Feature: Workspace assignment by number

Workspace assignments with bare numbers assign all workspaces with that
number to the specified output.

Workspace assignment by number is overridden by workspace assignment by
name.

src/util.c

@@ -21,6 +21,7 @@
 #include <pwd.h>
 #include <yajl/yajl_version.h>
 #include <libgen.h>
+#include <ctype.h>
 
 #define SN_API_NOT_YET_FROZEN 1
 #include <libsn/sn-launcher.h>
@@ -47,6 +48,38 @@ Rect rect_add(Rect a, Rect b) {
                   a.height + b.height};
 }
 
+/*
+ * Returns true if the name consists of only digits.
+ *
+ */
+__attribute__ ((pure)) bool name_is_digits(const char *name) {
+    /* positive integers and zero are interpreted as numbers */
+    for (int i = 0; i < strlen(name); i++)
+        if (!isdigit(name[i]))
+            return false;
+
+    return true;
+}
+
+/*
+ * Parses the workspace name as a number. Returns -1 if the workspace should be
+ * interpreted as a "named workspace".
+ *
+ */
+long ws_name_to_number(const char *name) {
+    /* positive integers and zero are interpreted as numbers */
+    char *endptr = NULL;
+    long parsed_num = strtol(name, &endptr, 10);
+    if (parsed_num == LONG_MIN ||
+            parsed_num == LONG_MAX ||
+            parsed_num < 0 ||
+            endptr == name) {
+        parsed_num = -1;
+    }
+
+    return parsed_num;
+}
+
 /*
  * Updates *destination with new_value and returns true if it was changed or false
  * if it was the same