i3bar: implement custom workspace numbers config

Implement the configuration option within the bar config directive for
custom workspace numbers with the directive `strip_workspace_numbers
yes`.

This directive strips the workspace name of the number prefix and
delimiter. When the workspace name consists only of the number, it will
default to show the number.

For example:

* "2:5" -> "5"
* "4:$" -> "$"
* "8" -> "8"

This allows customization of i3bar for alternate ordering of workspaces
which has a legitimate use for alternate keyboard layouts such as
Dvorak.

fixes #1131

i3bar/include/config.h

@@ -27,6 +27,7 @@ typedef struct config_t {
     struct xcb_color_strings_t colors;
     bool         disable_binding_mode_indicator;
     bool         disable_ws;
+    bool         strip_ws_numbers;
     char         *bar_id;
     char         *command;
     char         *fontname;

i3bar/include/workspaces.h

@@ -31,7 +31,8 @@ void free_workspaces(void);
 
 struct i3_ws {
     int                num;         /* The internal number of the ws */
-    i3String           *name;       /* The name of the ws */
+    char          *canonical_name;  /* The true name of the ws according to the ipc */
+    i3String           *name;       /* The name of the ws that is displayed on the bar */
     int                name_width;  /* The rendered width of the name */
     bool               visible;     /* If the ws is currently visible on an output */
     bool               focused;     /* If the ws is currently focused */

i3bar/src/config.c

@@ -193,6 +193,12 @@ static int config_boolean_cb(void *params_, int val) {
         return 1;
     }
 
+    if (!strcmp(cur_key, "strip_workspace_numbers")) {
+        DLOG("strip_workspace_numbers = %d\n", val);
+        config.strip_ws_numbers = val;
+        return 1;
+    }
+
     if (!strcmp(cur_key, "verbose")) {
         DLOG("verbose = %d\n", val);
         config.verbose = val;

i3bar/src/workspaces.c

@@ -105,14 +105,38 @@ static int workspaces_string_cb(void *params_, const unsigned char *val, size_t
         char *output_name;
 
         if (!strcmp(params->cur_key, "name")) {
-            /* Save the name */
-            params->workspaces_walk->name = i3string_from_utf8_with_length((const char *)val, len);
+            const char *ws_name = (const char*)val;
+            params->workspaces_walk->canonical_name = strndup(ws_name, len);
+
+            if (config.strip_ws_numbers && params->workspaces_walk->num >= 0) {
+                /* Special case: strip off the workspace number */
+                static char ws_num[10];
+
+                snprintf(ws_num, sizeof(ws_num), "%d", params->workspaces_walk->num);
+
+                /* Calculate the length of the number str in the name */
+                int offset = strspn(ws_name, ws_num);
+
+                /* Also strip off the conventional ws name delimiter */
+                if (offset && ws_name[offset] == ':')
+                    offset += 1;
+
+                /* Offset may be equal to length, in which case display the number */
+                params->workspaces_walk->name = (offset < len
+                        ? i3string_from_utf8_with_length(ws_name + offset, len - offset)
+                        : i3string_from_utf8(ws_num));
+
+            } else {
+                /* Default case: just save the name */
+                params->workspaces_walk->name = i3string_from_utf8_with_length(ws_name, len);
+            }
 
             /* Save its rendered width */
             params->workspaces_walk->name_width =
                 predict_text_width(params->workspaces_walk->name);
 
-            DLOG("Got Workspace %s, name_width: %d, glyphs: %zu\n",
+            DLOG("Got Workspace canonical: %s, name: '%s', name_width: %d, glyphs: %zu\n",
+                 params->workspaces_walk->canonical_name,
                  i3string_as_utf8(params->workspaces_walk->name),
                  params->workspaces_walk->name_width,
                  i3string_get_num_glyphs(params->workspaces_walk->name));
@@ -246,6 +270,7 @@ void free_workspaces(void) {
         if (outputs_walk->workspaces != NULL && !TAILQ_EMPTY(outputs_walk->workspaces)) {
             TAILQ_FOREACH(ws_walk, outputs_walk->workspaces, tailq) {
                 I3STRING_FREE(ws_walk->name);
+                FREE(ws_walk->canonical_name);
             }
             FREE_TAILQ(outputs_walk->workspaces, i3_ws);
         }

i3bar/src/xcb.c

@@ -418,7 +418,7 @@ void handle_button(xcb_button_press_event_t *event) {
      * buffer, then we copy character by character. */
     int num_quotes = 0;
     size_t namelen = 0;
-    const char *utf8_name = i3string_as_utf8(cur_ws->name);
+    const char *utf8_name = cur_ws->canonical_name;
     for (const char *walk = utf8_name; *walk != '\0'; walk++) {
         if (*walk == '"')
             num_quotes++;