TwigNodeTrans.php

<?php

namespace Drupal\Core\Template;

use Twig\Compiler;
use Twig\Error\SyntaxError;
use Twig\Node\CheckToStringNode;
use Twig\Node\Expression\AbstractExpression;
use Twig\Node\Expression\ConstantExpression;
use Twig\Node\Expression\FilterExpression;
use Twig\Node\Expression\FunctionExpression;
use Twig\Node\Expression\GetAttrExpression;
use Twig\Node\Expression\NameExpression;
use Twig\Node\Expression\TempNameExpression;
use Twig\Node\Node;
use Twig\Node\PrintNode;

/**
 * A class that defines the Twig 'trans' tag for Drupal.
 *
 * This Twig extension was originally based on Twig i18n extension. It has been
 * severely modified to work properly with the complexities of the Drupal
 * translation system.
 *
 * @see https://twig-extensions.readthedocs.io/en/latest/i18n.html
 * @see https://github.com/fabpot/Twig-extensions
 */
class TwigNodeTrans extends Node {
    
    /**
     * {@inheritdoc}
     */
    public function __construct(Node $body, Node $plural = NULL, AbstractExpression $count = NULL, AbstractExpression $options = NULL, $lineno, $tag = NULL) {
        $nodes['body'] = $body;
        if ($count !== NULL) {
            $nodes['count'] = $count;
        }
        if ($plural !== NULL) {
            $nodes['plural'] = $plural;
        }
        if ($options !== NULL) {
            $nodes['options'] = $options;
        }
        parent::__construct($nodes, [], $lineno, $tag);
    }
    
    /**
     * {@inheritdoc}
     */
    public function compile(Compiler $compiler) {
        $compiler->addDebugInfo($this);
        [
            $singular,
            $tokens,
        ] = $this->compileString($this->getNode('body'));
        $plural = NULL;
        if ($this->hasNode('plural')) {
            [
                $plural,
                $pluralTokens,
            ] = $this->compileString($this->getNode('plural'));
            $tokens = array_merge($tokens, $pluralTokens);
        }
        // Start writing with the function to be called.
        $compiler->write('echo ' . (empty($plural) ? 't' : '\\Drupal::translation()->formatPlural') . '(');
        // Move the count to the beginning of the parameters list.
        if (!empty($plural)) {
            $compiler->raw('abs(')
                ->subcompile($this->getNode('count'))
                ->raw('), ');
        }
        // Write the singular text parameter.
        $compiler->subcompile($singular);
        // Write the plural text parameter, if necessary.
        if (!empty($plural)) {
            $compiler->raw(', ')
                ->subcompile($plural);
        }
        // Write any tokens found as an associative array parameter, otherwise just
        // leave as an empty array.
        $compiler->raw(', array(');
        foreach ($tokens as $token) {
            $compiler->string($token->getAttribute('placeholder'))
                ->raw(' => ')
                ->subcompile($token)
                ->raw(', ');
        }
        $compiler->raw(')');
        // Write any options passed.
        if ($this->hasNode('options')) {
            $compiler->raw(', ')
                ->subcompile($this->getNode('options'));
        }
        // Write function closure.
        $compiler->raw(')');
        // @todo Add debug output, see https://www.drupal.org/node/2512672
        // End writing.
        $compiler->raw(";\n");
    }
    
    /**
     * Extracts the text and tokens for the "trans" tag.
     *
     * @param \Twig\Node\Node $body
     *   The node to compile.
     *
     * @return array
     *   Returns an array containing the two following parameters:
     *   - string $text
     *       The extracted text.
     *   - array $tokens
     *       The extracted tokens as new \Twig\Node\Expression\TempNameExpression
     *       instances.
     */
    protected function compileString(Node $body) {
        if ($body instanceof NameExpression || $body instanceof ConstantExpression || $body instanceof TempNameExpression) {
            return [
                $body,
                [],
            ];
        }
        $tokens = [];
        if (count($body)) {
            $text = '';
            foreach ($body as $node) {
                if ($node instanceof PrintNode) {
                    $n = $node->getNode('expr');
                    while ($n instanceof FilterExpression) {
                        $n = $n->getNode('node');
                    }
                    if ($n instanceof CheckToStringNode) {
                        $n = $n->getNode('expr');
                    }
                    $args = $n;
                    // Support TwigExtension->renderVar() function in chain.
                    if ($args instanceof FunctionExpression) {
                        $args = $n->getNode('arguments')
                            ->getNode(0);
                    }
                    // Detect if a token implements one of the filters reserved for
                    // modifying the prefix of a token. The default prefix used for
                    // translations is "@". This escapes the printed token and makes them
                    // safe for templates.
                    // @see TwigExtension::getFilters()
                    $argPrefix = '@';
                    while ($args instanceof FilterExpression) {
                        switch ($args->getNode('filter')
                            ->getAttribute('value')) {
                            case 'placeholder':
                                $argPrefix = '%';
                                break;
                        }
                        $args = $args->getNode('node');
                    }
                    if ($args instanceof CheckToStringNode) {
                        $args = $args->getNode('expr');
                    }
                    if ($args instanceof GetAttrExpression) {
                        $argName = [];
                        // Reuse the incoming expression.
                        $expr = $args;
                        // Assemble a valid argument name by walking through the expression.
                        $argName[] = $args->getNode('attribute')
                            ->getAttribute('value');
                        while ($args->hasNode('node')) {
                            $args = $args->getNode('node');
                            if ($args instanceof NameExpression) {
                                $argName[] = $args->getAttribute('name');
                            }
                            else {
                                $argName[] = $args->getNode('attribute')
                                    ->getAttribute('value');
                            }
                        }
                        $argName = array_reverse($argName);
                        $argName = implode('.', $argName);
                    }
                    else {
                        $argName = $n->getAttribute('name');
                        if (!is_null($args)) {
                            $argName = $args->getAttribute('name');
                        }
                        $expr = new NameExpression($argName, $n->getTemplateLine());
                    }
                    $placeholder = sprintf('%s%s', $argPrefix, $argName);
                    $text .= $placeholder;
                    $expr->setAttribute('placeholder', $placeholder);
                    $tokens[] = $expr;
                }
                else {
                    $text .= $node->getAttribute('data');
                }
            }
        }
        elseif (!$body->hasAttribute('data')) {
            throw new SyntaxError('{% trans %} tag cannot be empty');
        }
        else {
            $text = $body->getAttribute('data');
        }
        return [
            new Node([
                new ConstantExpression(trim($text), $body->getTemplateLine()),
            ]),
            $tokens,
        ];
    }

}