Provide support for CSI REP control code

kitty/control-codes.h

@@ -188,6 +188,9 @@
 // *Horizontal position relative*: Same as :data:`CUF`.
 #define HPR 'a'
 
+// Repeat the preceding graphic character Ps times.
+#define REP 'b'
+
 // *Device Attributes*.
 #define DA 'c'
 

kitty/line.c

@@ -550,6 +550,11 @@ left_shift(Line *self, PyObject *args) {
     Py_RETURN_NONE;
 }
 
+uint32_t
+line_get_char(Line *self, unsigned int at) {
+    return self->cpu_cells[at].ch;
+}
+
 void
 line_set_char(Line *self, unsigned int at, uint32_t ch, unsigned int width, Cursor *cursor, bool UNUSED is_second) {
     if (cursor == NULL) {

kitty/lineops.h

@@ -57,6 +57,7 @@ line_reset_cells(Line *line, index_type start, index_type num, GPUCell *gpu_cell
 typedef Line*(get_line_func)(void *, int);
 void line_clear_text(Line *self, unsigned int at, unsigned int num, char_type ch);
 void line_apply_cursor(Line *self, Cursor *cursor, unsigned int at, unsigned int num, bool clear_char);
+uint32_t line_get_char(Line *self, unsigned int at);
 void line_set_char(Line *, unsigned int , uint32_t , unsigned int , Cursor *, bool);
 void line_right_shift(Line *, unsigned int , unsigned int );
 void line_add_combining_char(Line *, uint32_t , unsigned int );

kitty/parser.c

@@ -652,6 +652,8 @@ dispatch_csi(Screen *screen, PyObject DUMP_UNUSED *dump_callback) {
         case ICH:
             NO_MODIFIERS(end_modifier, ' ', "Shift left escape code not implemented");
             CALL_CSI_HANDLER1(screen_insert_characters, 1);
+        case REP:
+            CALL_CSI_HANDLER1(screen_repeat_character, 1);
         case CUU:
             NO_MODIFIERS(end_modifier, ' ', "Shift right escape code not implemented");
             CALL_CSI_HANDLER1(screen_cursor_up2, 1);

kitty/screen.c

@@ -1251,6 +1251,25 @@ screen_insert_characters(Screen *self, unsigned int count) {
     }
 }
 
+void
+screen_repeat_character(Screen *self, unsigned int count) {
+    unsigned int top = self->margin_top, bottom = self->margin_bottom;
+    unsigned int x = self->cursor->x;
+    if (count == 0) count = 1;
+    if (top <= self->cursor->y && self->cursor->y <= bottom && x > 0) {
+        unsigned int num = MIN(count, self->columns - x);
+        linebuf_init_line(self->linebuf, self->cursor->y);
+        uint32_t ch = line_get_char(self->linebuf->line, x - 1);
+        if (is_ignored_char(ch) || is_combining_char(ch)) {
+            return;
+        }
+        while (num > 0) {
+            screen_draw(self, ch);
+            num--;
+        }
+    }
+}
+
 void
 screen_delete_characters(Screen *self, unsigned int count) {
     // Delete characters, later characters are moved left

kitty/screen.h

@@ -165,6 +165,7 @@ void screen_cursor_up1(Screen *self, unsigned int count/*=1*/);
 void screen_cursor_to_line(Screen *screen, unsigned int line);
 void screen_insert_lines(Screen *self, unsigned int count/*=1*/);
 void screen_delete_lines(Screen *self, unsigned int count/*=1*/);
+void screen_repeat_character(Screen *self, unsigned int count);
 void screen_delete_characters(Screen *self, unsigned int count);
 void screen_erase_characters(Screen *self, unsigned int count);
 void screen_set_margins(Screen *self, unsigned int top, unsigned int bottom);

kitty_tests/parser.py

@@ -177,6 +177,25 @@ class TestParser(BaseTest):
         pb('\033[3 A', ('Shift right escape code not implemented',))
         pb('\033[3;4 S', ('Select presentation directions escape code not implemented',))
 
+    def test_csi_code_rep(self):
+        s = self.create_screen(8)
+        pb = partial(self.parse_bytes_dump, s)
+        pb('\033[1b', ('screen_repeat_character', 1))
+        self.ae(str(s.line(0)), '')
+        pb('x\033[7b', 'x', ('screen_repeat_character', 7))
+        self.ae(str(s.line(0)), 'xxxxxxxx')
+        pb('\033[1;3H', ('screen_cursor_position', 1, 3))
+        pb('\033[byz\033[b', ('screen_repeat_character', 1), 'yz', ('screen_repeat_character', 1))
+        # repeat 'x' at 3, then 'yz' at 4-5, then repeat 'z' at 6
+        self.ae(str(s.line(0)), 'xxxyzzxx')
+        s.reset()
+        pb(' \033[3b', ' ', ('screen_repeat_character', 3))
+        self.ae(str(s.line(0)), '    ')
+        s.reset()
+        pb('\t\033[b', ('screen_tab',), ('screen_repeat_character', 1))
+        self.ae(str(s.line(0)), '\t')
+        s.reset()
+
     def test_osc_codes(self):
         s = self.create_screen()
         pb = partial(self.parse_bytes_dump, s)