TwigTransTokenParser.php

<?php

namespace Drupal\Core\Template;

use Twig\Error\SyntaxError;
use Twig\Node\Expression\FilterExpression;
use Twig\Node\Expression\GetAttrExpression;
use Twig\Node\Expression\NameExpression;
use Twig\Node\Node;
use Twig\Node\PrintNode;
use Twig\Node\TextNode;
use Twig\Token;
use Twig\TokenParser\AbstractTokenParser;

/**
 * A class that defines the Twig 'trans' token parser for Drupal.
 *
 * The token parser converts a token stream created from template source
 * code into an Abstract Syntax Tree (AST).  The AST will later be compiled
 * into PHP code usable for runtime execution of the template.
 *
 * @see https://twig-extensions.readthedocs.io/en/latest/i18n.html
 * @see https://github.com/fabpot/Twig-extensions
 */
class TwigTransTokenParser extends AbstractTokenParser {
    
    /**
     * {@inheritdoc}
     */
    public function parse(Token $token) {
        $lineno = $token->getLine();
        $stream = $this->parser
            ->getStream();
        $body = NULL;
        $options = NULL;
        $count = NULL;
        $plural = NULL;
        if (!$stream->test(Token::BLOCK_END_TYPE) && $stream->test(Token::STRING_TYPE)) {
            $body = $this->parser
                ->getExpressionParser()
                ->parseExpression();
        }
        if (!$stream->test(Token::BLOCK_END_TYPE) && $stream->test(Token::NAME_TYPE, 'with')) {
            $stream->next();
            $options = $this->parser
                ->getExpressionParser()
                ->parseExpression();
        }
        if (!$body) {
            $stream->expect(Token::BLOCK_END_TYPE);
            $body = $this->parser
                ->subparse([
                $this,
                'decideForFork',
            ]);
            if ('plural' === $stream->next()
                ->getValue()) {
                $count = $this->parser
                    ->getExpressionParser()
                    ->parseExpression();
                $stream->expect(Token::BLOCK_END_TYPE);
                $plural = $this->parser
                    ->subparse([
                    $this,
                    'decideForEnd',
                ], TRUE);
            }
        }
        $stream->expect(Token::BLOCK_END_TYPE);
        $this->checkTransString($body, $lineno);
        $node = new TwigNodeTrans($body, $plural, $count, $options, $lineno, $this->getTag());
        return $node;
    }
    
    /**
     * Detect a 'plural' switch or the end of a 'trans' tag.
     */
    public function decideForFork($token) {
        return $token->test([
            'plural',
            'endtrans',
        ]);
    }
    
    /**
     * Detect the end of a 'trans' tag.
     */
    public function decideForEnd($token) {
        return $token->test('endtrans');
    }
    
    /**
     * {@inheritdoc}
     */
    public function getTag() {
        return 'trans';
    }
    
    /**
     * Ensure that any nodes that are parsed are only of allowed types.
     *
     * @param \Twig\Node\Node $body
     *   The expression to check.
     * @param int $lineno
     *   The source line.
     *
     * @throws \Twig\Error\SyntaxError
     */
    protected function checkTransString(Node $body, $lineno) {
        foreach ($body as $node) {
            if ($node instanceof TextNode || $node instanceof PrintNode && $node->getNode('expr') instanceof NameExpression || $node instanceof PrintNode && $node->getNode('expr') instanceof GetAttrExpression || $node instanceof PrintNode && $node->getNode('expr') instanceof FilterExpression) {
                continue;
            }
            throw new SyntaxError(sprintf('The text to be translated with "trans" can only contain references to simple variables'), $lineno);
        }
    }

}