Remove parser dependency from ruff-python-ast (#6096)

crates/ruff_python_index/src/comment_ranges.rs

@@ -0,0 +1,84 @@
+use itertools::Itertools;
+use std::fmt::{Debug, Formatter};
+use std::ops::Deref;
+
+use ruff_text_size::TextRange;
+use rustpython_parser::Tok;
+
+/// 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 CommentRanges {
+    /// Returns `true` if the given range includes a comment.
+    pub fn intersects(&self, target: TextRange) -> bool {
+        self.raw
+            .binary_search_by(|range| {
+                if target.contains_range(*range) {
+                    std::cmp::Ordering::Equal
+                } else if range.end() < target.start() {
+                    std::cmp::Ordering::Less
+                } else {
+                    std::cmp::Ordering::Greater
+                }
+            })
+            .is_ok()
+    }
+
+    /// Returns the comments who are within the range
+    pub fn comments_in_range(&self, range: TextRange) -> &[TextRange] {
+        let start = self
+            .raw
+            .partition_point(|comment| comment.start() < range.start());
+        // We expect there are few comments, so switching to find should be faster
+        match self.raw[start..]
+            .iter()
+            .find_position(|comment| comment.end() > range.end())
+        {
+            Some((in_range, _element)) => &self.raw[start..start + in_range],
+            None => &self.raw[start..],
+        }
+    }
+}
+
+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 IntoIter = std::slice::Iter<'a, TextRange>;
+    type Item = &'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 }
+    }
+}