ComponentLoader.php

<?php

namespace Drupal\Core\Template\Loader;

use Drupal\Component\Discovery\YamlDirectoryDiscovery;
use Drupal\Core\Render\Component\Exception\ComponentNotFoundException;
use Drupal\Core\Theme\ComponentPluginManager;
use Drupal\Core\Utility\Error;
use Psr\Log\LoggerInterface;
use Twig\Error\LoaderError;
use Twig\Loader\LoaderInterface;
use Twig\Source;

/**
 * Lets you load templates using the component ID.
 */
class ComponentLoader implements LoaderInterface {
    
    /**
     * Constructs a new ComponentLoader object.
     *
     * @param \Drupal\Core\Theme\ComponentPluginManager $pluginManager
     *   The plugin manager.
     * @param \Psr\Log\LoggerInterface $logger
     *   The logger.
     */
    public function __construct(ComponentPluginManager $pluginManager, LoggerInterface $logger) {
    }
    
    /**
     * Finds a template in the file system based on the template name.
     *
     * @param string $name
     *   The template name.
     * @param bool $throw
     *   TRUE to throw an exception when the component is not found. FALSE to
     *   return NULL if the component cannot be found.
     *
     * @return string|null
     *   The path to the component.
     *
     * @throws \Twig\Error\LoaderError
     *   Thrown if a template matching $name cannot be found and $throw is TRUE.
     */
    protected function findTemplate(string $name, bool $throw = TRUE) : ?string {
        $path = $name;
        try {
            $component = $this->pluginManager
                ->find($name);
            $path = $component->getTemplatePath();
        } catch (ComponentNotFoundException $e) {
            if ($throw) {
                throw new LoaderError($e->getMessage(), $e->getCode(), $e);
            }
        }
        if ($path || !$throw) {
            return $path;
        }
        throw new LoaderError(sprintf('Unable to find template "%s" in the components registry.', $name));
    }
    
    /**
     * {@inheritdoc}
     */
    public function exists($name) : bool {
        if (!preg_match('/^[a-zA-Z][a-zA-Z0-9:_-]*[a-zA-Z0-9]?$/', $name)) {
            return FALSE;
        }
        try {
            $this->pluginManager
                ->find($name);
            return TRUE;
        } catch (ComponentNotFoundException $e) {
            Error::logException($this->logger, $e);
            return FALSE;
        }
    }
    
    /**
     * {@inheritdoc}
     */
    public function getSourceContext($name) : Source {
        try {
            $component = $this->pluginManager
                ->find($name);
            $path = $component->getTemplatePath();
        } catch (ComponentNotFoundException) {
            return new Source('', $name, '');
        }
        $original_code = file_get_contents($path);
        return new Source($original_code, $name, $path);
    }
    
    /**
     * {@inheritdoc}
     */
    public function getCacheKey($name) : string {
        try {
            $component = $this->pluginManager
                ->find($name);
        } catch (ComponentNotFoundException) {
            throw new LoaderError('Unable to find component');
        }
        return implode('--', array_filter([
            'components',
            $name,
            $component->getPluginDefinition()['provider'] ?? '',
        ]));
    }
    
    /**
     * {@inheritdoc}
     */
    public function isFresh(string $name, int $time) : bool {
        $file_is_fresh = static fn(string $path) => filemtime($path) < $time;
        try {
            $component = $this->pluginManager
                ->find($name);
        } catch (ComponentNotFoundException) {
            throw new LoaderError('Unable to find component');
        }
        // If any of the templates, or the component definition, are fresh. Then the
        // component is fresh.
        $metadata_path = $component->getPluginDefinition()[YamlDirectoryDiscovery::FILE_KEY];
        if ($file_is_fresh($metadata_path)) {
            return TRUE;
        }
        return $file_is_fresh($component->getTemplatePath());
    }

}