Flow\Parser::parseExtends PHP Method

    protected function parseExtends($token)
    {
        if (!is_null($this->extends)) {
            throw new SyntaxError('multiple extends tags', $token);
        }
        if (!empty($this->currentBlock)) {
            throw new SyntaxError('cannot declare extends inside blocks', $token);
        }
        if ($this->inMacro) {
            throw new SyntaxError('cannot declare extends inside macros', $token);
        }
        $parent = $this->parseExpression();
        $params = null;
        if ($this->stream->consume(Token::NAME, 'with')) {
            $this->stream->expect(Token::OPERATOR, '[');
            $params = $this->parseArrayExpression();
            $this->stream->expect(Token::OPERATOR, ']');
        }
        $this->extends = $this->parseIfModifier($token, new Node\ExtendsNode($parent, $params, $token->getLine()));
        $this->stream->expect(Token::BLOCK_END);
        return null;
    }