<?php

/*

 * This file is part of SwiftMailer.

 * (c) 2004-2009 Chris Corbyn

 *

 * For the full copyright and license information, please view the LICENSE

 * file that was distributed with this source code.

 */

/**

 * Defines the grammar to use for validation, implements the RFC 2822 (and friends) ABNF grammar definitions.

 * @package Swift

 * @subpackage Mime

 * @author Fabien Potencier

 * @author Chris Corbyn

 */

class Swift_Mime_Grammar

{

  /**

   * Special characters used in the syntax which need to be escaped.

   * @var string[]

   * @access private

   */

  private $_specials = array();

  /**

   * Tokens defined in RFC 2822 (and some related RFCs).

   * @var string[]

   * @access private

   */

  private $_grammar = array();

  /**

   * Initialize some RFC 2822 (and friends) ABNF grammar definitions.

   * @access protected

   */

  public function __construct()

  {

    $this->_specials = array(

      '(', ')', '<', '>', '[', ']',

      ':', ';', '@', ',', '.', '"'

      );

    /*** Refer to RFC 2822 for ABNF grammar ***/

    //All basic building blocks

    $this->_grammar['NO-WS-CTL'] = '[\x01-\x08\x0B\x0C\x0E-\x19\x7F]';

    $this->_grammar['WSP'] = '[ \t]';

    $this->_grammar['CRLF'] = '(?:\r\n)';

    $this->_grammar['FWS'] = '(?:(?:' . $this->_grammar['WSP'] . '*' .

        $this->_grammar['CRLF'] . ')?' . $this->_grammar['WSP'] . ')';

    $this->_grammar['text'] = '[\x00-\x08\x0B\x0C\x0E-\x7F]';

    $this->_grammar['quoted-pair'] = '(?:\\\\' . $this->_grammar['text'] . ')';

    $this->_grammar['ctext'] = '(?:' . $this->_grammar['NO-WS-CTL'] .

        '|[\x21-\x27\x2A-\x5B\x5D-\x7E])';

    //Uses recursive PCRE (?1) -- could be a weak point??

    $this->_grammar['ccontent'] = '(?:' . $this->_grammar['ctext'] . '|' .

        $this->_grammar['quoted-pair'] . '|(?1))';

    $this->_grammar['comment'] = '(\((?:' . $this->_grammar['FWS'] . '|' .

        $this->_grammar['ccontent']. ')*' . $this->_grammar['FWS'] . '?\))';

    $this->_grammar['CFWS'] = '(?:(?:' . $this->_grammar['FWS'] . '?' .

        $this->_grammar['comment'] . ')*(?:(?:' . $this->_grammar['FWS'] . '?' .

        $this->_grammar['comment'] . ')|' . $this->_grammar['FWS'] . '))';

    $this->_grammar['qtext'] = '(?:' . $this->_grammar['NO-WS-CTL'] .

        '|[\x21\x23-\x5B\x5D-\x7E])';

    $this->_grammar['qcontent'] = '(?:' . $this->_grammar['qtext'] . '|' .

        $this->_grammar['quoted-pair'] . ')';

    $this->_grammar['quoted-string'] = '(?:' . $this->_grammar['CFWS'] . '?"' .

        '(' . $this->_grammar['FWS'] . '?' . $this->_grammar['qcontent'] . ')*' .

        $this->_grammar['FWS'] . '?"' . $this->_grammar['CFWS'] . '?)';

    $this->_grammar['atext'] = '[a-zA-Z0-9!#\$%&\'\*\+\-\/=\?\^_`\{\}\|~]';

    $this->_grammar['atom'] = '(?:' . $this->_grammar['CFWS'] . '?' .

        $this->_grammar['atext'] . '+' . $this->_grammar['CFWS'] . '?)';

    $this->_grammar['dot-atom-text'] = '(?:' . $this->_grammar['atext'] . '+' .

        '(\.' . $this->_grammar['atext'] . '+)*)';

    $this->_grammar['dot-atom'] = '(?:' . $this->_grammar['CFWS'] . '?' .

        $this->_grammar['dot-atom-text'] . '+' . $this->_grammar['CFWS'] . '?)';

    $this->_grammar['word'] = '(?:' . $this->_grammar['atom'] . '|' .

        $this->_grammar['quoted-string'] . ')';

    $this->_grammar['phrase'] = '(?:' . $this->_grammar['word'] . '+?)';

    $this->_grammar['no-fold-quote'] = '(?:"(?:' . $this->_grammar['qtext'] .

        '|' . $this->_grammar['quoted-pair'] . ')*")';

    $this->_grammar['dtext'] = '(?:' . $this->_grammar['NO-WS-CTL'] .

        '|[\x21-\x5A\x5E-\x7E])';

    $this->_grammar['no-fold-literal'] = '(?:\[(?:' . $this->_grammar['dtext'] .

        '|' . $this->_grammar['quoted-pair'] . ')*\])';

    //Message IDs

    $this->_grammar['id-left'] = '(?:' . $this->_grammar['dot-atom-text'] . '|' .

        $this->_grammar['no-fold-quote'] . ')';

    $this->_grammar['id-right'] = '(?:' . $this->_grammar['dot-atom-text'] . '|' .

        $this->_grammar['no-fold-literal'] . ')';

    //Addresses, mailboxes and paths

    $this->_grammar['local-part'] = '(?:' . $this->_grammar['dot-atom'] . '|' .

        $this->_grammar['quoted-string'] . ')';

    $this->_grammar['dcontent'] = '(?:' . $this->_grammar['dtext'] . '|' .

        $this->_grammar['quoted-pair'] . ')';

    $this->_grammar['domain-literal'] = '(?:' . $this->_grammar['CFWS'] . '?\[(' .

        $this->_grammar['FWS'] . '?' . $this->_grammar['dcontent'] . ')*?' .

        $this->_grammar['FWS'] . '?\]' . $this->_grammar['CFWS'] . '?)';

    $this->_grammar['domain'] = '(?:' . $this->_grammar['dot-atom'] . '|' .

        $this->_grammar['domain-literal'] . ')';

    $this->_grammar['addr-spec'] = '(?:' . $this->_grammar['local-part'] . '@' .

        $this->_grammar['domain'] . ')';

  }

  /**

   * Get the grammar defined for $name token.

   * @param string $name execatly as written in the RFC

   * @return string

   */

  public function getDefinition($name)

  {

    if (array_key_exists($name, $this->_grammar))

    {

      return $this->_grammar[$name];

    }

    else

    {

      throw new Swift_RfcComplianceException(

        "No such grammar '" . $name . "' defined."

        );

    }

  }

  /**

   * Returns the tokens defined in RFC 2822 (and some related RFCs).

   * @return array

   */

  public function getGrammarDefinitions()

  {

    return $this->_grammar;

  }

  /**

   * Returns the current special characters used in the syntax which need to be escaped.

   * @return array

   */

  public function getSpecials()

  {

    return $this->_specials;

  }

  /**

   * Escape special characters in a string (convert to quoted-pairs).

   * @param string $token

   * @param string[] $include additonal chars to escape

   * @param string[] $exclude chars from escaping

   * @return string

   */

  public function escapeSpecials($token, $include = array(),

    $exclude = array())

  {

    foreach (

      array_merge(array('\\'), array_diff($this->_specials, $exclude), $include) as $char)

    {

      $token = str_replace($char, '\\' . $char, $token);

    }

    return $token;

  }

}