Move title_format from window to container.

This patch moves the title_format information from windows to containers.
Furthermore, it allows correctly setting it on window-less containers and
displays the title accordingly for split containers.

We now also dump and read title_format in GET_TREE / during restarts.

fixes #2120

include/con.h

@@ -433,3 +433,9 @@ char *con_get_tree_representation(Con *con);
  *
  */
 void con_force_split_parents_redraw(Con *con);
+
+/**
+ * Returns the window title considering the current title format.
+ *
+ */
+i3String *con_parse_title_format(Con *con);

include/data.h

@@ -376,8 +376,6 @@ struct Window {
 
     /** The name of the window. */
     i3String *name;
-    /** The format with which the window's name should be displayed. */
-    char *title_format;
 
     /** The WM_WINDOW_ROLE of this window (for example, the pidgin buddy window
      * sets "buddy list"). Useful to match specific windows in assignments or
@@ -588,6 +586,9 @@ struct Con {
 
     char *name;
 
+    /** The format with which the window's name should be displayed. */
+    char *title_format;
+
     /* a sticky-group is an identifier which bundles several containers to a
      * group. The contents are shared between all of them, that is they are
      * displayed on whichever of the containers is currently visible */

include/libi3.h

@@ -504,6 +504,20 @@ char *get_config_path(const char *override_configpath, bool use_system_paths);
 int mkdirp(const char *path, mode_t mode);
 #endif
 
+/** Helper structure for usage in format_placeholders(). */
+typedef struct placeholder_t {
+    /* The placeholder to be replaced, e.g., "%title". */
+    char *name;
+    /* The value this placeholder should be replaced with. */
+    char *value;
+} placeholder_t;
+
+/**
+ * Replaces occurences of the defined placeholders in the format string.
+ *
+ */
+char *format_placeholders(char *format, placeholder_t *placeholders, int num);
+
 #ifdef CAIRO_SUPPORT
 /* We need to flush cairo surfaces twice to avoid an assertion bug. See #1989
  * and https://bugs.freedesktop.org/show_bug.cgi?id=92455. */

include/util.h

@@ -20,7 +20,7 @@
         if (pointer == NULL)       \
             die(__VA_ARGS__);      \
     }
-#define STARTS_WITH(string, needle) (strncasecmp(string, needle, strlen(needle)) == 0)
+#define STARTS_WITH(string, needle) (strncasecmp((string), (needle), strlen((needle))) == 0)
 #define CIRCLEQ_NEXT_OR_NULL(head, elm, field) (CIRCLEQ_NEXT(elm, field) != CIRCLEQ_END(head) ? CIRCLEQ_NEXT(elm, field) : NULL)
 #define CIRCLEQ_PREV_OR_NULL(head, elm, field) (CIRCLEQ_PREV(elm, field) != CIRCLEQ_END(head) ? CIRCLEQ_PREV(elm, field) : NULL)
 #define FOR_TABLE(workspace)                             \

include/window.h

@@ -81,10 +81,3 @@ void window_update_hints(i3Window *win, xcb_get_property_reply_t *prop, bool *ur
  *
  */
 void window_update_motif_hints(i3Window *win, xcb_get_property_reply_t *prop, border_style_t *motif_border_style);
-
-/**
- * Returns the window title considering the current title format.
- * If no format is set, this will simply return the window's name.
- *
- */
-i3String *window_parse_title_format(i3Window *win);