Add Buffer::anchored_edits_since method

This method returns the anchor range associated with each edit. The
anchor ranges allow you to determine how each edit interacts with
an existing anchor range that the edit has touched.

crates/text/src/text.rs

@@ -382,6 +382,7 @@ struct Edits<'a, D: TextDimension, F: FnMut(&FragmentSummary) -> bool> {
     old_end: D,
     new_end: D,
     range: Range<(&'a Locator, usize)>,
+    buffer_id: u64,
 }
 
 #[derive(Clone, Debug, Default, Eq, PartialEq)]
@@ -1917,11 +1918,33 @@ impl BufferSnapshot {
         self.edits_since_in_range(since, Anchor::MIN..Anchor::MAX)
     }
 
+    pub fn anchored_edits_since<'a, D>(
+        &'a self,
+        since: &'a clock::Global,
+    ) -> impl 'a + Iterator<Item = (Edit<D>, Range<Anchor>)>
+    where
+        D: TextDimension + Ord,
+    {
+        self.anchored_edits_since_in_range(since, Anchor::MIN..Anchor::MAX)
+    }
+
     pub fn edits_since_in_range<'a, D>(
         &'a self,
         since: &'a clock::Global,
         range: Range<Anchor>,
     ) -> impl 'a + Iterator<Item = Edit<D>>
+    where
+        D: TextDimension + Ord,
+    {
+        self.anchored_edits_since_in_range(since, range)
+            .map(|item| item.0)
+    }
+
+    pub fn anchored_edits_since_in_range<'a, D>(
+        &'a self,
+        since: &'a clock::Global,
+        range: Range<Anchor>,
+    ) -> impl 'a + Iterator<Item = (Edit<D>, Range<Anchor>)>
     where
         D: TextDimension + Ord,
     {
@@ -1961,6 +1984,7 @@ impl BufferSnapshot {
             old_end: Default::default(),
             new_end: Default::default(),
             range: (start_fragment_id, range.start.offset)..(end_fragment_id, range.end.offset),
+            buffer_id: self.remote_id,
         }
     }
 }
@@ -2019,10 +2043,10 @@ impl<'a> RopeBuilder<'a> {
 }
 
 impl<'a, D: TextDimension + Ord, F: FnMut(&FragmentSummary) -> bool> Iterator for Edits<'a, D, F> {
-    type Item = Edit<D>;
+    type Item = (Edit<D>, Range<Anchor>);
 
     fn next(&mut self) -> Option<Self::Item> {
-        let mut pending_edit: Option<Edit<D>> = None;
+        let mut pending_edit: Option<Self::Item> = None;
         let cursor = self.fragments_cursor.as_mut()?;
 
         while let Some(fragment) = cursor.item() {
@@ -2041,11 +2065,25 @@ impl<'a, D: TextDimension + Ord, F: FnMut(&FragmentSummary) -> bool> Iterator fo
 
             if pending_edit
                 .as_ref()
-                .map_or(false, |change| change.new.end < self.new_end)
+                .map_or(false, |(change, _)| change.new.end < self.new_end)
             {
                 break;
             }
 
+            let timestamp = fragment.insertion_timestamp.local();
+            let start_anchor = Anchor {
+                timestamp,
+                offset: fragment.insertion_offset,
+                bias: Bias::Right,
+                buffer_id: Some(self.buffer_id),
+            };
+            let end_anchor = Anchor {
+                timestamp,
+                offset: fragment.insertion_offset + fragment.len,
+                bias: Bias::Left,
+                buffer_id: Some(self.buffer_id),
+            };
+
             if !fragment.was_visible(self.since, self.undos) && fragment.visible {
                 let mut visible_end = cursor.end(&None).visible;
                 if fragment.id == *self.range.end.0 {
@@ -2058,13 +2096,17 @@ impl<'a, D: TextDimension + Ord, F: FnMut(&FragmentSummary) -> bool> Iterator fo
                 let fragment_summary = self.visible_cursor.summary(visible_end);
                 let mut new_end = self.new_end.clone();
                 new_end.add_assign(&fragment_summary);
-                if let Some(pending_edit) = pending_edit.as_mut() {
+                if let Some((edit, range)) = pending_edit.as_mut() {
-                    pending_edit.new.end = new_end.clone();
+                    edit.new.end = new_end.clone();
+                    range.end = end_anchor;
                 } else {
-                    pending_edit = Some(Edit {
+                    pending_edit = Some((
-                        old: self.old_end.clone()..self.old_end.clone(),
+                        Edit {
-                        new: self.new_end.clone()..new_end.clone(),
+                            old: self.old_end.clone()..self.old_end.clone(),
-                    });
+                            new: self.new_end.clone()..new_end.clone(),
+                        },
+                        start_anchor..end_anchor,
+                    ));
                 }
 
                 self.new_end = new_end;
@@ -2083,13 +2125,17 @@ impl<'a, D: TextDimension + Ord, F: FnMut(&FragmentSummary) -> bool> Iterator fo
                 let fragment_summary = self.deleted_cursor.summary(deleted_end);
                 let mut old_end = self.old_end.clone();
                 old_end.add_assign(&fragment_summary);
-                if let Some(pending_edit) = pending_edit.as_mut() {
+                if let Some((edit, range)) = pending_edit.as_mut() {
-                    pending_edit.old.end = old_end.clone();
+                    edit.old.end = old_end.clone();
+                    range.end = end_anchor;
                 } else {
-                    pending_edit = Some(Edit {
+                    pending_edit = Some((
-                        old: self.old_end.clone()..old_end.clone(),
+                        Edit {
-                        new: self.new_end.clone()..self.new_end.clone(),
+                            old: self.old_end.clone()..old_end.clone(),
-                    });
+                            new: self.new_end.clone()..self.new_end.clone(),
+                        },
+                        start_anchor..end_anchor,
+                    ));
                 }
 
                 self.old_end = old_end;