LibraryDiscovery.php

<?php

namespace Drupal\Core\Asset;

use Drupal\Core\Cache\CacheCollectorInterface;

/**
 * Discovers available asset libraries in Drupal.
 */
class LibraryDiscovery implements LibraryDiscoveryInterface {
    
    /**
     * The library discovery cache collector.
     *
     * @var \Drupal\Core\Cache\CacheCollectorInterface
     */
    protected $collector;
    
    /**
     * The final library definitions, statically cached.
     *
     * Hooks hook_library_info_alter() and hook_js_settings_alter() allow modules
     * and themes to dynamically alter a library definition (once per request).
     *
     * @var array
     */
    protected $libraryDefinitions = [];
    
    /**
     * Constructs a new LibraryDiscovery instance.
     *
     * @param \Drupal\Core\Cache\CacheCollectorInterface $library_discovery_collector
     *   The library discovery cache collector.
     */
    public function __construct(CacheCollectorInterface $library_discovery_collector) {
        $this->collector = $library_discovery_collector;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getLibrariesByExtension($extension) {
        if (!isset($this->libraryDefinitions[$extension])) {
            $libraries = $this->collector
                ->get($extension);
            $this->libraryDefinitions[$extension] = [];
            foreach ($libraries as $name => $definition) {
                $this->libraryDefinitions[$extension][$name] = $definition;
            }
        }
        return $this->libraryDefinitions[$extension];
    }
    
    /**
     * {@inheritdoc}
     */
    public function getLibraryByName($extension, $name) {
        $libraries = $this->getLibrariesByExtension($extension);
        if (!isset($libraries[$name])) {
            return FALSE;
        }
        if (isset($libraries[$name]['deprecated'])) {
            @trigger_error(str_replace('%library_id%', "{$extension}/{$name}", $libraries[$name]['deprecated']), E_USER_DEPRECATED);
        }
        return $libraries[$name];
    }
    
    /**
     * {@inheritdoc}
     */
    public function clearCachedDefinitions() {
        $this->libraryDefinitions = [];
        $this->collector
            ->clear();
    }

}