root/branches/1.0/lib/i18n/sfMessageSource.class.php

<?php

/**
 * sfMessageSource class file.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the BSD License.
 *
 * Copyright(c) 2004 by Qiang Xue. All rights reserved.
 *
 * To contact the author write to {@link mailto:qiang.xue@gmail.com Qiang Xue}
 * The latest version of PRADO can be obtained from:
 * {@link http://prado.sourceforge.net/}
 *
 * @author     Wei Zhuo <weizhuo[at]gmail[dot]com>
 * @version    $Id$
 * @package    symfony
 * @subpackage i18n
 */

/**
 * Abstract sfMessageSource class.
 *
 * The base class for all sfMessageSources. Message sources must be instantiated
 * using the factory method. The default valid sources are
 *
 *  # XLIFF -- using XML XLIFF format to store the translation messages.
 *  # SQLite -- Store the translation messages in a SQLite database.
 *  # MySQL -- Using a MySQL database to store the messages.
 *  # gettext -- Translated messages are stored in the gettext format.
 *
 * A custom message source can be instantiated by specifying the filename
 * parameter to point to the custom class file. E.g.
 * <code>
 *   $resource = '...'; //custom message source resource
 *   $classfile = '../sfMessageSource_MySource.php'; //custom message source
 *   $source = sfMessageSource::factory('MySource', $resource, $classfile);
 * </code>
 *
 * If you are writting your own message sources, pay attention to the
 * loadCatalogue method. It details how the resources are loaded and cached.
 * See also the existing message source types as examples.
 *
 * The following example instantiates a MySQL message source, set the culture,
 * set the cache handler, and use the source in a message formatter.
 * The messages are store in a database named "messages". The source parameter
 * for the actory method is a PEAR DB style DSN.
 * <code>
 *   $dsn = 'mysql://username:password@localhost/messages';
 *   $source = sfMessageSource::factory('MySQL', $dsn);
 *
 *   //set the culture and cache, store the cache in the /tmp directory.
 *   $source->setCulture('en_AU')l
 *   $source->setCache(new sfMessageCache('/tmp'));
 *
 *   $formatter = new sfMessageFormat($source);
 * </code>
 *
 * @author Xiang Wei Zhuo <weizhuo[at]gmail[dot]com>
 * @version v1.0, last update on Fri Dec 24 19:55:49 EST 2004
 * @package    symfony
 * @subpackage i18n
 */
abstract class sfMessageSource implements sfIMessageSource
{
  /**
   * The culture name for this message source.
   * @var string
   */
  protected $culture;

  /**
   * Array of translation messages.
   * @var array
   */
  protected $messages = array();

  /**
   * The source of message translations.
   * @var string
   */
  protected $source;

  /**
   * The translation cache.
   * @var sfMessageCache
   */
  protected $cache;

  protected $untranslated = array();

  /**
   * Private constructor. sfMessageSource must be initialized using
   * the factory method.
   */
  private function __construct()
  {
    //throw new sfException('Please use the factory method to instantiate.');
  }

  /**
   * Factory method to instantiate a new sfMessageSource depending on the
   * source type. The built-in source types are 'XLIFF', 'SQLite',
   * 'MySQL', 'gettext' and Creole. The source parameter is dependent on the
   * source type. For 'gettext' and 'XLIFF', it should point to the directory
   * where the messages are stored. For database types, e.g. 'SQLite' and
   * 'MySQL', it should be a PEAR DB style DSN string.
   *
   * Custom message source are possible by supplying the a filename parameter
   * in the factory method.
   *
   * @param string the message source type.
   * @param string the location of the resource.
   * @param string the filename of the custom message source.
   * @return sfMessageSource a new message source of the specified type.
   * @throws sfException
   */
  static function factory($type, $source = '.', $filename = '')
  {
    if ($filename)
    {
      if (!is_file($filename))
      {
        throw new sfException(sprintf("File %s not found.", $filename));
      }

      include_once($filename);
    }

    $class = 'sfMessageSource_'.$type;
    if (!class_exists($class))
    {
      throw new sfException(sprintf('Unable to find type "%s".', $type));
    }

    return new $class($source);
  }

  /**
   * Loads a particular message catalogue. Use read() to
   * to get the array of messages. The catalogue loading sequence
   * is as follows:
   *
   *  # [1] Call getCatalogueList($catalogue) to get a list of variants for for the specified $catalogue.
   *  # [2] For each of the variants, call getSource($variant) to get the resource, could be a file or catalogue ID.
   *  # [3] Verify that this resource is valid by calling isValidSource($source)
   *  # [4] Try to get the messages from the cache
   *  # [5] If a cache miss, call load($source) to load the message array
   *  # [6] Store the messages to cache.
   *  # [7] Continue with the foreach loop, e.g. goto [2].
   *
   * @param  string  a catalogue to load
   * @return boolean always true
   * @see    read()
   */
  function load($catalogue = 'messages')
  {
    $variants = $this->getCatalogueList($catalogue);

    $this->messages = array();

    foreach ($variants as $variant)
    {
      $source = $this->getSource($variant);

      if ($this->isValidSource($source) == false)
      {
        continue;
      }

      $loadData = true;

      if ($this->cache)
      {
        $data = $this->cache->get($variant, $this->culture, $this->getLastModified($source));

        if (is_array($data))
        {
          $this->messages[$variant] = $data;
          $loadData = false;
        }

        unset($data);
      }

      if ($loadData)
      {
        $data = &$this->loadData($source);
        if (is_array($data))
        {
          $this->messages[$variant] = $data;
          if ($this->cache)
          {
            $this->cache->save($data, $variant, $this->culture);
          }
        }

        unset($data);
      }
    }

    return true;
  }

  /**
   * Gets the array of messages.
   *
   * @param parameter
   * @return array translation messages.
   */
  public function read()
  {
    return $this->messages;
  }

  /**
   * Gets the cache handler for this source.
   *
   * @return sfMessageCache cache handler
   */
  public function getCache()
  {
    return $this->cache;
  }

  /**
   * Sets the cache handler for caching the messages.
   *
   * @param sfMessageCache the cache handler.
   */
  public function setCache(sfMessageCache $cache)
  {
    $this->cache = $cache;
  }

  /**
   * Adds a untranslated message to the source. Need to call save()
   * to save the messages to source.
   *
   * @param string message to add
   */
  public function append($message)
  {
    if (!in_array($message, $this->untranslated))
    {
      $this->untranslated[] = $message;
    }
  }

  /**
   * Sets the culture for this message source.
   *
   * @param string culture name
   */
  public function setCulture($culture)
  {
    $this->culture = $culture;
  }

  /**
   * Gets the culture identifier for the source.
   *
   * @return string culture identifier.
   */
  public function getCulture()
  {
    return $this->culture;
  }

  /**
   * Gets the last modified unix-time for this particular catalogue+variant.
   *
   * @param string catalogue+variant
   * @return int last modified in unix-time format.
   */
  protected function getLastModified($source)
  {
    return 0;
  }

  /**
   * Loads the message for a particular catalogue+variant.
   * This methods needs to implemented by subclasses.
   *
   * @param string catalogue+variant.
   * @return array of translation messages.
   */
  protected function &loadData($variant)
  {
    return array();
  }

  /**
   * Gets the source, this could be a filename or database ID.
   *
   * @param string catalogue+variant
   * @return string the resource key
   */
  protected function getSource($variant)
  {
    return $variant;
  }

  /**
   * Determines if the source is valid.
   *
   * @param string catalogue+variant
   * @return boolean true if valid, false otherwise.
   */
  protected function isValidSource($source)
  {
    return false;
  }

  /**
   * Gets all the variants of a particular catalogue.
   * This method must be implemented by subclasses.
   *
   * @param string catalogue name
   * @return array list of all variants for this catalogue.
   */
  protected function getCatalogueList($catalogue)
  {
    return array();
  }
}