Generic "comment to node" association logic (#4642)

crates/ruff_python_ast/src/source_code/comment_ranges.rs

@@ -0,0 +1,50 @@
+use ruff_text_size::TextRange;
+use rustpython_parser::Tok;
+use std::fmt::{Debug, Formatter};
+use std::ops::Deref;
+
+/// Stores the ranges of comments sorted by [`TextRange::start`] in increasing order. No two ranges are overlapping.
+#[derive(Clone)]
+pub struct CommentRanges {
+    raw: Vec<TextRange>,
+}
+
+impl Deref for CommentRanges {
+    type Target = [TextRange];
+
+    fn deref(&self) -> &Self::Target {
+        self.raw.as_slice()
+    }
+}
+
+impl Debug for CommentRanges {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        f.debug_tuple("CommentRanges").field(&self.raw).finish()
+    }
+}
+
+impl<'a> IntoIterator for &'a CommentRanges {
+    type Item = &'a TextRange;
+    type IntoIter = std::slice::Iter<'a, TextRange>;
+
+    fn into_iter(self) -> Self::IntoIter {
+        self.raw.iter()
+    }
+}
+
+#[derive(Debug, Clone, Default)]
+pub struct CommentRangesBuilder {
+    ranges: Vec<TextRange>,
+}
+
+impl CommentRangesBuilder {
+    pub fn visit_token(&mut self, token: &Tok, range: TextRange) {
+        if token.is_comment() {
+            self.ranges.push(range);
+        }
+    }
+
+    pub fn finish(self) -> CommentRanges {
+        CommentRanges { raw: self.ranges }
+    }
+}