bendns' repos / rust-analyzer
Unnamed repository; edit this file 'description' to name the repository.
Diffstat (limited to 'crates/ide-ssr/src/nester.rs')
-rw-r--r--crates/ide-ssr/src/nester.rs95
1 files changed, 95 insertions, 0 deletions
diff --git a/crates/ide-ssr/src/nester.rs b/crates/ide-ssr/src/nester.rs
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+//! Converts a flat collection of matches into a nested form suitable for replacement. When there
+//! are multiple matches for a node, or that overlap, priority is given to the earlier rule. Nested
+//! matches are only permitted if the inner match is contained entirely within a placeholder of an
+//! outer match.
+//!
+//! For example, if our search pattern is `foo(foo($a))` and the code had `foo(foo(foo(foo(42))))`,
+//! then we'll get 3 matches, however only the outermost and innermost matches can be accepted. The
+//! middle match would take the second `foo` from the outer match.
+
+use ide_db::FxHashMap;
+use syntax::SyntaxNode;
+
+use crate::{Match, SsrMatches};
+
+pub(crate) fn nest_and_remove_collisions(
+ mut matches: Vec<Match>,
+ sema: &hir::Semantics<ide_db::RootDatabase>,
+) -> SsrMatches {
+ // We sort the matches by depth then by rule index. Sorting by depth means that by the time we
+ // see a match, any parent matches or conflicting matches will have already been seen. Sorting
+ // by rule_index means that if there are two matches for the same node, the rule added first
+ // will take precedence.
+ matches.sort_by(|a, b| a.depth.cmp(&b.depth).then_with(|| a.rule_index.cmp(&b.rule_index)));
+ let mut collector = MatchCollector::default();
+ for m in matches {
+ collector.add_match(m, sema);
+ }
+ collector.into()
+}
+
+#[derive(Default)]
+struct MatchCollector {
+ matches_by_node: FxHashMap<SyntaxNode, Match>,
+}
+
+impl MatchCollector {
+ /// Attempts to add `m` to matches. If it conflicts with an existing match, it is discarded. If
+ /// it is entirely within the a placeholder of an existing match, then it is added as a child
+ /// match of the existing match.
+ fn add_match(&mut self, m: Match, sema: &hir::Semantics<ide_db::RootDatabase>) {
+ let matched_node = m.matched_node.clone();
+ if let Some(existing) = self.matches_by_node.get_mut(&matched_node) {
+ try_add_sub_match(m, existing, sema);
+ return;
+ }
+ for ancestor in sema.ancestors_with_macros(m.matched_node.clone()) {
+ if let Some(existing) = self.matches_by_node.get_mut(&ancestor) {
+ try_add_sub_match(m, existing, sema);
+ return;
+ }
+ }
+ self.matches_by_node.insert(matched_node, m);
+ }
+}
+
+/// Attempts to add `m` as a sub-match of `existing`.
+fn try_add_sub_match(m: Match, existing: &mut Match, sema: &hir::Semantics<ide_db::RootDatabase>) {
+ for p in existing.placeholder_values.values_mut() {
+ // Note, no need to check if p.range.file is equal to m.range.file, since we
+ // already know we're within `existing`.
+ if p.range.range.contains_range(m.range.range) {
+ // Convert the inner matches in `p` into a temporary MatchCollector. When
+ // we're done, we then convert it back into an SsrMatches. If we expected
+ // lots of inner matches, it might be worthwhile keeping a MatchCollector
+ // around for each placeholder match. However we expect most placeholder
+ // will have 0 and a few will have 1. More than that should hopefully be
+ // exceptional.
+ let mut collector = MatchCollector::default();
+ for m in std::mem::take(&mut p.inner_matches.matches) {
+ collector.matches_by_node.insert(m.matched_node.clone(), m);
+ }
+ collector.add_match(m, sema);
+ p.inner_matches = collector.into();
+ break;
+ }
+ }
+}
+
+impl From<MatchCollector> for SsrMatches {
+ fn from(mut match_collector: MatchCollector) -> Self {
+ let mut matches = SsrMatches::default();
+ for (_, m) in match_collector.matches_by_node.drain() {
+ matches.matches.push(m);
+ }
+ matches.matches.sort_by(|a, b| {
+ // Order matches by file_id then by start range. This should be sufficient since ranges
+ // shouldn't be overlapping.
+ a.range
+ .file_id
+ .cmp(&b.range.file_id)
+ .then_with(|| a.range.range.start().cmp(&b.range.range.start()))
+ });
+ matches
+ }
+}