Collect some common patterns into methods on `Range`.

helix-core/src/movement.rs

@@ -31,15 +31,7 @@ pub fn move_horizontally(
     count: usize,
     behaviour: Movement,
 ) -> Range {
-    use Movement::Extend;
-
-    // Shift back one grapheme if needed, to account for
-    // the cursor being visually 1-width.
-    let pos = if range.head > range.anchor {
-        prev_grapheme_boundary(slice, range.head)
-    } else {
-        range.head
-    };
+    let pos = range.cursor(slice);
 
     // Compute the new position.
     let new_pos = if dir == Direction::Backward {
@@ -49,11 +41,7 @@ pub fn move_horizontally(
     };
 
     // Compute the final new range.
-    if behaviour == Extend {
-        range.move_head(slice, new_pos, true)
-    } else {
-        Range::point(new_pos)
-    }
+    range.put_cursor(slice, new_pos, behaviour == Movement::Extend)
 }
 
 pub fn move_vertically(
@@ -63,13 +51,7 @@ pub fn move_vertically(
     count: usize,
     behaviour: Movement,
 ) -> Range {
-    // Shift back one grapheme if needed, to account for
-    // the cursor being visually 1-width.
-    let pos = if range.head > range.anchor {
-        prev_grapheme_boundary(slice, range.head)
-    } else {
-        range.head
-    };
+    let pos = range.cursor(slice);
 
     // Compute the current position's 2d coordinates.
     let Position { row, col } = coords_at_pos(slice, pos);
@@ -89,24 +71,14 @@ pub fn move_vertically(
         )
     };
 
-    // Compute the new range according to the type of movement.
-    match behaviour {
-        Movement::Move => Range {
-            anchor: new_pos,
-            head: new_pos,
-            horiz: Some(horiz),
-        },
+    // Special-case to avoid moving to the end of the last non-empty line.
+    if behaviour == Movement::Extend && slice.line(new_row).len_chars() == 0 {
+        return range;
+    }
 
-        Movement::Extend => {
-            if slice.line(new_row).len_chars() > 0 {
-                let mut new_range = range.move_head(slice, new_pos, true);
+    let mut new_range = range.put_cursor(slice, new_pos, behaviour == Movement::Extend);
     new_range.horiz = Some(horiz);
     new_range
-            } else {
-                range
-            }
-        }
-    }
 }
 
 pub fn move_next_word_start(slice: RopeSlice, range: Range, count: usize) -> Range {
@@ -153,7 +125,7 @@ fn word_move(slice: RopeSlice, range: Range, count: usize, target: WordMotionTar
     // Prepare the range appropriately based on the target movement
     // direction.  This is addressing two things at once:
     //
-    //   1. 1-width range sementics.
+    //   1. Block-cursor semantics.
     //   2. The anchor position being irrelevant to the output result.
     #[allow(clippy::collapsible_else_if)] // Makes the structure clearer in this case.
     let start_range = if is_prev {

helix-core/src/selection.rs

@@ -73,16 +73,11 @@ impl Range {
         std::cmp::max(self.anchor, self.head)
     }
 
-    /// The line number that the head is on (using 1-width semantics).
+    /// The line number that the block-cursor is on.
     #[inline]
     #[must_use]
-    pub fn head_line(&self, text: RopeSlice) -> usize {
-        let head = if self.anchor < self.head {
-            prev_grapheme_boundary(text, self.head)
-        } else {
-            self.head
-        };
-        text.char_to_line(head)
+    pub fn cursor_line(&self, text: RopeSlice) -> usize {
+        text.char_to_line(self.cursor(text))
     }
 
     /// The (inclusive) range of lines that the range overlaps.
@@ -248,17 +243,29 @@ impl Range {
         }
     }
 
-    /// Moves the head of the `Range` to `char_idx`, adjusting the anchor
-    /// as needed to preserve 1-width range semantics.
+    /// Gets the left-side position of the block cursor.
+    #[must_use]
+    #[inline]
+    pub fn cursor(self, text: RopeSlice) -> usize {
+        if self.head > self.anchor {
+            prev_grapheme_boundary(text, self.head)
+        } else {
+            self.head
+        }
+    }
+
+    /// Puts the left side of the block cursor at `char_idx`, optionally extending.
     ///
-    /// `block_cursor` specifies whether it should treat `char_idx` as a block
-    /// cursor position or as a range-end position.
+    /// This follows "1-width" semantics, and therefore does a combination of anchor
+    /// and head moves to behave as if both the front and back of the range are 1-width
+    /// blocks
     ///
     /// This method assumes that the range and `char_idx` are already properly
     /// grapheme-aligned.
     #[must_use]
     #[inline]
-    pub fn move_head(self, text: RopeSlice, char_idx: usize, block_cursor: bool) -> Range {
+    pub fn put_cursor(self, text: RopeSlice, char_idx: usize, extend: bool) -> Range {
+        if extend {
             let anchor = if self.head >= self.anchor && char_idx < self.anchor {
                 next_grapheme_boundary(text, self.anchor)
             } else if self.head < self.anchor && char_idx >= self.anchor {
@@ -267,11 +274,14 @@ impl Range {
                 self.anchor
             };
 
-        if block_cursor && anchor <= char_idx {
+            if anchor <= char_idx {
                 Range::new(anchor, next_grapheme_boundary(text, char_idx))
             } else {
                 Range::new(anchor, char_idx)
             }
+        } else {
+            Range::point(char_idx)
+        }
     }
 
     // groupAt
@@ -309,18 +319,6 @@ impl Selection {
         self.ranges[self.primary_index]
     }
 
-    #[must_use]
-    pub fn cursor(&self, text: RopeSlice) -> usize {
-        let range = self.primary();
-
-        // For 1-width cursor semantics.
-        if range.anchor < range.head {
-            prev_grapheme_boundary(text, range.head).max(range.anchor)
-        } else {
-            range.head
-        }
-    }
-
     /// Ensure selection containing only the primary selection.
     pub fn into_single(self) -> Self {
         if self.ranges.len() == 1 {
@@ -452,17 +450,9 @@ impl Selection {
     }
 
     /// Transforms the selection into all of the left-side head positions,
-    /// using 1-width semantics.
+    /// using block-cursor semantics.
     pub fn cursors(self, text: RopeSlice) -> Self {
-        self.transform(|range| {
-            // For 1-width cursor semantics.
-            let pos = if range.anchor < range.head {
-                prev_grapheme_boundary(text, range.head).max(range.anchor)
-            } else {
-                range.head
-            };
-            Range::new(pos, pos)
-        })
+        self.transform(|range| Range::point(range.cursor(text)))
     }
 
     pub fn fragments<'a>(&'a self, text: RopeSlice<'a>) -> impl Iterator<Item = Cow<str>> + 'a {

helix-core/src/textobject.rs

@@ -59,17 +59,12 @@ pub fn textobject_word(
     textobject: TextObject,
     _count: usize,
 ) -> Range {
-    // For 1-width cursor semantics.
-    let head = if range.head > range.anchor {
-        prev_grapheme_boundary(slice, range.head)
-    } else {
-        range.head
-    };
+    let pos = range.cursor(slice);
 
-    let word_start = find_word_boundary(slice, head, Direction::Backward);
-    let word_end = match slice.get_char(head).map(categorize_char) {
-        None | Some(CharCategory::Whitespace | CharCategory::Eol) => head,
-        _ => find_word_boundary(slice, head + 1, Direction::Forward),
+    let word_start = find_word_boundary(slice, pos, Direction::Backward);
+    let word_end = match slice.get_char(pos).map(categorize_char) {
+        None | Some(CharCategory::Whitespace | CharCategory::Eol) => pos,
+        _ => find_word_boundary(slice, pos + 1, Direction::Forward),
     };
 
     // Special case.

helix-term/src/commands.rs

@@ -121,7 +121,10 @@ enum Align {
 }
 
 fn align_view(doc: &Document, view: &mut View, align: Align) {
-    let pos = doc.selection(view.id).cursor(doc.text().slice(..));
+    let pos = doc
+        .selection(view.id)
+        .primary()
+        .cursor(doc.text().slice(..));
     let line = doc.text().char_to_line(pos);
 
     let relative = match align {
@@ -372,17 +375,13 @@ fn goto_line_end(cx: &mut Context) {
     let text = doc.text().slice(..);
 
     let selection = doc.selection(view.id).clone().transform(|range| {
-        let line = range.head_line(text);
+        let line = range.cursor_line(text);
         let line_start = text.line_to_char(line);
 
         let pos = graphemes::prev_grapheme_boundary(text, line_end_char_index(&text, line))
             .max(line_start);
 
-        if doc.mode == Mode::Select {
-            range.move_head(text, pos, true)
-        } else {
-            Range::point(pos)
-        }
+        range.put_cursor(text, pos, doc.mode == Mode::Select)
     });
     doc.set_selection(view.id, selection);
 }
@@ -392,14 +391,10 @@ fn goto_line_end_newline(cx: &mut Context) {
     let text = doc.text().slice(..);
 
     let selection = doc.selection(view.id).clone().transform(|range| {
-        let line = range.head_line(text);
+        let line = range.cursor_line(text);
         let pos = line_end_char_index(&text, line);
 
-        if doc.mode == Mode::Select {
-            range.move_head(text, pos, true)
-        } else {
-            Range::point(pos)
-        }
+        range.put_cursor(text, pos, doc.mode == Mode::Select)
     });
     doc.set_selection(view.id, selection);
 }
@@ -409,15 +404,11 @@ fn goto_line_start(cx: &mut Context) {
     let text = doc.text().slice(..);
 
     let selection = doc.selection(view.id).clone().transform(|range| {
-        let line = range.head_line(text);
+        let line = range.cursor_line(text);
 
         // adjust to start of the line
         let pos = text.line_to_char(line);
-        if doc.mode == Mode::Select {
-            range.move_head(text, pos, true)
-        } else {
-            Range::point(pos)
-        }
+        range.put_cursor(text, pos, doc.mode == Mode::Select)
     });
     doc.set_selection(view.id, selection);
 }
@@ -427,15 +418,11 @@ fn goto_first_nonwhitespace(cx: &mut Context) {
     let text = doc.text().slice(..);
 
     let selection = doc.selection(view.id).clone().transform(|range| {
-        let line = range.head_line(text);
+        let line = range.cursor_line(text);
 
         if let Some(pos) = find_first_non_whitespace_char(text.line(line)) {
             let pos = pos + text.line_to_char(line);
-            if doc.mode == Mode::Select {
-                range.move_head(text, pos, true)
-            } else {
-                Range::point(pos)
-            }
+            range.put_cursor(text, pos, doc.mode == Mode::Select)
         } else {
             range
         }
@@ -579,8 +566,8 @@ fn extend_next_word_start(cx: &mut Context) {
         .min_width_1(text)
         .transform(|range| {
             let word = movement::move_next_word_start(text, range, count);
-            let pos = graphemes::prev_grapheme_boundary(text, word.head);
-            range.move_head(text, pos, true)
+            let pos = word.cursor(text);
+            range.put_cursor(text, pos, true)
         });
     doc.set_selection(view.id, selection);
 }
@@ -596,8 +583,8 @@ fn extend_prev_word_start(cx: &mut Context) {
         .min_width_1(text)
         .transform(|range| {
             let word = movement::move_prev_word_start(text, range, count);
-            let pos = word.head;
-            range.move_head(text, pos, true)
+            let pos = word.cursor(text);
+            range.put_cursor(text, pos, true)
         });
     doc.set_selection(view.id, selection);
 }
@@ -613,8 +600,8 @@ fn extend_next_word_end(cx: &mut Context) {
         .min_width_1(text)
         .transform(|range| {
             let word = movement::move_next_word_end(text, range, count);
-            let pos = graphemes::prev_grapheme_boundary(text, word.head);
-            range.move_head(text, pos, true)
+            let pos = word.cursor(text);
+            range.put_cursor(text, pos, true)
         });
     doc.set_selection(view.id, selection);
 }
@@ -663,18 +650,13 @@ where
 
         let selection = doc.selection(view.id).clone().transform(|range| {
             let range = if range.anchor < range.head {
-                // For 1-width cursor semantics.
+                // For block-cursor semantics.
                 Range::new(range.anchor, range.head - 1)
             } else {
                 range
             };
-            search_fn(text, ch, range.head, count, inclusive).map_or(range, |pos| {
-                if extend {
-                    range.move_head(text, pos, true)
-                } else {
-                    Range::point(pos)
-                }
-            })
+            search_fn(text, ch, range.head, count, inclusive)
+                .map_or(range, |pos| range.put_cursor(text, pos, extend))
         });
         doc.set_selection(view.id, selection);
     })
@@ -895,7 +877,9 @@ fn scroll(cx: &mut Context, offset: usize, direction: Direction) {
     let (view, doc) = current!(cx.editor);
     let cursor = coords_at_pos(
         doc.text().slice(..),
-        doc.selection(view.id).cursor(doc.text().slice(..)),
+        doc.selection(view.id)
+            .primary()
+            .cursor(doc.text().slice(..)),
     );
     let doc_last_line = doc.text().len_lines() - 1;
 
@@ -1220,12 +1204,7 @@ fn collapse_selection(cx: &mut Context) {
     let text = doc.text().slice(..);
 
     let selection = doc.selection(view.id).clone().transform(|range| {
-        let pos = if range.head > range.anchor {
-            // For 1-width cursor semantics.
-            graphemes::prev_grapheme_boundary(text, range.head)
-        } else {
-            range.head
-        };
+        let pos = range.cursor(text);
         Range::new(pos, pos)
     });
     doc.set_selection(view.id, selection);
@@ -2203,7 +2182,7 @@ fn append_to_line(cx: &mut Context) {
 
     let selection = doc.selection(view.id).clone().transform(|range| {
         let text = doc.text().slice(..);
-        let line = range.head_line(text);
+        let line = range.cursor_line(text);
         let pos = line_end_char_index(&text, line);
         Range::new(pos, pos)
     });
@@ -2264,7 +2243,7 @@ fn open(cx: &mut Context, open: Open) {
     let mut offs = 0;
 
     let mut transaction = Transaction::change_by_selection(contents, selection, |range| {
-        let line = range.head_line(text);
+        let line = range.cursor_line(text);
 
         let line = match open {
             // adjust position to the end of the line (next line - 1)
@@ -2472,7 +2451,9 @@ fn goto_definition(cx: &mut Context) {
 
     let pos = pos_to_lsp_pos(
         doc.text(),
-        doc.selection(view.id).cursor(doc.text().slice(..)),
+        doc.selection(view.id)
+            .primary()
+            .cursor(doc.text().slice(..)),
         offset_encoding,
     );
 
@@ -2513,7 +2494,9 @@ fn goto_type_definition(cx: &mut Context) {
 
     let pos = pos_to_lsp_pos(
         doc.text(),
-        doc.selection(view.id).cursor(doc.text().slice(..)),
+        doc.selection(view.id)
+            .primary()
+            .cursor(doc.text().slice(..)),
         offset_encoding,
     );
 
@@ -2554,7 +2537,9 @@ fn goto_implementation(cx: &mut Context) {
 
     let pos = pos_to_lsp_pos(
         doc.text(),
-        doc.selection(view.id).cursor(doc.text().slice(..)),
+        doc.selection(view.id)
+            .primary()
+            .cursor(doc.text().slice(..)),
         offset_encoding,
     );
 
@@ -2595,7 +2580,9 @@ fn goto_reference(cx: &mut Context) {
 
     let pos = pos_to_lsp_pos(
         doc.text(),
-        doc.selection(view.id).cursor(doc.text().slice(..)),
+        doc.selection(view.id)
+            .primary()
+            .cursor(doc.text().slice(..)),
         offset_encoding,
     );
 
@@ -2656,7 +2643,10 @@ fn goto_next_diag(cx: &mut Context) {
     let editor = &mut cx.editor;
     let (view, doc) = current!(editor);
 
-    let cursor_pos = doc.selection(view.id).cursor(doc.text().slice(..));
+    let cursor_pos = doc
+        .selection(view.id)
+        .primary()
+        .cursor(doc.text().slice(..));
     let diag = if let Some(diag) = doc
         .diagnostics()
         .iter()
@@ -2677,7 +2667,10 @@ fn goto_prev_diag(cx: &mut Context) {
     let editor = &mut cx.editor;
     let (view, doc) = current!(editor);
 
-    let cursor_pos = doc.selection(view.id).cursor(doc.text().slice(..));
+    let cursor_pos = doc
+        .selection(view.id)
+        .primary()
+        .cursor(doc.text().slice(..));
     let diag = if let Some(diag) = doc
         .diagnostics()
         .iter()
@@ -2705,7 +2698,9 @@ fn signature_help(cx: &mut Context) {
 
     let pos = pos_to_lsp_pos(
         doc.text(),
-        doc.selection(view.id).cursor(doc.text().slice(..)),
+        doc.selection(view.id)
+            .primary()
+            .cursor(doc.text().slice(..)),
         language_server.offset_encoding(),
     );
 
@@ -3457,7 +3452,10 @@ fn completion(cx: &mut Context) {
     };
 
     let offset_encoding = language_server.offset_encoding();
-    let cursor = doc.selection(view.id).cursor(doc.text().slice(..));
+    let cursor = doc
+        .selection(view.id)
+        .primary()
+        .cursor(doc.text().slice(..));
 
     let pos = pos_to_lsp_pos(doc.text(), cursor, offset_encoding);
 
@@ -3514,7 +3512,9 @@ fn hover(cx: &mut Context) {
 
     let pos = pos_to_lsp_pos(
         doc.text(),
-        doc.selection(view.id).cursor(doc.text().slice(..)),
+        doc.selection(view.id)
+            .primary()
+            .cursor(doc.text().slice(..)),
         language_server.offset_encoding(),
     );
 
@@ -3580,7 +3580,10 @@ fn match_brackets(cx: &mut Context) {
     let (view, doc) = current!(cx.editor);
 
     if let Some(syntax) = doc.syntax() {
-        let pos = doc.selection(view.id).cursor(doc.text().slice(..));
+        let pos = doc
+            .selection(view.id)
+            .primary()
+            .cursor(doc.text().slice(..));
         if let Some(pos) = match_brackets::find(syntax, doc.text(), pos) {
             let selection = Selection::point(pos);
             doc.set_selection(view.id, selection);
@@ -3684,7 +3687,10 @@ fn align_view_bottom(cx: &mut Context) {
 
 fn align_view_middle(cx: &mut Context) {
     let (view, doc) = current!(cx.editor);
-    let pos = doc.selection(view.id).cursor(doc.text().slice(..));
+    let pos = doc
+        .selection(view.id)
+        .primary()
+        .cursor(doc.text().slice(..));
     let pos = coords_at_pos(doc.text().slice(..), pos);
 
     const OFFSET: usize = 7; // gutters

helix-term/src/ui/completion.rs

@@ -86,7 +86,10 @@ impl Completion {
                     let item = item.unwrap();
 
                     // if more text was entered, remove it
-                    let cursor = doc.selection(view.id).cursor(doc.text().slice(..));
+                    let cursor = doc
+                        .selection(view.id)
+                        .primary()
+                        .cursor(doc.text().slice(..));
                     if trigger_offset < cursor {
                         let remove = Transaction::change(
                             doc.text(),
@@ -109,7 +112,10 @@ impl Completion {
                         )
                     } else {
                         let text = item.insert_text.as_ref().unwrap_or(&item.label);
-                        let cursor = doc.selection(view.id).cursor(doc.text().slice(..));
+                        let cursor = doc
+                            .selection(view.id)
+                            .primary()
+                            .cursor(doc.text().slice(..));
                         Transaction::change(
                             doc.text(),
                             vec![(cursor, cursor, Some(text.as_str().into()))].into_iter(),
@@ -155,7 +161,10 @@ impl Completion {
         // TODO: hooks should get processed immediately so maybe do it after select!(), before
         // looping?
 
-        let cursor = doc.selection(view.id).cursor(doc.text().slice(..));
+        let cursor = doc
+            .selection(view.id)
+            .primary()
+            .cursor(doc.text().slice(..));
         if self.trigger_offset <= cursor {
             let fragment = doc.text().slice(self.trigger_offset..cursor);
             let text = Cow::from(fragment);
@@ -212,7 +221,10 @@ impl Component for Completion {
                 .language()
                 .and_then(|scope| scope.strip_prefix("source."))
                 .unwrap_or("");
-            let cursor_pos = doc.selection(view.id).cursor(doc.text().slice(..));
+            let cursor_pos = doc
+                .selection(view.id)
+                .primary()
+                .cursor(doc.text().slice(..));
             let cursor_pos = (helix_core::coords_at_pos(doc.text().slice(..), cursor_pos).row
                 - view.first_line) as u16;
 

helix-term/src/ui/editor.rs

@@ -406,7 +406,10 @@ impl EditorView {
                     // TODO: set cursor position for IME
                     if let Some(syntax) = doc.syntax() {
                         use helix_core::match_brackets;
-                        let pos = doc.selection(view.id).cursor(doc.text().slice(..));
+                        let pos = doc
+                            .selection(view.id)
+                            .primary()
+                            .cursor(doc.text().slice(..));
                         let pos = match_brackets::find(syntax, doc.text(), pos)
                             .and_then(|pos| view.screen_coords_at_pos(doc, text, pos));
 
@@ -451,7 +454,10 @@ impl EditorView {
             widgets::{Paragraph, Widget},
         };
 
-        let cursor = doc.selection(view.id).cursor(doc.text().slice(..));
+        let cursor = doc
+            .selection(view.id)
+            .primary()
+            .cursor(doc.text().slice(..));
 
         let diagnostics = doc.diagnostics().iter().filter(|diagnostic| {
             diagnostic.range.start <= cursor && diagnostic.range.end >= cursor
@@ -565,7 +571,9 @@ impl EditorView {
         let position_info = {
             let pos = coords_at_pos(
                 doc.text().slice(..),
-                doc.selection(view.id).cursor(doc.text().slice(..)),
+                doc.selection(view.id)
+                    .primary()
+                    .cursor(doc.text().slice(..)),
             );
             format!("{}:{}", pos.row + 1, pos.col + 1) // convert to 1-indexing
         };

helix-view/src/editor.rs

@@ -145,7 +145,10 @@ impl Editor {
                     .entry(view.id)
                     .or_insert_with(|| Selection::point(0));
                 // TODO: reuse align_view
-                let pos = doc.selection(view.id).cursor(doc.text().slice(..));
+                let pos = doc
+                    .selection(view.id)
+                    .primary()
+                    .cursor(doc.text().slice(..));
                 let line = doc.text().char_to_line(pos);
                 view.first_line = line.saturating_sub(view.area.height as usize / 2);
 
@@ -295,7 +298,10 @@ impl Editor {
         const OFFSET: u16 = 7; // 1 diagnostic + 5 linenr + 1 gutter
         let view = view!(self);
         let doc = &self.documents[view.doc];
-        let cursor = doc.selection(view.id).cursor(doc.text().slice(..));
+        let cursor = doc
+            .selection(view.id)
+            .primary()
+            .cursor(doc.text().slice(..));
         if let Some(mut pos) = view.screen_coords_at_pos(doc, doc.text().slice(..), cursor) {
             pos.col += view.area.x as usize + OFFSET as usize;
             pos.row += view.area.y as usize;

helix-view/src/view.rs

@@ -84,7 +84,10 @@ impl View {
     }
 
     pub fn ensure_cursor_in_view(&mut self, doc: &Document) {
-        let cursor = doc.selection(self.id).cursor(doc.text().slice(..));
+        let cursor = doc
+            .selection(self.id)
+            .primary()
+            .cursor(doc.text().slice(..));
         let pos = coords_at_pos(doc.text().slice(..), cursor);
         let line = pos.row;
         let col = pos.col;