Add support for joining lines (#2636)

🚧 We have a couple more refinements to this to add 🚧 

Release Notes:

You can now join lines with `ctrl-j` or `shift-J` in Vim normal mode.

🍐'd with @ConradIrwin

assets/keymaps/default.json

@@ -411,6 +411,7 @@
       "ctrl-shift-k": "editor::DeleteLine",
       "cmd-shift-d": "editor::DuplicateLine",
       "cmd-shift-l": "editor::SplitSelectionIntoLines",
+      "ctrl-j": "editor::JoinLines",
       "ctrl-cmd-up": "editor::MoveLineUp",
       "ctrl-cmd-down": "editor::MoveLineDown",
       "ctrl-alt-backspace": "editor::DeleteToPreviousSubwordStart",

assets/keymaps/vim.json

@@ -143,6 +143,7 @@
         "Delete"
       ],
       "shift-d": "vim::DeleteToEndOfLine",
+      "shift-j": "editor::JoinLines",
       "y": [
         "vim::PushOperator",
         "Yank"

crates/editor/src/editor.rs

@@ -206,6 +206,7 @@ actions!(
         DuplicateLine,
         MoveLineUp,
         MoveLineDown,
+        JoinLines,
         Transpose,
         Cut,
         Copy,
@@ -321,6 +322,7 @@ pub fn init(cx: &mut AppContext) {
     cx.add_action(Editor::indent);
     cx.add_action(Editor::outdent);
     cx.add_action(Editor::delete_line);
+    cx.add_action(Editor::join_lines);
     cx.add_action(Editor::delete_to_previous_word_start);
     cx.add_action(Editor::delete_to_previous_subword_start);
     cx.add_action(Editor::delete_to_next_word_end);
@@ -3956,6 +3958,60 @@ impl Editor {
         });
     }
 
+    pub fn join_lines(&mut self, _: &JoinLines, cx: &mut ViewContext<Self>) {
+        let mut row_ranges = Vec::<Range<u32>>::new();
+        for selection in self.selections.all::<Point>(cx) {
+            let start = selection.start.row;
+            let end = if selection.start.row == selection.end.row {
+                selection.start.row + 1
+            } else {
+                selection.end.row
+            };
+
+            if let Some(last_row_range) = row_ranges.last_mut() {
+                if start <= last_row_range.end {
+                    last_row_range.end = end;
+                    continue;
+                }
+            }
+            row_ranges.push(start..end);
+        }
+
+        let snapshot = self.buffer.read(cx).snapshot(cx);
+        let mut cursor_positions = Vec::new();
+        for row_range in &row_ranges {
+            let anchor = snapshot.anchor_before(Point::new(
+                row_range.end - 1,
+                snapshot.line_len(row_range.end - 1),
+            ));
+            cursor_positions.push(anchor.clone()..anchor);
+        }
+
+        self.transact(cx, |this, cx| {
+            for row_range in row_ranges.into_iter().rev() {
+                for row in row_range.rev() {
+                    let end_of_line = Point::new(row, snapshot.line_len(row));
+                    let indent = snapshot.indent_size_for_line(row + 1);
+                    let start_of_next_line = Point::new(row + 1, indent.len);
+
+                    let replace = if snapshot.line_len(row + 1) > indent.len {
+                        " "
+                    } else {
+                        ""
+                    };
+
+                    this.buffer.update(cx, |buffer, cx| {
+                        buffer.edit([(end_of_line..start_of_next_line, replace)], None, cx)
+                    });
+                }
+            }
+
+            this.change_selections(Some(Autoscroll::fit()), cx, |s| {
+                s.select_anchor_ranges(cursor_positions)
+            });
+        });
+    }
+
     pub fn duplicate_line(&mut self, _: &DuplicateLine, cx: &mut ViewContext<Self>) {
         let display_map = self.display_map.update(cx, |map, cx| map.snapshot(cx));
         let buffer = &display_map.buffer_snapshot;

crates/editor/src/editor_tests.rs

@@ -1,7 +1,10 @@
 use super::*;
-use crate::test::{
+use crate::{
-    assert_text_with_selections, build_editor, editor_lsp_test_context::EditorLspTestContext,
+    test::{
-    editor_test_context::EditorTestContext, select_ranges,
+        assert_text_with_selections, build_editor, editor_lsp_test_context::EditorLspTestContext,
+        editor_test_context::EditorTestContext, select_ranges,
+    },
+    JoinLines,
 };
 use drag_and_drop::DragAndDrop;
 use futures::StreamExt;
@@ -2325,6 +2328,137 @@ fn test_delete_line(cx: &mut TestAppContext) {
     });
 }
 
+#[gpui::test]
+fn test_join_lines_with_single_selection(cx: &mut TestAppContext) {
+    init_test(cx, |_| {});
+
+    cx.add_window(|cx| {
+        let buffer = MultiBuffer::build_simple("aaa\nbbb\nccc\nddd\n\n", cx);
+        let mut editor = build_editor(buffer.clone(), cx);
+        let buffer = buffer.read(cx).as_singleton().unwrap();
+
+        assert_eq!(
+            editor.selections.ranges::<Point>(cx),
+            &[Point::new(0, 0)..Point::new(0, 0)]
+        );
+
+        // When on single line, replace newline at end by space
+        editor.join_lines(&JoinLines, cx);
+        assert_eq!(buffer.read(cx).text(), "aaa bbb\nccc\nddd\n\n");
+        assert_eq!(
+            editor.selections.ranges::<Point>(cx),
+            &[Point::new(0, 3)..Point::new(0, 3)]
+        );
+
+        // When multiple lines are selected, remove newlines that are spanned by the selection
+        editor.change_selections(None, cx, |s| {
+            s.select_ranges([Point::new(0, 5)..Point::new(2, 2)])
+        });
+        editor.join_lines(&JoinLines, cx);
+        assert_eq!(buffer.read(cx).text(), "aaa bbb ccc ddd\n\n");
+        assert_eq!(
+            editor.selections.ranges::<Point>(cx),
+            &[Point::new(0, 11)..Point::new(0, 11)]
+        );
+
+        // Undo should be transactional
+        editor.undo(&Undo, cx);
+        assert_eq!(buffer.read(cx).text(), "aaa bbb\nccc\nddd\n\n");
+        assert_eq!(
+            editor.selections.ranges::<Point>(cx),
+            &[Point::new(0, 5)..Point::new(2, 2)]
+        );
+
+        // When joining an empty line don't insert a space
+        editor.change_selections(None, cx, |s| {
+            s.select_ranges([Point::new(2, 1)..Point::new(2, 2)])
+        });
+        editor.join_lines(&JoinLines, cx);
+        assert_eq!(buffer.read(cx).text(), "aaa bbb\nccc\nddd\n");
+        assert_eq!(
+            editor.selections.ranges::<Point>(cx),
+            [Point::new(2, 3)..Point::new(2, 3)]
+        );
+
+        // We can remove trailing newlines
+        editor.join_lines(&JoinLines, cx);
+        assert_eq!(buffer.read(cx).text(), "aaa bbb\nccc\nddd");
+        assert_eq!(
+            editor.selections.ranges::<Point>(cx),
+            [Point::new(2, 3)..Point::new(2, 3)]
+        );
+
+        // We don't blow up on the last line
+        editor.join_lines(&JoinLines, cx);
+        assert_eq!(buffer.read(cx).text(), "aaa bbb\nccc\nddd");
+        assert_eq!(
+            editor.selections.ranges::<Point>(cx),
+            [Point::new(2, 3)..Point::new(2, 3)]
+        );
+
+        // reset to test indentation
+        editor.buffer.update(cx, |buffer, cx| {
+            buffer.edit(
+                [
+                    (Point::new(1, 0)..Point::new(1, 2), "  "),
+                    (Point::new(2, 0)..Point::new(2, 3), "  \n\td"),
+                ],
+                None,
+                cx,
+            )
+        });
+
+        // We remove any leading spaces
+        assert_eq!(buffer.read(cx).text(), "aaa bbb\n  c\n  \n\td");
+        editor.change_selections(None, cx, |s| {
+            s.select_ranges([Point::new(0, 1)..Point::new(0, 1)])
+        });
+        editor.join_lines(&JoinLines, cx);
+        assert_eq!(buffer.read(cx).text(), "aaa bbb c\n  \n\td");
+
+        // We don't insert a space for a line containing only spaces
+        editor.join_lines(&JoinLines, cx);
+        assert_eq!(buffer.read(cx).text(), "aaa bbb c\n\td");
+
+        // We ignore any leading tabs
+        editor.join_lines(&JoinLines, cx);
+        assert_eq!(buffer.read(cx).text(), "aaa bbb c d");
+
+        editor
+    });
+}
+
+#[gpui::test]
+fn test_join_lines_with_multi_selection(cx: &mut TestAppContext) {
+    init_test(cx, |_| {});
+
+    cx.add_window(|cx| {
+        let buffer = MultiBuffer::build_simple("aaa\nbbb\nccc\nddd\n\n", cx);
+        let mut editor = build_editor(buffer.clone(), cx);
+        let buffer = buffer.read(cx).as_singleton().unwrap();
+
+        editor.change_selections(None, cx, |s| {
+            s.select_ranges([
+                Point::new(0, 2)..Point::new(1, 1),
+                Point::new(1, 2)..Point::new(1, 2),
+                Point::new(3, 1)..Point::new(3, 2),
+            ])
+        });
+
+        editor.join_lines(&JoinLines, cx);
+        assert_eq!(buffer.read(cx).text(), "aaa bbb ccc\nddd\n");
+
+        assert_eq!(
+            editor.selections.ranges::<Point>(cx),
+            [
+                Point::new(0, 7)..Point::new(0, 7),
+                Point::new(1, 3)..Point::new(1, 3)
+            ]
+        );
+        editor
+    });
+}
+
 #[gpui::test]
 fn test_duplicate_line(cx: &mut TestAppContext) {
     init_test(cx, |_| {});