NullCoalesceExpression.php

<?php


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

use Twig\Compiler;
use Twig\Node\EmptyNode;
use Twig\Node\Expression\Binary\AndBinary;
use Twig\Node\Expression\Test\DefinedTest;
use Twig\Node\Expression\Test\NullTest;
use Twig\Node\Expression\Unary\NotUnary;
use Twig\Node\Node;
use Twig\TwigTest;
class NullCoalesceExpression extends ConditionalExpression {
    
    /**
     * @param AbstractExpression $left
     * @param AbstractExpression $right
     */
    public function __construct(Node $left, Node $right, int $lineno) {
        if (!$left instanceof AbstractExpression) {
            trigger_deprecation('twig/twig', '3.15', 'Not passing a "%s" instance to the "left" argument of "%s" is deprecated ("%s" given).', AbstractExpression::class, static::class, get_class($left));
        }
        if (!$right instanceof AbstractExpression) {
            trigger_deprecation('twig/twig', '3.15', 'Not passing a "%s" instance to the "right" argument of "%s" is deprecated ("%s" given).', AbstractExpression::class, static::class, get_class($right));
        }
        $test = new DefinedTest(clone $left, new TwigTest('defined'), new EmptyNode(), $left->getTemplateLine());
        // for "block()", we don't need the null test as the return value is always a string
        if (!$left instanceof BlockReferenceExpression) {
            $test = new AndBinary($test, new NotUnary(new NullTest($left, new TwigTest('null'), new EmptyNode(), $left->getTemplateLine()), $left->getTemplateLine()), $left->getTemplateLine());
        }
        parent::__construct($test, $left, $right, $lineno);
    }
    public function compile(Compiler $compiler) : void {
        
        /*
         * This optimizes only one case. PHP 7 also supports more complex expressions
         * that can return null. So, for instance, if log is defined, log("foo") ?? "..." works,
         * but log($a["foo"]) ?? "..." does not if $a["foo"] is not defined. More advanced
         * cases might be implemented as an optimizer node visitor, but has not been done
         * as benefits are probably not worth the added complexity.
         */
        if ($this->getNode('expr2') instanceof NameExpression) {
            $this->getNode('expr2')
                ->setAttribute('always_defined', true);
            $compiler->raw('((')
                ->subcompile($this->getNode('expr2'))
                ->raw(') ?? (')
                ->subcompile($this->getNode('expr3'))
                ->raw('))');
        }
        else {
            parent::compile($compiler);
        }
    }

}