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[yaffs-website] / web / core / lib / Drupal / Core / PageCache / RequestPolicyInterface.php

diff --git a/web/core/lib/Drupal/Core/PageCache/RequestPolicyInterface.php b/web/core/lib/Drupal/Core/PageCache/RequestPolicyInterface.php
new file mode 100644 (file)
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+++ b/web/core/lib/Drupal/Core/PageCache/RequestPolicyInterface.php
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+<?php
+
+namespace Drupal\Core\PageCache;
+
+use Symfony\Component\HttpFoundation\Request;
+
+/**
+ * Defines the interface for request policy implementations.
+ *
+ * The request policy is evaluated in order to determine whether delivery of a
+ * cached page should be attempted. The caller should do so if static::ALLOW is
+ * returned from the check() method.
+ */
+interface RequestPolicyInterface {
+
+  /**
+   * Allow delivery of cached pages.
+   */
+  const ALLOW = 'allow';
+
+  /**
+   * Deny delivery of cached pages.
+   */
+  const DENY = 'deny';
+
+  /**
+   * Determines whether delivery of a cached page should be attempted.
+   *
+   * Note that the request-policy check runs very early. In particular it is
+   * not possible to determine the logged in user. Also the current route match
+   * is not yet present when the check runs. Therefore, request-policy checks
+   * need to be designed in a way such that they do not depend on any other
+   * service and only take in account the information present on the incoming
+   * request.
+   *
+   * When matching against the request path, special attention is needed to
+   * support path prefixes which are often used on multilingual sites.
+   *
+   * @param \Symfony\Component\HttpFoundation\Request $request
+   *   The incoming request object.
+   *
+   * @return string|null
+   *   One of static::ALLOW, static::DENY or NULL. Calling code may attempt to
+   *   deliver a cached page if static::ALLOW is returned. Returns NULL if the
+   *   policy is not specified for the given request.
+   */
+  public function check(Request $request);
+
+}