Default.php

<?php

/*
 * This file is part of Twig.
 *
 * (c) 2011 Fabien Potencier
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

/**
 * Returns the value or the default value when it is undefined or empty.
 *
 * <pre>
 *  {{ var.foo|default('foo item on var is not defined') }}
 * </pre>
 *
 * @package twig
 * @author  Fabien Potencier <fabien@symfony.com>
 */
class Twig_Node_Expression_Filter_Default extends Twig_Node_Expression_Filter {
  public function __construct(Twig_NodeInterface $node, Twig_Node_Expression_Constant $filterName, Twig_NodeInterface $arguments, $lineno, $tag = null) {
    $default = new Twig_Node_Expression_Filter($node, new Twig_Node_Expression_Constant('_default', $node
      ->getLine()), $arguments, $node
      ->getLine());
    if ('default' === $filterName
      ->getAttribute('value') && ($node instanceof Twig_Node_Expression_Name || $node instanceof Twig_Node_Expression_GetAttr)) {
      $test = new Twig_Node_Expression_Test_Defined(clone $node, 'defined', new Twig_Node(), $node
        ->getLine());
      $false = count($arguments) ? $arguments
        ->getNode(0) : new Twig_Node_Expression_Constant('', $node
        ->getLine());
      $node = new Twig_Node_Expression_Conditional($test, $default, $false, $node
        ->getLine());
    }
    else {
      $node = $default;
    }
    parent::__construct($node, $filterName, $arguments, $lineno, $tag);
  }
  public function compile(Twig_Compiler $compiler) {
    $compiler
      ->subcompile($this
      ->getNode('node'));
  }

}