correctly sort numbered workspaces (+testcase)

Numbered workspaces (workspaces with a name containing only digits) will be
inserted in the correct order now. Named workspaces are always sorted after
numbered workspaces and in the order of creation.

src/con.c

@@ -72,6 +72,35 @@ void con_attach(Con *con, Con *parent) {
     con->parent = parent;
     Con *loop;
     Con *current = NULL;
+    struct nodes_head *nodes_head = &(parent->nodes_head);
+
+    /* Workspaces are handled differently: they need to be inserted at the
+     * right position. */
+    if (con->type == CT_WORKSPACE) {
+        DLOG("it's a workspace. num = %d\n", con->num);
+        if (con->num == -1 || TAILQ_EMPTY(nodes_head)) {
+            TAILQ_INSERT_TAIL(nodes_head, con, nodes);
+        } else {
+            current = TAILQ_FIRST(nodes_head);
+            if (con->num < current->num) {
+                /* we need to insert the container at the beginning */
+                TAILQ_INSERT_HEAD(nodes_head, con, nodes);
+                return;
+            }
+            while (current->num != -1 && con->num > current->num) {
+                current = TAILQ_NEXT(current, nodes);
+                if (current == TAILQ_END(nodes_head)) {
+                    current = NULL;
+                    break;
+                }
+            }
+            /* we need to insert con after current, if current is not NULL */
+            if (current)
+                TAILQ_INSERT_BEFORE(current, con, nodes);
+            else TAILQ_INSERT_TAIL(nodes_head, con, nodes);
+        }
+        goto add_to_focus_head;
+    }
 
     /* Get the first tiling container in focus stack */
     TAILQ_FOREACH(loop, &(parent->focus_head), focused) {
@@ -85,9 +114,10 @@ void con_attach(Con *con, Con *parent) {
     if (current) {
         DLOG("Inserting con = %p after last focused tiling con %p\n",
              con, current);
-        TAILQ_INSERT_AFTER(&(parent->nodes_head), current, con, nodes);
-    } else TAILQ_INSERT_TAIL(&(parent->nodes_head), con, nodes);
+        TAILQ_INSERT_AFTER(nodes_head, current, con, nodes);
+    } else TAILQ_INSERT_TAIL(nodes_head, con, nodes);
 
+add_to_focus_head:
     /* We insert to the TAIL because con_focus() will correct this.
      * This way, we have the option to insert Cons without having
      * to focus them. */

src/ipc.c

@@ -269,7 +269,9 @@ IPC_HANDLER(get_workspaces) {
             y(map_open);
 
             ystr("num");
-            y(integer, con_num_children(ws));
+            if (ws->num == -1)
+                y(null);
+            else y(integer, ws->num);
 
             ystr("name");
             ystr(ws->name);

src/tree.c

@@ -77,10 +77,12 @@ void tree_init() {
         free(name);
 
         /* add a workspace to this output */
-        ws = con_new(oc);
+        ws = con_new(NULL);
         ws->type = CT_WORKSPACE;
+        ws->num = c;
         asprintf(&(ws->name), "%d", c);
         c++;
+        con_attach(ws, oc);
 
         asprintf(&name, "[i3 con] workspace %s", ws->name);
         x_set_name(ws, name);

src/workspace.c

@@ -38,14 +38,28 @@ Con *workspace_get(const char *num) {
         LOG("need to create this one\n");
         output = con_get_output(focused);
         LOG("got output %p\n", output);
-        workspace = con_new(output);
+        /* We need to attach this container after setting its type. con_attach
+         * will handle CT_WORKSPACEs differently */
+        workspace = con_new(NULL);
         char *name;
         asprintf(&name, "[i3 con] workspace %s", num);
         x_set_name(workspace, name);
         free(name);
         workspace->type = CT_WORKSPACE;
         workspace->name = strdup(num);
+        /* We set ->num to the number if this workspace’s name consists only of
+         * a positive number. Otherwise it’s a named ws and num will be -1. */
+        char *end;
+        long parsed_num = strtol(num, &end, 10);
+        if (parsed_num == LONG_MIN ||
+            parsed_num == LONG_MAX ||
+            parsed_num < 0 ||
+            (end && *end != '\0'))
+            workspace->num = -1;
+        else workspace->num = parsed_num;
+        LOG("num = %d\n", workspace->num);
         workspace->orientation = HORIZ;
+        con_attach(workspace, output);
 
         ipc_send_event("workspace", I3_IPC_EVENT_WORKSPACE, "{\"change\":\"init\"}");
     }