ChainLoader.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\Loader;

use Twig\Error\LoaderError;
use Twig\Source;

/**
 * Loads templates from other loaders.
 *
 * @author Fabien Potencier <fabien@symfony.com>
 */
final class ChainLoader implements LoaderInterface {
    
    /**
     * @var array<string, bool>
     */
    private $hasSourceCache = [];
    
    /**
     * @param iterable<LoaderInterface> $loaders
     */
    public function __construct(iterable $loaders = []) {
    }
    public function addLoader(LoaderInterface $loader) : void {
        $current = $this->loaders;
        $this->loaders = (static function () use ($current, $loader) : \Generator {
            yield from $current;
            (yield $loader);
        })();
        $this->hasSourceCache = [];
    }
    
    /**
     * @return LoaderInterface[]
     */
    public function getLoaders() : array {
        if (!\is_array($this->loaders)) {
            $this->loaders = iterator_to_array($this->loaders, false);
        }
        return $this->loaders;
    }
    public function getSourceContext(string $name) : Source {
        $exceptions = [];
        foreach ($this->getLoaders() as $loader) {
            if (!$loader->exists($name)) {
                continue;
            }
            try {
                return $loader->getSourceContext($name);
            } catch (LoaderError $e) {
                $exceptions[] = $e->getMessage();
            }
        }
        throw new LoaderError(\sprintf('Template "%s" is not defined%s.', $name, $exceptions ? ' (' . implode(', ', $exceptions) . ')' : ''));
    }
    public function exists(string $name) : bool {
        if (isset($this->hasSourceCache[$name])) {
            return $this->hasSourceCache[$name];
        }
        foreach ($this->getLoaders() as $loader) {
            if ($loader->exists($name)) {
                return $this->hasSourceCache[$name] = true;
            }
        }
        return $this->hasSourceCache[$name] = false;
    }
    public function getCacheKey(string $name) : string {
        $exceptions = [];
        foreach ($this->getLoaders() as $loader) {
            if (!$loader->exists($name)) {
                continue;
            }
            try {
                return $loader->getCacheKey($name);
            } catch (LoaderError $e) {
                $exceptions[] = \get_class($loader) . ': ' . $e->getMessage();
            }
        }
        throw new LoaderError(\sprintf('Template "%s" is not defined%s.', $name, $exceptions ? ' (' . implode(', ', $exceptions) . ')' : ''));
    }
    public function isFresh(string $name, int $time) : bool {
        $exceptions = [];
        foreach ($this->getLoaders() as $loader) {
            if (!$loader->exists($name)) {
                continue;
            }
            try {
                return $loader->isFresh($name, $time);
            } catch (LoaderError $e) {
                $exceptions[] = \get_class($loader) . ': ' . $e->getMessage();
            }
        }
        throw new LoaderError(\sprintf('Template "%s" is not defined%s.', $name, $exceptions ? ' (' . implode(', ', $exceptions) . ')' : ''));
    }

}