oxc-markdown-parser 0.0.3

//! Inline phase.
//!
//! micromark-shaped single pass: special characters are scanned left to right;
//! code spans, autolinks and raw HTML resolve immediately (they outrank everything),
//! `*`/`_` runs and brackets are only recorded;
//! a bracket close and the end of the run resolve them (`emphasis`, `link`),
//! and the flat node list becomes a tree once (`emphasis::build`).
//!
//! Positions are ranges into the joined logical text ([`input::Input`]);
//! every emitted span goes through its exact per-line map back to source offsets (`lower`).

mod autolink;
pub mod emphasis;
mod extension;
mod gfm_autolink;
mod html;
pub mod input;
mod link;
mod lower;
mod refmap;

pub use gfm_autolink::{LiteralKind, literal_kind};
pub use refmap::RefMap;

use std::ops::Range;

use oxc_allocator::{Allocator, ArenaVec};

use crate::ast::*;
use crate::block::IrSeg;
use crate::options::Constructs;
use crate::syntax;
use emphasis::{Delim, Formed};
use input::Input;
use link::Bracket;

/// Proto-node over joined-text ranges; converted to the arena AST at the end.
pub enum PN {
    Text(Range<usize>),
    SoftBreak(usize),
    HardBreak {
        kind: HardBreakKind,
        r: Range<usize>,
    },
    Code {
        r: Range<usize>,
        content: Range<usize>,
    },
    Html {
        r: Range<usize>,
    },
    Autolink {
        r: Range<usize>,
        email: bool,
    },
    AutolinkLiteral(Range<usize>),
    FootnoteRef {
        label: Range<usize>,
        r: Range<usize>,
    },
    MathSpan(Range<usize>),
    WikiLink(Range<usize>),
    Liquid(Range<usize>),
    /// `len` marker characters each side: `**` / `__` is strong, `~` or `~~` strikethrough.
    Emph {
        marker: u8,
        len: u8,
        children: Vec<PN>,
        r: Range<usize>,
    },
    Link {
        image: bool,
        kind: PLinkKind,
        children: Vec<PN>,
        text: Range<usize>,
        r: Range<usize>,
    },
}

impl PN {
    fn start(&self) -> usize {
        match self {
            PN::SoftBreak(p) => *p,
            PN::Text(r)
            | PN::AutolinkLiteral(r)
            | PN::MathSpan(r)
            | PN::WikiLink(r)
            | PN::Liquid(r)
            | PN::HardBreak { r, .. }
            | PN::Code { r, .. }
            | PN::Html { r }
            | PN::Autolink { r, .. }
            | PN::FootnoteRef { r, .. }
            | PN::Emph { r, .. }
            | PN::Link { r, .. } => r.start,
        }
    }
}

pub enum PLinkKind {
    Inline { dest: Range<usize>, angle_bracketed: bool, title: Option<Range<usize>> },
    Reference { kind: ReferenceKind, label: Range<usize> },
}

pub fn inlines<'a>(
    allocator: &'a Allocator,
    source: &str,
    segments: &[IrSeg],
    refs: &RefMap,
    constructs: &Constructs,
) -> ArenaVec<'a, Inline<'a>> {
    if segments.is_empty() {
        return ArenaVec::new_in(&allocator);
    }
    let input = Input::new(source, segments);
    let mut tk = Tokenizer {
        t: &input.text,
        refs,
        constructs,
        pos: 0,
        text_start: 0,
        nodes: Vec::new(),
        delims: Vec::new(),
        brackets: Vec::new(),
        formed: Vec::new(),
        first_delim_tilde: None,
        liquid_exhausted: [false; 2],
        wiki_dead: 0,
    };
    tk.run();
    let mut out = ArenaVec::new_in(&allocator);
    for pn in emphasis::build(tk.nodes, &mut tk.formed) {
        lower::push_ast(allocator, &input, pn, &mut out);
    }
    out
}

pub struct Tokenizer<'i, 'r> {
    t: &'i str,
    refs: &'r RefMap,
    constructs: &'r Constructs,
    pos: usize,
    text_start: usize,
    nodes: Vec<PN>,
    delims: Vec<Delim>,
    brackets: Vec<Bracket>,
    /// Emphasis pairs resolved but not yet built into nodes.
    formed: Vec<Formed>,
    /// Whether the first family whose construct succeeded in this run was strikethrough
    /// (any `*`/`_` run, any valid-length `~` run, flanking irrelevant);
    /// decides which family resolves first at the end of the run.
    first_delim_tilde: Option<bool>,
    /// Per closer kind (`%}` / `}}`):
    /// a liquid scan already reached the end of input without finding this closer,
    /// so every later attempt of the same kind fails too, skip the rescans (quadratic otherwise).
    liquid_exhausted: [bool; 2],
    /// Where a wiki link scan last failed:
    /// every `[[` before it fails at the same place, skip the rescans (quadratic otherwise).
    wiki_dead: usize,
}

impl Tokenizer<'_, '_> {
    fn run(&mut self) {
        let bytes = self.t.as_bytes();
        while self.pos < bytes.len() {
            match bytes[self.pos] {
                b'\n' => self.line_ending(),
                b'\\' => match bytes.get(self.pos + 1) {
                    Some(b'\n') => {
                        self.flush_text(self.pos);
                        self.nodes.push(PN::HardBreak {
                            kind: HardBreakKind::Backslash,
                            r: self.pos..self.pos + 1,
                        });
                        self.pos += 2;
                        self.skip_line_ws();
                    }
                    _ if syntax::escapes_next(bytes, self.pos) => self.pos += 2,
                    _ => self.pos += 1,
                },
                b'`' => self.backticks(),
                b'$' if self.constructs.math_text => self.math_span(),
                b'{' if self.try_liquid() => {}
                b'<' => {
                    let handled = self.angle();
                    if !handled {
                        self.pos += 1;
                    }
                }
                // Extensions run before core constructs in micromark,
                // so a literal email may start at `_` (atext);
                // attention only gets the run when the email attempt fails.
                b'_' if self.try_autolink_literal() => {}
                b'*' | b'_' => self.delimiter_run(),
                b'~' if self.constructs.gfm_strikethrough => self.delimiter_run(),
                // GFM autolink literals start on alphanumerics and `+-.`
                // (`_` belongs to attention, which wins there);
                // the previous-character gates inside `scan` make most attempts O(1).
                // Suppressed inside an open bracket label.
                c if (c.is_ascii_alphanumeric() || matches!(c, b'+' | b'-' | b'.')) => {
                    if !self.try_autolink_literal() {
                        self.pos += 1;
                    }
                }
                // Footnote calls are extension constructs and outrank the core label start;
                // `![^…]` leaves the `!` as text.
                b'[' if self.try_footnote_call() => {}
                b'[' if self.try_wiki_link() => {}
                b'[' => self.open_bracket(false),
                b'!' if bytes.get(self.pos + 1) == Some(&b'[') => self.open_bracket(true),
                b']' => self.close_bracket(),
                _ => self.pos += 1,
            }
        }
        // Final line: trailing whitespace is stripped, never a break
        self.flush_text(self.t.trim_end_matches([' ', '\t']).len());
        self.process_emphasis_final();
    }

    /// GFM autolink literal attempt at the current byte.
    /// The previous- character gates inside the scanner keep failed attempts O(1);
    /// literals never start inside an open bracket label.
    fn try_autolink_literal(&mut self) -> bool {
        if !self.constructs.gfm_autolink_literal || !self.brackets.is_empty() {
            return false;
        }
        let prev = self.t[..self.pos].chars().next_back();
        let Some(end) = gfm_autolink::scan(self.t, self.pos, prev) else { return false };
        self.flush_text(self.pos);
        self.nodes.push(PN::AutolinkLiteral(self.pos..end));
        self.pos = end;
        self.text_start = end;
        true
    }

    /// A defined footnote label `[^…]` starting at `at`;
    /// returns (label range, position past the `]`).
    /// Skips all work when the document has no footnote definitions.
    pub(crate) fn footnote_label(&self, at: usize) -> Option<(Range<usize>, usize)> {
        if !self.constructs.gfm_footnote || self.refs.footnotes_is_empty() {
            return None;
        }
        let (label, end) = syntax::link_target::footnote_label(self.t, at)?;
        self.refs
            .contains_footnote(&syntax::label::normalize(&self.t[label.clone()]))
            .then_some((label, end))
    }

    /// GFM footnote call `[^label]` at the current `[`. Only defined labels match;
    /// anything else falls back to the ordinary bracket machinery.
    fn try_footnote_call(&mut self) -> bool {
        let Some((label, end)) = self.footnote_label(self.pos) else { return false };
        self.flush_text(self.pos);
        self.push_footnote_call(label, self.pos, end);
        true
    }

    /// Shared tail of the two footnote-call paths (plain `[^…]` and the failed-image fallback).
    pub(crate) fn push_footnote_call(&mut self, label: Range<usize>, at: usize, end: usize) {
        self.nodes.push(PN::FootnoteRef { label, r: at..end });
        self.pos = end;
        self.text_start = end;
    }

    fn open_bracket(&mut self, image: bool) {
        self.flush_text(self.pos);
        let width = 1 + usize::from(image);
        self.nodes.push(PN::Text(self.pos..self.pos + width));
        self.brackets.push(Bracket {
            node: self.nodes.len() - 1,
            delim_len: self.delims.len(),
            image,
            active: true,
            text_start: self.pos,
        });
        self.pos += width;
        self.text_start = self.pos;
    }

    /// Consumes leading whitespace of a (logical) line: stripped from text,
    /// but still present in the raw buffer for code spans.
    fn skip_line_ws(&mut self) {
        while matches!(self.t.as_bytes().get(self.pos), Some(b' ' | b'\t')) {
            self.pos += 1;
        }
        self.text_start = self.pos;
    }

    pub(crate) fn flush_text(&mut self, upto: usize) {
        if self.text_start < upto {
            self.nodes.push(PN::Text(self.text_start..upto));
        }
        self.text_start = upto.max(self.text_start);
    }

    fn line_ending(&mut self) {
        let p = self.pos;
        let run = &self.t[self.text_start..p];
        let trimmed = run.trim_end_matches([' ', '\t']);
        let trail = run.len() - trimmed.len();
        self.flush_text(p - trail);
        // A hard break needs a trailing run of two-plus spaces;
        // a tab in the run demotes it to stripped whitespace (micromark behavior).
        if trail >= 2 && run.as_bytes()[run.len() - trail..].iter().all(|&b| b == b' ') {
            self.nodes.push(PN::HardBreak { kind: HardBreakKind::Spaces, r: p - trail..p });
        } else {
            self.nodes.push(PN::SoftBreak(p));
        }
        self.pos = p + 1;
        self.skip_line_ws();
    }

    fn backticks(&mut self) {
        let start = self.pos;
        let n = syntax::run_len(&self.t.as_bytes()[start..], b'`');
        let Some(close) = matching_run(self.t.as_bytes(), start + n, b'`', n) else {
            self.pos = start + n;
            return;
        };
        let mut content = start + n..close;
        let c = &self.t[content.clone()];
        if c.len() >= 2
            && c.starts_with([' ', '\n'])
            && c.ends_with([' ', '\n'])
            && !c.bytes().all(|b| b == b' ' || b == b'\n')
        {
            content = content.start + 1..content.end - 1;
        }
        self.flush_text(start);
        self.nodes.push(PN::Code { r: start..close + n, content });
        self.pos = close + n;
        self.text_start = self.pos;
    }

    /// `<`: autolink, then raw HTML.
    /// Also the MDX JSX toggle point (the `mdx_jsx_text` construct hooks in here).
    fn angle(&mut self) -> bool {
        if self.constructs.autolink
            && let Some((end, email)) = autolink::scan(self.t, self.pos)
        {
            self.flush_text(self.pos);
            self.nodes.push(PN::Autolink { r: self.pos..end, email });
            self.pos = end;
            self.text_start = end;
            return true;
        }
        if self.constructs.html_text
            && let Some(end) = html::scan(self.t, self.pos)
        {
            self.flush_text(self.pos);
            self.nodes.push(PN::Html { r: self.pos..end });
            self.pos = end;
            self.text_start = end;
            return true;
        }
        false
    }
}

/// Start of the first run of exactly `n` `marker` bytes at or after `from`
/// (code spans and math share this closing-run rule).
pub fn matching_run(bytes: &[u8], from: usize, marker: u8, n: usize) -> Option<usize> {
    let mut j = from;
    loop {
        let at = j + bytes[j..].iter().position(|&b| b == marker)?;
        let m = syntax::run_len(&bytes[at..], marker);
        if m == n {
            return Some(at);
        }
        j = at + m;
    }
}