1 files changed, 35 insertions, 0 deletions
diff --git a/src/tools/rust-analyzer/crates/ide-ssr/src/from_comment.rs b/src/tools/rust-analyzer/crates/ide-ssr/src/from_comment.rs
new file mode 100644
index 000000000..5b6e01625
--- /dev/null
+++ b/src/tools/rust-analyzer/crates/ide-ssr/src/from_comment.rs
@@ -0,0 +1,35 @@
+//! This module allows building an SSR MatchFinder by parsing the SSR rule
+//! from a comment.
+
+use ide_db::{
+    base_db::{FilePosition, FileRange, SourceDatabase},
+    RootDatabase,
+};
+use syntax::{
+    ast::{self, AstNode, AstToken},
+    TextRange,
+};
+
+use crate::MatchFinder;
+
+/// Attempts to build an SSR MatchFinder from a comment at the given file
+/// range. If successful, returns the MatchFinder and a TextRange covering
+/// comment.
+pub fn ssr_from_comment(
+    db: &RootDatabase,
+    frange: FileRange,
+) -> Option<(MatchFinder<'_>, TextRange)> {
+    let comment = {
+        let file = db.parse(frange.file_id);
+        file.tree().syntax().token_at_offset(frange.range.start()).find_map(ast::Comment::cast)
+    }?;
+    let comment_text_without_prefix = comment.text().strip_prefix(comment.prefix()).unwrap();
+    let ssr_rule = comment_text_without_prefix.parse().ok()?;
+
+    let lookup_context = FilePosition { file_id: frange.file_id, offset: frange.range.start() };
+
+    let mut match_finder = MatchFinder::in_context(db, lookup_context, vec![]).ok()?;
+    match_finder.add_rule(ssr_rule).ok()?;
+
+    Some((match_finder, comment.syntax().text_range()))
+}