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//! Processes out `#[cfg]` and `#[cfg_attr]` attributes from the input for the derive macro
use std::{cell::OnceCell, ops::ControlFlow};
use ::tt::TextRange;
use base_db::Crate;
use cfg::CfgExpr;
use parser::T;
use smallvec::SmallVec;
use syntax::{
AstNode, PreorderWithTokens, SyntaxElement, SyntaxNode, SyntaxToken, WalkEvent,
ast::{self, HasAttrs, TokenTreeChildren},
};
use syntax_bridge::DocCommentDesugarMode;
use crate::{
attrs::{AttrId, Meta, expand_cfg_attr, is_item_tree_filtered_attr},
db::ExpandDatabase,
fixup::{self, SyntaxFixupUndoInfo},
span_map::SpanMapRef,
tt::{self, DelimSpan, Span},
};
struct ItemIsCfgedOut;
#[derive(Debug)]
struct ExpandedAttrToProcess {
range: TextRange,
}
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
enum NextExpandedAttrState {
NotStarted,
InTheMiddle,
}
#[derive(Debug)]
struct AstAttrToProcess {
range: TextRange,
expanded_attrs: SmallVec<[ExpandedAttrToProcess; 1]>,
expanded_attrs_idx: usize,
next_expanded_attr: NextExpandedAttrState,
pound_span: Span,
brackets_span: DelimSpan,
/// If `Some`, this is an inner attribute.
excl_span: Option<Span>,
}
fn macro_input_callback(
db: &dyn ExpandDatabase,
is_derive: bool,
censor_item_tree_attr_ids: &[AttrId],
krate: Crate,
default_span: Span,
span_map: SpanMapRef<'_>,
) -> impl FnMut(&mut PreorderWithTokens, &WalkEvent<SyntaxElement>) -> (bool, Vec<tt::Leaf>) {
let cfg_options = OnceCell::new();
let cfg_options = move || *cfg_options.get_or_init(|| krate.cfg_options(db));
let mut should_strip_attr = {
let mut item_tree_attr_id = 0;
let mut censor_item_tree_attr_ids_index = 0;
move || {
let mut result = false;
if let Some(&next_censor_attr_id) =
censor_item_tree_attr_ids.get(censor_item_tree_attr_ids_index)
&& next_censor_attr_id.item_tree_index() == item_tree_attr_id
{
censor_item_tree_attr_ids_index += 1;
result = true;
}
item_tree_attr_id += 1;
result
}
};
let mut attrs = Vec::new();
let mut attrs_idx = 0;
let mut has_inner_attrs_owner = false;
let mut in_attr = false;
let mut done_with_attrs = false;
let mut did_top_attrs = false;
move |preorder, event| {
match event {
WalkEvent::Enter(SyntaxElement::Node(node)) => {
if done_with_attrs {
return (true, Vec::new());
}
if ast::Attr::can_cast(node.kind()) {
in_attr = true;
let node_range = node.text_range();
while attrs
.get(attrs_idx)
.is_some_and(|it: &AstAttrToProcess| it.range != node_range)
{
attrs_idx += 1;
}
} else if !in_attr && let Some(has_attrs) = ast::AnyHasAttrs::cast(node.clone()) {
// Attributes of the form `key = value` have `ast::Expr` in them, which returns `Some` for
// `AnyHasAttrs::cast()`, so we also need to check `in_attr`.
if has_inner_attrs_owner {
has_inner_attrs_owner = false;
return (true, Vec::new());
}
if did_top_attrs && !is_derive {
// Derives need all attributes handled, but attribute macros need only the top attributes handled.
done_with_attrs = true;
return (true, Vec::new());
}
did_top_attrs = true;
if let Some(inner_attrs_node) = has_attrs.inner_attributes_node()
&& inner_attrs_node != *node
{
has_inner_attrs_owner = true;
}
let node_attrs = ast::attrs_including_inner(&has_attrs);
attrs.clear();
node_attrs.clone().for_each(|attr| {
let span_for = |token: Option<SyntaxToken>| {
token
.map(|token| span_map.span_for_range(token.text_range()))
.unwrap_or(default_span)
};
attrs.push(AstAttrToProcess {
range: attr.syntax().text_range(),
pound_span: span_for(attr.pound_token()),
brackets_span: DelimSpan {
open: span_for(attr.l_brack_token()),
close: span_for(attr.r_brack_token()),
},
excl_span: attr
.excl_token()
.map(|token| span_map.span_for_range(token.text_range())),
expanded_attrs: SmallVec::new(),
expanded_attrs_idx: 0,
next_expanded_attr: NextExpandedAttrState::NotStarted,
});
});
attrs_idx = 0;
let strip_current_item = expand_cfg_attr(
node_attrs,
&cfg_options,
|attr, _container, range, top_attr| {
// Find the attr.
while attrs[attrs_idx].range != top_attr.syntax().text_range() {
attrs_idx += 1;
}
let mut strip_current_attr = false;
match attr {
Meta::NamedKeyValue { name, .. } => {
if name
.is_none_or(|name| !is_item_tree_filtered_attr(name.text()))
{
strip_current_attr = should_strip_attr();
}
}
Meta::TokenTree { path, tt } => {
if path.is1("cfg") {
let cfg_expr = CfgExpr::parse_from_ast(
&mut TokenTreeChildren::new(&tt).peekable(),
);
if cfg_options().check(&cfg_expr) == Some(false) {
return ControlFlow::Break(ItemIsCfgedOut);
}
strip_current_attr = true;
} else if path.segments.len() != 1
|| !is_item_tree_filtered_attr(path.segments[0].text())
{
strip_current_attr = should_strip_attr();
}
}
Meta::Path { path } => {
if path.segments.len() != 1
|| !is_item_tree_filtered_attr(path.segments[0].text())
{
strip_current_attr = should_strip_attr();
}
}
}
if !strip_current_attr {
attrs[attrs_idx]
.expanded_attrs
.push(ExpandedAttrToProcess { range });
}
ControlFlow::Continue(())
},
);
attrs_idx = 0;
if strip_current_item.is_some() {
preorder.skip_subtree();
attrs.clear();
'eat_comma: {
// If there is a comma after this node, eat it too.
let mut events_until_comma = 0;
for event in preorder.clone() {
match event {
WalkEvent::Enter(SyntaxElement::Node(_))
| WalkEvent::Leave(_) => {}
WalkEvent::Enter(SyntaxElement::Token(token)) => {
let kind = token.kind();
if kind == T![,] {
break;
} else if !kind.is_trivia() {
break 'eat_comma;
}
}
}
events_until_comma += 1;
}
preorder.nth(events_until_comma);
}
return (false, Vec::new());
}
}
}
WalkEvent::Leave(SyntaxElement::Node(node)) => {
if ast::Attr::can_cast(node.kind()) {
in_attr = false;
attrs_idx += 1;
}
}
WalkEvent::Enter(SyntaxElement::Token(token)) => {
if !in_attr {
return (true, Vec::new());
}
let Some(ast_attr) = attrs.get_mut(attrs_idx) else {
return (true, Vec::new());
};
let token_range = token.text_range();
let Some(expanded_attr) = ast_attr.expanded_attrs.get(ast_attr.expanded_attrs_idx)
else {
// No expanded attributes in this `ast::Attr`, or we finished them all already, either way
// the remaining tokens should be discarded.
return (false, Vec::new());
};
match ast_attr.next_expanded_attr {
NextExpandedAttrState::NotStarted => {
if token_range.start() >= expanded_attr.range.start() {
// We started the next attribute.
let mut insert_tokens = Vec::with_capacity(3);
insert_tokens.push(tt::Leaf::Punct(tt::Punct {
char: '#',
spacing: tt::Spacing::Alone,
span: ast_attr.pound_span,
}));
if let Some(span) = ast_attr.excl_span {
insert_tokens.push(tt::Leaf::Punct(tt::Punct {
char: '!',
spacing: tt::Spacing::Alone,
span,
}));
}
insert_tokens.push(tt::Leaf::Punct(tt::Punct {
char: '[',
spacing: tt::Spacing::Alone,
span: ast_attr.brackets_span.open,
}));
ast_attr.next_expanded_attr = NextExpandedAttrState::InTheMiddle;
return (true, insert_tokens);
} else {
// Before any attribute or between the attributes.
return (false, Vec::new());
}
}
NextExpandedAttrState::InTheMiddle => {
if token_range.start() >= expanded_attr.range.end() {
// Finished the current attribute.
let insert_tokens = vec![tt::Leaf::Punct(tt::Punct {
char: ']',
spacing: tt::Spacing::Alone,
span: ast_attr.brackets_span.close,
})];
ast_attr.next_expanded_attr = NextExpandedAttrState::NotStarted;
ast_attr.expanded_attrs_idx += 1;
// It's safe to ignore the current token because between attributes
// there is always at least one token we skip - either the closing bracket
// in `#[]` or the comma in case of multiple attrs in `cfg_attr` expansion.
return (false, insert_tokens);
} else {
// Still in the middle.
return (true, Vec::new());
}
}
}
}
WalkEvent::Leave(SyntaxElement::Token(_)) => {}
}
(true, Vec::new())
}
}
pub(crate) fn attr_macro_input_to_token_tree(
db: &dyn ExpandDatabase,
node: &SyntaxNode,
span_map: SpanMapRef<'_>,
span: Span,
is_derive: bool,
censor_item_tree_attr_ids: &[AttrId],
krate: Crate,
) -> (tt::TopSubtree, SyntaxFixupUndoInfo) {
let fixups = fixup::fixup_syntax(span_map, node, span, DocCommentDesugarMode::ProcMacro);
(
syntax_bridge::syntax_node_to_token_tree_modified(
node,
span_map,
fixups.append,
fixups.remove,
span,
DocCommentDesugarMode::ProcMacro,
macro_input_callback(db, is_derive, censor_item_tree_attr_ids, krate, span, span_map),
),
fixups.undo_info,
)
}
pub fn check_cfg_attr_value(
db: &dyn ExpandDatabase,
attr: &ast::TokenTree,
krate: Crate,
) -> Option<bool> {
let cfg_expr = CfgExpr::parse_from_ast(&mut TokenTreeChildren::new(attr).peekable());
krate.cfg_options(db).check(&cfg_expr)
}