Viewing file:  NullCoalesceExpression.php (2.05 KB) -rw-r--r--
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<?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\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;
class NullCoalesceExpression extends ConditionalExpression
{
public function __construct(Node $left, Node $right, int $lineno)
{
$test = new DefinedTest(clone $left, 'defined', new Node(), $left->getTemplateLine());
// for "block()", we don't need the null test as the return value is always a string
if (!$left instanceof BlockReferenceExpression) {
$test = new AndBinary(
$test,
new NotUnary(new NullTest($left, 'null', new Node(), $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);
}
}
}
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