Implement move_to_next_word_boundary for buffer

Co-Authored-By: Nathan Sobo <nathan@zed.dev>

zed/src/editor/buffer_view.rs

@@ -54,6 +54,11 @@ pub fn init(app: &mut MutableAppContext) {
         Binding::new("down", "buffer:move_down", Some("BufferView")),
         Binding::new("left", "buffer:move_left", Some("BufferView")),
         Binding::new("right", "buffer:move_right", Some("BufferView")),
+        Binding::new(
+            "alt-right",
+            "buffer:move_to_next_word_boundary",
+            Some("BufferView"),
+        ),
         Binding::new(
             "cmd-left",
             "buffer:move_to_beginning_of_line",
@@ -141,6 +146,10 @@ pub fn init(app: &mut MutableAppContext) {
     app.add_action("buffer:move_down", BufferView::move_down);
     app.add_action("buffer:move_left", BufferView::move_left);
     app.add_action("buffer:move_right", BufferView::move_right);
+    app.add_action(
+        "buffer:move_to_next_word_boundary",
+        BufferView::move_to_next_word_boundary,
+    );
     app.add_action(
         "buffer:move_to_beginning_of_line",
         BufferView::move_to_beginning_of_line,
@@ -1085,6 +1094,24 @@ impl BufferView {
         self.update_selections(selections, true, ctx);
     }
 
+    pub fn move_to_next_word_boundary(&mut self, _: &(), ctx: &mut ViewContext<Self>) {
+        let app = ctx.as_ref();
+        let mut selections = self.selections(app).to_vec();
+        {
+            let map = self.display_map.read(app);
+            for selection in &mut selections {
+                let head = selection.head().to_display_point(map, app).unwrap();
+                let new_head = movement::next_word_boundary(map, head, app).unwrap();
+                let anchor = map.anchor_before(new_head, Bias::Left, app).unwrap();
+                selection.start = anchor.clone();
+                selection.end = anchor;
+                selection.reversed = false;
+                selection.goal_column = None;
+            }
+        }
+        self.update_selections(selections, true, ctx);
+    }
+
     pub fn move_to_beginning_of_line(&mut self, _: &(), ctx: &mut ViewContext<Self>) {
         let app = ctx.as_ref();
         let mut selections = self.selections(app).to_vec();

zed/src/editor/movement.rs

@@ -79,3 +79,42 @@ pub fn line_end(map: &DisplayMap, point: DisplayPoint, app: &AppContext) -> Resu
         map.line_len(point.row(), app)?,
     ))
 }
+
+pub fn prev_word_boundary(
+    map: &DisplayMap,
+    point: DisplayPoint,
+    app: &AppContext,
+) -> Result<DisplayPoint> {
+    todo!()
+}
+
+pub fn next_word_boundary(
+    map: &DisplayMap,
+    mut point: DisplayPoint,
+    app: &AppContext,
+) -> Result<DisplayPoint> {
+    let mut prev_c = None;
+    for c in map.chars_at(point, app)? {
+        if prev_c.is_some() && (c == '\n' || is_word_char(prev_c.unwrap()) != is_word_char(c)) {
+            break;
+        }
+
+        if c == '\n' {
+            *point.row_mut() += 1;
+            *point.column_mut() = 0;
+        } else {
+            *point.column_mut() += 1;
+        }
+        prev_c = Some(c);
+    }
+    Ok(point)
+}
+
+fn is_word_char(c: char) -> bool {
+    match c {
+        '/' | '\\' | '(' | ')' | '"' | '\'' | ':' | ',' | '.' | ';' | '<' | '>' | '~' | '!'
+        | '@' | '#' | '$' | '%' | '^' | '&' | '*' | '|' | '+' | '=' | '[' | ']' | '{' | '}'
+        | '`' | '?' | '-' | '…' | ' ' | '\n' => false,
+        _ => true,
+    }
+}