code: function(value, anyMatch, caseSensitive, exactMatch) {
          if (!value.exec) { // not a regex
              var er = Ext.String.escapeRegex;
              value = String(value);
  
              if (anyMatch === true) {
                  value = er(value);
              } else {
                  value = '^' + er(value);
                  if (exactMatch === true) {
                      value += '$';
                  }
              }
              value = new RegExp(value, caseSensitive ? '' : 'i');
          }
          return value;
      }
docs: Returns a regular expression based on the given value and matching options. This is used internally for finding and filtering,
  and by Ext.data.Store#filter
  @private
  @param {String} value The value to create the regex for. This is escaped using Ext.escapeRe
  @param {Boolean} anyMatch True to allow any match - no regex start/end line anchors will be added. Defaults to false
  @param {Boolean} caseSensitive True to make the regex case sensitive (adds 'i' switch to regex). Defaults to false.
  @param {Boolean} exactMatch True to force exact match (^ and $ characters added to the regex). Defaults to false. Ignored if anyMatch is true.
  @since Ext 3