public function parse(\Twig_Token $token)
{
if (!$this->parser->isMainScope()) {
throw new \Twig_Error_Syntax('Cannot extend from a block.', $token->getLine(), $this->parser->getFilename());
}
if (null !== $this->parser->getParent()) {
throw new \Twig_Error_Syntax('Multiple extends tags are forbidden.', $token->getLine(), $this->parser->getFilename());
}
$this->parser->setParent($this->parser->getExpressionParser()->parseExpression());
$this->parser->getStream()->expect(\Twig_Token::BLOCK_END_TYPE);
if (Helper::hasBuffer($this->parser->getFilename())) {
$parentName = $this->parser->getParent()->getAttribute('value');
$name = $this->parser->getFilename();
// If the parent has no buffer values, transfer them from the child template
if (is_null(Helper::getBuffer($parentName))) {
Helper::setBuffer($parentName, Helper::getBuffer($name));
}
}
}
