From.php

<?php

/*
 * This file is part of Twig.
 *
 * (c) 2010 Fabien Potencier
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

/**
 * Imports macros.
 *
 * <pre>
 *   {% from 'forms.html' import forms %}
 * </pre>
 */
class Twig_TokenParser_From extends Twig_TokenParser {

  /**
   * Parses a token and returns a node.
   *
   * @param Twig_Token $token A Twig_Token instance
   *
   * @return Twig_NodeInterface A Twig_NodeInterface instance
   */
  public function parse(Twig_Token $token) {
    $macro = $this->parser
      ->getExpressionParser()
      ->parseExpression();
    $stream = $this->parser
      ->getStream();
    $stream
      ->expect('import');
    $targets = array();
    do {
      $name = $stream
        ->expect(Twig_Token::NAME_TYPE)
        ->getValue();
      $alias = $name;
      if ($stream
        ->test('as')) {
        $stream
          ->next();
        $alias = $stream
          ->expect(Twig_Token::NAME_TYPE)
          ->getValue();
      }
      $targets[$name] = $alias;
      if (!$stream
        ->test(Twig_Token::PUNCTUATION_TYPE, ',')) {
        break;
      }
      $stream
        ->next();
    } while (true);
    $stream
      ->expect(Twig_Token::BLOCK_END_TYPE);
    $node = new Twig_Node_Import($macro, new Twig_Node_Expression_AssignName($this->parser
      ->getVarName(), $token
      ->getLine()), $token
      ->getLine(), $this
      ->getTag());
    foreach ($targets as $name => $alias) {
      $this->parser
        ->addImportedFunction($alias, 'get' . $name, $node
        ->getNode('var'));
    }
    return $node;
  }

  /**
   * Gets the tag name associated with this token parser.
   *
   * @return string The tag name
   */
  public function getTag() {
    return 'from';
  }

}