From f8225ed9219f23cf04bd378ec43e1e1a1059a0ed Mon Sep 17 00:00:00 2001
From: Pascal Kuthe
Date: Thu, 16 Feb 2023 22:15:06 +0100
Subject: fix panic when deleting overlapping ranges

Some deletion operations (especially those that use indentation)
can generate overlapping deletion ranges when using multiple cursors.
To fix that problem a new `Transaction::delete` and
`Transaction:delete_by_selection` function were added. These functions
merge overlapping deletion ranges instead of generating an invalid
transaction. This merging of changes is only possible for deletions
and not for other changes and therefore require its own function.

The function has been used in all commands that currently delete
text by using `Transaction::change_by_selection`.
---
 helix-term/src/commands.rs | 37 +++++++++++--------------------------
 1 file changed, 11 insertions(+), 26 deletions(-)

(limited to 'helix-term/src/commands.rs')

diff --git a/helix-term/src/commands.rs b/helix-term/src/commands.rs
index 80774cea..964d87ff 100644
--- a/helix-term/src/commands.rs
+++ b/helix-term/src/commands.rs
@@ -2315,9 +2315,8 @@ fn delete_selection_impl(cx: &mut Context, op: Operation) {
     };
 
     // then delete
-    let transaction = Transaction::change_by_selection(doc.text(), selection, |range| {
-        (range.from(), range.to(), None)
-    });
+    let transaction =
+        Transaction::delete_by_selection(doc.text(), selection, |range| (range.from(), range.to()));
     doc.apply(&transaction, view.id);
 
     match op {
@@ -2333,9 +2332,8 @@ fn delete_selection_impl(cx: &mut Context, op: Operation) {
 
 #[inline]
 fn delete_selection_insert_mode(doc: &mut Document, view: &mut View, selection: &Selection) {
-    let transaction = Transaction::change_by_selection(doc.text(), selection, |range| {
-        (range.from(), range.to(), None)
-    });
+    let transaction =
+        Transaction::delete_by_selection(doc.text(), selection, |range| (range.from(), range.to()));
     doc.apply(&transaction, view.id);
 }
 
@@ -3422,10 +3420,10 @@ pub mod insert {
         let auto_pairs = doc.auto_pairs(cx.editor);
 
         let transaction =
-            Transaction::change_by_selection(doc.text(), doc.selection(view.id), |range| {
+            Transaction::delete_by_selection(doc.text(), doc.selection(view.id), |range| {
                 let pos = range.cursor(text);
                 if pos == 0 {
-                    return (pos, pos, None);
+                    return (pos, pos);
                 }
                 let line_start_pos = text.line_to_char(range.cursor_line(text));
                 // consider to delete by indent level if all characters before `pos` are indent units.
@@ -3433,11 +3431,7 @@ pub mod insert {
                 if !fragment.is_empty() && fragment.chars().all(|ch| ch == ' ' || ch == '\t') {
                     if text.get_char(pos.saturating_sub(1)) == Some('\t') {
                         // fast path, delete one char
-                        (
-                            graphemes::nth_prev_grapheme_boundary(text, pos, 1),
-                            pos,
-                            None,
-                        )
+                        (graphemes::nth_prev_grapheme_boundary(text, pos, 1), pos)
                     } else {
                         let width: usize = fragment
                             .chars()
@@ -3464,7 +3458,7 @@ pub mod insert {
                                 _ => break,
                             }
                         }
-                        (start, pos, None) // delete!
+                        (start, pos) // delete!
                     }
                 } else {
                     match (
@@ -3482,17 +3476,12 @@ pub mod insert {
                             (
                                 graphemes::nth_prev_grapheme_boundary(text, pos, count),
                                 graphemes::nth_next_grapheme_boundary(text, pos, count),
-                                None,
                             )
                         }
                         _ =>
                         // delete 1 char
                         {
-                            (
-                                graphemes::nth_prev_grapheme_boundary(text, pos, count),
-                                pos,
-                                None,
-                            )
+                            (graphemes::nth_prev_grapheme_boundary(text, pos, count), pos)
                         }
                     }
                 }
@@ -3508,13 +3497,9 @@ pub mod insert {
         let (view, doc) = current!(cx.editor);
         let text = doc.text().slice(..);
         let transaction =
-            Transaction::change_by_selection(doc.text(), doc.selection(view.id), |range| {
+            Transaction::delete_by_selection(doc.text(), doc.selection(view.id), |range| {
                 let pos = range.cursor(text);
-                (
-                    pos,
-                    graphemes::nth_next_grapheme_boundary(text, pos, count),
-                    None,
-                )
+                (pos, graphemes::nth_next_grapheme_boundary(text, pos, count))
             });
         doc.apply(&transaction, view.id);
 
-- 
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