class Twig_Environment

AsseticExtensionTest::setUp in drupal/core/vendor/kriswallsmith/assetic/tests/Assetic/Test/Extension/Twig/AsseticExtensionTest.php

TwigFormulaLoaderTest::setUp in drupal/core/vendor/kriswallsmith/assetic/tests/Assetic/Test/Extension/Twig/TwigFormulaLoaderTest.php

TwigResourceTest::setUp in drupal/core/vendor/kriswallsmith/assetic/tests/Assetic/Test/Extension/Twig/TwigResourceTest.php

class Twig_Environment {
  const VERSION = '1.8.3';
  protected $charset;
  protected $loader;
  protected $debug;
  protected $autoReload;
  protected $cache;
  protected $lexer;
  protected $parser;
  protected $compiler;
  protected $baseTemplateClass;
  protected $extensions;
  protected $parsers;
  protected $visitors;
  protected $filters;
  protected $tests;
  protected $functions;
  protected $globals;
  protected $runtimeInitialized;
  protected $loadedTemplates;
  protected $strictVariables;
  protected $unaryOperators;
  protected $binaryOperators;
  protected $templateClassPrefix = '__TwigTemplate_';
  protected $functionCallbacks;
  protected $filterCallbacks;
  protected $staging;

  /**
   * Constructor.
   *
   * Available options:
   *
   *  * debug: When set to true, it automatically set "auto_reload" to true as
   *           well (default to false).
   *
   *  * charset: The charset used by the templates (default to utf-8).
   *
   *  * base_template_class: The base template class to use for generated
   *                         templates (default to Twig_Template).
   *
   *  * cache: An absolute path where to store the compiled templates, or
   *           false to disable compilation cache (default).
   *
   *  * auto_reload: Whether to reload the template is the original source changed.
   *                 If you don't provide the auto_reload option, it will be
   *                 determined automatically base on the debug value.
   *
   *  * strict_variables: Whether to ignore invalid variables in templates
   *                      (default to false).
   *
   *  * autoescape: Whether to enable auto-escaping (default to html):
   *                  * false: disable auto-escaping
   *                  * true: equivalent to html
   *                  * html, js: set the autoescaping to one of the supported strategies
   *                  * PHP callback: a PHP callback that returns an escaping strategy based on the template "filename"
   *
   *  * optimizations: A flag that indicates which optimizations to apply
   *                   (default to -1 which means that all optimizations are enabled;
   *                   set it to 0 to disable).
   *
   * @param Twig_LoaderInterface $loader  A Twig_LoaderInterface instance
   * @param array                $options An array of options
   */
  public function __construct(Twig_LoaderInterface $loader = null, $options = array()) {
    if (null !== $loader) {
      $this
        ->setLoader($loader);
    }
    $options = array_merge(array(
      'debug' => false,
      'charset' => 'UTF-8',
      'base_template_class' => 'Twig_Template',
      'strict_variables' => false,
      'autoescape' => 'html',
      'cache' => false,
      'auto_reload' => null,
      'optimizations' => -1,
    ), $options);
    $this->debug = (bool) $options['debug'];
    $this->charset = $options['charset'];
    $this->baseTemplateClass = $options['base_template_class'];
    $this->autoReload = null === $options['auto_reload'] ? $this->debug : (bool) $options['auto_reload'];
    $this->extensions = array(
      'core' => new Twig_Extension_Core(),
      'escaper' => new Twig_Extension_Escaper($options['autoescape']),
      'optimizer' => new Twig_Extension_Optimizer($options['optimizations']),
    );
    $this->strictVariables = (bool) $options['strict_variables'];
    $this->runtimeInitialized = false;
    $this
      ->setCache($options['cache']);
    $this->functionCallbacks = array();
    $this->filterCallbacks = array();
    $this->staging = array(
      'functions' => array(),
      'filters' => array(),
      'tests' => array(),
      'token_parsers' => array(),
      'visitors' => array(),
      'globals' => array(),
    );
  }

  /**
   * Gets the base template class for compiled templates.
   *
   * @return string The base template class name
   */
  public function getBaseTemplateClass() {
    return $this->baseTemplateClass;
  }

  /**
   * Sets the base template class for compiled templates.
   *
   * @param string $class The base template class name
   */
  public function setBaseTemplateClass($class) {
    $this->baseTemplateClass = $class;
  }

  /**
   * Enables debugging mode.
   */
  public function enableDebug() {
    $this->debug = true;
  }

  /**
   * Disables debugging mode.
   */
  public function disableDebug() {
    $this->debug = false;
  }

  /**
   * Checks if debug mode is enabled.
   *
   * @return Boolean true if debug mode is enabled, false otherwise
   */
  public function isDebug() {
    return $this->debug;
  }

  /**
   * Enables the auto_reload option.
   */
  public function enableAutoReload() {
    $this->autoReload = true;
  }

  /**
   * Disables the auto_reload option.
   */
  public function disableAutoReload() {
    $this->autoReload = false;
  }

  /**
   * Checks if the auto_reload option is enabled.
   *
   * @return Boolean true if auto_reload is enabled, false otherwise
   */
  public function isAutoReload() {
    return $this->autoReload;
  }

  /**
   * Enables the strict_variables option.
   */
  public function enableStrictVariables() {
    $this->strictVariables = true;
  }

  /**
   * Disables the strict_variables option.
   */
  public function disableStrictVariables() {
    $this->strictVariables = false;
  }

  /**
   * Checks if the strict_variables option is enabled.
   *
   * @return Boolean true if strict_variables is enabled, false otherwise
   */
  public function isStrictVariables() {
    return $this->strictVariables;
  }

  /**
   * Gets the cache directory or false if cache is disabled.
   *
   * @return string|false
   */
  public function getCache() {
    return $this->cache;
  }

  /**
   * Sets the cache directory or false if cache is disabled.
   *
   * @param string|false $cache The absolute path to the compiled templates,
   *                            or false to disable cache
   */
  public function setCache($cache) {
    $this->cache = $cache ? $cache : false;
  }

  /**
   * Gets the cache filename for a given template.
   *
   * @param string $name The template name
   *
   * @return string The cache file name
   */
  public function getCacheFilename($name) {
    if (false === $this->cache) {
      return false;
    }
    $class = substr($this
      ->getTemplateClass($name), strlen($this->templateClassPrefix));
    return $this
      ->getCache() . '/' . substr($class, 0, 2) . '/' . substr($class, 2, 2) . '/' . substr($class, 4) . '.php';
  }

  /**
   * Gets the template class associated with the given string.
   *
   * @param string  $name  The name for which to calculate the template class name
   * @param integer $index The index if it is an embedded template
   *
   * @return string The template class name
   */
  public function getTemplateClass($name, $index = null) {
    return $this->templateClassPrefix . md5($this->loader
      ->getCacheKey($name)) . (null === $index ? '' : '_' . $index);
  }

  /**
   * Gets the template class prefix.
   *
   * @return string The template class prefix
   */
  public function getTemplateClassPrefix() {
    return $this->templateClassPrefix;
  }

  /**
   * Renders a template.
   *
   * @param string $name    The template name
   * @param array  $context An array of parameters to pass to the template
   *
   * @return string The rendered template
   */
  public function render($name, array $context = array()) {
    return $this
      ->loadTemplate($name)
      ->render($context);
  }

  /**
   * Displays a template.
   *
   * @param string $name    The template name
   * @param array  $context An array of parameters to pass to the template
   */
  public function display($name, array $context = array()) {
    $this
      ->loadTemplate($name)
      ->display($context);
  }

  /**
   * Loads a template by name.
   *
   * @param string  $name  The template name
   * @param integer $index The index if it is an embedded template
   *
   * @return Twig_TemplateInterface A template instance representing the given template name
   */
  public function loadTemplate($name, $index = null) {
    $cls = $this
      ->getTemplateClass($name, $index);
    if (isset($this->loadedTemplates[$cls])) {
      return $this->loadedTemplates[$cls];
    }
    if (!class_exists($cls, false)) {
      if (false === ($cache = $this
        ->getCacheFilename($name))) {
        eval('?>' . $this
          ->compileSource($this->loader
          ->getSource($name), $name));
      }
      else {
        if (!is_file($cache) || $this
          ->isAutoReload() && !$this
          ->isTemplateFresh($name, filemtime($cache))) {
          $this
            ->writeCacheFile($cache, $this
            ->compileSource($this->loader
            ->getSource($name), $name));
        }
        require_once $cache;
      }
    }
    if (!$this->runtimeInitialized) {
      $this
        ->initRuntime();
    }
    return $this->loadedTemplates[$cls] = new $cls($this);
  }

  /**
   * Returns true if the template is still fresh.
   *
   * Besides checking the loader for freshness information,
   * this method also checks if the enabled extensions have
   * not changed.
   *
   * @param string    $name The template name
   * @param timestamp $time The last modification time of the cached template
   *
   * @return Boolean true if the template is fresh, false otherwise
   */
  public function isTemplateFresh($name, $time) {
    foreach ($this->extensions as $extension) {
      $r = new ReflectionObject($extension);
      if (filemtime($r
        ->getFileName()) > $time) {
        return false;
      }
    }
    return $this->loader
      ->isFresh($name, $time);
  }
  public function resolveTemplate($names) {
    if (!is_array($names)) {
      $names = array(
        $names,
      );
    }
    foreach ($names as $name) {
      if ($name instanceof Twig_Template) {
        return $name;
      }
      try {
        return $this
          ->loadTemplate($name);
      } catch (Twig_Error_Loader $e) {
      }
    }
    if (1 === count($names)) {
      throw $e;
    }
    throw new Twig_Error_Loader(sprintf('Unable to find one of the following templates: "%s".', implode('", "', $names)));
  }

  /**
   * Clears the internal template cache.
   */
  public function clearTemplateCache() {
    $this->loadedTemplates = array();
  }

  /**
   * Clears the template cache files on the filesystem.
   */
  public function clearCacheFiles() {
    if (false === $this->cache) {
      return;
    }
    foreach (new RecursiveIteratorIterator(new RecursiveDirectoryIterator($this->cache), RecursiveIteratorIterator::LEAVES_ONLY) as $file) {
      if ($file
        ->isFile()) {
        @unlink($file
          ->getPathname());
      }
    }
  }

  /**
   * Gets the Lexer instance.
   *
   * @return Twig_LexerInterface A Twig_LexerInterface instance
   */
  public function getLexer() {
    if (null === $this->lexer) {
      $this->lexer = new Twig_Lexer($this);
    }
    return $this->lexer;
  }

  /**
   * Sets the Lexer instance.
   *
   * @param Twig_LexerInterface A Twig_LexerInterface instance
   */
  public function setLexer(Twig_LexerInterface $lexer) {
    $this->lexer = $lexer;
  }

  /**
   * Tokenizes a source code.
   *
   * @param string $source The template source code
   * @param string $name   The template name
   *
   * @return Twig_TokenStream A Twig_TokenStream instance
   */
  public function tokenize($source, $name = null) {
    return $this
      ->getLexer()
      ->tokenize($source, $name);
  }

  /**
   * Gets the Parser instance.
   *
   * @return Twig_ParserInterface A Twig_ParserInterface instance
   */
  public function getParser() {
    if (null === $this->parser) {
      $this->parser = new Twig_Parser($this);
    }
    return $this->parser;
  }

  /**
   * Sets the Parser instance.
   *
   * @param Twig_ParserInterface A Twig_ParserInterface instance
   */
  public function setParser(Twig_ParserInterface $parser) {
    $this->parser = $parser;
  }

  /**
   * Parses a token stream.
   *
   * @param Twig_TokenStream $tokens A Twig_TokenStream instance
   *
   * @return Twig_Node_Module A Node tree
   */
  public function parse(Twig_TokenStream $tokens) {
    return $this
      ->getParser()
      ->parse($tokens);
  }

  /**
   * Gets the Compiler instance.
   *
   * @return Twig_CompilerInterface A Twig_CompilerInterface instance
   */
  public function getCompiler() {
    if (null === $this->compiler) {
      $this->compiler = new Twig_Compiler($this);
    }
    return $this->compiler;
  }

  /**
   * Sets the Compiler instance.
   *
   * @param Twig_CompilerInterface $compiler A Twig_CompilerInterface instance
   */
  public function setCompiler(Twig_CompilerInterface $compiler) {
    $this->compiler = $compiler;
  }

  /**
   * Compiles a Node.
   *
   * @param Twig_NodeInterface $node A Twig_NodeInterface instance
   *
   * @return string The compiled PHP source code
   */
  public function compile(Twig_NodeInterface $node) {
    return $this
      ->getCompiler()
      ->compile($node)
      ->getSource();
  }

  /**
   * Compiles a template source code.
   *
   * @param string $source The template source code
   * @param string $name   The template name
   *
   * @return string The compiled PHP source code
   */
  public function compileSource($source, $name = null) {
    try {
      return $this
        ->compile($this
        ->parse($this
        ->tokenize($source, $name)));
    } catch (Twig_Error $e) {
      $e
        ->setTemplateFile($name);
      throw $e;
    } catch (Exception $e) {
      throw new Twig_Error_Runtime(sprintf('An exception has been thrown during the compilation of a template ("%s").', $e
        ->getMessage()), -1, $name, $e);
    }
  }

  /**
   * Sets the Loader instance.
   *
   * @param Twig_LoaderInterface $loader A Twig_LoaderInterface instance
   */
  public function setLoader(Twig_LoaderInterface $loader) {
    $this->loader = $loader;
  }

  /**
   * Gets the Loader instance.
   *
   * @return Twig_LoaderInterface A Twig_LoaderInterface instance
   */
  public function getLoader() {
    return $this->loader;
  }

  /**
   * Sets the default template charset.
   *
   * @param string $charset The default charset
   */
  public function setCharset($charset) {
    $this->charset = $charset;
  }

  /**
   * Gets the default template charset.
   *
   * @return string The default charset
   */
  public function getCharset() {
    return $this->charset;
  }

  /**
   * Initializes the runtime environment.
   */
  public function initRuntime() {
    $this->runtimeInitialized = true;
    foreach ($this
      ->getExtensions() as $extension) {
      $extension
        ->initRuntime($this);
    }
  }

  /**
   * Returns true if the given extension is registered.
   *
   * @param string $name The extension name
   *
   * @return Boolean Whether the extension is registered or not
   */
  public function hasExtension($name) {
    return isset($this->extensions[$name]);
  }

  /**
   * Gets an extension by name.
   *
   * @param string $name The extension name
   *
   * @return Twig_ExtensionInterface A Twig_ExtensionInterface instance
   */
  public function getExtension($name) {
    if (!isset($this->extensions[$name])) {
      throw new Twig_Error_Runtime(sprintf('The "%s" extension is not enabled.', $name));
    }
    return $this->extensions[$name];
  }

  /**
   * Registers an extension.
   *
   * @param Twig_ExtensionInterface $extension A Twig_ExtensionInterface instance
   */
  public function addExtension(Twig_ExtensionInterface $extension) {
    $this->extensions[$extension
      ->getName()] = $extension;
    $this->parsers = null;
    $this->visitors = null;
    $this->filters = null;
    $this->tests = null;
    $this->functions = null;
    $this->globals = null;
  }

  /**
   * Removes an extension by name.
   *
   * @param string $name The extension name
   */
  public function removeExtension($name) {
    unset($this->extensions[$name]);
    $this->parsers = null;
    $this->visitors = null;
    $this->filters = null;
    $this->tests = null;
    $this->functions = null;
    $this->globals = null;
  }

  /**
   * Registers an array of extensions.
   *
   * @param array $extensions An array of extensions
   */
  public function setExtensions(array $extensions) {
    foreach ($extensions as $extension) {
      $this
        ->addExtension($extension);
    }
  }

  /**
   * Returns all registered extensions.
   *
   * @return array An array of extensions
   */
  public function getExtensions() {
    return $this->extensions;
  }

  /**
   * Registers a Token Parser.
   *
   * @param Twig_TokenParserInterface $parser A Twig_TokenParserInterface instance
   */
  public function addTokenParser(Twig_TokenParserInterface $parser) {
    $this->staging['token_parsers'][] = $parser;
    $this->parsers = null;
  }

  /**
   * Gets the registered Token Parsers.
   *
   * @return Twig_TokenParserBrokerInterface A broker containing token parsers
   */
  public function getTokenParsers() {
    if (null === $this->parsers) {
      $this->parsers = new Twig_TokenParserBroker();
      if (isset($this->staging['token_parsers'])) {
        foreach ($this->staging['token_parsers'] as $parser) {
          $this->parsers
            ->addTokenParser($parser);
        }
      }
      foreach ($this
        ->getExtensions() as $extension) {
        $parsers = $extension
          ->getTokenParsers();
        foreach ($parsers as $parser) {
          if ($parser instanceof Twig_TokenParserInterface) {
            $this->parsers
              ->addTokenParser($parser);
          }
          elseif ($parser instanceof Twig_TokenParserBrokerInterface) {
            $this->parsers
              ->addTokenParserBroker($parser);
          }
          else {
            throw new Twig_Error_Runtime('getTokenParsers() must return an array of Twig_TokenParserInterface or Twig_TokenParserBrokerInterface instances');
          }
        }
      }
    }
    return $this->parsers;
  }

  /**
   * Gets registered tags.
   *
   * Be warned that this method cannot return tags defined by Twig_TokenParserBrokerInterface classes.
   *
   * @return Twig_TokenParserInterface[] An array of Twig_TokenParserInterface instances
   */
  public function getTags() {
    $tags = array();
    foreach ($this
      ->getTokenParsers()
      ->getParsers() as $parser) {
      if ($parser instanceof Twig_TokenParserInterface) {
        $tags[$parser
          ->getTag()] = $parser;
      }
    }
    return $tags;
  }

  /**
   * Registers a Node Visitor.
   *
   * @param Twig_NodeVisitorInterface $visitor A Twig_NodeVisitorInterface instance
   */
  public function addNodeVisitor(Twig_NodeVisitorInterface $visitor) {
    $this->staging['visitors'][] = $visitor;
    $this->visitors = null;
  }

  /**
   * Gets the registered Node Visitors.
   *
   * @return Twig_NodeVisitorInterface[] An array of Twig_NodeVisitorInterface instances
   */
  public function getNodeVisitors() {
    if (null === $this->visitors) {
      foreach ($this
        ->getExtensions() as $extension) {
        foreach ($extension
          ->getNodeVisitors() as $visitor) {
          $this
            ->addNodeVisitor($visitor);
        }
      }
      $this->visitors = $this->staging['visitors'];
    }
    return $this->visitors;
  }

  /**
   * Registers a Filter.
   *
   * @param string               $name   The filter name
   * @param Twig_FilterInterface $filter A Twig_FilterInterface instance
   */
  public function addFilter($name, Twig_FilterInterface $filter) {
    $this->staging['filters'][$name] = $filter;
    $this->filters = null;
  }

  /**
   * Get a filter by name.
   *
   * Subclasses may override this method and load filters differently;
   * so no list of filters is available.
   *
   * @param string $name The filter name
   *
   * @return Twig_Filter|false A Twig_Filter instance or false if the filter does not exists
   */
  public function getFilter($name) {
    if (null === $this->filters) {
      $this
        ->getFilters();
    }
    if (isset($this->filters[$name])) {
      return $this->filters[$name];
    }
    foreach ($this->filters as $pattern => $filter) {
      $pattern = str_replace('\\*', '(.*?)', preg_quote($pattern, '#'), $count);
      if ($count) {
        if (preg_match('#^' . $pattern . '$#', $name, $matches)) {
          array_shift($matches);
          $filter
            ->setArguments($matches);
          return $filter;
        }
      }
    }
    foreach ($this->filterCallbacks as $callback) {
      if (false !== ($filter = call_user_func($callback, $name))) {
        return $filter;
      }
    }
    return false;
  }
  public function registerUndefinedFilterCallback($callable) {
    $this->filterCallbacks[] = $callable;
  }

  /**
   * Gets the registered Filters.
   *
   * Be warned that this method cannot return filters defined with registerUndefinedFunctionCallback.
   *
   * @return Twig_FilterInterface[] An array of Twig_FilterInterface instances
   *
   * @see registerUndefinedFilterCallback
   */
  public function getFilters() {
    if (null === $this->filters) {
      foreach ($this
        ->getExtensions() as $extension) {
        foreach ($extension
          ->getFilters() as $name => $filter) {
          $this
            ->addFilter($name, $filter);
        }
      }
      $this->filters = $this->staging['filters'];
    }
    return $this->filters;
  }

  /**
   * Registers a Test.
   *
   * @param string             $name The test name
   * @param Twig_TestInterface $test A Twig_TestInterface instance
   */
  public function addTest($name, Twig_TestInterface $test) {
    $this->staging['tests'][$name] = $test;
    $this->tests = null;
  }

  /**
   * Gets the registered Tests.
   *
   * @return Twig_TestInterface[] An array of Twig_TestInterface instances
   */
  public function getTests() {
    if (null === $this->tests) {
      foreach ($this
        ->getExtensions() as $extension) {
        foreach ($extension
          ->getTests() as $name => $test) {
          $this
            ->addTest($name, $test);
        }
      }
      $this->tests = $this->staging['tests'];
    }
    return $this->tests;
  }

  /**
   * Registers a Function.
   *
   * @param string                 $name     The function name
   * @param Twig_FunctionInterface $function A Twig_FunctionInterface instance
   */
  public function addFunction($name, Twig_FunctionInterface $function) {
    $this->staging['functions'][$name] = $function;
    $this->functions = null;
  }

  /**
   * Get a function by name.
   *
   * Subclasses may override this method and load functions differently;
   * so no list of functions is available.
   *
   * @param string $name function name
   *
   * @return Twig_Function|false A Twig_Function instance or false if the function does not exists
   */
  public function getFunction($name) {
    if (null === $this->functions) {
      $this
        ->getFunctions();
    }
    if (isset($this->functions[$name])) {
      return $this->functions[$name];
    }
    foreach ($this->functions as $pattern => $function) {
      $pattern = str_replace('\\*', '(.*?)', preg_quote($pattern, '#'), $count);
      if ($count) {
        if (preg_match('#^' . $pattern . '$#', $name, $matches)) {
          array_shift($matches);
          $function
            ->setArguments($matches);
          return $function;
        }
      }
    }
    foreach ($this->functionCallbacks as $callback) {
      if (false !== ($function = call_user_func($callback, $name))) {
        return $function;
      }
    }
    return false;
  }
  public function registerUndefinedFunctionCallback($callable) {
    $this->functionCallbacks[] = $callable;
  }

  /**
   * Gets registered functions.
   *
   * Be warned that this method cannot return functions defined with registerUndefinedFunctionCallback.
   *
   * @return Twig_FunctionInterface[] An array of Twig_FunctionInterface instances
   *
   * @see registerUndefinedFunctionCallback
   */
  public function getFunctions() {
    if (null === $this->functions) {
      foreach ($this
        ->getExtensions() as $extension) {
        foreach ($extension
          ->getFunctions() as $name => $function) {
          $this
            ->addFunction($name, $function);
        }
      }
      $this->functions = $this->staging['functions'];
    }
    return $this->functions;
  }

  /**
   * Registers a Global.
   *
   * @param string $name  The global name
   * @param mixed  $value The global value
   */
  public function addGlobal($name, $value) {
    $this->staging['globals'][$name] = $value;
    $this->globals = null;
  }

  /**
   * Gets the registered Globals.
   *
   * @return array An array of globals
   */
  public function getGlobals() {
    if (null === $this->globals) {
      $this->globals = isset($this->staging['globals']) ? $this->staging['globals'] : array();
      foreach ($this
        ->getExtensions() as $extension) {
        $this->globals = array_merge($this->globals, $extension
          ->getGlobals());
      }
    }
    return $this->globals;
  }

  /**
   * Merges a context with the defined globals.
   *
   * @param array $context An array representing the context
   *
   * @return array The context merged with the globals
   */
  public function mergeGlobals(array $context) {

    // we don't use array_merge as the context being generally
    // bigger than globals, this code is faster.
    foreach ($this
      ->getGlobals() as $key => $value) {
      if (!array_key_exists($key, $context)) {
        $context[$key] = $value;
      }
    }
    return $context;
  }

  /**
   * Gets the registered unary Operators.
   *
   * @return array An array of unary operators
   */
  public function getUnaryOperators() {
    if (null === $this->unaryOperators) {
      $this
        ->initOperators();
    }
    return $this->unaryOperators;
  }

  /**
   * Gets the registered binary Operators.
   *
   * @return array An array of binary operators
   */
  public function getBinaryOperators() {
    if (null === $this->binaryOperators) {
      $this
        ->initOperators();
    }
    return $this->binaryOperators;
  }
  public function computeAlternatives($name, $items) {
    $alternatives = array();
    foreach ($items as $item) {
      $lev = levenshtein($name, $item);
      if ($lev <= strlen($name) / 3 || false !== strpos($item, $name)) {
        $alternatives[$item] = $lev;
      }
    }
    asort($alternatives);
    return array_keys($alternatives);
  }
  protected function initOperators() {
    $this->unaryOperators = array();
    $this->binaryOperators = array();
    foreach ($this
      ->getExtensions() as $extension) {
      $operators = $extension
        ->getOperators();
      if (!$operators) {
        continue;
      }
      if (2 !== count($operators)) {
        throw new InvalidArgumentException(sprintf('"%s::getOperators()" does not return a valid operators array.', get_class($extension)));
      }
      $this->unaryOperators = array_merge($this->unaryOperators, $operators[0]);
      $this->binaryOperators = array_merge($this->binaryOperators, $operators[1]);
    }
  }
  protected function writeCacheFile($file, $content) {
    $dir = dirname($file);
    if (!is_dir($dir)) {
      if (false === @mkdir($dir, 0777, true) && !is_dir($dir)) {
        throw new RuntimeException(sprintf("Unable to create the cache directory (%s).", $dir));
      }
    }
    elseif (!is_writable($dir)) {
      throw new RuntimeException(sprintf("Unable to write in the cache directory (%s).", $dir));
    }
    $tmpFile = tempnam(dirname($file), basename($file));
    if (false !== @file_put_contents($tmpFile, $content)) {

      // rename does not work on Win32 before 5.2.6
      if (@rename($tmpFile, $file) || @copy($tmpFile, $file) && unlink($tmpFile)) {
        @chmod($file, 0666 & ~umask());
        return;
      }
    }
    throw new Twig_Error_Runtime(sprintf('Failed to write cache file "%s".', $file));
  }

}