editor: Fix DeleteToPreviousWordStart and DeleteToNextWordEnd interaction with newlines (#16848)

Closes #5285, #14389

Changes:
- `DeleteToPreviousWordStart` now deletes '\n' separately from preceding
words and whitespace.
- `DeleteToNextWordEnd` now deletes '\n' and any following whitespace
separately from subsequent words.
- Added an `ignore_newlines` flag to both actions to optionally retain
the old behavior.

These modifications align the behavior more closely with other popular
editors like VSCode and Sublime:
- `DeleteToPreviousWordStart` now matches the default <Ctrl+Backspace>
action in those editors.
- `DeleteToNextWordEnd` becomes more intuitive and closely resembles the
default <Ctrl+Delete> behavior in those editors.

Release Notes:

- Improved `DeleteToPreviousWordStart` and `DeleteToNextWordEnd`
interactions around newlines. You can opt-in into the previous behavior
by adding {"ignore_newlines": true} to either action's binds in your
keymap. ([#5285](https://github.com/zed-industries/zed/issues/5285),
[#14389](https://github.com/zed-industries/zed/issues/14389))

crates/editor/src/editor_tests.rs

@@ -2102,7 +2102,12 @@ fn test_delete_to_word_boundary(cx: &mut TestAppContext) {
                 DisplayPoint::new(DisplayRow(0), 9)..DisplayPoint::new(DisplayRow(0), 12),
             ])
         });
-        view.delete_to_previous_word_start(&DeleteToPreviousWordStart, cx);
+        view.delete_to_previous_word_start(
+            &DeleteToPreviousWordStart {
+                ignore_newlines: false,
+            },
+            cx,
+        );
         assert_eq!(view.buffer.read(cx).read(cx).text(), "e two te four");
     });
 
@@ -2115,11 +2120,94 @@ fn test_delete_to_word_boundary(cx: &mut TestAppContext) {
                 DisplayPoint::new(DisplayRow(0), 9)..DisplayPoint::new(DisplayRow(0), 10),
             ])
         });
-        view.delete_to_next_word_end(&DeleteToNextWordEnd, cx);
+        view.delete_to_next_word_end(
+            &DeleteToNextWordEnd {
+                ignore_newlines: false,
+            },
+            cx,
+        );
         assert_eq!(view.buffer.read(cx).read(cx).text(), "e t te our");
     });
 }
 
+#[gpui::test]
+fn test_delete_to_previous_word_start_or_newline(cx: &mut TestAppContext) {
+    init_test(cx, |_| {});
+
+    let view = cx.add_window(|cx| {
+        let buffer = MultiBuffer::build_simple("one\n2\nthree\n4", cx);
+        build_editor(buffer.clone(), cx)
+    });
+    let del_to_prev_word_start = DeleteToPreviousWordStart {
+        ignore_newlines: false,
+    };
+    let del_to_prev_word_start_ignore_newlines = DeleteToPreviousWordStart {
+        ignore_newlines: true,
+    };
+
+    _ = view.update(cx, |view, cx| {
+        view.change_selections(None, cx, |s| {
+            s.select_display_ranges([
+                DisplayPoint::new(DisplayRow(3), 1)..DisplayPoint::new(DisplayRow(3), 1)
+            ])
+        });
+        view.delete_to_previous_word_start(&del_to_prev_word_start, cx);
+        assert_eq!(view.buffer.read(cx).read(cx).text(), "one\n2\nthree\n");
+        view.delete_to_previous_word_start(&del_to_prev_word_start, cx);
+        assert_eq!(view.buffer.read(cx).read(cx).text(), "one\n2\nthree");
+        view.delete_to_previous_word_start(&del_to_prev_word_start, cx);
+        assert_eq!(view.buffer.read(cx).read(cx).text(), "one\n2\n");
+        view.delete_to_previous_word_start(&del_to_prev_word_start, cx);
+        assert_eq!(view.buffer.read(cx).read(cx).text(), "one\n2");
+        view.delete_to_previous_word_start(&del_to_prev_word_start_ignore_newlines, cx);
+        assert_eq!(view.buffer.read(cx).read(cx).text(), "one\n");
+        view.delete_to_previous_word_start(&del_to_prev_word_start_ignore_newlines, cx);
+        assert_eq!(view.buffer.read(cx).read(cx).text(), "");
+    });
+}
+
+#[gpui::test]
+fn test_delete_to_next_word_end_or_newline(cx: &mut TestAppContext) {
+    init_test(cx, |_| {});
+
+    let view = cx.add_window(|cx| {
+        let buffer = MultiBuffer::build_simple("\none\n   two\nthree\n   four", cx);
+        build_editor(buffer.clone(), cx)
+    });
+    let del_to_next_word_end = DeleteToNextWordEnd {
+        ignore_newlines: false,
+    };
+    let del_to_next_word_end_ignore_newlines = DeleteToNextWordEnd {
+        ignore_newlines: true,
+    };
+
+    _ = view.update(cx, |view, cx| {
+        view.change_selections(None, cx, |s| {
+            s.select_display_ranges([
+                DisplayPoint::new(DisplayRow(0), 0)..DisplayPoint::new(DisplayRow(0), 0)
+            ])
+        });
+        view.delete_to_next_word_end(&del_to_next_word_end, cx);
+        assert_eq!(
+            view.buffer.read(cx).read(cx).text(),
+            "one\n   two\nthree\n   four"
+        );
+        view.delete_to_next_word_end(&del_to_next_word_end, cx);
+        assert_eq!(
+            view.buffer.read(cx).read(cx).text(),
+            "\n   two\nthree\n   four"
+        );
+        view.delete_to_next_word_end(&del_to_next_word_end, cx);
+        assert_eq!(view.buffer.read(cx).read(cx).text(), "two\nthree\n   four");
+        view.delete_to_next_word_end(&del_to_next_word_end, cx);
+        assert_eq!(view.buffer.read(cx).read(cx).text(), "\nthree\n   four");
+        view.delete_to_next_word_end(&del_to_next_word_end_ignore_newlines, cx);
+        assert_eq!(view.buffer.read(cx).read(cx).text(), "\n   four");
+        view.delete_to_next_word_end(&del_to_next_word_end_ignore_newlines, cx);
+        assert_eq!(view.buffer.read(cx).read(cx).text(), "");
+    });
+}
+
 #[gpui::test]
 fn test_newline(cx: &mut TestAppContext) {
     init_test(cx, |_| {});