CurrentPathContext.php

<?php

namespace Drupal\rules\ContextProvider;

use Drupal\Core\Cache\CacheableMetadata;
use Drupal\Core\Path\CurrentPathStack;
use Drupal\Core\Plugin\Context\Context;
use Drupal\Core\Plugin\Context\ContextDefinition;
use Drupal\Core\Plugin\Context\ContextProviderInterface;
use Drupal\Core\StringTranslation\StringTranslationTrait;
use Drupal\Core\Url;

/**
 * Makes the current path available as a context variable.
 */
class CurrentPathContext implements ContextProviderInterface {
    use StringTranslationTrait;
    
    /**
     * The current path service.
     *
     * @var \Drupal\Core\Path\CurrentPathStack
     */
    protected $currentPathStack;
    
    /**
     * Constructs a new CurrentPathContext.
     *
     * @param \Drupal\Core\Path\CurrentPathStack $current_path_stack
     *   The current path stack service.
     */
    public function __construct(CurrentPathStack $current_path_stack) {
        $this->currentPathStack = $current_path_stack;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getRuntimeContexts(array $unqualified_context_ids) {
        $values = [
            'path' => $this->currentPathStack
                ->getPath(),
            'url' => Url::fromRoute('<current>', [], [
                'absolute' => TRUE,
            ])->toString(),
        ];
        $context_definition = new ContextDefinition('current_path', $this->t('Current path'));
        $context = new Context($context_definition, $values);
        $cacheability = new CacheableMetadata();
        $cacheability->setCacheContexts([
            'url.path',
        ]);
        $context->addCacheableDependency($cacheability);
        $result = [
            'current_path' => $context,
        ];
        return $result;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getAvailableContexts() {
        return $this->getRuntimeContexts([]);
    }

}