From 74fd348d22c83ae649e8ae5b6d8e1a931fa3739d Mon Sep 17 00:00:00 2001
From: Max Brunsfeld <maxbrunsfeld@gmail.com>
Date: Mon, 29 Aug 2022 16:51:31 -0700
Subject: [PATCH] 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 | 76 +++++++++++++++++++++++++++++++++--------
 1 file changed, 61 insertions(+), 15 deletions(-)

diff --git a/crates/text/src/text.rs b/crates/text/src/text.rs
index 39812740fb4ba8a5fc001b3b1ab4a86254ea224b..a7736cc8cc86d548f2fa7e7dcb58705850308ad5 100644
--- a/crates/text/src/text.rs
+++ b/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() {
-                    pending_edit.new.end = new_end.clone();
+                if let Some((edit, range)) = pending_edit.as_mut() {
+                    edit.new.end = new_end.clone();
+                    range.end = end_anchor;
                 } else {
-                    pending_edit = Some(Edit {
-                        old: self.old_end.clone()..self.old_end.clone(),
-                        new: self.new_end.clone()..new_end.clone(),
-                    });
+                    pending_edit = Some((
+                        Edit {
+                            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() {
-                    pending_edit.old.end = old_end.clone();
+                if let Some((edit, range)) = pending_edit.as_mut() {
+                    edit.old.end = old_end.clone();
+                    range.end = end_anchor;
                 } else {
-                    pending_edit = Some(Edit {
-                        old: self.old_end.clone()..old_end.clone(),
-                        new: self.new_end.clone()..self.new_end.clone(),
-                    });
+                    pending_edit = Some((
+                        Edit {
+                            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;