commands: Implement X as extend line.

helix-term/src/commands.rs

@@ -429,6 +429,25 @@ pub fn select_line(cx: &mut Context) {
 
     doc.set_selection(Selection::single(start, end));
 }
+pub fn extend_line(cx: &mut Context) {
+    let count = cx.count;
+    let doc = cx.doc();
+
+    let pos = doc.selection().primary();
+    let text = doc.text();
+
+    let line_start = text.char_to_line(pos.anchor);
+    let mut line = text.char_to_line(pos.head);
+    let line_end = text.line_to_char(line + 1).saturating_sub(1);
+    if line_start <= pos.anchor && pos.head == line_end && line != text.len_lines() {
+        line += 1;
+    }
+
+    let start = text.line_to_char(line_start);
+    let end = text.line_to_char(line + 1).saturating_sub(1);
+
+    doc.set_selection(Selection::single(start, end));
+}
 
 // heuristic: append changes to history after each command, unless we're in insert mode
 

helix-term/src/keymap.rs

@@ -177,7 +177,7 @@ pub fn default() -> Keymaps {
         alt!(';') => commands::flip_selections,
         key!('%') => commands::select_all,
         key!('x') => commands::select_line,
-        // key!('X') => commands::extend_line,
+        shift!('X') => commands::extend_line,
         // or select mode X?
         // extend_to_whole_line, crop_to_whole_line