ElementInfoManager.php

<?php

namespace Drupal\Core\Render;

use Drupal\Core\Cache\Cache;
use Drupal\Core\Cache\CacheBackendInterface;
use Drupal\Core\Cache\CacheTagsInvalidatorInterface;
use Drupal\Core\Extension\ModuleHandlerInterface;
use Drupal\Core\Plugin\DefaultPluginManager;
use Drupal\Core\Render\Element\FormElementInterface;
use Drupal\Core\Theme\ThemeManagerInterface;

/**
 * Provides a plugin manager for element plugins.
 *
 * @see \Drupal\Core\Render\Annotation\RenderElement
 * @see \Drupal\Core\Render\Annotation\FormElement
 * @see \Drupal\Core\Render\Element\RenderElement
 * @see \Drupal\Core\Render\Element\FormElement
 * @see \Drupal\Core\Render\Element\ElementInterface
 * @see \Drupal\Core\Render\Element\FormElementInterface
 * @see plugin_api
 */
class ElementInfoManager extends DefaultPluginManager implements ElementInfoManagerInterface {
    
    /**
     * Stores the available element information.
     *
     * @var array
     */
    protected $elementInfo;
    
    /**
     * The theme manager.
     *
     * @var \Drupal\Core\Theme\ThemeManagerInterface
     */
    protected $themeManager;
    
    /**
     * The cache tag invalidator.
     *
     * @var \Drupal\Core\Cache\CacheTagsInvalidatorInterface
     */
    protected $cacheTagInvalidator;
    
    /**
     * Constructs a ElementInfoManager object.
     *
     * @param \Traversable $namespaces
     *   An object that implements \Traversable which contains the root paths
     *   keyed by the corresponding namespace to look for plugin implementations.
     * @param \Drupal\Core\Cache\CacheBackendInterface $cache_backend
     *   Cache backend instance to use.
     * @param \Drupal\Core\Cache\CacheTagsInvalidatorInterface $cache_tag_invalidator
     *   The cache tag invalidator.
     * @param \Drupal\Core\Extension\ModuleHandlerInterface $module_handler
     *   The module handler to invoke the alter hook with.
     * @param \Drupal\Core\Theme\ThemeManagerInterface $theme_manager
     *   The theme manager.
     */
    public function __construct(\Traversable $namespaces, CacheBackendInterface $cache_backend, CacheTagsInvalidatorInterface $cache_tag_invalidator, ModuleHandlerInterface $module_handler, ThemeManagerInterface $theme_manager) {
        $this->setCacheBackend($cache_backend, 'element_info');
        $this->themeManager = $theme_manager;
        $this->cacheTagInvalidator = $cache_tag_invalidator;
        parent::__construct('Element', $namespaces, $module_handler, 'Drupal\\Core\\Render\\Element\\ElementInterface', 'Drupal\\Core\\Render\\Annotation\\RenderElement');
        $this->alterInfo('element_plugin');
    }
    
    /**
     * {@inheritdoc}
     */
    public function getInfo($type) {
        $theme_name = $this->themeManager
            ->getActiveTheme()
            ->getName();
        if (!isset($this->elementInfo[$theme_name])) {
            $this->elementInfo[$theme_name] = $this->buildInfo($theme_name);
        }
        $info = isset($this->elementInfo[$theme_name][$type]) ? $this->elementInfo[$theme_name][$type] : [];
        $info['#defaults_loaded'] = TRUE;
        return $info;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getInfoProperty($type, $property_name, $default = NULL) {
        $info = $this->getInfo($type);
        return isset($info[$property_name]) ? $info[$property_name] : $default;
    }
    
    /**
     * Builds up all element information.
     *
     * @param string $theme_name
     *   The theme name.
     *
     * @return array
     */
    protected function buildInfo($theme_name) {
        // Get cached definitions.
        $cid = $this->getCid($theme_name);
        if ($cache = $this->cacheBackend
            ->get($cid)) {
            return $cache->data;
        }
        // Otherwise, rebuild and cache.
        $info = [];
        foreach ($this->getDefinitions() as $element_type => $definition) {
            $element = $this->createInstance($element_type);
            $element_info = $element->getInfo();
            // If this is element is to be used exclusively in a form, denote that it
            // will receive input, and assign the value callback.
            if ($element instanceof FormElementInterface) {
                $element_info['#input'] = TRUE;
                $element_info['#value_callback'] = [
                    $definition['class'],
                    'valueCallback',
                ];
            }
            $info[$element_type] = $element_info;
        }
        foreach ($info as $element_type => $element) {
            $info[$element_type]['#type'] = $element_type;
        }
        // Allow modules to alter the element type defaults.
        $this->moduleHandler
            ->alter('element_info', $info);
        $this->themeManager
            ->alter('element_info', $info);
        $this->cacheBackend
            ->set($cid, $info, Cache::PERMANENT, [
            'element_info_build',
        ]);
        return $info;
    }
    
    /**
     * {@inheritdoc}
     *
     * @return \Drupal\Core\Render\Element\ElementInterface
     */
    public function createInstance($plugin_id, array $configuration = []) {
        return parent::createInstance($plugin_id, $configuration);
    }
    
    /**
     * {@inheritdoc}
     */
    public function clearCachedDefinitions() {
        $this->elementInfo = NULL;
        $this->cacheTagInvalidator
            ->invalidateTags([
            'element_info_build',
        ]);
        parent::clearCachedDefinitions();
    }
    
    /**
     * Returns the CID used to cache the element info.
     *
     * @param string $theme_name
     *   The theme name.
     *
     * @return string
     */
    protected function getCid($theme_name) {
        return 'element_info_build:' . $theme_name;
    }

}