From bc85c85501306f4d3e5e6c802590816cdaf29c13 Mon Sep 17 00:00:00 2001
From: Nathan Vegdahl
Date: Wed, 21 Jul 2021 09:23:01 -0700
Subject: Fix selections not being modified quite correctly with text edits.

---
 helix-core/src/selection.rs | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

(limited to 'helix-core/src')

diff --git a/helix-core/src/selection.rs b/helix-core/src/selection.rs
index beade27a..3d4ee768 100644
--- a/helix-core/src/selection.rs
+++ b/helix-core/src/selection.rs
@@ -109,8 +109,21 @@ impl Range {
     /// Map a range through a set of changes. Returns a new range representing the same position
     /// after the changes are applied.
     pub fn map(self, changes: &ChangeSet) -> Self {
-        let anchor = changes.map_pos(self.anchor, Assoc::After);
-        let head = changes.map_pos(self.head, Assoc::After);
+        use std::cmp::Ordering;
+        let (anchor, head) = match self.anchor.cmp(&self.head) {
+            Ordering::Equal => (
+                changes.map_pos(self.anchor, Assoc::After),
+                changes.map_pos(self.head, Assoc::After),
+            ),
+            Ordering::Less => (
+                changes.map_pos(self.anchor, Assoc::After),
+                changes.map_pos(self.head, Assoc::Before),
+            ),
+            Ordering::Greater => (
+                changes.map_pos(self.anchor, Assoc::Before),
+                changes.map_pos(self.head, Assoc::After),
+            ),
+        };
 
         // We want to return a new `Range` with `horiz == None` every time,
         // even if the anchor and head haven't changed, because we don't
-- 
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