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(Node $left, Node $right, int $lineno)
24    {
25        $test = new DefinedTest(clone $left, 'defined', new Node(), $left->getTemplateLine());
26        // for "block()", we don't need the null test as the return value is always a string
27        if (!$left instanceof BlockReferenceExpression) {
28            $test = new AndBinary(
29                $test,
30                new NotUnary(new NullTest($left, 'null', new Node(), $left->getTemplateLine()), $left->getTemplateLine()),
31                $left->getTemplateLine()
32            );
33        }
34
35        parent::__construct($test, $left, $right, $lineno);
36    }
37
38    public function compile(Compiler $compiler)
39    {
40        /*
41         * This optimizes only one case. PHP 7 also supports more complex expressions
42         * that can return null. So, for instance, if log is defined, log("foo") ?? "..." works,
43         * but log($a["foo"]) ?? "..." does not if $a["foo"] is not defined. More advanced
44         * cases might be implemented as an optimizer node visitor, but has not been done
45         * as benefits are probably not worth the added complexity.
46         */
47        if ($this->getNode('expr2') instanceof NameExpression) {
48            $this->getNode('expr2')->setAttribute('always_defined', true);
49            $compiler
50                ->raw('((')
51                ->subcompile($this->getNode('expr2'))
52                ->raw(') ?? (')
53                ->subcompile($this->getNode('expr3'))
54                ->raw('))')
55            ;
56        } else {
57            parent::compile($compiler);
58        }
59    }
60}
61
62class_alias('Twig\Node\Expression\NullCoalesceExpression', 'Twig_Node_Expression_NullCoalesce');
63