expandToken - simple mustache replacement

gistfile1.js

function expandToken(input, scope) {
  if (input && input.indexOf && input.indexOf('{{') >= 0) {
    var re = /(?:\{?[^{]+)|(?:\{\{([^}]+)\}\})/g,
        match,
        ret = [];
    function deref(token, scope) {
      var segments = token.split('.'),
          len = segments.length;
      for (var i = 0; scope && i < len; i++) {
        if (segments[i] !== 'this') {
          scope = scope[segments[i]];
        }
      }
      return scope;
    }
    while (match = re.exec(input)) {
      if (match[1]) {
        var params = match[1].split(/\s+/);
        if (params.length > 1) {
          var helper = params.shift();
          params = params.map(function(param) { return deref(param, scope); });
          if (Handlebars.helpers[helper]) {
            ret.push(Handlebars.helpers[helper].apply(scope, params));
          } else {
            // If the helper is not defined do nothing
            ret.push(match[0]);
          }
        } else {
          ret.push(deref(params[0], scope));
        }
      } else {
        ret.push(match[0]);
      }
    }
    input = ret.join('');
  }
  return input;
}