match(regex, content) {
    if (!(regex instanceof RegExp)) {
      throw new Error(`regex ${regex} is not instance of \`RegExp\``);
    }
    // fix cached regex
    regex = new RegExp(regex);
    var match = regex.exec(content) || [];
    match = match.slice(1, match.length);
    var versions = [];
    match.forEach((version) => {
      if (version) {
        version = this.parse(version);
        versions.push(version);
      }
    });
    return versions;
  }
compare version by regex
@param  {Regex}    regex     Regular expression to compare with content;
@param  {String}   content   String with version to parse;
@return {Array}              collection of versions;