editor: add select previous command (#2556)

Added a `select previous` command to complement `select next`.
Release Notes:

- Added "Select previous" editor command, mirroring `Select next`.
Ticket number: Z-366

assets/keymaps/atom.json

@@ -16,6 +16,12 @@
           "replace_newest": true
         }
       ],
+      "ctrl-cmd-g": [
+        "editor::SelectPrevious",
+        {
+          "replace_newest": true
+        }
+      ],
       "ctrl-shift-down": "editor::AddSelectionBelow",
       "ctrl-shift-up": "editor::AddSelectionAbove",
       "cmd-shift-backspace": "editor::DeleteToBeginningOfLine",

assets/keymaps/default.json

@@ -250,12 +250,24 @@
           "replace_newest": false
         }
       ],
+      "ctrl-cmd-d": [
+        "editor::SelectPrevious",
+        {
+          "replace_newest": false
+        }
+      ],
       "cmd-k cmd-d": [
         "editor::SelectNext",
         {
           "replace_newest": true
         }
       ],
+      "cmd-k ctrl-cmd-d": [
+        "editor::SelectPrevious",
+        {
+          "replace_newest": true
+        }
+      ],
       "cmd-k cmd-i": "editor::Hover",
       "cmd-/": [
         "editor::ToggleComments",

assets/keymaps/jetbrains.json

@@ -26,6 +26,12 @@
           "replace_newest": false
         }
       ],
+      "ctrl-cmd-g": [
+        "editor::SelectPrevious",
+        {
+          "replace_newest": false
+        }
+      ],
       "cmd-/": [
         "editor::ToggleComments",
         {

crates/editor/src/editor.rs

@@ -111,6 +111,12 @@ pub struct SelectNext {
     pub replace_newest: bool,
 }
 
+#[derive(Clone, Deserialize, PartialEq, Default)]
+pub struct SelectPrevious {
+    #[serde(default)]
+    pub replace_newest: bool,
+}
+
 #[derive(Clone, Deserialize, PartialEq)]
 pub struct SelectToBeginningOfLine {
     #[serde(default)]
@@ -272,6 +278,7 @@ impl_actions!(
     editor,
     [
         SelectNext,
+        SelectPrevious,
         SelectToBeginningOfLine,
         SelectToEndOfLine,
         ToggleCodeActions,
@@ -367,6 +374,7 @@ pub fn init(cx: &mut AppContext) {
     cx.add_action(Editor::add_selection_above);
     cx.add_action(Editor::add_selection_below);
     cx.add_action(Editor::select_next);
+    cx.add_action(Editor::select_previous);
     cx.add_action(Editor::toggle_comments);
     cx.add_action(Editor::select_larger_syntax_node);
     cx.add_action(Editor::select_smaller_syntax_node);
@@ -484,6 +492,7 @@ pub struct Editor {
     columnar_selection_tail: Option<Anchor>,
     add_selections_state: Option<AddSelectionsState>,
     select_next_state: Option<SelectNextState>,
+    select_prev_state: Option<SelectNextState>,
     selection_history: SelectionHistory,
     autoclose_regions: Vec<AutocloseRegion>,
     snippet_stack: InvalidationStack<SnippetState>,
@@ -539,6 +548,7 @@ pub struct EditorSnapshot {
 struct SelectionHistoryEntry {
     selections: Arc<[Selection<Anchor>]>,
     select_next_state: Option<SelectNextState>,
+    select_prev_state: Option<SelectNextState>,
     add_selections_state: Option<AddSelectionsState>,
 }
 
@@ -1286,6 +1296,7 @@ impl Editor {
             columnar_selection_tail: None,
             add_selections_state: None,
             select_next_state: None,
+            select_prev_state: None,
             selection_history: Default::default(),
             autoclose_regions: Default::default(),
             snippet_stack: Default::default(),
@@ -1507,6 +1518,7 @@ impl Editor {
         let buffer = &display_map.buffer_snapshot;
         self.add_selections_state = None;
         self.select_next_state = None;
+        self.select_prev_state = None;
         self.select_larger_syntax_node_stack.clear();
         self.invalidate_autoclose_regions(&self.selections.disjoint_anchors(), buffer);
         self.snippet_stack
@@ -5213,6 +5225,101 @@ impl Editor {
         }
     }
 
+    pub fn select_previous(&mut self, action: &SelectPrevious, cx: &mut ViewContext<Self>) {
+        self.push_to_selection_history();
+        let display_map = self.display_map.update(cx, |map, cx| map.snapshot(cx));
+        let buffer = &display_map.buffer_snapshot;
+        let mut selections = self.selections.all::<usize>(cx);
+        if let Some(mut select_prev_state) = self.select_prev_state.take() {
+            let query = &select_prev_state.query;
+            if !select_prev_state.done {
+                let first_selection = selections.iter().min_by_key(|s| s.id).unwrap();
+                let last_selection = selections.iter().max_by_key(|s| s.id).unwrap();
+                let mut next_selected_range = None;
+                // When we're iterating matches backwards, the oldest match will actually be the furthest one in the buffer.
+                let bytes_before_last_selection =
+                    buffer.reversed_bytes_in_range(0..last_selection.start);
+                let bytes_after_first_selection =
+                    buffer.reversed_bytes_in_range(first_selection.end..buffer.len());
+                let query_matches = query
+                    .stream_find_iter(bytes_before_last_selection)
+                    .map(|result| (last_selection.start, result))
+                    .chain(
+                        query
+                            .stream_find_iter(bytes_after_first_selection)
+                            .map(|result| (buffer.len(), result)),
+                    );
+                for (end_offset, query_match) in query_matches {
+                    let query_match = query_match.unwrap(); // can only fail due to I/O
+                    let offset_range =
+                        end_offset - query_match.end()..end_offset - query_match.start();
+                    let display_range = offset_range.start.to_display_point(&display_map)
+                        ..offset_range.end.to_display_point(&display_map);
+
+                    if !select_prev_state.wordwise
+                        || (!movement::is_inside_word(&display_map, display_range.start)
+                            && !movement::is_inside_word(&display_map, display_range.end))
+                    {
+                        next_selected_range = Some(offset_range);
+                        break;
+                    }
+                }
+
+                if let Some(next_selected_range) = next_selected_range {
+                    self.unfold_ranges([next_selected_range.clone()], false, true, cx);
+                    self.change_selections(Some(Autoscroll::newest()), cx, |s| {
+                        if action.replace_newest {
+                            s.delete(s.newest_anchor().id);
+                        }
+                        s.insert_range(next_selected_range);
+                    });
+                } else {
+                    select_prev_state.done = true;
+                }
+            }
+
+            self.select_prev_state = Some(select_prev_state);
+        } else if selections.len() == 1 {
+            let selection = selections.last_mut().unwrap();
+            if selection.start == selection.end {
+                let word_range = movement::surrounding_word(
+                    &display_map,
+                    selection.start.to_display_point(&display_map),
+                );
+                selection.start = word_range.start.to_offset(&display_map, Bias::Left);
+                selection.end = word_range.end.to_offset(&display_map, Bias::Left);
+                selection.goal = SelectionGoal::None;
+                selection.reversed = false;
+
+                let query = buffer
+                    .text_for_range(selection.start..selection.end)
+                    .collect::<String>();
+                let query = query.chars().rev().collect::<String>();
+                let select_state = SelectNextState {
+                    query: AhoCorasick::new_auto_configured(&[query]),
+                    wordwise: true,
+                    done: false,
+                };
+                self.unfold_ranges([selection.start..selection.end], false, true, cx);
+                self.change_selections(Some(Autoscroll::newest()), cx, |s| {
+                    s.select(selections);
+                });
+                self.select_prev_state = Some(select_state);
+            } else {
+                let query = buffer
+                    .text_for_range(selection.start..selection.end)
+                    .collect::<String>();
+                let query = query.chars().rev().collect::<String>();
+                self.select_prev_state = Some(SelectNextState {
+                    query: AhoCorasick::new_auto_configured(&[query]),
+                    wordwise: false,
+                    done: false,
+                });
+                self.select_previous(action, cx);
+            }
+        }
+    }
+
     pub fn toggle_comments(&mut self, action: &ToggleComments, cx: &mut ViewContext<Self>) {
         self.transact(cx, |this, cx| {
             let mut selections = this.selections.all::<Point>(cx);
@@ -5586,6 +5693,7 @@ impl Editor {
         if let Some(entry) = self.selection_history.undo_stack.pop_back() {
             self.change_selections(None, cx, |s| s.select_anchors(entry.selections.to_vec()));
             self.select_next_state = entry.select_next_state;
+            self.select_prev_state = entry.select_prev_state;
             self.add_selections_state = entry.add_selections_state;
             self.request_autoscroll(Autoscroll::newest(), cx);
         }
@@ -5598,6 +5706,7 @@ impl Editor {
         if let Some(entry) = self.selection_history.redo_stack.pop_back() {
             self.change_selections(None, cx, |s| s.select_anchors(entry.selections.to_vec()));
             self.select_next_state = entry.select_next_state;
+            self.select_prev_state = entry.select_prev_state;
             self.add_selections_state = entry.add_selections_state;
             self.request_autoscroll(Autoscroll::newest(), cx);
         }
@@ -6375,6 +6484,7 @@ impl Editor {
         self.selection_history.push(SelectionHistoryEntry {
             selections: self.selections.disjoint_anchors(),
             select_next_state: self.select_next_state.clone(),
+            select_prev_state: self.select_prev_state.clone(),
             add_selections_state: self.add_selections_state.clone(),
         });
     }

crates/editor/src/editor_tests.rs

@@ -3107,6 +3107,57 @@ async fn test_select_next(cx: &mut gpui::TestAppContext) {
     cx.assert_editor_state("«abcˇ»\n«abcˇ» «abcˇ»\ndefabc\n«abcˇ»");
 }
 
+#[gpui::test]
+async fn test_select_previous(cx: &mut gpui::TestAppContext) {
+    init_test(cx, |_| {});
+    {
+        // `Select previous` without a selection (selects wordwise)
+        let mut cx = EditorTestContext::new(cx).await;
+        cx.set_state("abc\nˇabc abc\ndefabc\nabc");
+
+        cx.update_editor(|e, cx| e.select_previous(&SelectPrevious::default(), cx));
+        cx.assert_editor_state("abc\n«abcˇ» abc\ndefabc\nabc");
+
+        cx.update_editor(|e, cx| e.select_previous(&SelectPrevious::default(), cx));
+        cx.assert_editor_state("«abcˇ»\n«abcˇ» abc\ndefabc\nabc");
+
+        cx.update_editor(|view, cx| view.undo_selection(&UndoSelection, cx));
+        cx.assert_editor_state("abc\n«abcˇ» abc\ndefabc\nabc");
+
+        cx.update_editor(|view, cx| view.redo_selection(&RedoSelection, cx));
+        cx.assert_editor_state("«abcˇ»\n«abcˇ» abc\ndefabc\nabc");
+
+        cx.update_editor(|e, cx| e.select_previous(&SelectPrevious::default(), cx));
+        cx.assert_editor_state("«abcˇ»\n«abcˇ» abc\ndefabc\n«abcˇ»");
+
+        cx.update_editor(|e, cx| e.select_previous(&SelectPrevious::default(), cx));
+        cx.assert_editor_state("«abcˇ»\n«abcˇ» «abcˇ»\ndefabc\n«abcˇ»");
+    }
+    {
+        // `Select previous` with a selection
+        let mut cx = EditorTestContext::new(cx).await;
+        cx.set_state("abc\n«ˇabc» abc\ndefabc\nabc");
+
+        cx.update_editor(|e, cx| e.select_previous(&SelectPrevious::default(), cx));
+        cx.assert_editor_state("«abcˇ»\n«ˇabc» abc\ndefabc\nabc");
+
+        cx.update_editor(|e, cx| e.select_previous(&SelectPrevious::default(), cx));
+        cx.assert_editor_state("«abcˇ»\n«ˇabc» abc\ndefabc\n«abcˇ»");
+
+        cx.update_editor(|view, cx| view.undo_selection(&UndoSelection, cx));
+        cx.assert_editor_state("«abcˇ»\n«ˇabc» abc\ndefabc\nabc");
+
+        cx.update_editor(|view, cx| view.redo_selection(&RedoSelection, cx));
+        cx.assert_editor_state("«abcˇ»\n«ˇabc» abc\ndefabc\n«abcˇ»");
+
+        cx.update_editor(|e, cx| e.select_previous(&SelectPrevious::default(), cx));
+        cx.assert_editor_state("«abcˇ»\n«ˇabc» abc\ndef«abcˇ»\n«abcˇ»");
+
+        cx.update_editor(|e, cx| e.select_previous(&SelectPrevious::default(), cx));
+        cx.assert_editor_state("«abcˇ»\n«ˇabc» «abcˇ»\ndef«abcˇ»\n«abcˇ»");
+    }
+}
+
 #[gpui::test]
 async fn test_select_larger_smaller_syntax_node(cx: &mut gpui::TestAppContext) {
     init_test(cx, |_| {});

crates/editor/src/multi_buffer.rs

@@ -196,6 +196,13 @@ pub struct MultiBufferBytes<'a> {
     chunk: &'a [u8],
 }
 
+pub struct ReversedMultiBufferBytes<'a> {
+    range: Range<usize>,
+    excerpts: Cursor<'a, Excerpt, usize>,
+    excerpt_bytes: Option<ExcerptBytes<'a>>,
+    chunk: &'a [u8],
+}
+
 struct ExcerptChunks<'a> {
     content_chunks: BufferChunks<'a>,
     footer_height: usize,
@@ -1967,7 +1974,6 @@ impl MultiBufferSnapshot {
         } else {
             None
         };
-
         MultiBufferBytes {
             range,
             excerpts,
@@ -1976,6 +1982,33 @@ impl MultiBufferSnapshot {
         }
     }
 
+    pub fn reversed_bytes_in_range<T: ToOffset>(
+        &self,
+        range: Range<T>,
+    ) -> ReversedMultiBufferBytes {
+        let range = range.start.to_offset(self)..range.end.to_offset(self);
+        let mut excerpts = self.excerpts.cursor::<usize>();
+        excerpts.seek(&range.end, Bias::Left, &());
+
+        let mut chunk = &[][..];
+        let excerpt_bytes = if let Some(excerpt) = excerpts.item() {
+            let mut excerpt_bytes = excerpt.reversed_bytes_in_range(
+                range.start - excerpts.start()..range.end - excerpts.start(),
+            );
+            chunk = excerpt_bytes.next().unwrap_or(&[][..]);
+            Some(excerpt_bytes)
+        } else {
+            None
+        };
+
+        ReversedMultiBufferBytes {
+            range,
+            excerpts,
+            excerpt_bytes,
+            chunk,
+        }
+    }
+
     pub fn buffer_rows(&self, start_row: u32) -> MultiBufferRows {
         let mut result = MultiBufferRows {
             buffer_row_range: 0..0,
@@ -3409,6 +3442,26 @@ impl Excerpt {
         }
     }
 
+    fn reversed_bytes_in_range(&self, range: Range<usize>) -> ExcerptBytes {
+        let content_start = self.range.context.start.to_offset(&self.buffer);
+        let bytes_start = content_start + range.start;
+        let bytes_end = content_start + cmp::min(range.end, self.text_summary.len);
+        let footer_height = if self.has_trailing_newline
+            && range.start <= self.text_summary.len
+            && range.end > self.text_summary.len
+        {
+            1
+        } else {
+            0
+        };
+        let content_bytes = self.buffer.reversed_bytes_in_range(bytes_start..bytes_end);
+
+        ExcerptBytes {
+            content_bytes,
+            footer_height,
+        }
+    }
+
     fn clip_anchor(&self, text_anchor: text::Anchor) -> text::Anchor {
         if text_anchor
             .cmp(&self.range.context.start, &self.buffer)
@@ -3727,6 +3780,38 @@ impl<'a> io::Read for MultiBufferBytes<'a> {
     }
 }
 
+impl<'a> ReversedMultiBufferBytes<'a> {
+    fn consume(&mut self, len: usize) {
+        self.range.end -= len;
+        self.chunk = &self.chunk[..self.chunk.len() - len];
+
+        if !self.range.is_empty() && self.chunk.is_empty() {
+            if let Some(chunk) = self.excerpt_bytes.as_mut().and_then(|bytes| bytes.next()) {
+                self.chunk = chunk;
+            } else {
+                self.excerpts.next(&());
+                if let Some(excerpt) = self.excerpts.item() {
+                    let mut excerpt_bytes =
+                        excerpt.bytes_in_range(0..self.range.end - self.excerpts.start());
+                    self.chunk = excerpt_bytes.next().unwrap();
+                    self.excerpt_bytes = Some(excerpt_bytes);
+                }
+            }
+        }
+    }
+}
+
+impl<'a> io::Read for ReversedMultiBufferBytes<'a> {
+    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
+        let len = cmp::min(buf.len(), self.chunk.len());
+        buf[..len].copy_from_slice(&self.chunk[..len]);
+        buf[..len].reverse();
+        if len > 0 {
+            self.consume(len);
+        }
+        Ok(len)
+    }
+}
 impl<'a> Iterator for ExcerptBytes<'a> {
     type Item = &'a [u8];
 

crates/rope/src/rope.rs

@@ -179,7 +179,11 @@ impl Rope {
     }
 
     pub fn bytes_in_range(&self, range: Range<usize>) -> Bytes {
-        Bytes::new(self, range)
+        Bytes::new(self, range, false)
+    }
+
+    pub fn reversed_bytes_in_range(&self, range: Range<usize>) -> Bytes {
+        Bytes::new(self, range, true)
     }
 
     pub fn chunks(&self) -> Chunks {
@@ -579,22 +583,33 @@ impl<'a> Iterator for Chunks<'a> {
 pub struct Bytes<'a> {
     chunks: sum_tree::Cursor<'a, Chunk, usize>,
     range: Range<usize>,
+    reversed: bool,
 }
 
 impl<'a> Bytes<'a> {
-    pub fn new(rope: &'a Rope, range: Range<usize>) -> Self {
+    pub fn new(rope: &'a Rope, range: Range<usize>, reversed: bool) -> Self {
         let mut chunks = rope.chunks.cursor();
-        chunks.seek(&range.start, Bias::Right, &());
-        Self { chunks, range }
+        if reversed {
+            chunks.seek(&range.end, Bias::Left, &());
+        } else {
+            chunks.seek(&range.start, Bias::Right, &());
+        }
+        Self {
+            chunks,
+            range,
+            reversed,
+        }
     }
 
     pub fn peek(&self) -> Option<&'a [u8]> {
         let chunk = self.chunks.item()?;
+        if self.reversed && self.range.start >= self.chunks.end(&()) {
+            return None;
+        }
         let chunk_start = *self.chunks.start();
         if self.range.end <= chunk_start {
             return None;
         }
-
         let start = self.range.start.saturating_sub(chunk_start);
         let end = self.range.end - chunk_start;
         Some(&chunk.0.as_bytes()[start..chunk.0.len().min(end)])
@@ -607,7 +622,11 @@ impl<'a> Iterator for Bytes<'a> {
     fn next(&mut self) -> Option<Self::Item> {
         let result = self.peek();
         if result.is_some() {
-            self.chunks.next(&());
+            if self.reversed {
+                self.chunks.prev(&());
+            } else {
+                self.chunks.next(&());
+            }
         }
         result
     }
@@ -617,10 +636,21 @@ impl<'a> io::Read for Bytes<'a> {
     fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
         if let Some(chunk) = self.peek() {
             let len = cmp::min(buf.len(), chunk.len());
-            buf[..len].copy_from_slice(&chunk[..len]);
-            self.range.start += len;
+            if self.reversed {
+                buf[..len].copy_from_slice(&chunk[chunk.len() - len..]);
+                buf[..len].reverse();
+                self.range.end -= len;
+            } else {
+                buf[..len].copy_from_slice(&chunk[..len]);
+                self.range.start += len;
+            }
+
             if len == chunk.len() {
-                self.chunks.next(&());
+                if self.reversed {
+                    self.chunks.prev(&());
+                } else {
+                    self.chunks.next(&());
+                }
             }
             Ok(len)
         } else {

crates/text/src/text.rs

@@ -1749,6 +1749,12 @@ impl BufferSnapshot {
         self.visible_text.bytes_in_range(start..end)
     }
 
+    pub fn reversed_bytes_in_range<T: ToOffset>(&self, range: Range<T>) -> rope::Bytes<'_> {
+        let start = range.start.to_offset(self);
+        let end = range.end.to_offset(self);
+        self.visible_text.reversed_bytes_in_range(start..end)
+    }
+
     pub fn text_for_range<T: ToOffset>(&self, range: Range<T>) -> Chunks<'_> {
         let start = range.start.to_offset(self);
         let end = range.end.to_offset(self);