class RouteCompiler implements RouteCompilerInterface {
  const REGEX_DELIMITER = '#';

  /**
   * This string defines the characters that are automatically considered separators in front of
   * optional placeholders (with default and no static text following). Such a single separator
   * can be left out together with the optional placeholder from matching and generating URLs.
   */
  const SEPARATORS = '/,;.:-_~+*=@|';

  /**
   * {@inheritdoc}
   *
   * @throws \LogicException  If a variable is referenced more than once
   * @throws \DomainException If a variable name is numeric because PHP raises an error for such
   *                          subpatterns in PCRE and thus would break matching, e.g. "(?P<123>.+)".
   */
  public static function compile(Route $route) {
    $hostVariables = array();
    $variables = array();
    $hostRegex = null;
    $hostTokens = array();
    if ('' !== ($host = $route
      ->getHost())) {
      $result = self::compilePattern($route, $host, true);
      $hostVariables = $result['variables'];
      $variables = $hostVariables;
      $hostTokens = $result['tokens'];
      $hostRegex = $result['regex'];
    }
    $path = $route
      ->getPath();
    $result = self::compilePattern($route, $path, false);
    $staticPrefix = $result['staticPrefix'];
    $pathVariables = $result['variables'];
    $variables = array_merge($variables, $pathVariables);
    $tokens = $result['tokens'];
    $regex = $result['regex'];
    return new CompiledRoute($staticPrefix, $regex, $tokens, $pathVariables, $hostRegex, $hostTokens, $hostVariables, array_unique($variables));
  }
  private static function compilePattern(Route $route, $pattern, $isHost) {
    $tokens = array();
    $variables = array();
    $matches = array();
    $pos = 0;
    $defaultSeparator = $isHost ? '.' : '/';

    // Match all variables enclosed in "{}" and iterate over them. But we only want to match the innermost variable
    // in case of nested "{}", e.g. {foo{bar}}. This in ensured because \w does not match "{" or "}" itself.
    preg_match_all('#\\{\\w+\\}#', $pattern, $matches, PREG_OFFSET_CAPTURE | PREG_SET_ORDER);
    foreach ($matches as $match) {
      $varName = substr($match[0][0], 1, -1);

      // get all static text preceding the current variable
      $precedingText = substr($pattern, $pos, $match[0][1] - $pos);
      $pos = $match[0][1] + strlen($match[0][0]);
      $precedingChar = strlen($precedingText) > 0 ? substr($precedingText, -1) : '';
      $isSeparator = '' !== $precedingChar && false !== strpos(static::SEPARATORS, $precedingChar);
      if (is_numeric($varName)) {
        throw new \DomainException(sprintf('Variable name "%s" cannot be numeric in route pattern "%s". Please use a different name.', $varName, $pattern));
      }
      if (in_array($varName, $variables)) {
        throw new \LogicException(sprintf('Route pattern "%s" cannot reference variable name "%s" more than once.', $pattern, $varName));
      }
      if ($isSeparator && strlen($precedingText) > 1) {
        $tokens[] = array(
          'text',
          substr($precedingText, 0, -1),
        );
      }
      elseif (!$isSeparator && strlen($precedingText) > 0) {
        $tokens[] = array(
          'text',
          $precedingText,
        );
      }
      $regexp = $route
        ->getRequirement($varName);
      if (null === $regexp) {
        $followingPattern = (string) substr($pattern, $pos);

        // Find the next static character after the variable that functions as a separator. By default, this separator and '/'
        // are disallowed for the variable. This default requirement makes sure that optional variables can be matched at all
        // and that the generating-matching-combination of URLs unambiguous, i.e. the params used for generating the URL are
        // the same that will be matched. Example: new Route('/{page}.{_format}', array('_format' => 'html'))
        // If {page} would also match the separating dot, {_format} would never match as {page} will eagerly consume everything.
        // Also even if {_format} was not optional the requirement prevents that {page} matches something that was originally
        // part of {_format} when generating the URL, e.g. _format = 'mobile.html'.
        $nextSeparator = self::findNextSeparator($followingPattern);
        $regexp = sprintf('[^%s%s]+', preg_quote($defaultSeparator, self::REGEX_DELIMITER), $defaultSeparator !== $nextSeparator && '' !== $nextSeparator ? preg_quote($nextSeparator, self::REGEX_DELIMITER) : '');
        if ('' !== $nextSeparator && !preg_match('#^\\{\\w+\\}#', $followingPattern) || '' === $followingPattern) {

          // When we have a separator, which is disallowed for the variable, we can optimize the regex with a possessive
          // quantifier. This prevents useless backtracking of PCRE and improves performance by 20% for matching those patterns.
          // Given the above example, there is no point in backtracking into {page} (that forbids the dot) when a dot must follow
          // after it. This optimization cannot be applied when the next char is no real separator or when the next variable is
          // directly adjacent, e.g. '/{x}{y}'.
          $regexp .= '+';
        }
      }
      $tokens[] = array(
        'variable',
        $isSeparator ? $precedingChar : '',
        $regexp,
        $varName,
      );
      $variables[] = $varName;
    }
    if ($pos < strlen($pattern)) {
      $tokens[] = array(
        'text',
        substr($pattern, $pos),
      );
    }

    // find the first optional token
    $firstOptional = PHP_INT_MAX;
    if (!$isHost) {
      for ($i = count($tokens) - 1; $i >= 0; --$i) {
        $token = $tokens[$i];
        if ('variable' === $token[0] && $route
          ->hasDefault($token[3])) {
          $firstOptional = $i;
        }
        else {
          break;
        }
      }
    }

    // compute the matching regexp
    $regexp = '';
    for ($i = 0, $nbToken = count($tokens); $i < $nbToken; ++$i) {
      $regexp .= self::computeRegexp($tokens, $i, $firstOptional);
    }
    return array(
      'staticPrefix' => 'text' === $tokens[0][0] ? $tokens[0][1] : '',
      'regex' => self::REGEX_DELIMITER . '^' . $regexp . '$' . self::REGEX_DELIMITER . 's' . ($isHost ? 'i' : ''),
      'tokens' => array_reverse($tokens),
      'variables' => $variables,
    );
  }

  /**
   * Returns the next static character in the Route pattern that will serve as a separator.
   *
   * @param string $pattern The route pattern
   *
   * @return string The next static character that functions as separator (or empty string when none available)
   */
  private static function findNextSeparator($pattern) {
    if ('' == $pattern) {

      // return empty string if pattern is empty or false (false which can be returned by substr)
      return '';
    }

    // first remove all placeholders from the pattern so we can find the next real static character
    $pattern = preg_replace('#\\{\\w+\\}#', '', $pattern);
    return isset($pattern[0]) && false !== strpos(static::SEPARATORS, $pattern[0]) ? $pattern[0] : '';
  }

  /**
   * Computes the regexp used to match a specific token. It can be static text or a subpattern.
   *
   * @param array $tokens        The route tokens
   * @param int   $index         The index of the current token
   * @param int   $firstOptional The index of the first optional token
   *
   * @return string The regexp pattern for a single token
   */
  private static function computeRegexp(array $tokens, $index, $firstOptional) {
    $token = $tokens[$index];
    if ('text' === $token[0]) {

      // Text tokens
      return preg_quote($token[1], self::REGEX_DELIMITER);
    }
    else {

      // Variable tokens
      if (0 === $index && 0 === $firstOptional) {

        // When the only token is an optional variable token, the separator is required
        return sprintf('%s(?P<%s>%s)?', preg_quote($token[1], self::REGEX_DELIMITER), $token[3], $token[2]);
      }
      else {
        $regexp = sprintf('%s(?P<%s>%s)', preg_quote($token[1], self::REGEX_DELIMITER), $token[3], $token[2]);
        if ($index >= $firstOptional) {

          // Enclose each optional token in a subpattern to make it optional.
          // "?:" means it is non-capturing, i.e. the portion of the subject string that
          // matched the optional subpattern is not passed back.
          $regexp = "(?:{$regexp}";
          $nbTokens = count($tokens);
          if ($nbTokens - 1 == $index) {

            // Close the optional subpatterns
            $regexp .= str_repeat(')?', $nbTokens - $firstOptional - (0 === $firstOptional ? 1 : 0));
          }
        }
        return $regexp;
      }
    }
  }

}

Members

Name	Modifiers	Type	Description	Overrides
RouteCompiler::compile	public static	function	Overrides RouteCompilerInterface::compile	1
RouteCompiler::compilePattern	private static	function
RouteCompiler::computeRegexp	private static	function	Computes the regexp used to match a specific token. It can be static text or a subpattern.
RouteCompiler::findNextSeparator	private static	function	Returns the next static character in the Route pattern that will serve as a separator.
RouteCompiler::REGEX_DELIMITER		constant		1
RouteCompiler::SEPARATORS		constant	This string defines the characters that are automatically considered separators in front of optional placeholders (with default and no static text following). Such a single separator can be left out together with the optional placeholder from matching…

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class RouteCompiler in Zircon Profile 8

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