New input parser based on http://vt100.net/emu/dec_ansi_parser.

tmux.h

@@ -719,43 +719,36 @@ struct screen_write_ctx {
 #define screen_hsize(s) ((s)->grid->hsize)
 #define screen_hlimit(s) ((s)->grid->hlimit)
 
-/* Input parser sequence argument. */
-struct input_arg {
-	u_char		 data[64];
-	size_t		 used;
-};
-
 /* Input parser context. */
 struct input_ctx {
-	struct window_pane *wp;
+	struct window_pane     *wp;
 	struct screen_write_ctx ctx;
 
-	u_char		*buf;
-	size_t		 len;
-	size_t		 off;
-	size_t		 was;
+	struct grid_cell	cell;
 
-	struct grid_cell cell;
+	struct grid_cell	old_cell;
+	u_int 			old_cx;
+	u_int			old_cy;
 
-	struct grid_cell saved_cell;
-	u_int		 saved_cx;
-	u_int		 saved_cy;
+	u_char			interm_buf[4];
+	size_t			interm_len;
 
-#define MAXSTRINGLEN	1024
-	u_char		*string_buf;
-	size_t		 string_len;
-	int		 string_type;
-#define STRING_SYSTEM 0
-#define STRING_APPLICATION 1
-#define STRING_NAME 2
+	u_char			param_buf[64];
+	size_t			param_len;
 
-	struct utf8_data utf8data;
+	u_char			input_buf[256];
+	size_t			input_len;
 
-	u_char		 intermediate;
-	void		*(*state)(u_char, struct input_ctx *);
+	int			param_list[24];	/* -1 not present */
+	u_int			param_list_len;
 
-	u_char		 private;
-	ARRAY_DECL(, struct input_arg) args;
+	struct utf8_data	utf8data;
+
+	int			ch;
+	int			flags;
+#define INPUT_DISCARD 0x1
+
+	const struct input_state *state;
 };
 
 /*
@@ -1825,6 +1818,10 @@ int		 window_pane_spawn(struct window_pane *, const char *,
 		     const char *, const char *, struct environ *,
 		     struct termios *, char **);
 void		 window_pane_resize(struct window_pane *, u_int, u_int);
+void		 window_pane_alternate_on(
+		     struct window_pane *, struct grid_cell *);
+void		 window_pane_alternate_off(
+		     struct window_pane *, struct grid_cell *);
 int		 window_pane_set_mode(
 		     struct window_pane *, const struct window_mode *);
 void		 window_pane_reset_mode(struct window_pane *);

window.c

@@ -623,6 +623,81 @@ window_pane_resize(struct window_pane *wp, u_int sx, u_int sy)
 		fatal("ioctl failed");
 }
 
+/*
+ * Enter alternative screen mode. A copy of the visible screen is saved and the
+ * history is not updated
+ */
+void
+window_pane_alternate_on(struct window_pane *wp, struct grid_cell *gc)
+{
+	struct screen	*s = &wp->base;
+	u_int		 sx, sy;
+
+	if (wp->saved_grid != NULL)
+		return;
+	if (!options_get_number(&wp->window->options, "alternate-screen"))
+		return;
+	sx = screen_size_x(s);
+	sy = screen_size_y(s);
+
+	wp->saved_grid = grid_create(sx, sy, 0);
+	grid_duplicate_lines(wp->saved_grid, 0, s->grid, screen_hsize(s), sy);
+	wp->saved_cx = s->cx;
+	wp->saved_cy = s->cy;
+	memcpy(&wp->saved_cell, gc, sizeof wp->saved_cell);
+
+	grid_view_clear(s->grid, 0, 0, sx, sy);
+
+	wp->base.grid->flags &= ~GRID_HISTORY;
+
+	wp->flags |= PANE_REDRAW;
+}
+
+/* Exit alternate screen mode and restore the copied grid. */
+void
+window_pane_alternate_off(struct window_pane *wp, struct grid_cell *gc)
+{
+	struct screen	*s = &wp->base;
+	u_int		 sx, sy;
+
+	if (wp->saved_grid == NULL)
+		return;
+	if (!options_get_number(&wp->window->options, "alternate-screen"))
+		return;
+	sx = screen_size_x(s);
+	sy = screen_size_y(s);
+
+	/*
+	 * If the current size is bigger, temporarily resize to the old size
+	 * before copying back.
+	 */
+	if (sy > wp->saved_grid->sy)
+		screen_resize(s, sx, wp->saved_grid->sy);
+
+	/* Restore the grid, cursor position and cell. */
+	grid_duplicate_lines(s->grid, screen_hsize(s), wp->saved_grid, 0, sy);
+	s->cx = wp->saved_cx;
+	if (s->cx > screen_size_x(s) - 1)
+		s->cx = screen_size_x(s) - 1;
+	s->cy = wp->saved_cy;
+	if (s->cy > screen_size_y(s) - 1)
+		s->cy = screen_size_y(s) - 1;
+	memcpy(gc, &wp->saved_cell, sizeof *gc);
+
+	/*
+	 * Turn history back on (so resize can use it) and then resize back to
+	 * the current size.
+	 */
+	wp->base.grid->flags |= GRID_HISTORY;
+	if (sy > wp->saved_grid->sy)
+		screen_resize(s, sx, sy);
+
+	grid_destroy(wp->saved_grid);
+	wp->saved_grid = NULL;
+
+	wp->flags |= PANE_REDRAW;
+}
+
 int
 window_pane_set_mode(struct window_pane *wp, const struct window_mode *mode)
 {