You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
45 lines
1.2 KiB
45 lines
1.2 KiB
<?php
|
|
/** @license MIT
|
|
* Copyright 2021 Dustin Wilson et al.
|
|
* See LICENSE file for details */
|
|
|
|
declare(strict_types=1);
|
|
namespace dW\Lit\Grammar;
|
|
use dW\Lit\Grammar;
|
|
|
|
|
|
/**
|
|
* Acts as a sort of lazy reference for repository items in grammars.
|
|
*/
|
|
class RepositoryReference extends Reference {
|
|
protected ?Grammar $grammar;
|
|
protected string $_name;
|
|
protected PatternList|Pattern|null|false $object = null;
|
|
|
|
|
|
public function __construct(string $name, Grammar $grammar) {
|
|
$this->_name = $name;
|
|
// Using a \WeakReference here doesn't work for some reason even though
|
|
// the grammar would still be stored in memory. Cloning works because grammars
|
|
// are immutable, so the referenced object never will change.
|
|
$this->grammar = clone $grammar;
|
|
}
|
|
|
|
|
|
public function get(): PatternList|Pattern|null {
|
|
if ($this->object !== null) {
|
|
return $this->object;
|
|
} elseif ($this->object === false) {
|
|
return null;
|
|
}
|
|
|
|
$grammar = $this->grammar;
|
|
if (!isset($grammar->repository[$this->name])) {
|
|
$this->object = false;
|
|
return null;
|
|
}
|
|
|
|
$this->object = $grammar->repository[$this->name];
|
|
return $this->object;
|
|
}
|
|
}
|