1<?php
2
3/*
4 * This file is part of Twig.
5 *
6 * (c) Fabien Potencier
7 *
8 * For the full copyright and license information, please view the LICENSE
9 * file that was distributed with this source code.
10 */
11
12namespace Twig\Node\Expression;
13
14use Twig\Compiler;
15use Twig\Node\Expression\Binary\AndBinary;
16use Twig\Node\Expression\Test\DefinedTest;
17use Twig\Node\Expression\Test\NullTest;
18use Twig\Node\Expression\Unary\NotUnary;
19use Twig\Node\Node;
20
21class NullCoalesceExpression extends ConditionalExpression
22{
23    public function __construct(\Twig_NodeInterface $left, \Twig_NodeInterface $right, $lineno)
24    {
25        $test = new AndBinary(
26            new DefinedTest(clone $left, 'defined', new Node(), $left->getTemplateLine()),
27            new NotUnary(new NullTest($left, 'null', new Node(), $left->getTemplateLine()), $left->getTemplateLine()),
28            $left->getTemplateLine()
29        );
30
31        parent::__construct($test, $left, $right, $lineno);
32    }
33
34    public function compile(Compiler $compiler)
35    {
36        /*
37         * This optimizes only one case. PHP 7 also supports more complex expressions
38         * that can return null. So, for instance, if log is defined, log("foo") ?? "..." works,
39         * but log($a["foo"]) ?? "..." does not if $a["foo"] is not defined. More advanced
40         * cases might be implemented as an optimizer node visitor, but has not been done
41         * as benefits are probably not worth the added complexity.
42         */
43        if (\PHP_VERSION_ID >= 70000 && $this->getNode('expr2') instanceof NameExpression) {
44            $this->getNode('expr2')->setAttribute('always_defined', true);
45            $compiler
46                ->raw('((')
47                ->subcompile($this->getNode('expr2'))
48                ->raw(') ?? (')
49                ->subcompile($this->getNode('expr3'))
50                ->raw('))')
51            ;
52        } else {
53            parent::compile($compiler);
54        }
55    }
56}
57
58class_alias('Twig\Node\Expression\NullCoalesceExpression', 'Twig_Node_Expression_NullCoalesce');
59