Add BufferSnapshot::edited_ranges_for_transaction

Co-Authored-By: Nathan Sobo <nathan@zed.dev>

crates/text/src/tests.rs

@@ -502,7 +502,7 @@ fn test_history() {
 }
 
 #[test]
-fn test_avoid_grouping_next_transaction() {
+fn test_finalize_last_transaction() {
     let now = Instant::now();
     let mut buffer = Buffer::new(0, 0, History::new("123456".into()));
 
@@ -536,6 +536,44 @@ fn test_avoid_grouping_next_transaction() {
     assert_eq!(buffer.text(), "ab2cde6");
 }
 
+#[test]
+fn test_edited_ranges_for_transaction() {
+    let now = Instant::now();
+    let mut buffer = Buffer::new(0, 0, History::new("1234567".into()));
+
+    buffer.start_transaction_at(now);
+    buffer.edit(vec![2..4], "cd");
+    buffer.edit(vec![6..6], "efg");
+    buffer.end_transaction_at(now);
+    assert_eq!(buffer.text(), "12cd56efg7");
+
+    let tx = buffer.finalize_last_transaction().unwrap().clone();
+    assert_eq!(
+        buffer
+            .edited_ranges_for_transaction::<usize>(&tx)
+            .collect::<Vec<_>>(),
+        [2..4, 6..9]
+    );
+
+    buffer.edit(vec![5..5], "hijk");
+    assert_eq!(buffer.text(), "12cd5hijk6efg7");
+    assert_eq!(
+        buffer
+            .edited_ranges_for_transaction::<usize>(&tx)
+            .collect::<Vec<_>>(),
+        [2..4, 10..13]
+    );
+
+    buffer.edit(vec![4..4], "l");
+    assert_eq!(buffer.text(), "12cdl5hijk6efg7");
+    assert_eq!(
+        buffer
+            .edited_ranges_for_transaction::<usize>(&tx)
+            .collect::<Vec<_>>(),
+        [2..4, 11..14]
+    );
+}
+
 #[test]
 fn test_concurrent_edits() {
     let text = "abcdef";

crates/text/src/text.rs

@@ -1730,14 +1730,6 @@ impl BufferSnapshot {
         self.visible_text.clip_point_utf16(point, bias)
     }
 
-    // pub fn point_for_offset(&self, offset: usize) -> Result<Point> {
-    //     if offset <= self.len() {
-    //         Ok(self.text_summary_for_range(0..offset))
-    //     } else {
-    //         Err(anyhow!("offset out of bounds"))
-    //     }
-    // }
-
     pub fn edits_since<'a, D>(
         &'a self,
         since: &'a clock::Global,
@@ -1748,6 +1740,42 @@ impl BufferSnapshot {
         self.edits_since_in_range(since, Anchor::min()..Anchor::max())
     }
 
+    pub fn edited_ranges_for_transaction<'a, D>(
+        &'a self,
+        transaction: &'a Transaction,
+    ) -> impl 'a + Iterator<Item = Range<D>>
+    where
+        D: TextDimension,
+    {
+        let mut cursor = self.fragments.cursor::<(VersionedFullOffset, usize)>();
+        let mut rope_cursor = self.visible_text.cursor(0);
+        let cx = Some(transaction.end.clone());
+        let mut position = D::default();
+        transaction.ranges.iter().map(move |range| {
+            cursor.seek_forward(&VersionedFullOffset::Offset(range.start), Bias::Right, &cx);
+            let mut start_offset = cursor.start().1;
+            if cursor
+                .item()
+                .map_or(false, |fragment| fragment.is_visible(&self.undo_map))
+            {
+                start_offset += range.start - cursor.start().0.full_offset()
+            }
+            position.add_assign(&rope_cursor.summary(start_offset));
+            let start = position.clone();
+
+            cursor.seek_forward(&VersionedFullOffset::Offset(range.end), Bias::Left, &cx);
+            let mut end_offset = cursor.start().1;
+            if cursor
+                .item()
+                .map_or(false, |fragment| fragment.is_visible(&self.undo_map))
+            {
+                end_offset += range.end - cursor.start().0.full_offset();
+            }
+            position.add_assign(&rope_cursor.summary(end_offset));
+            start..position.clone()
+        })
+    }
+
     pub fn edits_since_in_range<'a, D>(
         &'a self,
         since: &'a clock::Global,