockAttrs(self: *Editor, offset: usize, attrs: []const AST.KeyVal) Error!void {
const shape = self.syntax.block_attrs orelse return error.UnsupportedFormat;
// `assertCoherent` pins this non-null wherever the claim above is
// made, so the `orelse` is the compiler's requirement.
const render = self.syntax.renderBlock orelse return error.UnsupportedFormat;
if (offset > self.sourceBytes().len) return error.InvalidRange;
for (attrs) |kv| try checkAttr(kv);
const block = locate.innermostBlock(&self.splicer.doc, offset) orelse return error.NoBlock;
return switch (shape) {
.native => if (self.syntax.attr_spelling) |sp|
self.setBlockAttrsByLine(block, attrs, sp)
else
self.setNodeAttrsByRender(block, attrs, render),
.wrapped => self.setBlockAttrsByWrap(block, attrs, render),
};
}
/// `setBlockAttrs` where the format spells a block's attributes as a line
/// before it: rewrite that line in place.
fn setBlockAttrsByLine(self: *Editor, block: AST.Node.Id, attrs: []const AST.KeyVal, sp: syntax_mod.AttrSpelling) Error!void {
const doc = &self.splicer.doc;
const src = self.sourceBytes();
const allocator = self.splicer.allocator;
const existing = doc.attrsSpan(block);
// Attributes the node has but no single span describes — djot merges
// consecutive `{…}` blocks into one set — are not ours to rewrite: a
// new line would sit beside the old ones.
if (existing == null and !doc.ast.attrsOf(block).isEmpty()) return error.NotEditable;
var out: Writer.Allocating = .init(allocator);
defer out.deinit();
if (attrs.len != 0) attrs_writer.write(&out.writer, .{ .entries = attrs }, sp, "") catch return error.OutOfMemory;
if (existing) |es| {
if (attrs.len != 0) return self.commitSplice(es.start, es.end, out.written());
// Clearing takes the whole line when the block was alone on it —
// a quote's marker at most beside it — so no blank line is left
// where the attributes were.
const ls = locate.lineStartAt(src, es.start);
const le = locate.lineEndAt(src, es.end); // past the newline
const prefix = containerPrefix(src, es.start);
const before = src[ls..es.start];
const alone = std.mem.startsWith(u8, before, prefix) and
locate.isBlankLine(before[prefix.len..]) and
locate.isBlankLine(locate.lineBody(src[es.end..le]));
if (!alone) return self.commitSplice(es.start, es.end, "");
return self.commitSplice(ls, le, "");
}
if (attrs.len == 0) return;
// A fresh line above the block, carrying the block's own quote
// prefix. A block that starts on a list item's marker line has no
// line above it that is its own — the marker is there — so that is
// refused rather than written before the marker, where it would be
// the list's.
const bs = doc.span(block).start;
const ls = locate.lineStartAt(src, bs);
const prefix = containerPrefix(src, bs);
const content_start = @max(bs, ls + prefix.len);
if (!locate.isBlankLine(src[ls + prefix.len .. content_start])) return error.NotEditable;
var line: std.ArrayList(u8) = .empty;
defer line.deinit(allocator);
try line.appendSlice(allocator, prefix);
try line.appendSlice(allocator, out.written());
try line.append(allocator, '\n');
return self.commitSplice(ls, ls, line.items);
}
/// `setBlockAttrs` over a format whose attributes live on the block's own
/// spelling and which has no line to rewrite: rebuild the block with the
/// new set and print it, `setBlockByRender`'s path with the kind kept.
fn setNodeAttrsByRender(self: *Editor, block: AST.Node.Id, attrs: []const AST.KeyVal, render: RenderBlockFn) Error!void {
const doc = &self.splicer.doc;
const allocator = self.splicer.allocator;
var b = AST.Builder.init(allocator);
defer b.deinit();
var kids: std.ArrayList(AST.Node.Id) = .empty;
defer kids.deinit(allocator);
var child = doc.ast.nodes[block].first_child;
while (child) |c| : (child = doc.ast.nodes[c].next_sibling) {
try kids.append(allocator, try b.graftSubtree(&doc.ast, c));
}
const root = try b.addContainer(doc.ast.nodes[block].kind, kids.items);
if (attrs.len != 0) try b.setAttrs(root, .{ .entries = attrs });
const span = doc.span(block);
return self.spliceRendered(&b, root, render, span.start, span.end);
}
/// `setBlockAttrs` where the attributes come back on a container around
/// the block — Markdown's `<div>`: print the block inside one, or rewrite
/// the one it is already the sole child of.
fn setBlockAttrsByWrap(self: *Editor, block: AST.Node.Id, attrs: []const AST.KeyVal, render: RenderBlockFn) Error!void {
const doc = &self.splicer.doc;
const ast = &doc.ast;
const allocator = self.splicer.allocator;
const block_span = doc.span(block);
var chain: std.ArrayList(AST.Node.Id) = .empty;
defer chain.deinit(allocator);
try locate.ancestorChain(allocator, doc, block_span.start, &chain);
// The wrapper: the block's parent when that is a div — a fenced
// container that is anonymous or named `div`, and not one the parser
// read as a directive — with the block as its only child.
var wrapper: ?AST.Node.Id = null;
for (chain.items, 0..) |id, i| {
if (id != block or i == 0) continue;
const parent = chain.items[i - 1];
const c = switch (ast.nodes[parent].kind) {
.container => |c| c,
else => break,
};
if (c.form != .block_fenced) break;
if (c.name.len != 0 and !std.mem.eql(u8, c.name, "div")) break;
if (c.name.len != 0 and doc.containerOrigin(parent) == .directive) break;
if (ast.nodes[parent].first_child != block or ast.nodes[block].next_sibling != null) break;
wrapper = parent;
break;
}
// The printed lines take the block's quote prefix; a list item's
// continuation indent is not one `containerPrefix` reproduces.
if (insideListItem(doc, chain.items)) return error.NotEditable;
var b = AST.Builder.init(allocator);
defer b.deinit();
const grafted = try b.graftSubtree(ast, block);
const target = if (wrapper) |w| doc.span(w) else block_span;
if (attrs.len == 0) {
// Nothing to wrap in: the block alone, over the wrapper if any.
if (wrapper == null) return;
return self.spliceRenderedPrefixed(&b, grafted, render, target);
}
const root = try b.addContainer(.{ .container = .{ .name = "div", .form = .block_fenced } }, &.{grafted});
try b.setAttrs(root, .{ .entries = attrs });
return self.spliceRenderedPrefixed(&b, root, render, target);
}
/// Wrap `[start, end)` in an anonymous inline container carrying `attrs`
/// — djot's `[text]{…}`, HTML's and Markdown's `<span …>` — or, when the
/// range lies inside one already, REPLACE that container's attributes
/// instead of nesting a second; an empty set there unwraps it. That is the
/// rule `insertLink` applies to a link covering the range, for the same
/// reason: re-styling is the common gesture, and it must not build
/// `[[text]{.a}]{.b}`. An anonymous span and one named `span` are the
/// same node here — HTML and Markdown hand the name back, djot does not —
/// and a `:span[…]` the Markdown parser read as a directive is neither.
///
/// The inline half of `setBlockAttrs`, with the same vocabulary rule: twig
/// spells the pairs and interprets none. The bytes are the format's,
/// through `renderBlock` over the container — the covered inline nodes
/// grafted under it as `insertLinkByRender` grafts them under a link — so
/// a mark inside the range rides along. Unwrapping splices the node's
/// CONTENT bytes over the node, which needs no renderer and keeps them.
///
/// `error.UnsupportedFormat` where `Syntax.inline_attrs` is not claimed —
/// AsciiDoc, whose `[#id.role]#text#` keeps two keys and drops a third,
/// and Markdown without `html_elements`; `error.InvalidRange` for a bad
/// range; `error.InvalidAttribute` as `setBlockAttrs`; `error.NotEditable`
/// for an empty range with no span to re-style, or a range that cuts a
/// node it cannot slice (see `coveredInlines`).
pub fn wrapRangeAttrs(self: *Editor, span: Span, attrs: []const AST.KeyVal) Error!void {
if (!self.syntax.inline_attrs) return error.UnsupportedFormat;
const render = self.syntax.renderBlock orelse return error.UnsupportedFormat;
try self.checkRange(span.start, span.end);
for (attrs) |kv| try checkAttr(kv);
const doc = &self.splicer.doc;
const ast = self.astView();
const allocator = self.splicer.allocator;
const src = self.sourceBytes();
var chain: std.ArrayList(AST.Node.Id) = .empty;
defer chain.deinit(allocator);
try locate.ancestorChain(allocator, doc, span.start, &chain);
// The innermost attributed span covering the range.
var existing: ?AST.Node.Id = null;
var i = chain.items.len;
while (i > 0) {
i -= 1;
const id = chain.items[i];
const c = switch (ast.nodes[id].kind) {
.container => |c| c,
else => continue,
};
if (c.form != .inline_text) continue;
if (c.name.len != 0 and !std.mem.eql(u8, c.name, "span")) continue;
// djot's own span is anonymous and, being lightweight markup,
// carries the `directive` origin too; the one to leave alone is a
// NAMED span with it — Markdown's `:span[…]` directive.
if (c.name.len != 0 and doc.containerOrigin(id) == .directive) continue;
const sp = doc.span(id);
if (sp.start <= span.start and sp.end >= span.end) {
existing = id;
break;
}
}
var b = AST.Builder.init(allocator);
defer b.deinit();
var kids: std.ArrayList(AST.Node.Id) = .empty;
defer kids.deinit(allocator);
var target = span;
if (existing) |id| {
target = doc.span(id);
if (target.start == 0 and target.end == 0) return error.NotEditable;
// djot's `{…}` follows the brackets OUTSIDE the node's span, and
// the document recorded where; a set merged from several blocks
// has no single span and is not ours to rewrite. HTML's and
// Markdown's attributes sit inside the tag, inside the span — the
// formats whose `block_attrs` path is the line rewrite are the
// ones whose attributes lie outside, as `setBlockAttrs` reads it.
if (doc.attrsSpan(id)) |as| {
target = Span.init(@min(target.start, as.start), @max(target.end, as.end));
} else if (self.syntax.block_attrs == .native and self.syntax.attr_spelling != null and !ast.attrsOf(id).isEmpty()) {
return error.NotEditable;
}
if (attrs.len == 0) {
const cs = doc.contentSpan(id) orelse return error.NotEditable;
return self.commitSplice(target.start, target.end, src[cs.start..cs.end]);
}
var child = ast.nodes[id].first_child;
while (child) |c| : (child = ast.nodes[c].next_sibling) {
try kids.append(allocator, try b.graftSubtree(ast, c));
}
} else {
if (attrs.len == 0) return;
if (span.end == span.start) return error.NotEditable;
const covered = try coveredInlines(allocator, doc, span.start, span.end);
defer allocator.free(covered);
for (covered) |piece| {
try kids.append(allocator, if (piece.text) |t|
try b.addLeaf(.{ .str = t })
else
try b.graftSubtree(ast, piece.node));
}
}
const root = try b.addContainer(.{ .container = .{ .name = "", .form = .inline_text } }, kids.items);
try b.setAttrs(root, .{ .entries = attrs });
return self.spliceRendered(&b, root, render, target.start, target.end);
}
/// `spliceRendered` for a fragment of several lines going into a quote:
/// every line after the first takes the quote prefix the first already
/// sits behind, a blank line its marker alone.
fn spliceRenderedPrefixed(self: *Editor, b: *const AST.Builder, root: AST.Node.Id, render: RenderBlockFn, target: Span) Error!void {
const allocator = self.splicer.allocator;
const src = self.sourceBytes();
const prefix = containerPrefix(src, target.start);
const blank = std.mem.trimEnd(u8, prefix, " ");
// A Markdown block's span starts at column zero, quote marker
// included; the first printed line goes after that marker, which is
// then the prefix every later line copies.
const start = @max(target.start, locate.lineStartAt(src, target.start) + prefix.len);
const view = b.view(root);
var out: Writer.Allocating = .init(allocator);
defer out.deinit();
try renderNode(allocator, render, &view, root, &out.writer);
const rendered = std.mem.trimEnd(u8, out.written(), "\r\n");
if (prefix.len == 0) return self.commitSplice(start, target.end, rendered);
var text: std.ArrayList(u8) = .empty;
defer text.deinit(allocator);
var lines = std.mem.splitScalar(u8, rendered, '\n');
var first = true;
while (lines.next()) |l| {
if (!first) {
try text.append(allocator, '\n');
try text.appendSlice(allocator, if (l.len == 0) blank else prefix);
}
first = false;
try text.appendSlice(allocator, l);
}
return self.commitSplice(start, target.end, text.items);
}
// ── Node attributes ────────────────────────────────────────────────────
/// Replace the attribute set of node `id` with `attrs` — an element,
/// addressed by id rather than by offset because the caller that wants
/// this holds a tree and not a caret: a canvas editor over an SVG names
/// the shape it is dragging, and no byte position stands for it. Ids are
/// the CURRENT tree's, as the splicer's node ops take them, and a
/// successful edit reparses, so read the tree again before the next call.
///
/// The run is written where the format keeps it: on the node's own
/// opening spelling, at the span the parser recorded
/// (`Document.attrsSpan`), as a tag interior — ` key="value"` pairs with
/// `&`, `<`, `>` and `"` as entities. Every other byte of the node, its
/// children included, stays where it is; a `<g>` holding a thousand paths
/// is not re-printed to move it. A node with no attributes yet has no
/// span, so the run is inserted right after the name, where the parser
/// reads the first one. Replace, not merge, as `setBlockAttrs`: read the
/// node's attributes, edit the list, pass it back whole. An empty set
/// removes the run, and removing what is already absent is a no-op.
///
/// `error.UnsupportedFormat` where `Syntax.node_attrs` is not claimed,
/// before anything is read. `error.InvalidRange` for an id no node has;
/// `error.InvalidAttribute` as `setBlockAttrs` (see `checkAttr`);
/// `error.NotEditable` for a node that is not an element — a text run, a
/// comment, a container some other format's parser made — and for an
/// element whose attributes the parser gave no span to, which no parser
/// in the tree does but a grafted tree could.
pub fn setNodeAttrs(self: *Editor, id: AST.Node.Id, attrs: []const AST.KeyVal) Error!void {
const spelling = self.syntax.node_attrs orelse return error.UnsupportedFormat;
const doc = &self.splicer.doc;
if (id >= doc.ast.nodes.len) return error.InvalidRange;
for (attrs) |kv| try checkAttr(kv);
const c = switch (doc.ast.nodes[id].kind) {
.container => |c| c,
else => return error.NotEditable,
};
if (doc.containerOrigin(id) != .element) return error.NotEditable;
const existing = doc.attrsSpan(id);
if (existing == null and !doc.ast.attrsOf(id).isEmpty()) return error.NotEditable;
var out: Writer.Allocating = .init(self.splicer.allocator);
defer out.deinit();
attrs_writer.writeHtmlAttrs(&out.writer, .{ .entries = attrs }) catch return error.OutOfMemory;
if (existing) |es| return self.commitSplice(es.start, es.end, out.written());
if (attrs.len == 0) return;
const at = doc.span(id).start + spelling.open.len + c.name.len;
return self.commitSplice(at, at, out.written());
}
// ── Splitting a block ────────────────────────────────────────────────────
/// Split the block at `offset` in two AT THE CARET, both halves the SAME
/// KIND — Enter in the middle of a paragraph, and the gesture
/// `insertThematicBreak` deliberately isn't.
///
/// Nearly a pure INSERTION at `offset`: what is minted is the separator
/// between the halves, and the only bytes REMOVED are the second half's
/// leading spaces and tabs. Those are structure rather than content at the
/// start of a block — a split at `- b| c` that kept its space would write
/// `- c`, setting that item's content indent to three. A code block sheds
/// nothing, because there leading whitespace IS the content. What the
/// separator is, is the only other thing that varies:
///
/// * A PARAGRAPH gets a blank line — `ab` -> `a`/`b`. Inside a quote the
/// blank carries the quote's marker and the second half its full prefix
/// (`> ab` -> `> a`/`>`/`> b`), so the split happens INSIDE the quote
/// rather than ending it.
/// * A paragraph in a LIST ITEM gets the item's MARKER instead of a blank,
/// so the second half is a sibling item and not a paragraph that ends
/// the list: `- this is |a list item` -> `- this is `/`- a list item`.
/// The marker is repeated VERBATIM, ordered numbers included, so a split
/// `1.` item yields two `1.` items — both formats renumber on render,
/// and `renumberOrderedLists` is the gesture for fixing the source when
/// the caller wants it fixed. A TASK item's new half is an UNCHECKED
/// box regardless of the original's state: splitting one done thing in
/// two does not make the remainder done. The marker is taken from the
/// END OF ANY QUOTE PREFIX rather than from the bullet, so a NESTED
/// item's indent rides along with it and the new sibling stays in its
/// own list instead of dropping to column zero and joining the
/// enclosing one.
/// * A HEADING repeats its own marker at its own level, because both
/// halves being the same kind is what "split" means here; `setBlock` is
/// how the caller demotes the second half if that is what they wanted.
/// * A CODE BLOCK becomes two code blocks — the first closed with a fence,
/// the second reopened with the opening fence line REPRODUCED VERBATIM,
/// so its width and its info string both survive. Splitting code is a
/// real request (one listing becoming two), and a consumer that doesn't
/// want the gesture live there can ask the tree what kind of block the
/// caret is in before offering it.
///
/// AT A BLOCK BOUNDARY this still splits, which is what makes it Enter: at
/// the end of a list item it opens an EMPTY sibling item (`- a|` -> `- a`/
/// `- `), which is exactly the empty block the caller wants to type into.
/// The paragraph case is the one place the "empty block" is unrepresentable
/// — no format spells an empty paragraph — so `a|` gains a trailing blank
/// line and reparses as ONE paragraph. The caret is where the next one will
/// begin; the node appears when there is text to hold.
///
/// `error.NotEditable` for the blocks where a caret-split has no honest
/// meaning:
/// * A TABLE, whose structure is rows and cells rather than lines — a
/// newline mid-cell doesn't divide a table, it destroys one. Splitting a
/// table INTO TWO TABLES is a real gesture, but it is a table gesture
/// (it has to decide what the second table's header is), not this one.
/// * A SETEXT heading, whose `---` underline belongs to a block that would
/// no longer be under it. `setBlock` normalises one to ATX, which makes
/// this work; doing that silently here would rewrite the half the caller
/// didn't touch.
/// * An INDENTED code block, where a blank line is interior rather than a
/// separator, so the "split" would parse back as one block.
///
/// `error.NoBlock` when nothing covers `offset` — an empty document has no
/// block to divide.
///
/// `error.UnsupportedFormat` when the format has no `block_separator`, and
/// that is checked FIRST, before a single byte of source is read: the blank
/// line every case above writes is only a divider where blank lines divide
/// blocks. In HTML it is insignificant whitespace inside the `<p>`, so the
/// gesture used to report success over a document it had not changed the
/// shape of at all.
pub fn splitBlock(self: *Editor, offset: usize) Error!void {
const separator = self.syntax.block_separator orelse return error.UnsupportedFormat;
const src = self.sourceBytes();
if (offset > src.len) return error.InvalidRange;
const doc = &self.splicer.doc;
const found = splitTarget(doc, offset) orelse return error.NoBlock;
const block_start = doc.span(found.block).start;
const prefix = containerPrefix(src, block_start);
// As in `insertThematicBreak`: a quote's blank line carries its marker
// but not the space after it.
const blank = std.mem.trimEnd(u8, prefix, " ");
// When the caret already sits at a line start, the line end before it is
// the separator's first newline — emitting another would leave a blank
// line trailing inside the FIRST half (and, in a code block, inside its
// body). This only decides whether the separator needs to open a line or
// is already on one.
const at_line_start = offset == 0 or src[offset - 1] == '\n';
const allocator = self.splicer.allocator;
var out: std.ArrayList(u8) = .empty;
defer out.deinit(allocator);
// How many bytes after the caret the second half must SHED. Leading
// spaces at the start of a block are structure, not content — a split at
// `- b| c` whose second half kept its space would write `- c`, setting
// that item's content indent to three. This is the one place the gesture
// isn't a pure insertion, and it is deliberately not done for a code
// block, where leading whitespace IS the content.
var shed: usize = 0;
switch (splitShape(std.meta.activeTag(doc.ast.nodes[found.block].kind))) {
.text => {
var marker: std.ArrayList(u8) = .empty;
defer marker.deinit(allocator);
const in_item = try self.splitMarker(found, block_start, &marker);
while (offset + shed < src.len and
(src[offset + shed] == ' ' or src[offset + shed] == '\t')) shed += 1;
if (!at_line_start) try out.append(allocator, '\n');
// A list item's halves stay in ONE list, so no blank line
// between them — a blank there loosens the list, changing every
// sibling's rendering. Everywhere else the blank IS the divider.
if (!in_item) {
try out.appendSlice(allocator, blank);
try out.appendSlice(allocator, separator);
}
try out.appendSlice(allocator, prefix);
try out.appendSlice(allocator, marker.items);
},
.code => {
const fence = self.syntax.code_fence orelse return error.UnsupportedFormat;
const open = src[locate.lineStartAt(src, block_start)..locate.lineEndAt(src, block_start)];
// No fence on the opening line means an INDENTED code block,
// where a blank line is interior and would not divide anything.
const at = fenceAt(open, fence.char, fence.min) orelse return error.NotEditable;
if (!at_line_start) try out.append(allocator, '\n');
try out.appendSlice(allocator, prefix);
try out.appendNTimes(allocator, fence.char, at.width);
try out.append(allocator, '\n');
try out.appendSlice(allocator, blank);
try out.appendSlice(allocator, separator);
// Verbatim from the fence character on, so width and info
// string both survive; the prefix is re-minted, not copied.
try out.appendSlice(allocator, prefix);
try out.appendSlice(allocator, locate.lineBody(open)[at.start..]);
try out.append(allocator, '\n');
},
.refuse => return error.NotEditable,
}
return self.commitSplice(offset, offset + shed, out.items);
}
/// Append to `out` what the second half of a split must carry to come back
/// as the SAME KIND as the first — a list item's marker, a heading's marker,
/// both when a heading sits in an item, or nothing for a plain paragraph.
/// Returns whether the block is in a LIST ITEM, which is what decides
/// whether a blank line may separate the halves.
///
/// The list case reads the marker off the ITEM'S OWN first line rather than
/// rebuilding it from `Syntax`, so `*` stays `*`, `1)` stays `1)`, and the
/// document keeps the spelling its author chose.
fn splitMarker(
self: *Editor,
found: locate.LineBlock,
block_start: usize,
out: *std.ArrayList(u8),
) Error!bool {
const allocator = self.splicer.allocator;
const src = self.sourceBytes();
const doc = &self.splicer.doc;
const parent_tag = std.meta.activeTag(doc.ast.nodes[found.parent].kind);
const in_item = parent_tag == .list_item or parent_tag == .task_list_item;
if (in_item) {
const item_start = doc.span(found.parent).start;
const line = src[locate.lineStartAt(src, item_start)..locate.lineEndAt(src, item_start)];
var from: usize = 0;
while (skipQuoteMarker(line, from)) |j| from = j;
const m = listMarkerAt(line, from) orelse return error.NotEditable;
// From the end of the quote prefix, NOT from `m.start` — the run of
// spaces between them is the item's NESTING DEPTH, and dropping it
// moves the new sibling to column zero, out of its own list and into
// the enclosing one. `listMarkerAt` puts `start` at the bullet on
// purpose (its other callers want the indent left where it is), so
// taking it back is this caller's job.
try out.appendSlice(allocator, line[from..m.end]);
// A task item's new half is an UNCHECKED box: the marker as written,
// then this format's empty box rather than the original's state.
if (parent_tag == .task_list_item) {
const box = self.syntax.task_marker orelse return error.NotEditable;
try out.appendSlice(allocator, box.unchecked);
try out.appendSlice(allocator, box.space);
}
}
if (std.meta.activeTag(doc.ast.nodes[found.block].kind) != .heading) return in_item;
// A heading repeats its own marker. A SETEXT one has none on its first
// line — its `---` sits UNDER the block, and would end up under the
// second half alone — so it is refused rather than silently normalised.
const marker = self.syntax.heading_marker orelse return error.UnsupportedFormat;
const line = src[locate.lineStartAt(src, block_start)..locate.lineEndAt(src, block_start)];
var i: usize = 0;
while (skipQuoteMarker(line, i)) |j| i = j;
if (listMarkerAt(line, i)) |m| i = m.end;
while (i < line.len and line[i] == ' ') i += 1;
if (i >= line.len or line[i] != marker) return error.NotEditable;
try out.appendNTimes(allocator, marker, doc.ast.nodes[found.block].kind.heading.level);
try out.append(allocator, ' ');
return in_item;
}
// ── Joining two blocks ───────────────────────────────────────────────────
/// Join the block at `offset` into the block BEFORE it — Backspace at the
/// start of a block, and forward Delete at the end of the one above it.
/// The inverse of `splitBlock`, and the reason it is a gesture rather than
/// a host's own delete: what joins two blocks is a fact about the FORMAT,
/// and a host that deletes the newline between them is right only for two
/// Markdown paragraphs at the top level. In HTML that byte is the `>` of
/// `</p>`; under a heading it leaves two blocks; after a Markdown `<div>`
/// it deletes the blank line the div needed and breaks the div.
///
/// ── The two blocks ─────────────────────────────────────────────────────
/// **B** is the innermost `para`/`heading` covering `offset` — the block
/// being joined UPWARD, and the one whose identity is given up. **A** is
/// the LEAF BLOCK immediately before it in document order: the nearest
/// preceding node holding no blocks of its own, with no other leaf block
/// between the two. A is found by document order rather than by sibling
/// order because the caret does not know about containers: the block
/// visually above `below` in `above`/`<div>`/`hello`/`</div>`/`below` is
/// `hello`, three levels down, and joining into `above` would be joining
/// into the wrong paragraph.
///
/// ── What the result is made of ─────────────────────────────────────────
/// One splice over `[A.ce, R_end)`, assembled from four pieces:
///
/// * **The separator.** `Syntax.line_join` followed by the CONTAINER
/// PREFIX A's own first line sits behind (`locate.continuationPrefix`
/// — a quote's `> ` repeated, a list item's marker's WIDTH in spaces,
/// nothing at the top level). That prefix is what keeps the joined
/// line inside its containers in a format with no lazy continuation,
/// which is djot: `- a` + `below` is `- a`/` below` and not `- a`/
/// `below`, which would end the list. The one exception is a heading A
/// with a LEADING MARKER (`# Title`, AsciiDoc's `== Title`): such a
/// heading is one line by its own spelling, so the separator is a
/// single SPACE and `# Title` + `below` is `# Title below`. A SETEXT
/// heading A takes the line end like everything else — its content may
/// already span lines, and its underline rides along in A's tail.
/// * **B's content**, `[B.cs, B.ce)` — its text and nothing else.
/// * **A's tail**, `[A.ce, span(a_top).end)`, carried PAST the joined
/// text: A's own closing markup (an ATX closing `#` run, a setext
/// underline, `</p>`) followed by the closers of every container A
/// sits in below the two blocks' lowest common ancestor (a Markdown
/// `</div>`, a djot `:::` fence). `a_top` is the LCA's own child
/// holding A, so this is exactly what has to be re-closed after the
/// text that was pulled in. A is necessarily the last leaf in those
/// containers, since B follows it immediately. Its trailing SEPARATOR
/// LINES are trimmed first — see `trimTailSeparators`, without which a
/// Markdown quote's own trailing `>` line travelled past the joined
/// text and piled up there.
/// * **Everything else between them vanishes**: the blank line, B's
/// markers (`# `, `- `), B's attribute line (djot's `{…}`,
/// AsciiDoc's `[…]`), B's opening tags (`<div class="center">`,
/// `<p class="x">`). B's ATTRIBUTES ARE DISCARDED on purpose — the
/// joined text is A's block, so it takes A's presentation.
///
/// `R_end` is `span(B).end`, so B's own closing markup goes with it. When
/// B's ancestor chain below the LCA passes through a DELIMITED container —
/// one spelled with closing bytes of its own after its children, which is
/// the `container` kind (a Markdown `<div>`, an HTML element, a djot `:::`
/// fence, a directive) — it is the OUTERMOST of those whose span end is
/// used instead, because B leaving it means that container's closers go
/// too. The PREFIX containers (a quote, a list item, a list, a section, a
/// definition item) have no closers, so whatever follows B inside them
/// simply stays where it is: joining the first item's text out of a list
/// leaves the other items a list.
///
/// ── What is refused ────────────────────────────────────────────────────
/// `error.NoBlock` when no `para`/`heading` covers `offset`, and when B is
/// the document's FIRST block — there is nothing above to join into, which
/// is the ordinary Backspace-at-the-top-of-the-document answer.
///
/// `error.NotEditable` for the shapes with no honest result:
/// * **A is not a `para` or a `heading`** — a code block, a table, a
/// rule, a raw block, a reference definition. There is no text to join
/// into, and pulling B's prose into a fence or a table would destroy
/// the block a caller was standing next to.
/// * **Either block is in a TABLE CELL.** A cell's blocks are not the
/// document's lines; a newline between two of them divides nothing and
/// a join across a cell boundary is not a join at all.
/// * **B is a SETEXT heading**, whose underline is how it is spelled at
/// all. `setBlock` normalises one to ATX, which makes this work;
/// doing that silently here would rewrite the half the caller did not
/// point at, exactly as `splitBlock` refuses one for its own half.
/// * **B would have to leave a delimited container that has more content
/// after it.** That container's closers cannot move up past content
/// that is still inside it, and there is no single obvious thing to do
/// instead — split the container in two, or drag the rest out with B —
/// so this is the one shape the gesture refuses rather than guesses at.
/// * **The GAP between A and B holds anything but separation** — see
/// `gapIsClean`. The splice destroys everything between the two that
/// is on neither's chain, and a definition is not in the tree at all,
/// so nothing above can notice it. This is the guard, and it is read
/// off the SOURCE for that reason.
///
/// `error.InvalidRange` when `offset` is past the source.
///
/// `error.UnsupportedFormat` when the format has no `Syntax.line_join`,
/// checked FIRST, before a byte of source is read: a join writes a line
/// break INSIDE a block, which is a spelling and not a universal. It is a
/// different gate from `splitBlock`'s `block_separator` and deliberately a
/// wider one — HTML has no blank-line block separator and so cannot be
/// split, while a newline inside its `<p>` is precisely what a join needs.
pub fn joinBlocks(self: *Editor, offset: usize) Error!void {
const join = self.syntax.line_join orelse return error.UnsupportedFormat;
const src = self.sourceBytes();
if (offset > src.len) return error.InvalidRange;
const doc = &self.splicer.doc;
const allocator = self.splicer.allocator;
// A caret in a TABLE, before B is looked for at all. A pipe table's
// cell holds its text directly, with no `para` under it, so the
// `innermostBlock` below would answer `null` there and the refusal
// would come back as `NoBlock` — "there is nothing here", about a
// caret sitting in plain view inside a cell. `lineOwningBlock` stops
// at the table (a `cell` is deliberately not a block parent), which
// makes this the same position answer for every format, whether or
// not its cells wrap their content in a block.
if (locate.lineOwningBlock(doc, offset)) |lb| {
if (std.meta.activeTag(doc.ast.nodes[lb.block].kind) == .table) return error.NotEditable;
}
const b = locate.innermostBlock(doc, offset) orelse return error.NoBlock;
if (isSetextHeading(doc, b)) return error.NotEditable;
var b_chain: std.ArrayList(AST.Node.Id) = .empty;
defer b_chain.deinit(allocator);
if (!try nodePath(allocator, doc, b, &b_chain)) return error.NoBlock;
if (passesThroughTable(doc, b_chain.items)) return error.NotEditable;
const a = precedingLeafBlock(doc, b) orelse return error.NoBlock;
switch (std.meta.activeTag(doc.ast.nodes[a].kind)) {
.para, .heading => {},
else => return error.NotEditable,
}
var a_chain: std.ArrayList(AST.Node.Id) = .empty;
defer a_chain.deinit(allocator);
if (!try nodePath(allocator, doc, a, &a_chain)) return error.NotEditable;
if (passesThroughTable(doc, a_chain.items)) return error.NotEditable;
// Where the two chains diverge. Both start at the root and neither is a
// prefix of the other — A is a leaf, so B cannot be inside it, and B is
// not A — so this index exists in both. It is never 0: the root is the
// first element of both chains, so the loop below runs at least once.
// Running off the end of either chain would mean one block is inside
// the other, which the two facts above rule out; refusing beats
// indexing past the end should a future kind make it reachable.
var i: usize = 0;
while (i < a_chain.items.len and i < b_chain.items.len and
a_chain.items[i] == b_chain.items[i]) i += 1;
if (i >= a_chain.items.len or i >= b_chain.items.len) return error.NotEditable;
const a_top = a_chain.items[i];
const b_top = b_chain.items[i];
// Everything between the two that is on neither chain is about to be
// destroyed. This is the one guard against that, and the shapes it
// catches are ones no walk above could have — see `gapIsClean`.
if (!gapIsClean(doc, src, a_chain.items[0..i], a_top, b_top)) return error.NotEditable;
// B's own closing markup goes; a delimited container it is leaving
// takes its closers with it, and the OUTERMOST such container is the
// one whose span bounds the removal.
var r_end = doc.span(b).end;
for (b_chain.items[i .. b_chain.items.len - 1]) |id| {
// Delimited by what it WRITES, not by its kind: HTML's
// `<blockquote>` and `<ul>`, and AsciiDoc's `____`, close with
// markup a quote or list spelled by line prefixes never has.
if (!writesClosers(doc, src, id)) continue;
// Nothing may be left behind inside a container whose closers are
// about to move up past it.
if (lastLeafBlock(doc, id) != b) return error.NotEditable;
r_end = doc.span(id).end;
break;
}
// B leaving a PREFIX container that goes on after it leaves behind the
// container's blank line that separated B from what followed — `>`,
// still carrying the prefix. With B gone, that line separates A from
// the rest of the container, and A is outside it: kept as it was, it
// is no separator at all where A sits, and a format whose paragraphs
// run to a blank line (djot) reads the rest of the quote into A. It
// is taken with B and written back as a blank line at A's level.
var separate_rest = false;
if (b_top != b and r_end == doc.span(b).end) {
// `lineEndAt` answers one past the line's `\n`.
const line_start = if (r_end > 0 and src[r_end - 1] == '\n') r_end else locate.lineEndAt(src, r_end);
const line_end = locate.lineEndAt(src, line_start);
if (line_start < src.len and line_end < doc.span(b_top).end) {
const line = locate.lineBody(src[line_start..line_end]);
var k: usize = 0;
while (skipQuoteMarker(line, k)) |j| k = j;
if (k > 0 and std.mem.trim(u8, line[k..], " \t").len == 0) {
r_end = line_end;
separate_rest = true;
}
}
}
const a_content = blockContent(doc, a);
const b_content = blockContent(doc, b);
const a_tail = trimTailSeparators(src[a_content.end..doc.span(a_top).end]);
const b_text = src[b_content.start..b_content.end];
var out: std.ArrayList(u8) = .empty;
defer out.deinit(allocator);
// A heading written with a leading marker is ONE LINE, so what
// continues it is a space, not a line end. `markerSpan` is the whole
// test: an HTML `<h1>` has no marker and takes the line end, and
// `<h1>a\nb</h1>` is the one heading it should be.
if (std.meta.activeTag(doc.ast.nodes[a].kind) == .heading and doc.markerSpan(a) != null) {
try out.append(allocator, ' ');
// B may be several lines; the heading is one. Each of B's line
// ends becomes the space that continues the sentence, or `# T` +
// `xx`/`yy` would be a heading `# T xx` with `yy` left below it
// as a paragraph — two blocks, from a gesture that reports having
// made one.
try appendAsOneLine(allocator, b_text, &out);
} else {
try out.appendSlice(allocator, join);
_ = try locate.continuationPrefix(allocator, doc, a_content.start, &out);
try appendAsContinuation(allocator, self.syntax, b_text, &out);
}
try out.appendSlice(allocator, a_tail);
// The removed region ran to the end of a line in every format whose
// block span covers its own terminator (djot's does, Markdown's does
// not), and A's tail only ends at one when A's container did. Put the
// terminator back when B's removal took it and the tail did not supply
// it, so the document keeps the line structure it had. `out` is never
// empty — the separator above is at least one byte — but the index is
// guarded rather than argued, since a `line_join` of `""` would make
// the argument false and the panic real.
if (r_end > a_content.end and src[r_end - 1] == '\n' and
(out.items.len == 0 or out.items[out.items.len - 1] != '\n')) try out.append(allocator, '\n');
if (separate_rest) {
if (out.items.len == 0 or out.items[out.items.len - 1] != '\n') try out.append(allocator, '\n');
var prefix: std.ArrayList(u8) = .empty;
defer prefix.deinit(allocator);
_ = try locate.continuationPrefix(allocator, doc, a_content.start, &prefix);
try out.appendSlice(allocator, std.mem.trimEnd(u8, prefix.items, " "));
try out.append(allocator, '\n');
}
return self.commitSplice(a_content.end, r_end, out.items);
}
// ── Moving a block ───────────────────────────────────────────────────────
/// Move the block at `from` to the boundary `to` names, spelling the line
/// prefixes of the container it lands in — a drag-and-drop, or Alt+↑/↓,
/// in a host that has a caret and no tree.
///
/// The splicer's `moveNode` reorders two nodes by their bytes, and says so:
/// a quote's `> ` does not travel, a list item's continuation indent is
/// not written. That is right for an XML element and wrong for every drop
/// that restructures prose — a paragraph dragged out of a quote keeps its
/// `> ` and is still a quote, one dragged under a list item's text lands
/// at column zero and ends the list. Which prefix a line needs where is
/// the per-format knowledge `toggleBlockContainer` and
/// `locate.continuationPrefix` already hold, and this is the gesture that
/// applies it to a move.
///
/// ── The block ──────────────────────────────────────────────────────────
/// `from` names the deepest block owning the line it is on — the
/// `para`/`heading` `setBlock` acts on, or the code block, table or rule
/// where there is no text block — widened to the LIST ITEM when it is the
/// item's first block: a bullet's text is the bullet, and dragging it
/// takes the item and everything under it. A block later in an item's tail
/// moves alone. `error.NoBlock` on a blank line.
///
/// ── The boundary ───────────────────────────────────────────────────────
/// `to` is a position BETWEEN blocks: at or before a block's first content
/// byte (before it), at or after its last (after it), on a blank line, or
/// the source's length (the document's end, whether or not the last line
/// is terminated). The block lands there and takes the prefixes of the
/// container that boundary is inside — the innermost one, so `to` at the
/// first content byte of a quote's first paragraph is inside the quote,
/// and a block moved there is quoted. `error.NotEditable` for a `to`
/// interior to a block — inside a fence, a table, a paragraph's second
/// line — as `setBlock` answers for a blank line there;
/// `error.InvalidArgument` for a `to` inside the block being moved, or at
/// a boundary it already sits on, which would move nothing.
///
/// A boundary at a container's edge is two boundaries — before its first
/// block and before the container, after its last and after the
/// container — and each is spelled:
///
/// * At the container's OPENING — at or before its marker, or at the
/// first byte of a delimited container's opening line — is before
/// the container, at its parent's level; the first content byte is
/// inside it. `> > a` at 0 is before both quotes, at 2 before the
/// inner one alone, and at 4 inside both. This is the one offset that
/// can name "above" a quote nothing precedes.
/// * A boundary the block already sits on, when the block is the
/// container's first or last, is read as the boundary before or after
/// the CONTAINER: the last block of a quote dropped at its own end —
/// the one offset that is both after it and after the quote — or on
/// the blank line after the quote, leaves the quote; its first block
/// dropped at its own start leaves it upward. A block between two
/// others has only its own boundary there, and moves nothing.
///
/// Two adjustments where a list item is involved, both because a list holds
/// items and nothing else:
///
/// * A boundary BEFORE an item's first block is before the ITEM, at the
/// list's level — a block dropped above a bullet's text is above the
/// bullet, not the bullet's new text. A boundary after an item's last
/// block is inside the item, which is how a block reaches an item's
/// tail (`to` at the end of the item's text).
/// * A moved ITEM is always a sibling: dropped anywhere inside another
/// item it lands after that item (before it, for the boundary above),
/// and it stays a bullet wherever else it lands — a one-item list
/// between two paragraphs, a quoted bullet in a quote. Nesting one
/// under another is `toggleBlockContainer`'s to spell.
///
/// ── What is written ────────────────────────────────────────────────────
/// One splice covering the block's old lines and the boundary. The block's
/// lines are taken whole — stripped of every prefix its old containers put
/// on them (the ancestors' markers on its first line, their continuation
/// width on the rest, read off the marker spans the way
/// `locate.continuationPrefix` reads them) and written behind the
/// destination chain's own. The separator lines that kept it apart from
/// its old neighbours go with it, so no doubled blank line is left where
/// it was, and a quote or list it was the only content of goes too rather
/// than standing empty. At the destination it is blank-separated from
/// whatever it lands beside (`block_separator` after the container's
/// blank-line prefix, so `>` inside a quote), except between items of a
/// tight list — where a blank would loosen the list — and in a format that
/// separates blocks by nothing (HTML). A format that attaches a block to
/// an item by a line of its own (`Syntax.list_attach`, AsciiDoc's `+`)
/// gets that line in place of the blank, and the block at column zero.
///
/// Within one container the result is what `Splicer.moveNode` writes:
/// the same lines, in the new order, with the same separators.
///
/// `error.NotEditable` also when the block shares a line with something
/// else — an HTML `<p>` written beside another on one line — since what
/// moves is lines. `error.InvalidRange` past the source.
pub fn moveBlock(self: *Editor, from: usize, to: usize) Error!void {
if (!supports(self.syntax, .move_block)) return error.UnsupportedFormat;
const src = self.sourceBytes();
if (from > src.len or to > src.len) return error.InvalidRange;
const doc = &self.splicer.doc;
const allocator = self.splicer.allocator;
const unit = movableUnit(doc, from) orelse return error.NoBlock;
var unit_chain: std.ArrayList(AST.Node.Id) = .empty;
defer unit_chain.deinit(allocator);
if (!try nodePath(allocator, doc, unit, &unit_chain)) return error.NoBlock;
const ancestors = unit_chain.items[0 .. unit_chain.items.len - 1];
const lines = try unitLines(doc, unit, ancestors);
// Strictly inside the block's own text — its content, or for an
// item everything behind its marker up to its last byte, a line end
// aside. Its edges are boundaries.
const own = if (isListItem(doc.ast.nodes[unit].kind)) blk: {
const sp = doc.span(unit);
var end = sp.end;
if (end > sp.start and src[end - 1] == '\n') end -= 1;
break :blk Span.init(if (doc.markerSpan(unit)) |m| m.end else sp.start, end);
} else blockContent(doc, unit);
if (to > own.start and to < own.end) return error.InvalidArgument;
const unit_is_item = isListItem(doc.ast.nodes[unit].kind);
var dest = try resolveBoundary(allocator, self.syntax, doc, to, unit);
// The prefix every moved line takes: the destination chain's, minus a
// list item where the format attaches by a line rather than an indent.
var dest_chain: std.ArrayList(AST.Node.Id) = .empty;
defer dest_chain.deinit(allocator);
if (!try nodePath(allocator, doc, dest.container, &dest_chain)) return error.NotEditable;
for (dest_chain.items) |id| if (id == unit) return error.InvalidArgument;
// A boundary on the separator lines that leave with the block — the
// blank line after a quote the block was the only content of — is
// the boundary where those lines were.
const removal = removalLines(self.syntax, doc, unit_chain.items, lines);
if (dest.pos > removal.start and dest.pos < removal.end) dest.pos = removal.start;
var dest_walk: std.ArrayList(AST.Node.Id) = .empty;
defer dest_walk.deinit(allocator);
try prefixChain(allocator, self.syntax, doc, dest_chain.items, &dest_walk);
var prefix: std.ArrayList(u8) = .empty;
defer prefix.deinit(allocator);
_ = try locate.continuationPrefixAlong(allocator, doc, dest_walk.items, &prefix);
const blank_prefix = std.mem.trimEnd(u8, prefix.items, " \t");
// The line that keeps the block apart from a neighbour in its new
// container, or nothing where the format has no such line.
var sep: std.ArrayList(u8) = .empty;
defer sep.deinit(allocator);
const separates = self.syntax.block_separator != null and
!(unit_is_item and isTightList(doc.ast.nodes[dest.container].kind));
if (separates) {
try sep.appendSlice(allocator, blank_prefix);
if (self.syntax.list_attach) |attach| {
if (isListItem(doc.ast.nodes[dest.container].kind)) try sep.appendSlice(allocator, attach);
}
try sep.appendSlice(allocator, self.syntax.block_separator.?);
}
// The prefix the block's OLD containers put on its lines, to strip.
var old_walk: std.ArrayList(AST.Node.Id) = .empty;
defer old_walk.deinit(allocator);
try prefixChain(allocator, self.syntax, doc, ancestors, &old_walk);
var old_prefix: std.ArrayList(u8) = .empty;
defer old_prefix.deinit(allocator);
const old_cols = try locate.continuationPrefixAlong(allocator, doc, old_walk.items, &old_prefix);
const own_start = if (doc.markerSpan(unit)) |m| m.start else blockContent(doc, unit).start;
var out: std.ArrayList(u8) = .empty;
defer out.deinit(allocator);
// A tight item's bare text takes a paragraph around it where a block
// joins it in a format whose paragraphs are delimited: `<li>x</li>`
// gaining a `<p>` under it is `<li><p>x</p><p>y</p></li>`, which is
// what its list being loose means there, and what the parser reads
// as a paragraph without its tags is exactly a paragraph whose span
// is its content. A format that separates blocks by a line has
// nothing to wrap — Markdown's `- x` is a tight item's spelling and a
// loose one's alike.
var rewrap: ?Span = null;
var rewrapped: Writer.Allocating = .init(allocator);
defer rewrapped.deinit();
if (self.syntax.block_separator == null and isListItem(doc.ast.nodes[dest.container].kind)) {
if (dest.prev) |p| if (isBareParagraph(doc, p)) {
rewrap = try self.rewrapBlock(p, &rewrapped.writer);
};
}
// Three edits, at most, applied in source order over the one region
// they span: the removal, the rewrap, and the insertion at `pos`. The
// kept bytes between them are copied through, so the whole move is
// one splice — one reparse, one undo step.
var edits: [3]MoveEdit = undefined;
var n: usize = 0;
edits[n] = .{ .span = removal, .kind = .removal };
n += 1;
if (rewrap) |r| {
edits[n] = .{ .span = r, .kind = .rewrap };
n += 1;
}
edits[n] = .{ .span = Span.init(dest.pos, dest.pos), .kind = .insert };
n += 1;
std.mem.sort(MoveEdit, edits[0..n], {}, MoveEdit.before);
const region_start = edits[0].span.start;
const region_end = edits[n - 1].span.end;
var scratch: std.ArrayList(u8) = .empty;
defer scratch.deinit(allocator);
var cur = region_start;
for (edits[0..n], 0..) |e, i| {
if (e.span.start < cur) return error.NotEditable;
try out.appendSlice(allocator, src[cur..e.span.start]);
cur = e.span.end;
switch (e.kind) {
.removal => {},
.rewrap => try out.appendSlice(allocator, std.mem.trimEnd(u8, rewrapped.written(), "\r\n")),
.insert => {
// What precedes the insertion once the edits before it
// are applied, and what follows it: the two lines the
// separators are decided against.
const before = try lastLineOf(allocator, src[0..region_start], out.items, &scratch);
if (!before.terminated) try out.append(allocator, '\n');
if (separates and dest.prev != null and !before.empty and !isSeparatorLine(self.syntax, before.body)) {
try out.appendSlice(allocator, sep.items);
}
try self.appendMovedLines(&out, lines, ancestors, unit_is_item, dest.container, old_cols, own_start, prefix.items, blank_prefix);
const rest_to = if (i + 1 < n) edits[i + 1].span.start else src.len;
const rest_from = if (i + 1 < n) edits[i + 1].span.end else src.len;
const after = firstLineOf(src[e.span.end..rest_to], src[rest_from..]);
if (separates and dest.next != null and after.len != 0 and !isSeparatorLine(self.syntax, after)) {
try out.appendSlice(allocator, sep.items);
}
},
}
}
try out.appendSlice(allocator, src[cur..region_end]);
// A document that did not end in a line end does not gain one for a
// block landing at its end.
if (region_end == src.len and src.len > 0 and src[src.len - 1] != '\n' and
out.items.len > 0 and out.items[out.items.len - 1] == '\n') out.items.len -= 1;
return self.commitSplice(region_start, region_end, out.items);
}
/// One of `moveBlock`'s edits, in source order.
const MoveEdit = struct {
span: Span,
kind: enum { removal, rewrap, insert },
/// Source order; an insertion at the start of a removal goes first,
/// since it lands where the removed lines began.
fn before(_: void, a: MoveEdit, b: MoveEdit) bool {
if (a.span.start != b.span.start) return a.span.start < b.span.start;
return a.span.end < b.span.end;
}
};
/// The block's lines, each behind the destination prefix, appended to
/// `out`. An item landing outside a list brings its list's own opening
/// and closing lines with it — the bytes a list has apart from its items,
/// which is `<ul>`/`</ul>` in HTML and nothing in a format whose list is
/// spelled by its items' markers.
fn appendMovedLines(
self: *Editor,
out: *std.ArrayList(u8),
lines: Span,
ancestors: []const AST.Node.Id,
unit_is_item: bool,
container: AST.Node.Id,
old_cols: usize,
own_start: usize,
prefix: []const u8,
blank_prefix: []const u8,
) Allocator.Error!void {
const allocator = self.splicer.allocator;
const doc = &self.splicer.doc;
const src = doc.source;
var wrap: ListWrap = .{};
if (unit_is_item and !isList(doc.ast.nodes[container].kind)) {
wrap = listWrap(doc, ancestors[ancestors.len - 1], lines);
}
var first = true;
for ([_]Span{ wrap.open, lines, wrap.close }) |part| {
var at = part.start;
while (at < part.end) {
const le = locate.lineEndAt(src, at);
const body = locate.lineBody(src[at..le]);
var strip = stripColumns(body, old_cols);
if (first) {
// Its first line also sheds the markers its ancestors open
// there, which may reach past their continuation width —
// an outer item's `- ` ahead of the inner item being moved.
for (ancestors) |a| {
if (doc.markerSpan(a)) |m| {
if (m.start >= at and m.start < le and m.end - at > strip) strip = m.end - at;
}
}
if (own_start > at and own_start - at < strip) strip = own_start - at;
}
const rest = body[strip..];
if (locate.isBlankLine(rest)) {
try out.appendSlice(allocator, blank_prefix);
} else {
try out.appendSlice(allocator, prefix);
try out.appendSlice(allocator, rest);
}
try out.append(allocator, '\n');
first = false;
at = le;
}
}
}
/// Print `block` through the format's renderer into `w`, returning the
/// span the print replaces. `error.UnsupportedFormat` with no renderer,
/// which `supports` rules out for the one format this is reached in.
fn rewrapBlock(self: *Editor, block: AST.Node.Id, w: *Writer) Error!Span {
const render = self.syntax.renderBlock orelse return error.UnsupportedFormat;
const doc = &self.splicer.doc;
const allocator = self.splicer.allocator;
var b = AST.Builder.init(allocator);
defer b.deinit();
const root = try b.graftSubtree(&doc.ast, block);
const view = b.view(root);
try renderNode(allocator, render, &view, root, w);
return doc.span(block);
}
// ── Code blocks ──────────────────────────────────────────────────────────
/// Toggle a fenced code block over the blocks `[start, end)` covers: fence
/// them if the caret isn't in a code block, unfence the one it is in if it
/// is. `lang` is the info string to tag the opening fence with, ignored when
/// unfencing.
///
/// Fencing is an INSERTION at the covered region's edges, not a rewrite of
/// its lines: the body is source that already parsed where it sits, and its
/// enclosing container's prefix is already on its lines, so leaving them
/// alone is what keeps a fence inside a quote working (`> a` becomes
/// `` > ``` ``/`> a`/`` > ``` ``). Only the two fence lines are minted, and
/// they carry the containers' prefix so the block stays inside them.
///
/// INSIDE A LIST ITEM that prefix is not on every line: an item holds its
/// content by INDENTATION to its content column, and its marker is on its
/// first line alone. So the first line's HEAD — every marker opening on it,
/// `- `, `1. `, `> - `, a task item's `- [ ] ` — moves onto the opening
/// fence, and the body's first line takes the continuation in its place:
/// `- a` becomes `` - ``` ``/` a`/`` ``` `` two columns in. The fence sits
/// at the item's content column and the block stays the item's; a fence at
/// column zero would have swallowed the `- ` into the code body instead. A
/// task item's content column is its list marker's, not its box's — the box
/// stays on the fence line and the item stays a task. The one other line
/// rewritten is a LAZY one, a paragraph continuation that left its
/// containers' prefix off: a code body cannot, so it is given it.
///
/// Where the format attaches a block to an item by a line of its own
/// (`Syntax.list_attach`, AsciiDoc's `+`), an attached block's lines are at
/// column zero and fence there. The item's own first line is its principal
/// text, where a fence is only more text, so that is `error.NotEditable`.
///
/// The fence is measured, not fixed: it is one byte longer than the longest
/// run of the fence character anywhere in the body, so fencing text that
/// itself holds a fence nests instead of closing early. `CodeFence.min` is
/// the floor.
///
/// Unfencing peels the opening line and — when it is one — the closing fence
/// line, leaving the interior verbatim but for its first line, which takes
/// the opening line's head back in place of its continuation: `- ```` over
/// ` a` is `- a` again. An item's first line is never left blank where
/// something follows (an item opening on a blank line holds nothing past
/// the next blank one): the body's leading blank lines are passed over,
/// and an empty body keeps the item, empty, with a block after it in the
/// item brought up under the marker. A Markdown INDENTED code block has no
/// fences to peel, so it is dedented by up to four spaces a line instead;
/// that is the same construct with a different spelling, and refusing it
/// would make the toggle irreversible on a document that merely happens to
/// use the older form.
///
/// Unfencing is the one gesture here that can produce something other than
/// what it removed: a code body is by definition text the parser did not
/// read as markup, so `# x` inside a fence becomes a heading once the fence
/// is gone. That is what unfencing MEANS, not a defect — but it is why this
/// is a toggle over whole blocks rather than an "unwrap" that promises to
/// give the same tree back.
///
/// TWO SPELLINGS, in `setBlock`'s order: the fence above where the format
/// has one, and where it has none but carries a `renderBlock`, a
/// `code_block` node the format prints — see `toggleCodeBlockByRender`.
pub fn toggleCodeBlock(self: *Editor, span: Span, lang: ?[]const u8) Error!void {
try self.checkRange(span.start, span.end);
const fence = self.syntax.code_fence orelse {
if (self.syntax.renderBlock) |render| return self.toggleCodeBlockByRender(span, lang, render);
return error.UnsupportedFormat;
};
if (lang) |l| try checkInfoString(fence, l);
const allocator = self.splicer.allocator;
const src = self.sourceBytes();
const doc = &self.splicer.doc;
var chain: std.ArrayList(AST.Node.Id) = .empty;
defer chain.deinit(allocator);
try locate.ancestorChain(allocator, doc, span.start, &chain);
var out: std.ArrayList(u8) = .empty;
defer out.deinit(allocator);
if (locate.innermostOfKind(doc, chain.items, .code_block)) |cb| {
const at = std.mem.indexOfScalar(AST.Node.Id, chain.items, cb).?;
var frame = try CodeFrame.init(allocator, self.syntax, doc, chain.items[0..at]);
defer frame.deinit(allocator);
const b = doc.span(cb);
const region_start = locate.lineStartAt(src, b.start);
const region_end = locate.lineEndAt(src, b.end -| 1);
const end = try buildUnfence(allocator, doc, &frame, cb, region_start, region_end, fence, &out);
return self.commitSplice(region_start, end, out.items);
}
const blocks = coveredBlocks(allocator, doc, span.start, span.end) catch |err| switch (err) {
error.OutOfMemory => return error.OutOfMemory,
else => return error.NoBlock,
};
defer allocator.free(blocks.chain);
const region_start = locate.lineStartAt(src, doc.span(blocks.first).start);
const region_end = locate.lineEndAt(src, doc.span(blocks.last).end -| 1);
const at = std.mem.indexOfScalar(AST.Node.Id, blocks.chain, blocks.first) orelse return error.NoBlock;
var frame = try CodeFrame.init(allocator, self.syntax, doc, blocks.chain[0..at]);
defer frame.deinit(allocator);
// An item's own first line, where the format attaches its blocks by a
// line rather than an indent: that line is the item's principal text,
// and a fence written after its marker is text too — refused rather
// than mangled. See the doc comment.
if (self.syntax.list_attach != null and frame.opensItem(doc, region_start)) return error.NotEditable;
const width = fenceWidth(src[region_start..region_end], fence.char, fence.min);
// The opening fence takes the first line's head — the markers opening
// there, a list item's among them — and the body's first line takes
// the continuation in its place. Where nothing opens on it, the fence
// takes the continuation and the line is like any other.
const head = frame.headLen(doc, region_start);
if (head) |h| {
try out.appendSlice(allocator, src[region_start .. region_start + h]);
} else {
try out.appendSlice(allocator, frame.prefix.items);
}
try out.appendNTimes(allocator, fence.char, width);
if (lang) |l| try out.appendSlice(allocator, l);
try out.append(allocator, '\n');
var line_start = region_start;
while (line_start < region_end) {
const line_end = locate.lineEndAt(src, line_start);
const body = locate.lineBody(src[line_start..line_end]);
const ending = src[line_start + body.len .. line_end];
const st = frame.strip(body);
if (line_start == region_start and head != null) {
try frame.writeLine(allocator, &out, 0, body[head.?..], ending);
} else if (st.full) {
try out.appendSlice(allocator, src[line_start..line_end]);
} else {
// A lazy continuation line: a paragraph may leave its
// container's prefix off, a code body may not.
try frame.writeLine(allocator, &out, 0, body[st.len..], ending);
}
line_start = line_end;
}
// An unterminated last line would otherwise fuse with the closing fence.
if (out.items[out.items.len - 1] != '\n') try out.append(allocator, '\n');
try out.appendSlice(allocator, frame.prefix.items);
try out.appendNTimes(allocator, fence.char, width);
try out.append(allocator, '\n');
return self.commitSplice(region_start, region_end, out.items);
}
/// Retag the code block at `offset` with `lang`, or clear its info string
/// when `lang` is null — the "language" dropdown next to a code block.
///
/// Only the info string is rewritten; the fence's own width is kept, because
/// it was measured against a body this gesture doesn't touch. An INDENTED
/// Markdown code block is `error.NotEditable`: it has no fence, so it has
/// nowhere to carry a language (convert it with `toggleCodeBlock` twice).
///
/// Where the format has no fence but a `renderBlock`, the block is
/// rebuilt with the new language and printed — see
/// `setCodeLanguageByRender`.
pub fn setCodeLanguage(self: *Editor, offset: usize, lang: ?[]const u8) Error!void {
const fence = self.syntax.code_fence orelse {
if (self.syntax.renderBlock) |render| return self.setCodeLanguageByRender(offset, lang, render);
return error.UnsupportedFormat;
};
if (lang) |l| try checkInfoString(fence, l);
const src = self.sourceBytes();
if (offset > src.len) return error.InvalidRange;
const allocator = self.splicer.allocator;
const doc = &self.splicer.doc;
var chain: std.ArrayList(AST.Node.Id) = .empty;
defer chain.deinit(allocator);
try locate.ancestorChain(allocator, doc, offset, &chain);
const cb = locate.innermostOfKind(doc, chain.items, .code_block) orelse return error.NoBlock;
const line_start = locate.lineStartAt(src, doc.span(cb).start);
const line = src[line_start..locate.lineEndAt(src, line_start)];
const f = fenceAt(line, fence.char, fence.min) orelse return error.NotEditable;
const info_start = line_start + f.start + f.width;
const info_end = line_start + locate.lineBody(line).len;
return self.commitSplice(info_start, info_end, lang orelse "");
}
/// `toggleCodeBlock` over a format with no fence but a fragment renderer:
/// BUILD the code block and let the format print it, or take one apart.
///
/// The fence path works on SOURCE — the covered lines go inside the fence
/// verbatim, and unfencing gives them back — because in a lightweight
/// format a paragraph's source is its text. Here it is not (`<p>a
/// & b</p>`), so the payload is the covered blocks' TEXT
/// (`blockTextInto`): the selection's words, with its marks dropped, is
/// what a listing made from prose holds. And toggling OFF puts the
/// listing's text under a paragraph the format prints, so `a < b` reads
/// back as those five characters and mints no markup — the one thing the
/// fence path's "unfencing means the body is read as source" cannot
/// promise, and the reason this direction is a render too.
///
/// A paragraph in, the same paragraph out: toggle twice on plain prose and
/// the document is what it was. Prose carrying marks loses them on the way
/// in, which is what a code block MEANS.
///
/// Nothing here is about a list item: a wrapping pair has no column to
/// keep, where a fence has its item's content column.
fn toggleCodeBlockByRender(self: *Editor, span: Span, lang: ?[]const u8, render: RenderBlockFn) Error!void {
if (lang) |l| try checkLanguageToken(l);
const allocator = self.splicer.allocator;
const src = self.sourceBytes();
const doc = &self.splicer.doc;
const ast = self.astView();
var chain: std.ArrayList(AST.Node.Id) = .empty;
defer chain.deinit(allocator);
try locate.ancestorChain(allocator, doc, span.start, &chain);
if (locate.innermostOfKind(doc, chain.items, .code_block)) |cb| {
var b = AST.Builder.init(allocator);
defer b.deinit();
const text = try b.addLeaf(.{ .str = ast.nodes[cb].kind.code_block.text });
const root = try b.addContainer(.para, &.{text});
const t = doc.span(cb);
return self.spliceRendered(&b, root, render, t.start, blockSpanEnd(src, t));
}
const blocks = coveredBlocks(allocator, doc, span.start, span.end) catch |err| switch (err) {
error.OutOfMemory => return error.OutOfMemory,
else => return error.NoBlock,
};
defer allocator.free(blocks.chain);
var text: std.ArrayList(u8) = .empty;
defer text.deinit(allocator);
var cur: ?AST.Node.Id = blocks.first;
while (cur) |c| : (cur = if (c == blocks.last) null else ast.nodes[c].next_sibling) {
if (c != blocks.first) try text.append(allocator, '\n');
try blockTextInto(allocator, ast, c, &text);
}
var b = AST.Builder.init(allocator);
defer b.deinit();
const root = try b.addLeaf(.{ .code_block = .{ .lang = lang, .text = text.items } });
const first = doc.span(blocks.first);
const last = doc.span(blocks.last);
return self.spliceRendered(&b, root, render, first.start, blockSpanEnd(src, last));
}
/// `setCodeLanguage` over a format with no fence but a fragment renderer:
/// the block is rebuilt with `lang` over the same text — its attributes
/// along — and printed in its place.
fn setCodeLanguageByRender(self: *Editor, offset: usize, lang: ?[]const u8, render: RenderBlockFn) Error!void {
if (lang) |l| try checkLanguageToken(l);
const src = self.sourceBytes();
if (offset > src.len) return error.InvalidRange;
const allocator = self.splicer.allocator;
const doc = &self.splicer.doc;
const ast = self.astView();
var chain: std.ArrayList(AST.Node.Id) = .empty;
defer chain.deinit(allocator);
try locate.ancestorChain(allocator, doc, offset, &chain);
const cb = locate.innermostOfKind(doc, chain.items, .code_block) orelse return error.NoBlock;
var b = AST.Builder.init(allocator);
defer b.deinit();
const root = try b.addLeaf(.{ .code_block = .{ .lang = lang, .text = ast.nodes[cb].kind.code_block.text } });
if (ast.nodes[cb].attrs) |ai| try b.setAttrs(root, ast.attrs[ai]);
const t = doc.span(cb);
return self.spliceRendered(&b, root, render, t.start, blockSpanEnd(src, t));
}
// ── Task list checkboxes ─────────────────────────────────────────────────
// A checkbox is not a node an editor wraps a range in: it is a marker on an
// ITEM, so every gesture here is addressed by a caret `offset` and edits the
// few bytes after that item's list marker. Nothing else on the line moves —
// in particular the box is INLINE CONTENT of the item's first paragraph, not
// part of the marker, so adding or removing one leaves the item's
// continuation-line indentation alone (unlike `toggleBlockContainer`, which
// has to re-indent).
/// Add a checkbox to the list item at `offset`, or take one away — the
/// gesture that converts between a `list_item` and a `task_list_item`. A box
/// is added UNCHECKED; use `setTaskChecked` to tick it.
///
/// `error.NoBlock` when `offset` is in no list item, `error.NotEditable`
/// when the item's line carries no recognizable list marker to hang a box
/// off (a lazy continuation line).
pub fn toggleTaskItem(self: *Editor, offset: usize) Error!void {
const tm = self.syntax.task_marker orelse return error.UnsupportedFormat;
const found = try self.locateTaskBox(offset);
if (found.box) |b| return self.commitSplice(b.start, b.end + found.space, "");
const allocator = self.splicer.allocator;
var out: std.ArrayList(u8) = .empty;
defer out.deinit(allocator);
try out.appendSlice(allocator, tm.unchecked);
try out.appendSlice(allocator, tm.space);
return self.commitSplice(found.at, found.at, out.items);
}
/// Tick or untick the task item at `offset` — a click on the checkbox.
///
/// Rewrites the BOX ALONE, never the space after it, so an item spelled with
/// unusual spacing keeps it. A no-op (no edit, no undo step) when the box is
/// already in the requested state. `error.NotEditable` when the item has no
/// box: minting one here would make a "set checked" call silently convert a
/// bullet into a task, which is `toggleTaskItem`'s job to do explicitly.
pub fn setTaskChecked(self: *Editor, offset: usize, checked: bool) Error!void {
const tm = self.syntax.task_marker orelse return error.UnsupportedFormat;
const found = try self.locateTaskBox(offset);
const b = found.box orelse return error.NotEditable;
if (found.checked == checked) return;
return self.commitSplice(b.start, b.end, if (checked) tm.checked else tm.unchecked);
}
/// Flip the task item at `offset` — `setTaskChecked` against its current
/// state, which is what a checkbox click actually is when the caller doesn't
/// already know the state.
pub fn toggleTaskChecked(self: *Editor, offset: usize) Error!void {
if (self.syntax.task_marker == null) return error.UnsupportedFormat;
const found = try self.locateTaskBox(offset);
if (found.box == null) return error.NotEditable;
return self.setTaskChecked(offset, !found.checked);
}
/// Where the checkbox on the list item at `offset` is, or would go. The
/// shared body of the three gestures above.
fn locateTaskBox(self: *Editor, offset: usize) Error!TaskBox {
const src = self.sourceBytes();
if (offset > src.len) return error.InvalidRange;
const tm = self.syntax.task_marker orelse return error.UnsupportedFormat;
const allocator = self.splicer.allocator;
const doc = &self.splicer.doc;
var chain: std.ArrayList(AST.Node.Id) = .empty;
defer chain.deinit(allocator);
try locate.ancestorChain(allocator, doc, offset, &chain);
// The innermost item of EITHER kind, walked directly rather than through
// two `innermostOfKind` calls: a plain item can gain a box and a task
// item can lose one, so both are targets and whichever is deeper wins.
var item: ?AST.Node.Id = null;
var i = chain.items.len;
while (i > 0) {
i -= 1;
switch (std.meta.activeTag(doc.ast.nodes[chain.items[i]].kind)) {
.list_item, .task_list_item => {
item = chain.items[i];
break;
},
else => {},
}
}
const id = item orelse return error.NoBlock;
// The item's FIRST line, which is the only one a marker can open. Djot
// starts a quoted item at its marker and Markdown at column 0, so the
// line start is taken from the span rather than the span itself.
const line_start = locate.lineStartAt(src, doc.span(id).start);
const line = src[line_start..locate.lineEndAt(src, line_start)];
var from: usize = 0;
while (skipQuoteMarker(line, from)) |j| from = j;
const m = listMarkerAt(line, from) orelse return error.NotEditable;
const at = line_start + m.end;
const rest = line[m.end..];
const width = tm.unchecked.len;
if (rest.len >= width and rest[0] == '[' and rest[width - 1] == ']') {
// The box's INTERIOR, read rather than compared against the two
// spellings: source in the wild writes `[X]` as well as `[x]`, and a
// literal match would call the capital form "not a checkbox at all"
// and hand the caller a second box to insert beside it.
const inner = rest[1 .. width - 1];
const checked = std.mem.indexOfAny(u8, inner, tm.checked_chars) != null;
if (checked or locate.isBlankLine(inner)) return .{
.at = at,
.box = Span.init(at, at + width),
// However the author spaced it — removing the box takes the
// separator with it, ticking it leaves the separator alone.
.space = if (rest.len > width and rest[width] == ' ') 1 else 0,
.checked = checked,
};
}
return .{ .at = at, .box = null, .space = 0, .checked = false };
}
// ── Tables ───────────────────────────────────────────────────────────────
// A table is a grid, not a run of delimited text, so its edits are grid
// surgery (add/remove/move a row or column, set a column's alignment) rather
// than a toggle. The grid is lifted from the AST, mutated, and the whole
// table re-spelled in one splice — see `table_edit.zig`. Every gesture is
// addressed by a caret `offset`; the cell it lands in is the anchor.
/// Insert an empty row below (`after`) or above the caret's row.
pub fn tableInsertRow(self: *Editor, offset: usize, after: bool) Error!void {
return self.tableEdit(offset, .{ .insert_row = if (after) .after else .before });
}
/// Delete the caret's row. `error.NotEditable` for a header row or the last
/// body row (a table keeps a header and at least one body row).
pub fn tableDeleteRow(self: *Editor, offset: usize) Error!void {
return self.tableEdit(offset, .delete_row);
}
/// Insert an empty column right (`after`) or left of the caret's column.
pub fn tableInsertColumn(self: *Editor, offset: usize, after: bool) Error!void {
return self.tableEdit(offset, .{ .insert_column = if (after) .after else .before });
}
/// Delete the caret's column. `error.NotEditable` when it is the only one.
pub fn tableDeleteColumn(self: *Editor, offset: usize) Error!void {
return self.tableEdit(offset, .delete_column);
}
/// Set the caret's column to `alignment`.
pub fn tableSetAlignment(self: *Editor, offset: usize, alignment: AST.Alignment) Error!void {
return self.tableEdit(offset, .{ .set_alignment = alignment });
}
/// Move the caret's row one place down (`down`) or up, within the body rows.
pub fn tableMoveRow(self: *Editor, offset: usize, down: bool) Error!void {
return self.tableEdit(offset, .{ .move_row = if (down) .after else .before });
}
/// Move the caret's column one place right (`right`) or left.
pub fn tableMoveColumn(self: *Editor, offset: usize, right: bool) Error!void {
return self.tableEdit(offset, .{ .move_column = if (right) .after else .before });
}
const TableOp = union(enum) {
insert_row: table_edit.Side,
delete_row,
insert_column: table_edit.Side,
delete_column,
set_alignment: AST.Alignment,
move_row: table_edit.Side,
move_column: table_edit.Side,
};
/// Lift the table at `offset`, apply one grid op, and splice the rebuilt
/// table back — the shared body of every table gesture above.
///
/// The spelling is fetched FIRST, before the grid is extracted and long
/// before anything is spliced, and that ordering is the whole fix rather
/// than a tidiness: a format can have a table this file can READ and no
/// table it can WRITE. HTML is exactly that — `html/parser.zig` lowers
/// `<table>/<tr>/<td>` to the same `table`/`row`/`cell` nodes a pipe table
/// produces, so extraction succeeded and the rebuilt pipe text went over the
/// `<table>…</table>` region, which HTML then reparsed as a paragraph. A
/// document that still parses is one the splicer will not roll back, so the
/// table was destroyed without an error anywhere.
fn tableEdit(self: *Editor, offset: usize, op: TableOp) Error!void {
const spelling = self.syntax.table_spelling orelse return error.UnsupportedFormat;
const src = self.sourceBytes();
if (offset > src.len) return error.InvalidRange;
const allocator = self.splicer.allocator;
var grid = table_edit.extract(allocator, &self.splicer.doc, offset) catch |e| return mapTableErr(e);
defer grid.deinit();
(switch (op) {
.insert_row => |s| table_edit.insertRow(&grid, s),
.delete_row => table_edit.deleteRow(&grid),
.insert_column => |s| table_edit.insertColumn(&grid, s),
.delete_column => table_edit.deleteColumn(&grid),
.set_alignment => |a| table_edit.setAlignment(&grid, a),
.move_row => |d| table_edit.moveRow(&grid, d),
.move_column => |d| table_edit.moveColumn(&grid, d),
}) catch |e| return mapTableErr(e);
const bytes = table_edit.emit(allocator, &grid, spelling) catch |e| return mapTableErr(e);
defer allocator.free(bytes);
return self.commitSplice(grid.region.start, grid.region.end, bytes);
}
/// Map a `table_edit` error onto the `Editor` error set: "not in a table"
/// reads as no block for the gesture, a refused (degenerate) edit as not
/// editable.
fn mapTableErr(e: table_edit.Error) Error {
return switch (e) {
error.NotInTable => error.NoBlock,
error.Refused => error.NotEditable,
error.OutOfMemory => error.OutOfMemory,
};
}
// ── Links ──────────────────────────────────────────────────────────────
/// Link `[start, end)` to `destination`, or repoint the link already there.
///
/// Decisions:
/// * An EXISTING link covering the range has its destination REPLACED, its
/// text kept. Re-linking is the common gesture (fix a URL), and it keeps
/// the op idempotent instead of nesting `[[t](a)](b)`. Removing a link is
/// already `Splicer.unwrapNode`, which peels a node to its interior.
/// * A RANGE INSIDE an existing autolink re-points it the same way, but
/// there is no text to keep: an autolink's text IS its destination, so
/// the node is respelled whole for the new one (canonically — see below
/// — so a `<url>` re-pointed at a relative path becomes `[dest](dest)`,
/// not a broken `<>`). Without this the op reads the URL as ordinary text
/// and splices a link into the middle of it:
/// `<https<https://y.dev>://x.dev>`.
///
/// This covers a caret AND any selection the autolink contains —
/// including one covering it exactly. An autolink's URL is not editable
/// text: no part of it can host a `[`, so "link half this URL" has no
/// spelling, and the selection carries no text a splice could keep.
///
/// A selection that starts or ends strictly INSIDE an autolink but isn't
/// contained by it (`see <https://x` … `.dev> ok`) is refused with
/// `error.NotEditable`: half of it is real text, so there is nothing to
/// re-point, and any splice would rewrite the URL. Refusing beats
/// silently changing the caller's URL, for the same reason a newline
/// destination is `error.InvalidDestination`.
///
/// A range inside BOTH a link and an autolink (`[<https://x.dev>](d)`)
/// re-points the link, not the autolink: a link's text is separable from
/// its destination, so re-pointing it keeps text that re-pointing the
/// autolink would discard.
///
/// A range that CONTAINS an autolink whole plus text around it is
/// untouched by all of the above — it splices at the autolink's edges,
/// corrupting nothing, and the autolink stays as the new link's text.
/// * A link with NO TEXT gets the canonical spelling for the destination it
/// was given, never `[](dest)`: a childless link has nothing to render,
/// so consumers fall back to showing the destination and the caret has
/// nowhere correct to sit. Where the format can spell an autolink it gets
/// `<dest>`; where it can't it gets `[dest](dest)`, the destination
/// doubling as text so it stays visible and editable. Which destinations
/// autolink, and how each format spells one, is twig's knowledge — a
/// consumer guessing would turn `<foo>` into raw HTML (Markdown) or
/// literal text (both). See `Syntax.spellsAutolink`.
/// * A destination is escaped per format (see `writeLinkDestination`); a
/// newline in one is `error.InvalidDestination`, since neither format can
/// hold it (Djot strips it, Markdown's `<…>` form forbids it) and
/// silently changing the caller's URL is worse than refusing.
///
/// TWO SPELLINGS, in `setBlock`'s order: `[text](dest)` from the escape
/// alphabets where the format has them, and where it has none but carries
/// a `renderBlock`, a `link` node over the selection's inline nodes that
/// the format prints — see `insertLinkByRender`.
pub fn insertLink(self: *Editor, span: Span, dest: []const u8) Error!void {
try self.checkRange(span.start, span.end);
if (std.mem.indexOfAny(u8, dest, "\r\n") != null) return error.InvalidDestination;
// A format with no link spelling refuses before anything else is read.
if (self.syntax.link_text_escapes == null) {
if (self.syntax.renderBlock) |render| return self.insertLinkByRender(span, dest, render, .link);
return error.UnsupportedFormat;
}
const start = span.start;
const end = span.end;
const allocator = self.splicer.allocator;
const src = self.sourceBytes();
const ast = self.astView();
var chain: std.ArrayList(AST.Node.Id) = .empty;
defer chain.deinit(allocator);
try locate.ancestorChain(allocator, &self.splicer.doc, start, &chain);
// The text to sit in the brackets, and the span the rebuilt link
// replaces. Re-pointing an existing link rebuilds the whole node: a
// destination is a string payload with no span of its own, so there is
// nothing smaller to splice (see `splicer.zig`'s module doc).
var text: []const u8 = src[start..end];
var target = Span.init(start, end);
var repoint = locate.innermostCovering(&self.splicer.doc, chain.items, &.{.link}, start, end);
if (repoint == null) repoint = autolinkCovering(&self.splicer.doc, chain.items, start, end);
// Not covered by an autolink, but still landing inside one: the range
// runs from ordinary text into the middle of a URL (either end can be the
// one inside). There is nothing to re-point — half the selection is real
// text — and no way to spell the result, so refuse rather than corrupt
// the URL.
if (repoint == null and start != end) {
const splits =
(try splitsAutolink(allocator, &self.splicer.doc, start)) or
(try splitsAutolink(allocator, &self.splicer.doc, end));
if (splits) return error.NotEditable;
}
if (repoint) |id| {
const node = ast.nodes[id];
const rp = self.splicer.doc.span(id);
if (rp.start == 0 and rp.end == 0) return error.NotEditable;
// An autolink has no `[text]` half: the text it shows is the OLD
// destination, so keeping it would spell the new link with the URL it
// was meant to replace. Empty text sends it through the canonical
// spelling below, exactly as a caret on bare text goes.
text = switch (node.kind) {
// An autolink's visible text IS its destination; the caller
// supplies that, so the node contributes nothing.
.text_leaf => |l| if (l.kind == .url or l.kind == .email) "" else if (self.splicer.doc.contentSpan(id)) |cs| src[cs.start..cs.end] else "",
else => if (self.splicer.doc.contentSpan(id)) |cs| src[cs.start..cs.end] else "",
};
target = rp;
}
var out: std.ArrayList(u8) = .empty;
defer out.deinit(allocator);
// Keyed on the TEXT being empty, not the range: re-pointing an existing
// `[](old)` is an empty range too, and it has the same childless link to
// avoid. A non-empty range always carries text, so it never lands here.
if (text.len == 0) {
if (self.syntax.spellsAutolink) |spells| {
try out.append(allocator, '<');
try out.appendSlice(allocator, dest);
try out.append(allocator, '>');
// Ask about the exact bytes we would emit, so the test and the
// output cannot disagree about what was spelled.
if (spells(out.items)) return self.commitSplice(target.start, target.end, out.items);
out.clearRetainingCapacity();
}
}
try out.append(allocator, '[');
if (text.len == 0) {
// `dest` is a raw string being repurposed as text, so it needs
// escaping for that position — unlike `text`, which is already source
// the author (or a prior parse) spelled and which must be copied
// through verbatim.
try writeLinkText(allocator, self.syntax, dest, &out);
} else {
try out.appendSlice(allocator, text);
}
try out.appendSlice(allocator, "](");
try writeLinkDestination(allocator, self.syntax, dest, &out);
try out.append(allocator, ')');
return self.commitSplice(target.start, target.end, out.items);
}
/// Spell `[start, end)` as an image pointing at `dest` — ``, the
/// selected source becoming the alt text.
///
/// Shares `insertLink`'s destination spelling, which is the whole reason this
/// belongs here rather than in a caller's format string: an image destination
/// is the *same grammar production* as a link's, so it needs the same
/// per-format treatment — Markdown moving a destination that holds whitespace
/// into the `<…>` form, Djot taking it bare because `<…>` means nothing there
/// and would link the literal characters. A caller spelling ``
/// by hand writes something Markdown does not read as an image at all, and
/// cannot fix without reproducing `writeLinkDestination`.
///
/// Simpler than a link in two ways. There is no autolink form to prefer and no
/// re-point reasoning: an image has no bare-URL spelling, and re-pointing an
/// existing one is `imageDestinationAt`-then-insert above this op rather than a
/// shape to detect here. And empty text stays empty — `` is a perfectly
/// good image, where the `[](dest)` that `insertLink` works to avoid is a link
/// with nothing to click.
///
/// The same two spellings as `insertLink`: where the format has no
/// alphabet but a renderer, an `image` node over the selection's inline
/// nodes — its alt text — is printed instead (`insertLinkByRender`, with
/// `.image`).
pub fn insertImage(self: *Editor, span: Span, dest: []const u8) Error!void {
try self.checkRange(span.start, span.end);
if (std.mem.indexOfAny(u8, dest, "\r\n") != null) return error.InvalidDestination;
if (self.syntax.link_text_escapes == null or self.syntax.link_dest_escapes == null) {
if (self.syntax.renderBlock) |render| return self.insertLinkByRender(span, dest, render, .image);
return error.UnsupportedFormat;
}
const allocator = self.splicer.allocator;
const src = self.sourceBytes();
// Already-parsed source, copied verbatim — the same distinction
// `insertLink` draws between a span of the document and a raw argument.
const text = src[span.start..span.end];
var out: std.ArrayList(u8) = .empty;
defer out.deinit(allocator);
try out.appendSlice(allocator, "![");
try out.appendSlice(allocator, text);
try out.appendSlice(allocator, "](");
try writeLinkDestination(allocator, self.syntax, dest, &out);
try out.append(allocator, ')');
return self.commitSplice(span.start, span.end, out.items);
}
/// `insertLink`/`insertImage` over a format with no link alphabet but a
/// fragment renderer: BUILD the node over the selection and let the format
/// print it.
///
/// The alphabet path copies the selected SOURCE between `[` and `]`, which
/// works because in a lightweight format a selection's source is text the
/// format reads back. A renderer prints a TREE, so the selection has to be
/// one: the inline nodes it covers (`coveredInlines`), grafted under a
/// fresh `link` or `image`. A selection that starts or ends inside a plain
/// text run takes the run's covered part; one that cuts through anything
/// else — a mark, a code span, a text run whose source spells characters
/// as entities so that a byte offset names no character in it — is
/// `error.NotEditable`, as a range into the middle of an autolink is on the
/// alphabet path. Refusing beats a link whose text is not what was
/// selected.
///
/// Re-pointing an existing link keeps its children and attributes and
/// replaces its destination — the alphabet path's rule, on the tree. An
/// empty selection gets a link whose text IS the destination, which is
/// the alphabet path's `[dest](dest)` for a format with no autolink form;
/// an empty selection makes an image with empty alt text, as ``
/// does.
fn insertLinkByRender(
self: *Editor,
span: Span,
dest: []const u8,
render: RenderBlockFn,
shape: enum { link, image },
) Error!void {
const allocator = self.splicer.allocator;
const doc = &self.splicer.doc;
const ast = self.astView();
var b = AST.Builder.init(allocator);
defer b.deinit();
var kids: std.ArrayList(AST.Node.Id) = .empty;
defer kids.deinit(allocator);
var target = span;
var attrs: ?AST.Attrs = null;
var chain: std.ArrayList(AST.Node.Id) = .empty;
defer chain.deinit(allocator);
try locate.ancestorChain(allocator, doc, span.start, &chain);
const repoint = if (shape == .link)
locate.innermostCovering(doc, chain.items, &.{.link}, span.start, span.end)
else
null;
if (repoint) |id| {
target = doc.span(id);
if (target.start == 0 and target.end == 0) return error.NotEditable;
if (ast.nodes[id].attrs) |ai| attrs = ast.attrs[ai];
var child = ast.nodes[id].first_child;
while (child) |c| : (child = ast.nodes[c].next_sibling) {
try kids.append(allocator, try b.graftSubtree(ast, c));
}
} else if (span.end > span.start) {
const covered = try coveredInlines(allocator, doc, span.start, span.end);
defer allocator.free(covered);
for (covered) |piece| {
try kids.append(allocator, if (piece.text) |t|
try b.addLeaf(.{ .str = t })
else
try b.graftSubtree(ast, piece.node));
}
}
if (shape == .link and kids.items.len == 0) try kids.append(allocator, try b.addLeaf(.{ .str = dest }));
const payload: AST.Node.Kind.Link = .{ .destination = dest, .reference = null };
const root = try b.addContainer(switch (shape) {
.link => .{ .link = payload },
.image => .{ .image = payload },
}, kids.items);
if (attrs) |a| try b.setAttrs(root, a);
return self.spliceRendered(&b, root, render, target.start, target.end);
}
// ── Footnotes ────────────────────────────────────────────────────────────
/// Insert a footnote reference at `offset` and, unless one already exists,
/// the matching definition at the end of the document.
///
/// Decisions:
/// * It writes BOTH HALVES, because in neither format is half a footnote a
/// footnote: a bare `[^a]` with nothing defining it renders as the
/// literal four characters. That is also why `Syntax.footnote` is one
/// field holding both spellings rather than a reference entry in
/// `text_leaf_delims` (which is there for the serializer, and which
/// `assertCoherent` pins to this).
/// * The definition body is left EMPTY, and that parses — both parsers
/// read `[^a]: ` as a footnote with no children. The caller then types
/// into it like any other block; minting a placeholder body here would be
/// text the author has to delete.
/// * A label that is ALREADY DEFINED gets only the reference. Referring to
/// an existing footnote twice is an ordinary thing to want, and appending
/// a second definition for the same label is not — the parsers keep one
/// and the other becomes dead source.
/// * It is ONE splice, spanning the caret to the end of the document, even
/// though the two halves are far apart and the bytes between them are
/// rewritten unchanged. Two splices would be less wasteful and strictly
/// worse: the pair would take two undo steps to reverse, and `lastChange`
/// — the range a caller re-renders from — would describe only the second,
/// silently omitting the reference the caret is sitting in.
///
/// `error.InvalidLabel` for a label that is empty or holds a line end or a
/// reference bracket; `error.UnsupportedFormat` where the format has no
/// footnotes.
pub fn insertFootnote(self: *Editor, offset: usize, label: []const u8) Error!void {
try self.checkRange(offset, offset);
const fs = self.syntax.footnote orelse return error.UnsupportedFormat;
if (label.len == 0) return error.InvalidLabel;
if (std.mem.indexOfAny(u8, label, "\r\n") != null) return error.InvalidLabel;
if (std.mem.indexOfAny(u8, label, fs.label_forbids) != null) return error.InvalidLabel;
const allocator = self.splicer.allocator;
const src = self.sourceBytes();
var out: std.ArrayList(u8) = .empty;
defer out.deinit(allocator);
try out.appendSlice(allocator, fs.ref_open);
try out.appendSlice(allocator, label);
try out.appendSlice(allocator, fs.ref_close);
if (footnoteDefined(self.astView(), label)) {
return self.commitSplice(offset, offset, out.items);
}
try out.appendSlice(allocator, src[offset..]);
// The definition is a block of its own at the end of the document, so it
// needs a line to itself and a blank line above it.
if (src.len > 0 and src[src.len - 1] != '\n') try out.append(allocator, '\n');
if (!endsWithBlankLine(src)) try out.append(allocator, '\n');
try out.appendSlice(allocator, fs.ref_open);
try out.appendSlice(allocator, label);
try out.appendSlice(allocator, fs.ref_close);
try out.appendSlice(allocator, fs.def_suffix);
try out.append(allocator, '\n');
return self.commitSplice(offset, src.len, out.items);
}
// ── Math ─────────────────────────────────────────────────────────────────
/// Insert `formula` at `offset` as an INLINE formula — Markdown's `$x$`,
/// djot's `` $`x` ``, AsciiDoc's `stem:[x]` — a math leaf whose text is
/// `formula` byte for byte.
///
/// Decisions:
/// * The formula is the HOST's notation (TeX, usually), and twig reads
/// none of it. It goes between the format's delimiters with nothing
/// escaped, because a math body is read literally: `\$` inside `$…$`
/// is two bytes of TeX, not an escaped dollar, and `insertLiteral`'s
/// alphabets would write backslashes into the formula.
/// * The bytes are the SERIALIZER's, printed through `Syntax.renderBlock`
/// from a leaf built with `AST.Builder`, as `insertDirective` prints its
/// container. `text_leaf_delims` is the gate and not the spelling: a
/// fixed `Delims` pair cannot say how djot's run widens around a
/// backtick in the formula, and the serializer already does.
/// * A formula the format cannot hold is REFUSED rather than written.
/// Markdown's `$` will not open onto a space or close after one, has
/// no spelling for an empty formula, and ends at the first `$`
/// inside; djot's run holds nearly anything. Rather than restate each
/// parser's rule here, the print is parsed ON ITS OWN and must come
/// back holding this kind of formula with exactly these bytes —
/// `error.InvalidFormula` when it does not.
/// * And it must come back IN PLACE. The splice is kept only if the
/// edited document holds the formula inside the inserted bytes, so a
/// caret in a code span or a code block — where the bytes are code —
/// or flush against a `$` that Markdown pairs differently is
/// `error.NotEditable`, and nothing changes. This is the one check
/// `insertLiteral` cannot make, because a literal has no node to look
/// for.
///
/// Gated on the format's inline-math delimiters being authorable and a
/// renderer to print through, which `assertCoherent` pins together.
/// Markdown authors one only under `ParseOptions.math`, so an editor over
/// a document parsed without it gets `error.UnsupportedFormat`, exactly
/// as `setMarkColor` does without `highlight_colors`. `error.InvalidRange`
/// for an `offset` past the source.
pub fn insertInlineMath(self: *Editor, offset: usize, formula: []const u8) Error!void {
try self.checkRange(offset, offset);
const render = try self.mathRenderer(.inline_math);
const allocator = self.splicer.allocator;
var out: Writer.Allocating = .init(allocator);
defer out.deinit();
const bytes = try self.printFormula(render, .inline_math, formula, &out);
const want: FormulaCheck = .{
.kind = .inline_math,
.formula = formula,
.within = Span.init(offset, offset + bytes.len),
};
return self.commitSpliceChecked(offset, offset, bytes, want.check());
}
/// Insert `formula` as a DISPLAY formula — Markdown's `$$x$$`, djot's
/// `` $$`x` `` — in a paragraph of its own after the block `offset` sits
/// in.
///
/// Everything `insertInlineMath` decides about the bytes holds here: the
/// serializer prints them, the formula is written unescaped, a formula the
/// format cannot hold is `error.InvalidFormula`, and one that does not come
/// back in place is `error.NotEditable`.
///
/// What differs is the placement, which is `insertThematicBreak`'s,
/// decision for decision, through the `insertBlockAfter` it shares with the
/// table and the directive: after the caret's block rather than at the
/// caret, blank-separated on both sides, a quote's prefix on every line of
/// a formula that runs over several, and column zero after a list item.
/// Both formats parse display math as an inline node like any other, so
/// nothing in either would stop one landing mid-sentence — but a display
/// formula is set on a line of its own when rendered, and a paragraph
/// holding only the formula is what that looks like in the source.
///
/// Gated like the inline form, on the display delimiters. AsciiDoc spells
/// display math with the same `stem:[…]` macro it uses inline and reads it
/// back as inline, so it authors the inline form and not this one.
pub fn insertDisplayMath(self: *Editor, offset: usize, formula: []const u8) Error!void {
try self.checkRange(offset, offset);
const render = try self.mathRenderer(.display_math);
const allocator = self.splicer.allocator;
var out: Writer.Allocating = .init(allocator);
defer out.deinit();
const bytes = try self.printFormula(render, .display_math, formula, &out);
var block: std.ArrayList(u8) = .empty;
defer block.deinit(allocator);
const pos = try self.blockAfter(offset, bytes, &block);
const want: FormulaCheck = .{
.kind = .display_math,
.formula = formula,
.within = Span.init(pos, pos + block.items.len),
};
return self.commitSpliceChecked(pos, pos, block.items, want.check());
}
/// The renderer a formula of `kind` is printed through, or
/// `error.UnsupportedFormat` where the format does not author one.
fn mathRenderer(self: *const Editor, kind: AST.TextLeafKind) Error!RenderBlockFn {
if (self.syntax.authorableDelimsFor(.{ .text_leaf = kind }) == null) return error.UnsupportedFormat;
// `assertCoherent` pins a renderer wherever the claim above is made,
// so this is the compiler's `orelse` rather than a second gate.
return self.syntax.renderBlock orelse error.UnsupportedFormat;
}
/// Print `formula` as a math leaf of `kind`, alone in a paragraph, and
/// answer the leaf's bytes — `error.InvalidFormula` unless those bytes,
/// parsed on their own, come back as that formula.
fn printFormula(
self: *Editor,
render: RenderBlockFn,
kind: AST.TextLeafKind,
formula: []const u8,
out: *Writer.Allocating,
) Error![]const u8 {
const allocator = self.splicer.allocator;
var b = AST.Builder.init(allocator);
defer b.deinit();
// A paragraph around the leaf, because a paragraph is what every
// renderer is written to print; the paragraph itself adds nothing but
// the line end trimmed below.
const leaf = try b.addLeaf(.{ .text_leaf = .{ .kind = kind, .text = formula } });
const root = try b.addContainer(.para, &.{leaf});
const view = b.view(root);
try renderNode(allocator, render, &view, root, &out.writer);
const bytes = std.mem.trimEnd(u8, out.written(), "\r\n");
var alone = self.splicer.parse_fn(self.splicer.parse_ctx, allocator, bytes) catch |err| switch (err) {
error.OutOfMemory => return error.OutOfMemory,
else => return error.InvalidFormula,
};
defer alone.deinit();
const want: FormulaCheck = .{ .kind = kind, .formula = formula, .within = Span.init(0, bytes.len) };
if (!want.holds(&alone)) return error.InvalidFormula;
return bytes;
}
/// What a math gesture looks for in the reparse: a leaf of `kind` holding
/// exactly `formula`, lying within the bytes it wrote.
const FormulaCheck = struct {
kind: AST.TextLeafKind,
formula: []const u8,
within: Span,
fn holds(self: *const FormulaCheck, doc: *const Document) bool {
for (doc.ast.nodes, 0..) |n, i| {
const leaf = switch (n.kind) {
.text_leaf => |l| l,
else => continue,
};
if (leaf.kind != self.kind or !std.mem.eql(u8, leaf.text, self.formula)) continue;
const sp = doc.span(@intCast(i));
if (sp.start >= self.within.start and sp.end <= self.within.end) return true;
}
return false;
}
fn accept(ctx: *const anyopaque, doc: *const Document) bool {
const self: *const FormulaCheck = @ptrCast(@alignCast(ctx));
return self.holds(doc);
}
fn check(self: *const FormulaCheck) Splicer.Check {
return .{ .ctx = self, .accept = accept };
}
};
// ── Literal text ─────────────────────────────────────────────────────────
/// Insert `text` at `offset` as a LITERAL run: every byte the format reads as
/// markup is backslash-escaped so the run reparses as exactly `text`, never as
/// emphasis, a code span, a link, an entity, or — at a line start — a heading,
/// quote or list. This is the inverse of the serializer, which writes an
/// already-parsed `str` verbatim: that byte survived a parse in place, whereas
/// `text` is arbitrary input that has to be MADE safe.
///
/// The escaping is positional. `Syntax.text_escapes` fires anywhere on the
/// line (`*`, `` ` ``, `[`, `<`…); `Syntax.block_start_escapes` fires only
/// while `offset` sits in its line's leading whitespace (`#`, `>`, `-`…),
/// where those bytes open a block — so an inserted "5 - 3" keeps its `-` but
/// an inserted "- item" at column zero does not become a bullet. An embedded
/// newline in `text` re-enters that line-start zone for the bytes after it.
///
/// Like the link ops, this guards the inserted run's OWN bytes; it does not
/// reason about source already flanking `offset`. The shared
/// splice+reparse+rollback path is the backstop: an insertion that somehow
/// still corrupts the document yields `error.EditConflict` and changes
/// nothing. `error.UnsupportedFormat` when the format can spell no literal
/// (`text_escapes == null`), `error.InvalidRange` when `offset` is past the
/// source.
///
/// Two constructs a fixed byte-alphabet cannot reach, and so does not: a GFM
/// bare-URL autolink (`https://x.com`, linkified with no delimiter to
/// backslash) and an ordered-list marker (`1.`/`1)`, special only after a
/// digit run, not per-byte). Both mint at most a link or a list from
/// literal-looking text, never corruption; a caller that must suppress them
/// does so above this op.
///
/// INSIDE A CODE SPAN, a code block or a raw node the run is written in
/// `verbatim` position instead: the format reads that body literally, so a
/// backslash format writes the bytes as they are (an escape there would
/// SHOW its backslash) and an entity format still escapes. The one byte no
/// position can hold is the span's own closing delimiter, which is the same
/// "guards its own bytes" limit as above.
///
/// The engine here decides WHERE each byte lands; the format decides how a
/// byte is written there. That split is `Syntax.renderText`: Markdown, djot
/// and AsciiDoc share one renderer over their alphabets, and HTML — which
/// has no backslash to spell a literal with — writes entities. The editor
/// never sees either rule.
pub fn insertLiteral(self: *Editor, offset: usize, text: []const u8) Error!void {
try self.checkRange(offset, offset);
const render = self.syntax.renderText orelse return error.UnsupportedFormat;
const allocator = self.splicer.allocator;
const src = self.sourceBytes();
// At a line start iff every byte from this line's start up to `offset` is
// leading whitespace — the same zone in which a block marker bites.
var at_line_start = true;
for (src[locate.lineStartAt(src, offset)..offset]) |c| {
if (c != ' ' and c != '\t') {
at_line_start = false;
break;
}
}
var out: Writer.Allocating = .init(allocator);
defer out.deinit();
const in_verbatim = try self.insideVerbatim(offset);
writeLiteral(self.syntax, render, text, at_line_start, in_verbatim, &out.writer) catch |err| switch (err) {
error.WriteFailed => return error.OutOfMemory,
};
return self.commitSplice(offset, offset, out.written());
}
/// Whether writing at `offset` lands inside a body the format reads
/// LITERALLY — a code span, a code block, a raw node — where the inline and
/// block-start alphabets mean nothing. Inclusive at both ends of the body
/// (`content_span`), because text written flush against either delimiter
/// still ends up inside it; a node with no interior is a leaf whose bytes
/// ARE its delimiters, and a splice at its edge lands beside it.
fn insideVerbatim(self: *const Editor, offset: usize) Allocator.Error!bool {
const doc = &self.splicer.doc;
var chain: std.ArrayList(AST.Node.Id) = .empty;
defer chain.deinit(self.splicer.allocator);
try locate.ancestorChain(self.splicer.allocator, doc, offset, &chain);
for (chain.items) |id| {
const literal = switch (doc.ast.nodes[id].kind) {
.code_block, .raw_block, .raw_inline => true,
.text_leaf => |l| switch (l.kind) {
.verbatim, .inline_math, .display_math => true,
else => false,
},
else => false,
};
if (!literal) continue;
const cs = doc.contentSpan(id) orelse continue;
if (cs.start <= offset and offset <= cs.end) return true;
}
return false;
}
/// Insert a hard line break *inside a table cell* at `offset`, spelled the
/// format's way (`Syntax.cell_line_break` — `<br>` for Markdown). A row is a
/// single source line, so this is the one break the cell can hold; the
/// spliced `<br>` reparses as a `hard_break` in cell context (see
/// `markdown/inline.zig`), so the caller reads back a semantic node, not raw
/// HTML. In HTML itself `<br>` is not borrowed at all — it is simply the
/// break, and the cell restriction here understates what the format allows.
///
/// Errors:
/// - `UnsupportedFormat` — the format has no in-cell break spelling (djot,
/// XML). Checked first: it is a property of the format, not the caret.
/// - `NoBlock` — `offset` is not inside a table cell. Only the in-cell
/// gesture is spelled today; a general (non-cell) hard break is future work.
/// - `EditConflict` — the splice would no longer parse as the same table; the
/// splicer rolled it back and nothing changed (the standard contract).
pub fn insertLineBreak(self: *Editor, offset: usize) Error!void {
try self.checkRange(offset, offset);
// Format capability before caret position: a format with no in-cell
// break spelling can never satisfy this gesture, wherever the caret is.
const spelling = self.syntax.cell_line_break orelse return error.UnsupportedFormat;
const allocator = self.splicer.allocator;
var chain: std.ArrayList(AST.Node.Id) = .empty;
defer chain.deinit(allocator);
try locate.ancestorChain(allocator, &self.splicer.doc, offset, &chain);
if (locate.innermostOfKind(&self.splicer.doc, chain.items, .cell) == null) return error.NoBlock;
return self.commitSplice(offset, offset, spelling);
}
};
// ── Block-container internals ──────────────────────────────────────────────
/// The blocks `[start, end)` touches: sibling `first`…`last` under the nearest
/// ancestor whose children are blocks. You cannot quote half a paragraph, so a
/// container op always widens to whole blocks first.
const BlockRange = struct {
first: AST.Node.Id,
last: AST.Node.Id,
/// The ancestor chain down to `start`, reused for container detection.
chain: []const AST.Node.Id,
};
/// Resolve `[start, end)` to the sibling blocks it touches. `end` is pulled back
/// off a trailing newline first: a block's span stops at its text in Markdown,
/// so a selection ending on the line break would otherwise resolve above the
/// block and drag the whole document in.
fn coveredBlocks(
allocator: Allocator,
doc: *const Document,
start: usize,
end: usize,
) !BlockRange {
var last_off = if (end > start) end - 1 else start;
while (last_off > start and (doc.source[last_off] == '\n' or doc.source[last_off] == '\r')) last_off -= 1;
var chain_a: std.ArrayList(AST.Node.Id) = .empty;
errdefer chain_a.deinit(allocator);
try locate.ancestorChain(allocator, doc, start, &chain_a);
var chain_b: std.ArrayList(AST.Node.Id) = .empty;
defer chain_b.deinit(allocator);
try locate.ancestorChain(allocator, doc, last_off, &chain_b);
var i: usize = 0;
while (i + 1 < chain_a.items.len and i + 1 < chain_b.items.len and
chain_a.items[i + 1] == chain_b.items[i + 1]) : (i += 1)
{}
// Climb to the nearest ancestor that holds blocks: the deepest shared node
// may be an inline (a `str`), and a container wraps blocks, not words.
var p = i;
while (p > 0 and !locate.isBlockParent(doc.ast.nodes[chain_a.items[p]].kind)) p -= 1;
if (p + 1 >= chain_a.items.len) return error.NoBlock;
const first = chain_a.items[p + 1];
const last = if (p + 1 < chain_b.items.len) chain_b.items[p + 1] else first;
return .{
.first = first,
.last = last,
.chain = try chain_a.toOwnedSlice(allocator),
};
}
/// True when the range's lines cover every block `target` holds — the condition
/// for toggling the container OFF rather than nesting inside it.
///
/// The test is "are all its blocks covered?", NOT "is its span inside the
/// region?": a container's span can run past its last block, because the blank
/// `>` line continuing a quote belongs to the quote and to no paragraph in it
/// (Djot spans `> > a\n>\n` as the inner quote, ending two bytes past its only
/// paragraph). Comparing spans there reads a fully-covered quote as partial and
/// nests forever.
fn containerFullyCovered(
doc: *const Document,
target: AST.Node.Id,
region_start: usize,
region_end: usize,
) bool {
const first = doc.ast.nodes[target].first_child orelse return false;
var last = first;
var cur: ?AST.Node.Id = first;
while (cur) |c| {
last = c;
cur = doc.ast.nodes[c].next_sibling;
}
const lo = locate.lineStartAt(doc.source, doc.span(first).start);
const hi = locate.lineEndAt(doc.source, doc.span(last).end -| 1);
return region_start <= lo and region_end >= hi;
}
/// The node `toggleBlockContainerByRender` builds for a `ContainerKind`. A
/// list built here is decimal from 1: a fresh list has no other numbering to
/// keep, and the marker path's `1. ` says the same.
fn containerNodeKind(kind: syntax_mod.ContainerKind, tight: bool) AST.Node.Kind {
return switch (kind) {
.block_quote => .block_quote,
.bullet_list => .{ .bullet_list = .{ .tight = tight } },
.ordered_list => .{ .ordered_list = .{ .numbering = .decimal, .tight = tight, .start = null } },
};
}
/// Where a splice over a block span ENDS: the span's end, minus the line end
/// some parsers fold into a block's span after its closing bytes. A rendered
/// fragment carries no trailing line end (`spliceRendered` trims it), so
/// leaving the source's in place is what keeps the next block on its own line.
fn blockSpanEnd(src: []const u8, span: Span) usize {
var end = span.end;
if (end > span.start and src[end - 1] == '\n') end -= 1;
if (end > span.start and src[end - 1] == '\r') end -= 1;
return end;
}
/// The render path's `containerFullyCovered`: true when the covered blocks
/// hold `target` whole, or reach from the FIRST leaf block under its first
/// child to the LAST under its last — the tree's statement of "every line the
/// container holds", for a format whose lines say nothing. `blocks.first` may
/// be an ancestor of that leaf (a nested list the range covers whole), which
/// is why each end tests a path and not a node.
fn coversContainer(ast: *const AST, target: AST.Node.Id, blocks: BlockRange) bool {
// The range covers a block that holds `target` whole — a list selected
// from outside it, the way a range over every line of one is. Both are
// on the chain to the range's start, so the shallower one contains the
// other.
const first_at = std.mem.indexOfScalar(AST.Node.Id, blocks.chain, blocks.first).?;
const target_at = std.mem.indexOfScalar(AST.Node.Id, blocks.chain, target).?;
if (first_at <= target_at) return true;
const first = ast.nodes[target].first_child orelse return false;
var last = first;
while (ast.nodes[last].next_sibling) |n| last = n;
return onEdgePath(ast, first, blocks.first, .first) and onEdgePath(ast, last, blocks.last, .last);
}
/// Whether `node` lies on the path of first (or last) children descending
/// from `from`, `from` itself included.
fn onEdgePath(ast: *const AST, from: AST.Node.Id, node: AST.Node.Id, edge: enum { first, last }) bool {
var cur = from;
while (true) {
if (cur == node) return true;
cur = ast.nodes[cur].first_child orelse return false;
if (edge == .last) {
while (ast.nodes[cur].next_sibling) |n| cur = n;
}
}
}
/// The empty container of `kind` the caret sits in, if the innermost node on
/// `chain` is one — or is an empty item that is the ONLY child of one — so
/// that `openContainerByRender` can take it back off. `null` otherwise.
fn emptyContainerOf(ast: *const AST, chain: []const AST.Node.Id, kind: syntax_mod.ContainerKind) ?AST.Node.Id {
if (chain.len == 0) return null;
const deepest = chain[chain.len - 1];
if (ast.nodes[deepest].first_child != null) return null;
const tag = std.meta.activeTag(ast.nodes[deepest].kind);
if (tag == kindTag(kind)) return deepest;
if (tag == .list_item and chain.len >= 2) {
const list = chain[chain.len - 2];
const only = ast.nodes[list].first_child == deepest and ast.nodes[deepest].next_sibling == null;
if (only and std.meta.activeTag(ast.nodes[list].kind) == kindTag(kind)) return list;
}
return null;
}
/// The TEXT of a subtree, for a code block's payload: every text payload in
/// order, a break as a line end, and a line end between sibling blocks. This
/// is `select.textOf` with the breaks kept as breaks rather than folded to
/// spaces — a listing is the one place a paragraph's line structure is the
/// content, so a `<br>` in a poem becomes the line end it displayed as.
fn blockTextInto(allocator: Allocator, ast: *const AST, id: AST.Node.Id, out: *std.ArrayList(u8)) Allocator.Error!void {
switch (ast.nodes[id].kind) {
.str => |t| try out.appendSlice(allocator, t),
.text_leaf => |l| try out.appendSlice(allocator, l.text),
.smart_punctuation => |v| try out.appendSlice(allocator, v.ascii()),
.raw_inline => |v| try out.appendSlice(allocator, v.text),
.code_block => |v| try out.appendSlice(allocator, v.text),
.raw_block => |v| try out.appendSlice(allocator, v.text),
.non_breaking_space => try out.append(allocator, ' '),
.soft_break, .hard_break => try out.append(allocator, '\n'),
else => {
var child = ast.nodes[id].first_child;
var first = true;
while (child) |c| : (child = ast.nodes[c].next_sibling) {
if (!first and ast.nodes[c].kind.level() == .block) try out.append(allocator, '\n');
try blockTextInto(allocator, ast, c, out);
first = false;
}
},
}
}
/// How many quotes enclose `target` on the chain — the number of `>` markers to
/// step over before the one that belongs to `target`.
fn quoteDepthAbove(ast: *const AST, chain: []const AST.Node.Id, target: AST.Node.Id) usize {
var depth: usize = 0;
for (chain) |id| {
if (id == target) break;
if (std.meta.activeTag(ast.nodes[id].kind) == .block_quote) depth += 1;
}
return depth;
}
// ── Join internals ─────────────────────────────────────────────────────────
/// The interior of a BLOCK, for the formats whose parsers record one and for
/// the ones that do not — `Editor.joinBlocks` needs both halves of a block's
/// bytes (its content, and the markup around it) and AsciiDoc's parser records
/// no `content_span` at all.
///
/// The fallback is the marker: a block with a leading marker holds its content
/// from the marker's end to its own end, and one with neither a content span
/// nor a marker is all content. That is a reconstruction, not a guess — it is
/// the same relation `Document.node_content_spans` states for the parsers that
/// do fill it in, read off `node_marker_spans` instead.
fn blockContent(doc: *const Document, id: AST.Node.Id) Span {
if (doc.contentSpan(id)) |c| return c;
const sp = doc.span(id);
if (doc.markerSpan(id)) |m| {
if (m.end >= sp.start and m.end <= sp.end) return Span.init(m.end, sp.end);
}
// Neither: the INLINE CHILDREN are where the text is, and the block's own
// span is not. AsciiDoc is the format that forces this — a paragraph's
// span opens at its METADATA (`[.lead]`, a `.Title` line), which is markup
// and not content, and nothing records where it ends. Handing the whole
// span back spliced those bytes into the middle of the joined line, so
// `above` + `[.lead]`/`below` read `above`/`[.lead]`/`below` with the
// attribute line now literal text. The first child's start and the last
// child's end are the same relation `node_content_spans` states, read off
// the tree where no span table answers.
var it = doc.children(id);
const first = it.next() orelse return sp;
var last = first.id;
while (it.next()) |child| last = child.id;
const start = doc.span(first.id).start;
const end = doc.span(last).end;
if (start >= sp.start and end <= sp.end and start <= end) return Span.init(start, end);
return sp;
}
/// A's tail with its trailing SEPARATOR LINES removed — what is left is the
/// closing markup and the closers `joinBlocks`'s doc comment says travel past
/// the joined text, and nothing else.
///
/// A container's span can reach past its last block: a Markdown `block_quote`
/// covers its own trailing marker lines (`> a\n>\n` is `0..5`), so the tail of
/// `a` there is `"\n>\n"` — a `>` line that, written after the joined text,
/// left a stray quote line below it, and piled one up per join. Those lines
/// separate; they close nothing.
///
/// WHOLE LINES only, which is the whole care needed here: `</div>` ends in a
/// `>`, and a byte-wise trim over the same alphabet would eat it and unclose
/// the div. The line end this drops is put back by `joinBlocks`'s
/// trailing-terminator rule wherever the removal took one.
fn trimTailSeparators(tail: []const u8) []const u8 {
var end = tail.len;
while (std.mem.lastIndexOfScalar(u8, tail[0..end], '\n')) |nl| {
if (!isSeparatorRun(tail[nl + 1 .. end])) break;
end = nl;
}
return tail[0..end];
}
/// Whether `bytes` are only what SEPARATES two blocks: line ends, spaces, tabs
/// and quote markers. A `>` is separation because a quote's marker is on every
/// line of it, blank ones included.
fn isSeparatorRun(bytes: []const u8) bool {
for (bytes) |c| switch (c) {
' ', '\t', '\r', '\n', '>' => {},
else => return false,
};
return true;
}
/// Whether the region between A's and B's topmost ancestors below the LCA
/// holds nothing the join would destroy. `joinBlocks`'s one data-loss guard.
///
/// The splice writes `[A.ce, R_end)` out of A's tail and B's content alone, so
/// whatever else lies in there is gone. Neither walk that found A and B can
/// see all of it. `precedingLeafBlock` steps over any node HOLDING NO LEAF
/// BLOCK — an empty `<div>`, a bare `>`, a bare `-`, an empty djot `:::`
/// fence — and a Markdown LINK REFERENCE DEFINITION (`[ref]: /zed`), a
/// FOOTNOTE DEFINITION (`[^n]: note`) and a djot CAPTION (`^ caption`) are not
/// in the tree at all: Markdown keeps a definition as a lookup table and not
/// as a node, so no tree walk could be written that sees one. `alpha` +
/// `[ref]: /zed` + `beta` joined to `alpha\nbeta\n` and the definition, along
/// with every link that resolved through it, was simply gone.
///
/// So the region is read twice, once against each thing that can be true of
/// it:
///
/// * **No node that HOLDS BLOCKS may overlap it** other than the two
/// blocks' COMMON ANCESTORS, which necessarily do. `holdsBlocks` is the
/// same classifier `precedingLeafBlock` descends by, and that is why it is
/// the right one: a node in the gap holding a leaf block WOULD BE A, so
/// what can be in there is exactly what that walk stepped over. It is
/// also why a bare `>` is refused where the `>` of a quote holding both
/// blocks is not — the bytes are identical and the tree is not. Inline
/// nodes are passed over: HTML keeps the newline between two elements as
/// a `str`, and the byte rule below is what judges those bytes.
/// * **What is left may only SEPARATE**, by `isSeparatorRun` — with B's own
/// PREAMBLE peeled off the right first. That preamble is the run of
/// non-blank whole lines directly above B with no blank line between: a
/// djot attribute line (`{.center}`) sits there, outside the span the
/// parser gives B, and B's attributes are discarded by design. A
/// definition is a block, so a blank line divides it from B and the peel
/// never reaches one — and the node check above holds it anyway.
///
/// A's extent reaching PAST B's start is false here too. Nothing produces it
/// now that djot's section spans are right, and it would make A's tail a slice
/// running through B.
fn gapIsClean(
doc: *const Document,
src: []const u8,
common: []const AST.Node.Id,
a_top: AST.Node.Id,
b_top: AST.Node.Id,
) bool {
const start = doc.span(a_top).end;
const b_start = doc.span(b_top).start;
if (start > b_start or b_start > src.len) return false;
for (doc.ast.nodes, 0..) |_, idx| {
const id: AST.Node.Id = @intCast(idx);
const sp = doc.span(id);
if (sp.start >= b_start or sp.end <= start) continue;
if (!holdsBlocks(doc, id)) continue;
if (std.mem.indexOfScalar(AST.Node.Id, common, id) == null) return false;
}
var end = b_start;
while (end > start and src[end - 1] == '\n') {
const line_start = locate.lineStartAt(src, end - 1);
if (line_start < start) break;
if (isSeparatorRun(src[line_start .. end - 1])) break;
end = line_start;
}
return isSeparatorRun(src[start..end]);
}
/// B's content written as ONE LINE — what a marker heading A can hold. Each of
/// B's line ends becomes a single space, and the CONTINUATION PREFIX behind it
/// (a list item's indent, a quote's `> `) goes with it, since a heading's one
/// line sits behind its own prefix already.
fn appendAsOneLine(
allocator: Allocator,
text: []const u8,
out: *std.ArrayList(u8),
) Allocator.Error!void {
var rest = text;
while (std.mem.indexOfScalar(u8, rest, '\n')) |nl| {
try out.appendSlice(allocator, std.mem.trimEnd(u8, rest[0..nl], " \t\r"));
try out.append(allocator, ' ');
rest = rest[nl + 1 ..];
var k: usize = 0;
while (k < rest.len and (rest[k] == ' ' or rest[k] == '\t' or rest[k] == '>')) k += 1;
rest = rest[k..];
}
try out.appendSlice(allocator, rest);
}
/// B's content written as a CONTINUATION LINE of A, which is one byte more
/// than verbatim in exactly one shape.
///
/// A line of `=` or `-` under a paragraph is a SETEXT UNDERLINE, and it is the
/// only line-start construct that rewrites the block ABOVE it rather than
/// opening one of its own: `above` + `===` joined to `above\n===\n` reparsed
/// as a single heading and no paragraph at all — B's text became A's spelling.
/// A backslash on its first byte is what `insertLiteral` writes for the same
/// bytes at the same position, and `\` before ASCII punctuation is that
/// character in every format stating the alphabet, so the gate is
/// `block_start_escapes` being stated at all.
///
/// Nothing else is escaped, and that is deliberate: `#`, `>`, `-` + space, a
/// table's `|` all open a BLOCK of their own as a continuation line, so the
/// join merely fails to merge two blocks into one — it does not rewrite A.
fn appendAsContinuation(
allocator: Allocator,
syntax: *const Syntax,
text: []const u8,
out: *std.ArrayList(u8),
) Allocator.Error!void {
if (syntax.block_start_escapes != null and isUnderlineLine(text)) {
const lead = text.len - std.mem.trimStart(u8, text, " \t").len;
try out.appendSlice(allocator, text[0..lead]);
try out.append(allocator, '\\');
try out.appendSlice(allocator, text[lead..]);
return;
}
try out.appendSlice(allocator, text);
}
/// Whether `text`'s FIRST line is a run of `=` or a run of `-` and nothing
/// else — a setext underline, whichever level it spells.
fn isUnderlineLine(text: []const u8) bool {
const first = text[0 .. std.mem.indexOfScalar(u8, text, '\n') orelse text.len];
const trimmed = std.mem.trim(u8, first, " \t\r");
if (trimmed.len == 0) return false;
for (trimmed) |c| if (c != trimmed[0]) return false;
return trimmed[0] == '=' or trimmed[0] == '-';
}
/// Whether `id` is a heading spelled by an UNDERLINE rather than by a marker —
/// Markdown's setext form, the one `Editor.splitBlock` refuses for its own half
/// and `joinBlocks` refuses for B.
///
/// Three conditions, and all three are needed. No recorded marker rules out
/// every ATX-ish heading (`# x`, AsciiDoc's `== x`). Content starting where the
/// block does rules out a WRAPPING spelling — an HTML `<h1>a</h1>` records no
/// marker either, and its content starts after the opening tag. Content ending
/// before the block does is the underline itself.
fn isSetextHeading(doc: *const Document, id: AST.Node.Id) bool {
if (std.meta.activeTag(doc.ast.nodes[id].kind) != .heading) return false;
if (doc.markerSpan(id) != null) return false;
const content = doc.contentSpan(id) orelse return false;
const sp = doc.span(id);
return content.start == sp.start and content.end < sp.end;
}
/// Whether a node on `chain` is a table. A table's cells hold paragraphs, so a
/// `para` inside one is a perfectly ordinary leaf block to the walks below —
/// and joining one into the cell above it, or into the paragraph before the
/// table, is not a join of two lines but a hole in a grid. Stated as a chain
/// test rather than as a kind test for exactly that reason: what is refused is
/// the POSITION, not the node.
fn passesThroughTable(doc: *const Document, chain: []const AST.Node.Id) bool {
for (chain) |id| {
if (std.meta.activeTag(doc.ast.nodes[id].kind) == .table) return true;
}
return false;
}
/// The path of node ids from the root down to `target`, appended to `out`.
///
/// A tree walk rather than `locate.ancestorChain`, which descends by OFFSET: two
/// nodes can share a start byte (a Markdown `list_item` and its first `para`
/// both begin at column zero), so an offset names a path and not a node.
/// `joinBlocks` already holds the node, and what it needs is that node's own
/// ancestors — for the lowest common ancestor, which is what decides how much
/// of A's closing markup has to travel.
fn nodePath(
allocator: Allocator,
doc: *const Document,
target: AST.Node.Id,
out: *std.ArrayList(AST.Node.Id),
) Allocator.Error!bool {
try out.append(allocator, doc.ast.root);
if (target == doc.ast.root) return true;
if (try descendTo(allocator, doc, doc.ast.root, target, out)) return true;
out.clearRetainingCapacity();
return false;
}
fn descendTo(
allocator: Allocator,
doc: *const Document,
id: AST.Node.Id,
target: AST.Node.Id,
out: *std.ArrayList(AST.Node.Id),
) Allocator.Error!bool {
var it = doc.children(id);
while (it.next()) |child| {
try out.append(allocator, child.id);
if (child.id == target) return true;
if (try descendTo(allocator, doc, child.id, target, out)) return true;
_ = out.pop();
}
return false;
}
/// True for a node that HOLDS BLOCKS, and so is a container the leaf walks
/// below descend into rather than a block they stop at.
///
/// `contentModel` is the classifier rather than a hand-kept list, because it is
/// already the exhaustive answer to this exact question and a new kind has to
/// declare one. It puts a `table` on the container side — its rows hold cells
/// which hold paragraphs — which is why `passesThroughTable` exists rather than
/// a "is a table a leaf?" special case here.
fn holdsBlocks(doc: *const Document, id: AST.Node.Id) bool {
return doc.ast.nodes[id].kind.contentModel() == .blocks;
}
/// The last LEAF BLOCK inside `root`'s subtree in document order, or `null` when
/// it holds none — how `joinBlocks` asks whether B is the last thing in a
/// delimited container it is about to pull out of.
fn lastLeafBlock(doc: *const Document, root: AST.Node.Id) ?AST.Node.Id {
if (!holdsBlocks(doc, root)) return root;
var last: ?AST.Node.Id = null;
var it = doc.children(root);
while (it.next()) |child| {
if (lastLeafBlock(doc, child.id)) |leaf| last = leaf;
}
return last;
}
/// The leaf block immediately before `target` in DOCUMENT ORDER — the block a
/// caret at the start of `target` has visually above it, wherever in the tree
/// that is. `null` when `target` is the document's first block.
///
/// Document order rather than sibling order is the whole point: the block above
/// a paragraph following a `<div>` is the div's LAST paragraph, and the block
/// above the first paragraph INSIDE the div is whatever preceded the div.
/// Sibling order answers "the div" to the first and "nothing" to the second,
/// and both are the wrong block to join into.
fn precedingLeafBlock(doc: *const Document, target: AST.Node.Id) ?AST.Node.Id {
var state: PrecedingLeaf = .{ .doc = doc, .target = target };
scanLeaves(&state, doc.ast.root);
return if (state.found) state.last else null;
}
const PrecedingLeaf = struct {
doc: *const Document,
target: AST.Node.Id,
last: ?AST.Node.Id = null,
found: bool = false,
};
fn scanLeaves(state: *PrecedingLeaf, id: AST.Node.Id) void {
if (id == state.target) {
state.found = true;
return;
}
if (!holdsBlocks(state.doc, id)) {
state.last = id;
return;
}
var it = state.doc.children(id);
while (it.next()) |child| {
scanLeaves(state, child.id);
if (state.found) return;
}
}
/// What `Editor.splitBlock` does with a block of a given kind. Having ONE
/// exhaustive switch answer this — rather than a "can I split it?" predicate
/// beside the switch that builds the separator — is what keeps `splitTarget`
/// and the builder from drifting apart about which kinds are splittable.
const SplitShape = enum { text, code, refuse };
/// Spelled out rather than left to an `else`, so a new `Kind` is a compile error
/// here and gets an answer on purpose — this switch is the checklist.
fn splitShape(tag: locate.KindTag) SplitShape {
return switch (tag) {
// The line-owning text blocks: a blank line divides them, unless a list
// item's marker has to be repeated instead.
.para, .heading => .text,
.code_block => .code,
// Structure whose parts are not lines, or containers a split would have
// to descend into rather than divide.
.table,
.doc,
.section,
.block_quote,
.bullet_list,
.ordered_list,
.task_list,
.definition_list,
.line_block,
.list_item,
.task_list_item,
.definition_list_item,
.term,
.definition,
.line,
.row,
.cell,
.column,
.caption,
.footnote,
.reference,
.citation,
.substitution,
.container,
// Blocks with no interior to divide: a rule is one line, and metadata
// and raw blocks are inert islands whose bytes are not ours to
// punctuate.
.thematic_break,
.metadata,
.raw_block,
// Inlines. `lineOwningBlock` cannot return one — it stops at a block
// parent's child — but naming them is what keeps this exhaustive, and a
// refusal is the right answer if that ever changes.
.str,
.soft_break,
.hard_break,
.non_breaking_space,
.text_leaf,
.raw_inline,
.smart_punctuation,
.link,
.image,
.inline_mark,
.markup_leaf,
.processing_instruction,
=> .refuse,
};
}
/// The block `Editor.splitBlock` should divide for a caret at `offset`, which is
/// not simply "the block at `offset`" — because of where a caret at the END of a
/// block actually lands.
///
/// Spans are half-open, so a caret at a block's end is outside it. Whether it is
/// outside EVERYTHING depends on the format, and the two authorable ones
/// disagree: djot's `list_item` covers its trailing newline (`[0,6)` for
/// `- one\n`), while Markdown's stops before it (`[0,5)`). So for
/// `- one|\n- two\n` the caret at 5 is inside djot's item but, in Markdown, in
/// the GAP between two items — inside the `bullet_list` and inside no item at
/// all. A lookup that trusts the deepest hit gets the LIST, which is not
/// splittable, and "Enter at the end of an item" — the single most common way
/// this gesture is asked for — fails on the format where lists are commonest.
///
/// Retrying one byte back is therefore not a null-check: the answer at `offset`
/// can be non-null and still wrong. What makes it wrong is that it isn't
/// splittable, so that is what the retry keys on. A caret in any gap resolves to
/// the block that just ENDED, which is where the text cursor visually sits.
///
/// When neither position yields a splittable block the ORIGINAL is returned, so
/// a genuine refusal (a caret in a table) still reports `NotEditable` against
/// the block the caller actually pointed at rather than `NoBlock`.
fn splitTarget(doc: *const Document, offset: usize) ?locate.LineBlock {
const at = locate.lineOwningBlock(doc, offset);
if (at) |lb| {
if (splitShape(std.meta.activeTag(doc.ast.nodes[lb.block].kind)) != .refuse) return lb;
}
if (offset > 0) {
if (locate.lineOwningBlock(doc, offset - 1)) |back| {
if (splitShape(std.meta.activeTag(doc.ast.nodes[back.block].kind)) != .refuse) return back;
}
}
return at;
}
/// Advance past one `>` quote marker — its optional indent, the `>`, and the one
/// optional space after it — or `null` if `line[i..]` doesn't start one.
/// Whether the line ENDING at `line_start` carries content — anything past its
/// own quote markers. `false` at the start of the source, where there is no
/// preceding line to run into.
///
/// What `openBlockOnBlankLine` consults to decide whether it must mint a blank
/// separator: a marker written flush under a paragraph line is that paragraph's
/// text in djot, not a heading.
fn precedingLineHasContent(src: []const u8, line_start: usize) bool {
if (line_start == 0) return false;
const prev = locate.lineBody(src[locate.lineStartAt(src, line_start - 1)..line_start]);
var i: usize = 0;
while (skipQuoteMarker(prev, i)) |j| i = j;
return !locate.isBlankLine(prev[i..]);
}
/// The marker that opens `sp`'s `ordinal`-th item — `sp.marker` for a fixed
/// spelling, the ordinal itself for a numbered one, which is why `buf` is the
/// caller's (the returned slice borrows it).
///
/// Shared by `buildContainerAdd`, which writes one per covered block, and
/// `openContainerOnBlankLine`, which writes exactly one: `1. ` and `- ` have to
/// be spelled the same by both, and two `{d}. ` format strings is one too many.
fn listMarker(sp: ContainerSpelling, ordinal: u32, buf: *[24]u8) []const u8 {
if (!sp.numbered) return sp.marker;
return std.fmt.bufPrint(buf, "{d}. ", .{ordinal}) catch unreachable;
}
/// Whether the byte opening a list marker (`listMarkerAt`'s `start`) opens an
/// ORDERED one — a digit, or the `(` of `(1)`. The complement is a `-`/`*`/`+`
/// bullet. Lets `openContainerOnBlankLine` tell "the same button again" from
/// "the other list button" against `ContainerSpelling.numbered`.
fn isOrderedMarker(c: u8) bool {
return c == '(' or c == '.' or (c >= '0' and c <= '9');
}
fn skipQuoteMarker(line: []const u8, i: usize) ?usize {
var j = i;
var indent: usize = 0;
while (j < line.len and line[j] == ' ' and indent < 3) : (indent += 1) j += 1;
if (j >= line.len or line[j] != '>') return null;
j += 1;
if (j < line.len and line[j] == ' ') j += 1;
return j;
}
/// The `[start, end)` of a list marker on `line`, scanning from `from` —
/// `start` at the bullet/first digit (so the indent before it stays put, keeping
/// an enclosing container's prefix intact) and `end` past the marker's trailing
/// spaces. `null` if the line doesn't open a list item.
///
/// `from` is how a caller skips a prefix the marker sits after: the checkbox
/// gestures pass the end of the line's quote markers, so `> - [ ] a` is found.
/// The container builders pass 0, which is the whole line.
fn listMarkerAt(line: []const u8, from: usize) ?struct { start: usize, end: usize } {
var j: usize = from;
while (j < line.len and (line[j] == ' ' or line[j] == '\t')) j += 1;
const start = j;
if (j >= line.len) return null;
if (line[j] == '-' or line[j] == '*' or line[j] == '+') {
j += 1;
} else if (line[j] == '.') {
// AsciiDoc's ordered marker: a run of dots, its depth its nesting.
while (j < line.len and line[j] == '.') j += 1;
} else {
if (line[j] == '(') j += 1;
var digits: usize = 0;
while (j < line.len and line[j] >= '0' and line[j] <= '9') : (digits += 1) j += 1;
if (digits == 0) return null;
if (j >= line.len or (line[j] != '.' and line[j] != ')')) return null;
j += 1;
}
// A marker must be followed by whitespace (or end the line): `-x` is a
// paragraph starting with a hyphen, not a bullet.
if (j < line.len and line[j] != ' ' and line[j] != '\n' and line[j] != '\r') return null;
while (j < line.len and line[j] == ' ') j += 1;
return .{ .start = start, .end = j };
}
/// True if one of the covered blocks begins on `[line_start, line_end)` — the
/// test for "this line opens a new list item". Djot starts a quoted block at its
/// text (after `> `), Markdown at the line start; either way it lands on the
/// block's first line, which is all this asks.
fn blockStartsOnLine(doc: *const Document, blocks: BlockRange, line_start: usize, line_end: usize) bool {
var cur: ?AST.Node.Id = blocks.first;
while (cur) |id| {
const s = doc.span(id).start;
if (s >= line_start and s < line_end) return true;
if (id == blocks.last) break;
cur = doc.ast.nodes[id].next_sibling;
}
return false;
}
/// True if one of `list`'s items begins on `[line_start, line_end)`.
fn itemStartsOnLine(doc: *const Document, list: AST.Node.Id, line_start: usize, line_end: usize) bool {
var it = doc.children(list);
while (it.next()) |item| {
const s = doc.span(item.id).start;
if (s >= line_start and s < line_end) return true;
}
return false;
}
/// Wrap every line of `[region_start, region_end)` in `kind`'s prefix, one item
/// per covered block. The lines already carry any enclosing container's prefix,
/// so prefixing at column 0 nests naturally (`> a` -> `> > a`).
fn buildContainerAdd(
allocator: Allocator,
src: []const u8,
doc: *const Document,
blocks: BlockRange,
region_start: usize,
region_end: usize,
sp: ContainerSpelling,
out: *std.ArrayList(u8),
) !void {
var ordinal: u32 = 1;
var cont: []const u8 = sp.cont;
var line_start = region_start;
while (line_start < region_end) {
const line_end = locate.lineEndAt(src, line_start);
const line = src[line_start..line_end];
const body = locate.lineBody(line);
if (locate.isBlankLine(body)) {
// A blank line inside the region: mark it for a quote (else the quote
// ends here), leave it bare for a list (it separates items).
if (sp.blank.len > 0) {
try out.appendSlice(allocator, sp.blank);
try out.appendSlice(allocator, line[body.len..]);
} else {
try out.appendSlice(allocator, line);
}
line_start = line_end;
continue;
}
if (blockStartsOnLine(doc, blocks, line_start, line_end)) {
var num_buf: [24]u8 = undefined;
const marker = listMarker(sp, ordinal, &num_buf);
if (sp.numbered) cont = container_indent[0..@min(marker.len, container_indent.len)];
try out.appendSlice(allocator, marker);
try out.appendSlice(allocator, line);
ordinal += 1;
} else {
try out.appendSlice(allocator, cont);
try out.appendSlice(allocator, line);
}
line_start = line_end;
}
}
/// Strip the quote marker `target` contributes from each of its lines, leaving
/// any outer quote levels untouched: `depth` is how many quotes enclose it, so
/// the marker removed is the `depth`-th + 1 on every line. That's what makes
/// toggling off a nested quote peel exactly one level (`> > a` -> `> a`).
fn buildQuoteStrip(
allocator: Allocator,
src: []const u8,
region_start: usize,
region_end: usize,
depth: usize,
out: *std.ArrayList(u8),
) !void {
var line_start = region_start;
while (line_start < region_end) {
const line_end = locate.lineEndAt(src, line_start);
const line = src[line_start..line_end];
var keep: usize = 0;
var d: usize = 0;
while (d < depth) : (d += 1) keep = skipQuoteMarker(line, keep) orelse break;
if (d == depth) {
if (skipQuoteMarker(line, keep)) |after| {
try out.appendSlice(allocator, line[0..keep]);
try out.appendSlice(allocator, line[after..]);
line_start = line_end;
continue;
}
}
// A line with no marker at this level (a lazy continuation) is already
// outside the level being removed — pass it through untouched.
try out.appendSlice(allocator, line);
line_start = line_end;
}
}
/// Rewrite the list `target`'s item markers: `sp == null` removes the list
/// (toggle off), otherwise it converts one list kind to the other in place. The
/// text before a marker (an enclosing quote's `> `, a nesting indent) is kept
/// verbatim; a block's continuation lines are re-indented to the new marker's
/// width so they stay attached to their item.
///
/// Removing a list has to keep its items separate BLOCKS: a tight `- a\n- b\n`
/// would strip to `a\nb\n`, which is one two-line paragraph, not two. So a blank
/// line is injected between items that had none — the structure the items had is
/// what survives, not their tightness.
fn buildListRewrite(
allocator: Allocator,
src: []const u8,
doc: *const Document,
target: AST.Node.Id,
region_start: usize,
region_end: usize,
sp: ?ContainerSpelling,
out: *std.ArrayList(u8),
) !void {
var ordinal: u32 = 1;
var old_width: usize = 0;
var new_width: usize = 0;
var seen_item = false;
var last_blank = true;
var line_start = region_start;
while (line_start < region_end) {
const line_end = locate.lineEndAt(src, line_start);
const line = src[line_start..line_end];
const body = locate.lineBody(line);
if (locate.isBlankLine(body)) {
try out.appendSlice(allocator, line);
last_blank = true;
line_start = line_end;
continue;
}
if (itemStartsOnLine(doc, target, line_start, line_end)) {
// Only when the list is going away: a conversion keeps the items as
// items, so it must not loosen a tight list.
if (sp == null and seen_item and !last_blank) try out.append(allocator, '\n');
const m = listMarkerAt(line, 0) orelse {
try out.appendSlice(allocator, line);
line_start = line_end;
continue;
};
var num_buf: [24]u8 = undefined;
const marker: []const u8 = if (sp) |s|
(if (s.numbered)
std.fmt.bufPrint(&num_buf, "{d}. ", .{ordinal}) catch unreachable
else
s.marker)
else
"";
try out.appendSlice(allocator, line[0..m.start]);
try out.appendSlice(allocator, marker);
try out.appendSlice(allocator, line[m.end..]);
old_width = m.end - m.start;
new_width = marker.len;
ordinal += 1;
seen_item = true;
last_blank = false;
} else {
// A continuation line: swap the old marker's indent for the new one's
// so the line stays inside its item.
var j: usize = 0;
while (j < line.len and j < old_width and line[j] == ' ') j += 1;
try out.appendSlice(allocator, container_indent[0..@min(new_width, container_indent.len)]);
try out.appendSlice(allocator, line[j..]);
last_blank = false;
}
line_start = line_end;
}
}
/// One left-to-right rewrite of `[region_start, region_end)` that renumbers
/// ordered-list items by their indentation depth — the body of
/// [`Editor.renumberOrderedLists`], where its reasoning lives.
fn buildRenumber(
allocator: Allocator,
src: []const u8,
region_start: usize,
region_end: usize,
item_lines: []const usize,
out: *std.ArrayList(u8),
) !void {
// A small stack of (indent column, next number), one entry per open nesting
// level. Documents don't nest lists dozens deep; 32 is plenty and keeps this
// allocation-free. A level deeper than 32 just isn't renumbered (copied).
var cols: [32]usize = undefined;
var nums: [32]u32 = undefined;
var depth: usize = 0;
// `item_lines` ascends and so does the walk, so one cursor answers "does an
// item open here" for every line without a search.
var next_item: usize = 0;
var line_start = region_start;
while (line_start < region_end) {
const line_end = locate.lineEndAt(src, line_start);
const line = src[line_start..line_end];
while (next_item < item_lines.len and item_lines[next_item] < line_start) next_item += 1;
const opens_item = next_item < item_lines.len and item_lines[next_item] == line_start;
// Past any `>` markers first. A quoted list's items sit BEHIND a prefix,
// and scanning from column zero finds `>` where it wants a bullet or a
// digit — so every line of `> 1. a` failed the marker test, the whole
// region was copied verbatim, and the gesture reported success having
// changed nothing. `splitMarker` skips the same way for the same reason.
var from: usize = 0;
while (skipQuoteMarker(line, from)) |j| from = j;
const m = if (opens_item) listMarkerAt(line, from) else null;
const numbered = if (m) |mm| isNumberedMarker(line[mm.start..mm.end]) else false;
if (numbered) {
const mm = m.?;
// Leading whitespace measured from AFTER the quote prefix, not from
// column zero: the prefix's own width is not this list's nesting
// depth, and counting it would put a quoted top-level item at a
// deeper level than an unquoted one.
const indent = mm.start - from;
// Drop levels deeper than this item; then resume this level or open it.
while (depth > 0 and cols[depth - 1] > indent) depth -= 1;
var number: u32 = 1;
if (depth > 0 and cols[depth - 1] == indent) {
number = nums[depth - 1];
nums[depth - 1] += 1;
} else if (depth < cols.len) {
cols[depth] = indent;
nums[depth] = 2; // this item is 1; its next sibling will be 2
depth += 1;
}
// Emit: indentation, an optional `(`, the new number, then the
// delimiter and everything after it verbatim.
try out.appendSlice(allocator, line[0..mm.start]);
var d = mm.start;
if (d < line.len and line[d] == '(') {
try out.append(allocator, '(');
d += 1;
}
var num_buf: [16]u8 = undefined;
const digits = std.fmt.bufPrint(&num_buf, "{d}", .{number}) catch unreachable;
try out.appendSlice(allocator, digits);
var k = d;
while (k < line.len and line[k] >= '0' and line[k] <= '9') k += 1;
try out.appendSlice(allocator, line[k..]);
} else {
// A bullet item, a blank line, or prose — including prose that LOOKS
// like a marker but opens no item: verbatim. A bullet doesn't disturb
// the ordered counters at other columns, and neither does prose.
try out.appendSlice(allocator, line);
}
line_start = line_end;
}
}
/// Whether a marker (as returned by `listMarkerAt`) is an ordered one — a run of
/// digits, allowing a leading `(` for the `(1)` form — rather than a bullet.
fn isNumberedMarker(marker: []const u8) bool {
var j: usize = 0;
if (j < marker.len and marker[j] == '(') j += 1;
return j < marker.len and marker[j] >= '0' and marker[j] <= '9';
}
/// The run of QUOTE MARKERS opening the line `at` sits on — the prefix a new
/// block written beside it must repeat to stay in the same containers.
///
/// Quote markers only, because a quote's marker is on EVERY line it covers
/// while a list item's is on its first line alone — a list item holds its
/// content by indentation of the marker's width, which this cannot see from one
/// line. `insertThematicBreak` accepts landing at column zero (it splits the
/// list, corrupting nothing); `toggleCodeBlock`, where the same gap would pull
/// the item's marker into the code body, reads the item's column off the tree
/// instead — see `CodeFrame`.
fn containerPrefix(src: []const u8, at: usize) []const u8 {
const line_start = locate.lineStartAt(src, at);
const line = src[line_start..locate.lineEndAt(src, at)];
var i: usize = 0;
while (skipQuoteMarker(line, i)) |j| i = j;
return line[0..i];
}
/// Whether container `id` ends in markup of its own — bytes after its last
/// child that are not whitespace: `</blockquote>`, `:::`, `____`. A container
/// spelled by line prefixes ends where its last child does.
fn writesClosers(doc: *const Document, src: []const u8, id: AST.Node.Id) bool {
var last: ?AST.Node.Id = null;
var c = doc.ast.nodes[id].first_child;
while (c) |ch| : (c = doc.ast.nodes[ch].next_sibling) last = ch;
const end = doc.span(id).end;
const tail_start = if (last) |l| doc.span(l).end else doc.span(id).start;
if (tail_start >= end) return false;
for (src[tail_start..end]) |byte| {
if (!std.ascii.isWhitespace(byte)) return true;
}
return false;
}
/// Whether `chain` passes through a list item — the containers `containerPrefix`
/// cannot reproduce, and so the ones a gesture that relies on it must refuse.
fn insideListItem(doc: *const Document, chain: []const AST.Node.Id) bool {
for (chain) |id| {
switch (std.meta.activeTag(doc.ast.nodes[id].kind)) {
.list_item, .task_list_item => return true,
else => {},
}
}
return false;
}
// ── Move internals ─────────────────────────────────────────────────────────
/// Where `Editor.moveBlock` puts a block: the container whose prefixes it
/// takes, the blocks it lands between (either may be absent), and the line
/// start — or the source's end — its lines are written at.
const Dest = struct {
container: AST.Node.Id,
prev: ?AST.Node.Id,
next: ?AST.Node.Id,
pos: usize,
};
/// A node `moveBlock` descends INTO looking for the block at an offset,
/// rather than stopping at: the line-owning containers, and a list, whose
/// items own lines even though the list itself is not on `isBlockParent`'s
/// list.
fn descendsInto(kind: AST.Node.Kind) bool {
return locate.isBlockParent(kind) or switch (kind) {
.bullet_list, .ordered_list, .task_list => true,
else => false,
};
}
fn isListItem(kind: AST.Node.Kind) bool {
return switch (kind) {
.list_item, .task_list_item => true,
else => false,
};
}
fn isList(kind: AST.Node.Kind) bool {
return switch (kind) {
.bullet_list, .ordered_list, .task_list => true,
else => false,
};
}
/// The lines a list has apart from its items, as whole lines: what opens it
/// before its first item's line and closes it after its last item's, each
/// empty where the list is spelled by its items' markers alone.
const ListWrap = struct { open: Span = Span.init(0, 0), close: Span = Span.init(0, 0) };
fn listWrap(doc: *const Document, list: AST.Node.Id, item_lines: Span) ListWrap {
if (!isList(doc.ast.nodes[list].kind)) return .{};
const src = doc.source;
const sp = doc.span(list);
if (sp.end <= sp.start) return .{};
const first = doc.ast.nodes[list].first_child orelse return .{};
var last = first;
while (doc.ast.nodes[last].next_sibling) |n| last = n;
const lo = locate.lineStartAt(src, sp.start);
const hi = locate.lineEndAt(src, sp.end - 1);
const first_line = locate.lineStartAt(src, doc.span(first).start);
const last_sp = doc.span(last);
const last_line = if (last_sp.end > last_sp.start) locate.lineEndAt(src, last_sp.end - 1) else item_lines.end;
return .{
.open = Span.init(lo, @max(lo, @min(first_line, item_lines.start))),
.close = Span.init(@min(hi, @max(last_line, item_lines.end)), hi),
};
}
/// A paragraph the parser read without any markup around it — its span is
/// its content — which is how a tight HTML `<li>x</li>` holds its text.
fn isBareParagraph(doc: *const Document, id: AST.Node.Id) bool {
if (doc.ast.nodes[id].kind != .para) return false;
const content = doc.contentSpan(id) orelse return false;
const sp = doc.span(id);
return content.start == sp.start and content.end == sp.end;
}
fn isTightList(kind: AST.Node.Kind) bool {
return switch (kind) {
.bullet_list => |l| l.tight,
.ordered_list => |l| l.tight,
.task_list => |l| l.tight,
else => false,
};
}
/// An inline node — what a list item holds DIRECTLY in a format that gives
/// its text no paragraph (AsciiDoc, a tight HTML `<li>`), and so what the
/// descent may land on under an item. Its text stands for the item's first
/// block.
fn isInlineKind(kind: AST.Node.Kind) bool {
return switch (kind) {
.str,
.soft_break,
.hard_break,
.non_breaking_space,
.text_leaf,
.raw_inline,
.smart_punctuation,
.link,
.image,
.inline_mark,
.substitution,
.reference,
=> true,
.container => |c| c.form == .inline_text,
else => false,
};
}
/// The block `moveBlock` moves for a caret at `offset`: the deepest block
/// owning the caret's line, widened to its list item when it is the item's
/// first block (or the item's own text). `null` on a blank line.
fn movableUnit(doc: *const Document, offset: usize) ?AST.Node.Id {
if (doc.ast.nodes.len == 0) return null;
var cur = doc.ast.root;
while (true) {
const child = locate.caretChildContaining(doc, cur, offset) orelse {
// Inside an item's own marker: the item.
if (isListItem(doc.ast.nodes[cur].kind)) {
if (doc.markerSpan(cur)) |m| if (offset < m.end) return cur;
}
return null;
};
const kind = doc.ast.nodes[child].kind;
if (descendsInto(kind)) {
cur = child;
continue;
}
if (isListItem(doc.ast.nodes[cur].kind)) {
if (isInlineKind(kind) or doc.ast.nodes[cur].first_child == child) return cur;
} else if (isInlineKind(kind)) return null;
return child;
}
}
/// The whole lines `unit` owns, trailing separator lines trimmed —
/// `error.NotEditable` when it shares its first or last line with something
/// that is not a container prefix, since lines are what move.
fn unitLines(doc: *const Document, unit: AST.Node.Id, ancestors: []const AST.Node.Id) Editor.Error!Span {
const src = doc.source;
const sp = doc.span(unit);
if (sp.end <= sp.start) return error.NotEditable;
const start = locate.lineStartAt(src, sp.start);
var end = locate.lineEndAt(src, sp.end - 1);
while (end > start) {
const ls = locate.lineStartAt(src, end - 1);
if (ls <= start) break;
if (!isSeparatorRun(locate.lineBody(src[ls..end]))) break;
end = ls;
}
if (!lineHeadIsPrefix(doc, ancestors, start, sp.start)) return error.NotEditable;
if (sp.end < end and !locate.isBlankLine(locate.lineBody(src[sp.end..end]))) return error.NotEditable;
return Span.init(start, end);
}
/// Whether the bytes `[line_start, at)` are all container prefix: blanks,
/// quote markers, or inside a marker one of `chain`'s nodes opens there.
fn lineHeadIsPrefix(doc: *const Document, chain: []const AST.Node.Id, line_start: usize, at: usize) bool {
var i = line_start;
scan: while (i < at) : (i += 1) {
switch (doc.source[i]) {
' ', '\t', '>' => continue :scan,
else => {},
}
for (chain) |id| {
if (doc.markerSpan(id)) |m| {
if (i >= m.start and i < m.end) continue :scan;
}
}
return false;
}
return true;
}
/// Resolve `to` to the boundary `moveBlock` lands on — see its doc comment
/// for the rules, and `Dest` for the answer. `unit` is the block moving,
/// which is what tells a boundary it already sits on from one it does not.
fn resolveBoundary(
allocator: Allocator,
syntax: *const Syntax,
doc: *const Document,
to: usize,
unit: AST.Node.Id,
) Editor.Error!Dest {
const src = doc.source;
const unit_is_item = isListItem(doc.ast.nodes[unit].kind);
var chain: std.ArrayList(AST.Node.Id) = .empty;
defer chain.deinit(allocator);
try chain.append(allocator, doc.ast.root);
var container = chain.items[chain.items.len - 1];
var prev: ?AST.Node.Id = null;
var next: ?AST.Node.Id = null;
const Side = enum { before, after, gap };
var side: Side = .gap;
// The source's length is the document's end, whether or not the last
// line is terminated: after the last top-level block, and not inside
// it or any container it closes.
const at_end = to == src.len and src.len > 0 and src[src.len - 1] != '\n';
var anchor: ?AST.Node.Id = null;
if (!at_end) {
while (locate.caretChildContaining(doc, chain.items[chain.items.len - 1], to)) |child| {
if (!descendsInto(doc.ast.nodes[child].kind)) {
anchor = child;
break;
}
try chain.append(allocator, child);
}
container = chain.items[chain.items.len - 1];
}
if (anchor) |a| {
// A block holding opaque text — a fence, a raw block — is interior
// from its first byte to its last: the end of its body's last line
// is inside the fence, not after the block.
const content = if (doc.ast.nodes[a].kind.contentModel() == .text) blk: {
const sp = doc.span(a);
var end = sp.end;
if (end > sp.start and src[end - 1] == '\n') end -= 1;
break :blk Span.init(sp.start, end);
} else blockContent(doc, a);
if (to <= content.start) {
side = .before;
} else if (to >= content.end) {
side = .after;
} else return error.NotEditable;
const inline_anchor = isInlineKind(doc.ast.nodes[a].kind);
if (side == .before) {
// Between two inlines of an item's text is inside that text.
if (inline_anchor and doc.ast.nodes[container].first_child != a) return error.NotEditable;
prev = prevSibling(doc, container, a);
next = a;
} else {
var n = doc.ast.nodes[a].next_sibling;
if (inline_anchor) {
if (n != null and isInlineKind(doc.ast.nodes[n.?].kind)) return error.NotEditable;
n = null;
var it = doc.children(container);
var seen = false;
while (it.next()) |c| {
if (seen and !isInlineKind(doc.ast.nodes[c.id].kind)) {
n = c.id;
break;
}
if (c.id == a) seen = true;
}
}
prev = a;
next = n;
}
} else {
var it = doc.children(container);
while (it.next()) |c| {
const sp = doc.span(c.id);
if (sp.start < to) {
prev = c.id;
} else if (next == null) next = c.id;
}
if (at_end and prev != null) side = .after;
}
// At a container's opening — at or before its marker, or its opening
// line's first byte where it has lines of its own — is BEFORE the
// container, at its parent's level: the boundary inside it is the first
// content byte, and this is the one offset that can name the other when
// nothing precedes the container. The outermost such container on
// `to`'s line, so `> > a` at 0 is before both quotes and at 2 before
// the inner one alone.
const to_line = locate.lineStartAt(src, to);
for (chain.items[1..], 1..) |c, depth| {
// A list opens where its first item does; its edge is the list-edge
// rule's below, which knows an item joins it there.
if (isList(doc.ast.nodes[c].kind)) continue;
const open = if (doc.markerSpan(c)) |m| m.start else doc.span(c).start;
if (to > open or locate.lineStartAt(src, open) != to_line) continue;
chain.items.len = depth;
container = chain.items[depth - 1];
side = .before;
prev = prevSibling(doc, container, c);
next = c;
break;
}
// The list adjustments, and then the climb: a boundary the block already
// sits on — after itself, before itself — is, inside a container, the
// same boundary as the one after or before the CONTAINER, read at the
// parent's level, which is the reading that moves it. At the top level
// it moves nothing. The adjustments run again after the climb, since it
// can land at an item's head or a list's edge.
var climbed = false;
while (true) {
// Inside a list item: a boundary before its first block is before the
// item, and a moved item is a sibling wherever it is dropped.
if (isListItem(doc.ast.nodes[container].kind) and chain.items.len >= 2) {
const item = container;
const at_head = prev == null or (next != null and next.? == doc.ast.nodes[item].first_child);
if (at_head or unit_is_item) {
_ = chain.pop();
container = chain.items[chain.items.len - 1];
if (at_head) {
side = .before;
prev = prevSibling(doc, container, item);
next = item;
} else {
side = .after;
prev = item;
next = doc.ast.nodes[item].next_sibling;
}
}
}
// At a list's edge, a block that is not an item is beside the LIST:
// the list contributes no prefix, so the boundary is the same place,
// but its neighbours are the list's own, which is what tells a block
// already there from one that moves.
if (!unit_is_item and isList(doc.ast.nodes[container].kind) and chain.items.len >= 2) {
const list = container;
if (next != null and next.? == doc.ast.nodes[list].first_child) {
_ = chain.pop();
container = chain.items[chain.items.len - 1];
side = .before;
prev = prevSibling(doc, container, list);
next = list;
} else if (next == null) {
_ = chain.pop();
container = chain.items[chain.items.len - 1];
side = .after;
prev = list;
next = doc.ast.nodes[list].next_sibling;
}
}
const after_self = prev != null and prev.? == unit;
const before_self = next != null and next.? == unit;
if (!after_self and !before_self) break;
// Only the container's last block is also after the container, and
// only its first is also before it; for any other the boundary is
// one it sits on and nothing else.
const at_edge = if (after_self) doc.ast.nodes[unit].next_sibling == null else doc.ast.nodes[container].first_child == unit;
if (climbed or !at_edge or chain.items.len < 2) return error.InvalidArgument;
const c = container;
_ = chain.pop();
container = chain.items[chain.items.len - 1];
if (after_self) {
side = .after;
prev = c;
next = doc.ast.nodes[c].next_sibling;
} else {
side = .before;
prev = prevSibling(doc, container, c);
next = c;
}
climbed = true;
}
const pos = switch (side) {
.before => blk: {
const sp = doc.span(next.?);
const ls = locate.lineStartAt(src, sp.start);
if (!lineHeadIsPrefix(doc, chain.items, ls, sp.start)) return error.NotEditable;
break :blk ls;
},
.after => blk: {
const sp = doc.span(prev.?);
if (sp.end <= sp.start) return error.NotEditable;
const le = locate.lineEndAt(src, sp.end - 1);
if (sp.end < le and !locate.isBlankLine(locate.lineBody(src[sp.end..le]))) return error.NotEditable;
break :blk le;
},
.gap => blk: {
const ls = locate.lineStartAt(src, to);
if (!isSeparatorLine(syntax, locate.lineBody(src[ls..locate.lineEndAt(src, to)]))) return error.NotEditable;
break :blk ls;
},
};
return .{ .container = container, .prev = prev, .next = next, .pos = pos };
}
fn prevSibling(doc: *const Document, parent: AST.Node.Id, id: AST.Node.Id) ?AST.Node.Id {
var prev: ?AST.Node.Id = null;
var it = doc.children(parent);
while (it.next()) |c| {
if (c.id == id) return prev;
prev = c.id;
}
return null;
}
/// The lines `moveBlock` removes: the block's own, plus the separator lines
/// that kept it apart from its neighbours inside its parent — the ones after
/// it, or when nothing but separators follows it there, those before it too,
/// so that no doubled blank is left and a container's trailing `>` line does
/// not outlive its last block. The parent is climbed first through every
/// prefix-spelled container the block is the only content of (a quote whose
/// one paragraph leaves, a list whose one item does), since such a container
/// has no lines of its own and is gone once its content is.
fn removalLines(syntax: *const Syntax, doc: *const Document, chain: []const AST.Node.Id, lines: Span) Span {
const src = doc.source;
var r: usize = chain.len - 1;
while (r > 0) {
const parent = chain[r - 1];
if (parent == doc.ast.root or !spelledByPrefix(doc, parent)) break;
if (doc.ast.nodes[parent].first_child != chain[r] or doc.ast.nodes[chain[r]].next_sibling != null) break;
r -= 1;
}
// The climbed container's own lines, where it has any beyond the
// block's (a delimited list's `<ul>`/`</ul>`).
var lo = lines.start;
var hi = lines.end;
if (r < chain.len - 1) {
const rsp = doc.span(chain[r]);
if (rsp.end > rsp.start) {
lo = @min(lo, locate.lineStartAt(src, rsp.start));
hi = @max(hi, locate.lineEndAt(src, rsp.end - 1));
}
}
const parent = chain[r - 1];
var parent_start: usize = 0;
var parent_end: usize = src.len;
if (parent != doc.ast.root) {
// Its interior, where the parent records one: a delimited
// container's closing line is the parent's own, not something that
// follows the block inside it.
const psp = doc.contentSpan(parent) orelse doc.span(parent);
if (psp.end > psp.start) {
parent_start = locate.lineStartAt(src, psp.start);
parent_end = @max(locate.lineEndAt(src, psp.end - 1), hi);
}
}
var after = hi;
while (after < parent_end) {
const le = locate.lineEndAt(src, after);
if (!isSeparatorLine(syntax, locate.lineBody(src[after..le]))) break;
after = le;
}
var before = lo;
if (after >= parent_end) {
while (before > parent_start) {
const ls = locate.lineStartAt(src, before - 1);
if (ls < parent_start) break;
if (!isSeparatorLine(syntax, locate.lineBody(src[ls..before]))) break;
before = ls;
}
}
return Span.init(before, after);
}
/// Whether `parent` goes when its only child does: a container spelled by
/// prefixes on the child's lines and nothing else (a `>` quote, a
/// marker-prefixed item), or a list, whose lines are its items' spelling.
/// A delimited container (`____`, `:::`, `<blockquote>`) has lines of its
/// own and stands when emptied — it may carry attributes a move must not
/// drop.
fn spelledByPrefix(doc: *const Document, parent: AST.Node.Id) bool {
return switch (doc.ast.nodes[parent].kind) {
// A list is its items' spelling either way: a marker-spelled one has
// no lines of its own, and a delimited one (`<ul>`) travels with its
// only item — see `listWrap`.
.bullet_list, .ordered_list, .task_list => true,
.block_quote, .list_item, .task_list_item => doc.markerSpan(parent) != null,
.section => true,
else => false,
};
}
/// `chain` as the prefix walk should see it, appended to `out`: whole, or
/// without its list items where the format attaches a block to an item by a
/// line of its own rather than by the item's indent (`Syntax.list_attach`).
fn prefixChain(
allocator: Allocator,
syntax: *const Syntax,
doc: *const Document,
chain: []const AST.Node.Id,
out: *std.ArrayList(AST.Node.Id),
) Allocator.Error!void {
for (chain) |id| {
if (syntax.list_attach != null and isListItem(doc.ast.nodes[id].kind)) continue;
try out.append(allocator, id);
}
}
/// `isSeparatorRun` for a whole line, plus the format's attach line where it
/// has one: AsciiDoc's `+` separates an item's text from an attached block
/// the way a blank line separates two paragraphs, and travels the same way.
fn isSeparatorLine(syntax: *const Syntax, body: []const u8) bool {
if (isSeparatorRun(body)) return true;
const attach = syntax.list_attach orelse return false;
return std.mem.eql(u8, std.mem.trim(u8, body, " \t\r"), attach);
}
/// How many bytes of `body` are prefix inside the first `cols` columns:
/// blanks and quote markers, a tab advancing to its stop. Stops at the first
/// byte that is neither, so a lazy continuation line sheds nothing.
fn stripColumns(body: []const u8, cols: usize) usize {
var i: usize = 0;
var col: usize = 0;
while (i < body.len and col < cols) : (i += 1) {
switch (body[i]) {
' ', '>' => col += 1,
'\t' => col += 4 - col % 4,
else => break,
}
}
return i;
}
/// The line that ends the text `a ++ b`: its body (with a line end taken
/// off), whether that line end was there, and whether the text was empty.
/// `scratch` holds the body where it straddles the two slices.
const LastLine = struct { body: []const u8, terminated: bool, empty: bool };
fn lastLineOf(allocator: Allocator, a: []const u8, b: []const u8, scratch: *std.ArrayList(u8)) Allocator.Error!LastLine {
if (a.len == 0 and b.len == 0) return .{ .body = "", .terminated = true, .empty = true };
var text_a = a;
var text_b = b;
var terminated = false;
if (text_b.len > 0) {
if (text_b[text_b.len - 1] == '\n') {
terminated = true;
text_b = text_b[0 .. text_b.len - 1];
}
} else if (text_a[text_a.len - 1] == '\n') {
terminated = true;
text_a = text_a[0 .. text_a.len - 1];
}
if (std.mem.lastIndexOfScalar(u8, text_b, '\n')) |nl| {
return .{ .body = std.mem.trimEnd(u8, text_b[nl + 1 ..], "\r"), .terminated = terminated, .empty = false };
}
const a_tail = if (std.mem.lastIndexOfScalar(u8, text_a, '\n')) |nl| text_a[nl + 1 ..] else text_a;
if (text_b.len == 0) return .{ .body = std.mem.trimEnd(u8, a_tail, "\r"), .terminated = terminated, .empty = false };
scratch.clearRetainingCapacity();
try scratch.appendSlice(allocator, a_tail);
try scratch.appendSlice(allocator, text_b);
return .{ .body = std.mem.trimEnd(u8, scratch.items, "\r"), .terminated = terminated, .empty = false };
}
/// The first line of the text `a ++ b`, without its line end — a whole
/// slice of one or the other, since the separator decision only needs to
/// know whether it is content, and a line that starts content in `a` and
/// runs into `b` is content already.
fn firstLineOf(a: []const u8, b: []const u8) []const u8 {
const text = if (a.len > 0) a else b;
const line = text[0 .. std.mem.indexOfScalar(u8, text, '\n') orelse text.len];
return std.mem.trimEnd(u8, line, "\r");
}
// ── Code-fence internals ───────────────────────────────────────────────────
/// How many fence characters a fence over `body` needs: one more than the
/// longest run of `char` anywhere in it, floored at `min`. That is what lets a
/// code block hold a code block — the outer fence simply outgrows the inner one.
fn fenceWidth(body: []const u8, char: u8, min: usize) usize {
var longest: usize = 0;
var run: usize = 0;
for (body) |c| {
if (c != char) {
run = 0;
continue;
}
run += 1;
if (run > longest) longest = run;
}
return @max(min, longest + 1);
}
/// The fence opening `line`: where its first character sits and how many there
/// are, after any quote prefix and up to three spaces of indentation. `null`
/// when the line opens no fence — which is not a malformed document but the
/// ordinary shape of a Markdown INDENTED code block.
fn fenceAt(line: []const u8, char: u8, min: usize) ?struct { start: usize, width: usize } {
var i: usize = 0;
while (skipQuoteMarker(line, i)) |j| i = j;
var indent: usize = 0;
while (i < line.len and line[i] == ' ' and indent < 3) : (indent += 1) i += 1;
const start = i;
while (i < line.len and line[i] == char) i += 1;
return if (i - start >= min) .{ .start = start, .width = i - start } else null;
}
/// Where a code block's lines sit: the containers around it, as
/// `Editor.toggleCodeBlock` strips them off a line it reads and writes them
/// onto a line it mints.
///
/// A quote's marker is on every line it holds, but a list item's is on its
/// first line alone — the rest are held by INDENTATION to the item's content
/// column. So a line has two shapes here: the first line of a block that
/// opens a container, whose HEAD is the markers opening on it (`- `, `> `,
/// `> 1. `), and every other, which carries the continuation `prefix` (` `,
/// `> `, `> `). Fencing moves the head onto the opening fence and gives the
/// body's first line the continuation in its place; unfencing does the
/// reverse.
const CodeFrame = struct {
ancestors: []const AST.Node.Id,
/// What a line inside the containers opens with where nothing opens on
/// it: a quote's marker again, a list item's content column in spaces.
prefix: std.ArrayList(u8) = .empty,
/// `prefix`'s width in columns.
cols: usize = 0,
/// The frame of a block whose ancestors are `ancestors`, outermost first.
///
/// This is `locate.continuationPrefixAlong` but for two things, both
/// because a code body is read to the column where a paragraph is read
/// loosely:
///
/// * A TASK item's content column is its list marker's, not its
/// checkbox's: the box is the first paragraph's, and a fence written
/// after it opens a block at the item's content column like any other.
/// A body at the box's column would be indented past it — its closing
/// fence four columns in, where it closes nothing.
/// * A list item is left out where the format attaches a block to an
/// item by a line of its own (`Syntax.list_attach`) — the block's
/// lines are at column zero there, as `moveBlock` writes them.
fn init(allocator: Allocator, syntax: *const Syntax, doc: *const Document, ancestors: []const AST.Node.Id) Allocator.Error!CodeFrame {
var self: CodeFrame = .{ .ancestors = ancestors };
errdefer self.prefix.deinit(allocator);
const src = doc.source;
for (ancestors) |id| {
const kind = doc.ast.nodes[id].kind;
if (!frames(kind)) continue;
if (syntax.list_attach != null and isListItem(kind)) continue;
const m = doc.markerSpan(id) orelse continue;
var end = m.end;
if (kind == .task_list_item) {
if (listMarkerAt(src[m.start..m.end], 0)) |lm| end = m.start + lm.end;
}
const start_col = locate.columnOf(src, m.start);
const end_col = locate.columnOf(src, end);
while (self.cols < start_col) : (self.cols += 1) try self.prefix.append(allocator, ' ');
if (end_col > self.cols) {
if (kind == .block_quote) {
try self.prefix.appendSlice(allocator, src[m.start..end]);
} else {
try self.prefix.appendNTimes(allocator, ' ', end_col - self.cols);
}
self.cols = end_col;
}
}
return self;
}
fn deinit(self: *CodeFrame, allocator: Allocator) void {
self.prefix.deinit(allocator);
}
/// The containers that put a prefix on the lines they hold — the ones a
/// frame is made of. Not every node with a marker: an AsciiDoc
/// admonition's `NOTE: ` is its paragraph's, and a fence written after
/// it would be that paragraph's text.
fn frames(kind: AST.Node.Kind) bool {
return switch (kind) {
.block_quote, .list_item, .task_list_item, .definition_list_item, .definition, .footnote => true,
else => false,
};
}
/// What a blank line inside the containers carries: a quote's `>`, and
/// nothing for a list item — see `locate.blankLinePrefix`.
fn blank(self: *const CodeFrame) []const u8 {
return std.mem.trimEnd(u8, self.prefix.items, " \t");
}
/// How many bytes of the line starting at `at` are markers opening there
/// — through the last of them, a task item's checkbox included, since it
/// stays on the item's first line — or null where none opens and the line
/// carries only the continuation.
fn headLen(self: *const CodeFrame, doc: *const Document, at: usize) ?usize {
const le = locate.lineEndAt(doc.source, at);
const body_len = locate.lineBody(doc.source[at..le]).len;
var n: ?usize = null;
for (self.ancestors) |a| {
if (!frames(doc.ast.nodes[a].kind)) continue;
const m = doc.markerSpan(a) orelse continue;
if (m.start >= at and m.start < le) n = @min(body_len, @max(n orelse 0, m.end - at));
}
return n;
}
/// Whether a list item's marker opens on the line starting at `at` — the
/// block there is the item's first, and the line its only marker.
fn opensItem(self: *const CodeFrame, doc: *const Document, at: usize) bool {
const le = locate.lineEndAt(doc.source, at);
for (self.ancestors) |a| {
if (!isListItem(doc.ast.nodes[a].kind)) continue;
const m = doc.markerSpan(a) orelse continue;
if (m.start >= at and m.start < le) return true;
}
return false;
}
/// How much of `body` is the continuation prefix: `len` bytes of blanks
/// and quote markers up to `cols` columns, stopping at anything else (a
/// lazy line), and `full` when all `cols` were there. A tab that crosses
/// the prefix's edge is taken whole and its columns past the edge are
/// `pad` — content indentation to write back as spaces.
const Strip = struct { len: usize, pad: usize, full: bool };
fn strip(self: *const CodeFrame, body: []const u8) Strip {
var i: usize = 0;
var col: usize = 0;
while (i < body.len and col < self.cols) : (i += 1) {
switch (body[i]) {
' ', '>' => col += 1,
'\t' => col += 4 - col % 4,
else => break,
}
}
return .{ .len = i, .pad = col -| self.cols, .full = col >= self.cols };
}
/// `rest` behind the continuation prefix and `pad` spaces, or behind the
/// blank prefix where it is blank, then `ending`.
fn writeLine(self: *const CodeFrame, allocator: Allocator, out: *std.ArrayList(u8), pad: usize, rest: []const u8, ending: []const u8) Allocator.Error!void {
if (locate.isBlankLine(rest)) {
try out.appendSlice(allocator, self.blank());
} else {
try out.appendSlice(allocator, self.prefix.items);
try out.appendNTimes(allocator, ' ', pad);
try out.appendSlice(allocator, rest);
}
try out.appendSlice(allocator, ending);
}
};
/// The interior of the code block `cb` occupying `[region_start, region_end)`,
/// with its framing removed — the body of `Editor.toggleCodeBlock`'s unfence
/// half, where its reasoning lives — written to `out`. Returns where the
/// splice ends, which is past `region_end` in the one case below that takes
/// the blank lines after the block.
///
/// Where markers open on the fence line (`frame.headLen`), they are not
/// framing but the containers': they go onto the first line of the body in
/// place of its continuation, which is what keeps a list item's marker when
/// its first block is the one unfenced. Where the item's first line would be
/// left blank, that is not a place to stop: an item whose first line is
/// blank holds nothing past a blank line after it, so the body's leading
/// blank lines are skipped to its first line of content, and an EMPTY body
/// takes the blank lines after the block with it, so that a block following
/// in the item is still the item's.
fn buildUnfence(
allocator: Allocator,
doc: *const Document,
frame: *const CodeFrame,
cb: AST.Node.Id,
region_start: usize,
region_end: usize,
fence: syntax_mod.CodeFence,
out: *std.ArrayList(u8),
) !usize {
const src = doc.source;
const head = frame.headLen(doc, region_start);
const first_end = locate.lineEndAt(src, region_start);
const first_body = locate.lineBody(src[region_start..first_end]);
const opening = first_body[head orelse frame.strip(first_body).len ..];
if (fenceAt(opening, fence.char, fence.min) == null) {
// No opening fence: a Markdown indented code block, whose framing IS its
// indentation. Four spaces is the marker; a line indented further keeps
// the rest, which is the indentation the code itself carried.
var line_start = region_start;
while (line_start < region_end) {
const line_end = locate.lineEndAt(src, line_start);
const body = locate.lineBody(src[line_start..line_end]);
const ending = src[line_start + body.len .. line_end];
const on_head = line_start == region_start and head != null;
const st: CodeFrame.Strip = if (on_head) .{ .len = head.?, .pad = 0, .full = true } else frame.strip(body);
var rest = body[st.len..];
var pad = st.pad;
var indent: usize = @min(pad, 4);
pad -= indent;
while (indent < 4 and rest.len > 0 and rest[0] == ' ') : (indent += 1) rest = rest[1..];
if (on_head) {
try appendHeadLine(allocator, out, src[region_start .. region_start + head.?], pad, rest, ending);
} else {
try frame.writeLine(allocator, out, pad, rest, ending);
}
line_start = line_end;
}
return region_end;
}
// Fenced: drop the opening line, and the closing one when there IS one — an
// unterminated fence at the end of the document has no closing line, and its
// last line is content that must survive.
var body_end = region_end;
const last_start = locate.lineStartAt(src, region_end -| 1);
if (last_start >= first_end) {
const last = locate.lineBody(src[last_start..region_end]);
if (fenceAt(last[frame.strip(last).len..], fence.char, fence.min) != null) body_end = last_start;
}
body_end = @max(body_end, first_end);
const h = head orelse {
// Nothing opens on the fence line: the interior already carries its
// containers' prefix, and is kept verbatim.
try out.appendSlice(allocator, src[first_end..body_end]);
return region_end;
};
const head_bytes = src[region_start .. region_start + h];
const item = frame.opensItem(doc, region_start);
// The line the head goes onto: the body's first, or in an item its first
// with content.
var line_start = first_end;
if (item) {
while (line_start < body_end) {
const le = locate.lineEndAt(src, line_start);
const body = locate.lineBody(src[line_start..le]);
if (!locate.isBlankLine(body[frame.strip(body).len..])) break;
line_start = le;
}
}
if (line_start >= body_end) {
// An empty body. Nothing is left of the block — but where the fence
// line held a list item's marker, the item is kept, empty, and a block
// after this one in the item is brought up under it.
if (!item) return region_end;
try out.appendSlice(allocator, std.mem.trimEnd(u8, head_bytes, " \t"));
try out.append(allocator, '\n');
var end = region_end;
if (doc.ast.nodes[cb].next_sibling != null) {
while (end < src.len) {
const le = locate.lineEndAt(src, end);
const body = locate.lineBody(src[end..le]);
if (!locate.isBlankLine(body[frame.strip(body).len..])) break;
end = le;
}
}
return end;
}
const le = locate.lineEndAt(src, line_start);
const body = locate.lineBody(src[line_start..le]);
const st = frame.strip(body);
try appendHeadLine(allocator, out, head_bytes, st.pad, body[st.len..], src[line_start + body.len .. le]);
try out.appendSlice(allocator, src[le..@max(le, body_end)]);
return region_end;
}
/// `rest` behind the head of a block's first line — where the line's markers
/// are — and `pad` spaces; a blank `rest` leaves the head without its
/// trailing blanks.
fn appendHeadLine(allocator: Allocator, out: *std.ArrayList(u8), head: []const u8, pad: usize, rest: []const u8, ending: []const u8) Allocator.Error!void {
if (locate.isBlankLine(rest)) {
try out.appendSlice(allocator, std.mem.trimEnd(u8, head, " \t"));
} else {
try out.appendSlice(allocator, head);
try out.appendNTimes(allocator, ' ', pad);
try out.appendSlice(allocator, rest);
}
try out.appendSlice(allocator, ending);
}
/// Refuse an info string this format's fence cannot carry back out: a line end
/// (which would end the fence line), the fence character itself (which would
/// widen or close the fence), and whatever else the format forbids — Markdown
/// ends its info string at whitespace, so a space there would come back
/// truncated rather than broken, which is worse.
fn checkInfoString(fence: syntax_mod.CodeFence, lang: []const u8) Editor.Error!void {
if (std.mem.indexOfAny(u8, lang, "\r\n") != null) return error.InvalidLanguage;
if (std.mem.indexOfScalar(u8, lang, fence.char) != null) return error.InvalidLanguage;
if (std.mem.indexOfAny(u8, lang, fence.info_forbids) != null) return error.InvalidLanguage;
}
/// Refuse a directive name that would not come back as the name of a
/// container. The grammar is `markdown/attributes.zig`'s `scanName` — an ASCII
/// letter, then letters, digits, `-` and `_` — minus the colon that one also
/// admits, and it is checked HERE, once, rather than per format, because a
/// name is written where a delimiter would otherwise be in every spelling of
/// one. The failures are not subtle and they differ per format, which is
/// exactly why the editor takes the intersection:
///
/// * A SPACE: Markdown reads `::a b` as a paragraph holding an INLINE
/// directive named `a`, djot reads `::: a b` as a paragraph of literal
/// colons, and HTML truncates `<a b>` to a tag named `a` with an
/// attribute. Three different wrong answers from one gesture.
/// * A BRACKET or a brace: `::]{ ` is no container at all, in any of them.
/// * A LEADING DIGIT: Markdown's own `scanName` requires a letter, so
/// `::1x` is a paragraph — the rule that keeps `:30` from being a name.
/// * A COLON is the one Markdown itself would accept, and djot would not:
/// its class grammar has none, so `::: a:b` reparses as a paragraph. A
/// format-neutral gesture cannot mint a name only some formats read.
///
/// Case is not checked, because it is not a refusal: HTML folds a tag name, so
/// an upper-case name comes back lower-cased there while every other format
/// keeps it. That is a spelling difference, not a lost node.
/// The grammar an attribute must fit for every format to read it back: a key
/// that is an ASCII letter or `_` followed by letters, digits, `-`, `_` and
/// `:` (the intersection of djot's, Markdown's and HTML's attribute names), a
/// value — a BARE key is HTML's alone; djot's `{…}` has no spelling for one
/// and reads the whole block as text — and no line end or double quote in
/// it, the two bytes a quoted value cannot hold in every spelling at once.
fn checkAttr(kv: AST.KeyVal) Editor.Error!void {
if (kv.key.len == 0) return error.InvalidAttribute;
if (!std.ascii.isAlphabetic(kv.key[0]) and kv.key[0] != '_') return error.InvalidAttribute;
for (kv.key[1..]) |c| {
if (!std.ascii.isAlphanumeric(c) and c != '-' and c != '_' and c != ':') return error.InvalidAttribute;
}
const value = kv.value orelse return error.InvalidAttribute;
if (std.mem.indexOfAny(u8, value, "\r\n\"") != null) return error.InvalidAttribute;
}
fn checkDirectiveName(name: []const u8) Editor.Error!void {
if (name.len == 0) return error.InvalidName;
if (!std.ascii.isAlphabetic(name[0])) return error.InvalidName;
for (name[1..]) |c| {
if (!std.ascii.isAlphanumeric(c) and c != '-' and c != '_') return error.InvalidName;
}
}
// ── Task-checkbox internals ────────────────────────────────────────────────
/// Where a list item's checkbox is, or would go. `box` is the brackets and what
/// is between them and NOTHING else — `space` counts the separator after it
/// separately, because ticking a box must not touch the author's spacing while
/// removing one must take the separator with it.
const TaskBox = struct {
at: usize,
box: ?Span,
space: usize,
checked: bool,
};
// ── Footnote internals ─────────────────────────────────────────────────────
/// Whether `label` already has a DEFINITION in this tree.
///
/// A linear scan of `ast.nodes` rather than a walk from the root, because a
/// footnote definition is attached to no parent: both parsers resolve them by
/// label, not by position, so the node is a detached root that a child walk
/// never reaches.
/// `checkInfoString` for the render path, which has no fence to measure
/// against: a language is ONE TOKEN in every format that spells one — a
/// `class="language-…"` splits on whitespace as an info string ends at it —
/// so any whitespace is `error.InvalidLanguage`. Whatever else the token
/// holds is the renderer's to escape, and the reparse's to check.
fn checkLanguageToken(lang: []const u8) Editor.Error!void {
for (lang) |c| if (std.ascii.isWhitespace(c)) return error.InvalidLanguage;
}
/// One inline node a selection covers: the node whole, or — for a `str` the
/// selection starts or ends inside — the covered part of its text.
const InlinePiece = struct { node: AST.Node.Id, text: ?[]const u8 };
/// The inline nodes `[start, end)` covers, in order: the children of the
/// deepest node containing both ends, from the one holding `start` to the one
/// holding `end - 1`, each of which must be inline-level. Caller frees.
///
/// The ends may fall inside a `str`, and only a `str`: its covered part is a
/// slice of its text, which is exact only where the text is the source
/// byte-for-byte (`span.len == text.len`) — a run spelling `&` has no
/// character at every byte, and slicing it would put an entity's tail in the
/// link. Anything else the range cuts through is `error.NotEditable`, and so
/// is a range whose ends sit in nothing (`error.NoBlock`) or that crosses a
/// block boundary.
fn coveredInlines(allocator: Allocator, doc: *const Document, start: usize, end: usize) Editor.Error![]InlinePiece {
const ast = &doc.ast;
var chain_a: std.ArrayList(AST.Node.Id) = .empty;
defer chain_a.deinit(allocator);
try locate.ancestorChain(allocator, doc, start, &chain_a);
var chain_b: std.ArrayList(AST.Node.Id) = .empty;
defer chain_b.deinit(allocator);
try locate.ancestorChain(allocator, doc, end - 1, &chain_b);
var i: usize = 0;
while (i + 1 < chain_a.items.len and i + 1 < chain_b.items.len and
chain_a.items[i + 1] == chain_b.items[i + 1]) : (i += 1)
{}
const common = chain_a.items[i];
var pieces: std.ArrayList(InlinePiece) = .empty;
errdefer pieces.deinit(allocator);
// The range IS one node (`<em>this</em>` selected whole): that node.
const common_span = doc.span(common);
if (common_span.start >= start and common_span.end <= end) {
if (ast.nodes[common].kind.level() != .@"inline") return error.NotEditable;
try pieces.append(allocator, .{ .node = common, .text = null });
return pieces.toOwnedSlice(allocator);
}
// Both ends in one text run: its covered part, and nothing else.
if (ast.nodes[common].kind == .str) {
try pieces.append(allocator, .{ .node = common, .text = try strSlice(doc, common, start, end) });
return pieces.toOwnedSlice(allocator);
}
if (i + 1 >= chain_a.items.len or i + 1 >= chain_b.items.len) return error.NoBlock;
const first = chain_a.items[i + 1];
const last = chain_b.items[i + 1];
var cur: ?AST.Node.Id = first;
while (cur) |c| : (cur = if (c == last) null else ast.nodes[c].next_sibling) {
if (ast.nodes[c].kind.level() != .@"inline") return error.NotEditable;
const sp = doc.span(c);
const cut = (c == first and sp.start < start) or (c == last and sp.end > end);
try pieces.append(allocator, .{
.node = c,
.text = if (cut) try strSlice(doc, c, @max(sp.start, start), @min(sp.end, end)) else null,
});
}
return pieces.toOwnedSlice(allocator);
}
/// The part of `str` node `id`'s text that `[start, end)` covers, where the
/// text is its source byte-for-byte; `error.NotEditable` for any other node,
/// or a run whose source spells a character some other way.
fn strSlice(doc: *const Document, id: AST.Node.Id, start: usize, end: usize) Editor.Error![]const u8 {
const text = switch (doc.ast.nodes[id].kind) {
.str => |t| t,
else => return error.NotEditable,
};
const sp = doc.span(id);
if (sp.end - sp.start != text.len) return error.NotEditable;
return text[start - sp.start .. end - sp.start];
}
fn footnoteDefined(ast: *const AST, label: []const u8) bool {
for (ast.nodes) |n| {
if (std.meta.activeTag(n.kind) != .footnote) continue;
if (std.mem.eql(u8, n.kind.footnote.label, label)) return true;
}
return false;
}
/// Whether `src` already ends in a blank line — so appending a block needs only
/// a line of its own, not a separator too. An EMPTY document counts: there is
/// nothing above for the new block to fuse with.
fn endsWithBlankLine(src: []const u8) bool {
if (src.len == 0) return true;
if (src[src.len - 1] != '\n') return false;
const last = locate.lineStartAt(src, src.len - 1);
return locate.isBlankLine(locate.lineBody(src[last..]));
}
// ── Link internals ─────────────────────────────────────────────────────────
// `toggleInline` can't spell a link: its delimiters are a fixed `(open, close)`
// pair, and a link's closing half carries a payload (`](dest)`). Hence a
// dedicated gesture with a destination argument — and with the escaping that
// payload needs.
/// Write `dest` into `out` spelled so the format parses it back byte-for-byte.
///
/// This is the sharp edge of the whole gesture, and it is NOT one escape table:
///
/// * Markdown ends a destination at the first space — `[t](a b)` is not a link
/// at all, it is literal text — so a destination holding whitespace has to
/// move into the `<…>` form, where `<`/`>`/`\` are what need escaping.
/// * Djot takes spaces literally and gives `<…>` NO meaning: `[t](<a b>)`
/// links to the seven characters `<a b>`. Wrapping there would corrupt the
/// URL rather than protect it.
///
/// That difference is `DestEscapes.angle`: non-null means the format HAS an
/// angle form to escape into. The algorithm is the same either way, which is why
/// it lives here once and the alphabets live in `syntax.zig`.
///
/// Both formats honour a backslash escape inside the destination, which is what
/// keeps an unbalanced `)` from closing the link early.
fn writeLinkDestination(
allocator: Allocator,
syntax: *const Syntax,
dest: []const u8,
out: *std.ArrayList(u8),
) !void {
const de = syntax.link_dest_escapes orelse return error.UnsupportedFormat;
const angle: ?[]const u8 = if (de.angle) |a|
(if (std.mem.indexOfAny(u8, dest, " \t") != null) a.escapes else null)
else
null;
if (angle != null) try out.append(allocator, '<');
const escapes = angle orelse de.plain;
for (dest) |c| {
if (std.mem.indexOfScalar(u8, escapes, c) != null) try out.append(allocator, '\\');
try out.append(allocator, c);
}
if (angle != null) try out.append(allocator, '>');
}
fn writeLinkText(
allocator: Allocator,
syntax: *const Syntax,
text: []const u8,
out: *std.ArrayList(u8),
) !void {
const escapes = syntax.link_text_escapes orelse return error.UnsupportedFormat;
for (text) |c| {
if (std.mem.indexOfScalar(u8, escapes, c) != null) try out.append(allocator, '\\');
try out.append(allocator, c);
}
}
/// Write `text` through `render`, one run per `TextPosition`. The engine's half
/// of `Editor.insertLiteral`: it decides which bytes sit at a LINE START —
/// `at_line_start` seeds that zone for the first line; a `\n` re-enters it, and
/// spaces/tabs (a block marker tolerates up to three leading spaces) hold it, so
/// `\n # h` still hands the `#` over in `block_start` position — and which sit
/// in a verbatim body, where the whole run goes over at once. Every run given
/// to `render` lies in exactly one position, so the format spells bytes and
/// never re-derives where a line starts.
fn writeLiteral(
syntax: *const Syntax,
render: RenderTextFn,
text: []const u8,
at_line_start: bool,
in_verbatim: bool,
out: *Writer,
) Writer.Error!void {
if (in_verbatim) return render(syntax, text, .verbatim, out);
var rest = text;
var block_pos = at_line_start;
while (rest.len > 0) {
const nl = std.mem.indexOfScalar(u8, rest, '\n') orelse rest.len - 1;
const line = rest[0 .. nl + 1];
rest = rest[nl + 1 ..];
var body = line;
if (block_pos) {
// The leading whitespace and the byte that ends it: the run in
// which a block marker bites.
var i: usize = 0;
while (i < line.len and (line[i] == ' ' or line[i] == '\t')) i += 1;
const zone = @min(i + 1, line.len);
try render(syntax, line[0..zone], .block_start, out);
body = line[zone..];
}
if (body.len > 0) try render(syntax, body, .inline_text, out);
// A line end re-enters the zone for whatever follows it.
block_pos = line[line.len - 1] == '\n';
}
}
/// The innermost autolink — the `<https://x.dev>` / `<a@b.dev>` form — on the
/// chain that wholly contains `[start, end)`.
///
/// Both node kinds are matched in both formats because the split is not the one
/// the names suggest — it follows the FORMAT, not just the destination.
/// `<mailto:a@b.dev>` parses as a `url` in Markdown and an `email` in djot, so
/// picking one kind per format would miss half the autolinks it was meant to
/// catch.
fn autolinkCovering(doc: *const Document, chain: []const AST.Node.Id, start: usize, end: usize) ?AST.Node.Id {
const id = locate.innermostCovering(doc, chain, &.{.text_leaf}, start, end) orelse return null;
const l = doc.ast.nodes[id].kind.text_leaf;
return if (l.kind == .url or l.kind == .email) id else null;
}
/// Whether writing at `pos` would land STRICTLY INSIDE an autolink's URL — an
/// autolink covers `pos`, and `pos` is neither of its edges. A splice at an edge
/// is safe (it lands beside the node); one strictly inside rewrites the URL
/// itself, which is never what any caller meant. See `Editor.insertLink`.
///
/// Builds its own chain because the caller's is rooted at `start`, and the offset
/// that lands inside can be `end` (a selection running from ordinary text into
/// the middle of a URL).
fn splitsAutolink(allocator: Allocator, doc: *const Document, pos: usize) Allocator.Error!bool {
var chain: std.ArrayList(AST.Node.Id) = .empty;
defer chain.deinit(allocator);
try locate.ancestorChain(allocator, doc, pos, &chain);
const id = autolinkCovering(doc, chain.items, pos, pos) orelse return false;
const span = doc.span(id);
return span.start < pos and pos < span.end;
}
test {
_ = @import("editor_test.zig");
}