Function switchRouteMatcher

tools/ngui/static/js/lib/angular.js:7368–7400

* @param on {string} current url * @param when {string} route when template to match the url against * @return {?Object}

(on, when)

     * @return {?Object}
     */
    function switchRouteMatcher(on, when) {
      // TODO(i): this code is convoluted and inefficient, we should construct the route matching
      //   regex only once and then reuse it

      // Escape regexp special characters.
      when = '^' + when.replace(/[-\/\\^$*+?.()|[\]{}]/g, "\\$&") + '$';
      var regex = '',
          params = [],
          dst = {};

      var re = /:(\w+)/g,
          paramMatch,
          lastMatchedIndex = 0;

      while ((paramMatch = re.exec(when)) !== null) {
        // Find each :param in `when` and replace it with a capturing group.
        // Append all other sections of when unchanged.
        regex += when.slice(lastMatchedIndex, paramMatch.index);
        regex += '([^\\/]*)';
        params.push(paramMatch[1]);
        lastMatchedIndex = re.lastIndex;
      }
      // Append trailing path part.
      regex += when.substr(lastMatchedIndex);

      var match = on.match(new RegExp(regex));
      if (match) {
        forEach(params, function(name, index) {
          dst[name] = match[index + 1];
        });
      }
      return match ? dst : null;
    }

    function updateRoute() {
      var next = parseRoute(),