From 0477d0289476c34e6b4d11a28165fee0c49063b3 Mon Sep 17 00:00:00 2001
From: Ivan Tham <pickfire@riseup.net>
Date: Wed, 11 May 2022 09:12:27 +0800
Subject: [PATCH] Exclude cursor when doing ctrl-w (#2431)

Currently ctrl-w in insert mode deletes the cursor which results in
unexpected behavior. The patch also reduces the selection to cursor before
performing prev word to remove the behavior of removing unnecessary text
when nothing should be removed.

1. `::#(|)#::` after `ctrl-w` should be `#(|)#::`, previously `#(|)#:`
2. `#(|::)#` after `ctrl-w` should be `#(|::)#`, previously `#(|)#`

Fix #2390
---
 helix-term/src/commands.rs | 21 +++++++++++++++++----
 1 file changed, 17 insertions(+), 4 deletions(-)

diff --git a/helix-term/src/commands.rs b/helix-term/src/commands.rs
index c2bc04e0..f0b54e0b 100644
--- a/helix-term/src/commands.rs
+++ b/helix-term/src/commands.rs
@@ -2632,6 +2632,18 @@ pub mod insert {
     pub type Hook = fn(&Rope, &Selection, char) -> Option<Transaction>;
     pub type PostHook = fn(&mut Context, char);
 
+    /// Exclude the cursor in range.
+    fn exclude_cursor(text: RopeSlice, range: Range, cursor: Range) -> Range {
+        if range.to() == cursor.to() {
+            Range::new(
+                range.from(),
+                graphemes::prev_grapheme_boundary(text, cursor.to()),
+            )
+        } else {
+            range
+        }
+    }
+
     // It trigger completion when idle timer reaches deadline
     // Only trigger completion if the word under cursor is longer than n characters
     pub fn idle_completion(cx: &mut Context) {
@@ -2948,10 +2960,11 @@ pub mod insert {
         let (view, doc) = current!(cx.editor);
         let text = doc.text().slice(..);
 
-        let selection = doc
-            .selection(view.id)
-            .clone()
-            .transform(|range| movement::move_prev_word_start(text, range, count));
+        let selection = doc.selection(view.id).clone().transform(|range| {
+            let cursor = Range::point(range.cursor(text));
+            let next = movement::move_prev_word_start(text, cursor, count);
+            exclude_cursor(text, next, range)
+        });
         delete_selection_insert_mode(doc, view, &selection);
     }