mirror of
https://github.com/rust-lang/rust-analyzer
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94 lines
4.1 KiB
Rust
94 lines
4.1 KiB
Rust
//! Converts a flat collection of matches into a nested form suitable for replacement. When there
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//! are multiple matches for a node, or that overlap, priority is given to the earlier rule. Nested
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//! matches are only permitted if the inner match is contained entirely within a placeholder of an
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//! outer match.
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//!
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//! For example, if our search pattern is `foo(foo($a))` and the code had `foo(foo(foo(foo(42))))`,
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//! then we'll get 3 matches, however only the outermost and innermost matches can be accepted. The
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//! middle match would take the second `foo` from the outer match.
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use crate::{Match, SsrMatches};
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use rustc_hash::FxHashMap;
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use syntax::SyntaxNode;
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pub(crate) fn nest_and_remove_collisions(
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mut matches: Vec<Match>,
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sema: &hir::Semantics<ide_db::RootDatabase>,
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) -> SsrMatches {
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// We sort the matches by depth then by rule index. Sorting by depth means that by the time we
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// see a match, any parent matches or conflicting matches will have already been seen. Sorting
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// by rule_index means that if there are two matches for the same node, the rule added first
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// will take precedence.
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matches.sort_by(|a, b| a.depth.cmp(&b.depth).then_with(|| a.rule_index.cmp(&b.rule_index)));
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let mut collector = MatchCollector::default();
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for m in matches {
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collector.add_match(m, sema);
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}
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collector.into()
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}
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#[derive(Default)]
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struct MatchCollector {
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matches_by_node: FxHashMap<SyntaxNode, Match>,
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}
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impl MatchCollector {
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/// Attempts to add `m` to matches. If it conflicts with an existing match, it is discarded. If
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/// it is entirely within the a placeholder of an existing match, then it is added as a child
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/// match of the existing match.
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fn add_match(&mut self, m: Match, sema: &hir::Semantics<ide_db::RootDatabase>) {
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let matched_node = m.matched_node.clone();
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if let Some(existing) = self.matches_by_node.get_mut(&matched_node) {
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try_add_sub_match(m, existing, sema);
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return;
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}
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for ancestor in sema.ancestors_with_macros(m.matched_node.clone()) {
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if let Some(existing) = self.matches_by_node.get_mut(&ancestor) {
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try_add_sub_match(m, existing, sema);
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return;
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}
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}
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self.matches_by_node.insert(matched_node, m);
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}
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}
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/// Attempts to add `m` as a sub-match of `existing`.
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fn try_add_sub_match(m: Match, existing: &mut Match, sema: &hir::Semantics<ide_db::RootDatabase>) {
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for p in existing.placeholder_values.values_mut() {
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// Note, no need to check if p.range.file is equal to m.range.file, since we
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// already know we're within `existing`.
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if p.range.range.contains_range(m.range.range) {
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// Convert the inner matches in `p` into a temporary MatchCollector. When
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// we're done, we then convert it back into an SsrMatches. If we expected
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// lots of inner matches, it might be worthwhile keeping a MatchCollector
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// around for each placeholder match. However we expect most placeholder
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// will have 0 and a few will have 1. More than that should hopefully be
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// exceptional.
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let mut collector = MatchCollector::default();
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for m in std::mem::replace(&mut p.inner_matches.matches, Vec::new()) {
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collector.matches_by_node.insert(m.matched_node.clone(), m);
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}
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collector.add_match(m, sema);
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p.inner_matches = collector.into();
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break;
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}
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}
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}
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impl From<MatchCollector> for SsrMatches {
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fn from(mut match_collector: MatchCollector) -> Self {
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let mut matches = SsrMatches::default();
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for (_, m) in match_collector.matches_by_node.drain() {
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matches.matches.push(m);
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}
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matches.matches.sort_by(|a, b| {
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// Order matches by file_id then by start range. This should be sufficient since ranges
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// shouldn't be overlapping.
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a.range
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.file_id
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.cmp(&b.range.file_id)
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.then_with(|| a.range.range.start().cmp(&b.range.range.start()))
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});
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matches
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}
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}
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