Token.php

<?php

namespace Drupal\Core\Utility;

use Drupal\Component\Render\HtmlEscapedText;
use Drupal\Component\Render\MarkupInterface;
use Drupal\Core\Cache\CacheableDependencyInterface;
use Drupal\Core\Cache\CacheBackendInterface;
use Drupal\Core\Cache\CacheTagsInvalidatorInterface;
use Drupal\Core\Extension\ModuleHandlerInterface;
use Drupal\Core\Language\LanguageInterface;
use Drupal\Core\Language\LanguageManagerInterface;
use Drupal\Core\Render\AttachmentsInterface;
use Drupal\Core\Render\BubbleableMetadata;
use Drupal\Core\Render\RendererInterface;

/**
 * Drupal placeholder/token replacement system.
 *
 * API functions for replacing placeholders in text with meaningful values.
 *
 * For example: When configuring automated emails, an administrator enters
 * standard text for the email. Variables like the title of a node and the date
 * the email was sent can be entered as placeholders like [node:title] and
 * [date:short]. When a Drupal module prepares to send the email, it can call
 * the Token::replace() function, passing in the text. The token system will
 * scan the text for placeholder tokens, give other modules an opportunity to
 * replace them with meaningful text, then return the final product to the
 * original module.
 *
 * Tokens follow the form: [$type:$name], where $type is a general class of
 * tokens like 'node', 'user', or 'comment' and $name is the name of a given
 * placeholder. For example, [node:title] or [node:created:since].
 *
 * In addition to raw text containing placeholders, modules may pass in an array
 * of objects to be used when performing the replacement. The objects should be
 * keyed by the token type they correspond to. For example:
 *
 * @code
 * // Load a node and a user, then replace tokens in the text.
 * $text = 'On [date:short], [user:name] read [node:title].';
 * $node = Node::load(1);
 * $user = User::load(1);
 *
 * // [date:...] tokens use the current date automatically.
 * $data = array('node' => $node, 'user' => $user);
 * return Token::replace($text, $data);
 * @endcode
 *
 * Some tokens may be chained in the form of [$type:$pointer:$name], where $type
 * is a normal token type, $pointer is a reference to another token type, and
 * $name is the name of a given placeholder. For example, [node:author:mail]. In
 * that example, 'author' is a pointer to the 'user' account that created the
 * node, and 'mail' is a placeholder available for any 'user'.
 *
 * @see Token::replace()
 * @see hook_tokens()
 * @see hook_token_info()
 */
class Token {
    
    /**
     * The tag to cache token info with.
     */
    const TOKEN_INFO_CACHE_TAG = 'token_info';
    
    /**
     * The token cache.
     *
     * @var \Drupal\Core\Cache\CacheBackendInterface
     */
    protected $cache;
    
    /**
     * The language manager.
     *
     * @var \Drupal\Core\Language\LanguageManagerInterface
     */
    protected $languageManager;
    
    /**
     * Token definitions.
     *
     * @var array[]|null
     *   An array of token definitions, or NULL when the definitions are not set.
     *
     * @see self::setInfo()
     * @see self::getInfo()
     * @see self::resetInfo()
     */
    protected $tokenInfo;
    
    /**
     * The module handler service.
     *
     * @var \Drupal\Core\Extension\ModuleHandlerInterface
     */
    protected $moduleHandler;
    
    /**
     * The cache tags invalidator.
     *
     * @var \Drupal\Core\Cache\CacheTagsInvalidatorInterface
     */
    protected $cacheTagsInvalidator;
    
    /**
     * The renderer.
     *
     * @var \Drupal\Core\Render\RendererInterface
     */
    protected $renderer;
    
    /**
     * Constructs a new class instance.
     *
     * @param \Drupal\Core\Extension\ModuleHandlerInterface $module_handler
     *   The module handler.
     * @param \Drupal\Core\Cache\CacheBackendInterface $cache
     *   The token cache.
     * @param \Drupal\Core\Language\LanguageManagerInterface $language_manager
     *   The language manager.
     * @param \Drupal\Core\Cache\CacheTagsInvalidatorInterface $cache_tags_invalidator
     *   The cache tags invalidator.
     * @param \Drupal\Core\Render\RendererInterface $renderer
     *   The renderer.
     */
    public function __construct(ModuleHandlerInterface $module_handler, CacheBackendInterface $cache, LanguageManagerInterface $language_manager, CacheTagsInvalidatorInterface $cache_tags_invalidator, RendererInterface $renderer) {
        $this->cache = $cache;
        $this->languageManager = $language_manager;
        $this->moduleHandler = $module_handler;
        $this->cacheTagsInvalidator = $cache_tags_invalidator;
        $this->renderer = $renderer;
    }
    
    /**
     * Replaces all tokens in a given string with appropriate values.
     *
     * @param string $text
     *   An HTML string containing replaceable tokens. The caller is responsible
     *   for calling \Drupal\Component\Utility\Html::escape() in case the $text
     *   was plain text.
     * @param array $data
     *   (optional) An array of keyed objects. For simple replacement scenarios
     *   'node', 'user', and others are common keys, with an accompanying node or
     *   user object being the value. Some token types, like 'site', do not require
     *   any explicit information from $data and can be replaced even if it is
     *   empty.
     * @param array $options
     *   (optional) A keyed array of settings and flags to control the token
     *   replacement process. Supported options are:
     *   - langcode: A language code to be used when generating locale-sensitive
     *     tokens.
     *   - callback: A callback function that will be used to post-process the
     *     array of token replacements after they are generated.
     *   - clear: A boolean flag indicating that tokens should be removed from the
     *     final text if no replacement value can be generated.
     * @param \Drupal\Core\Render\BubbleableMetadata|null $bubbleable_metadata
     *   (optional) An object to which static::generate() and the hooks and
     *   functions that it invokes will add their required bubbleable metadata.
     *
     *   To ensure that the metadata associated with the token replacements gets
     *   attached to the same render array that contains the token-replaced text,
     *   callers of this method are encouraged to pass in a BubbleableMetadata
     *   object and apply it to the corresponding render array. For example:
     *   @code
     *     $bubbleable_metadata = new BubbleableMetadata();
     *     $build['#markup'] = $token_service->replace('Tokens: [node:nid] [current-user:uid]', ['node' => $node], [], $bubbleable_metadata);
     *     $bubbleable_metadata->applyTo($build);
     *   @endcode
     *
     *   When the caller does not pass in a BubbleableMetadata object, this
     *   method creates a local one, and applies the collected metadata to the
     *   Renderer's currently active render context.
     *
     * @return string
     *   The token result is the entered HTML text with tokens replaced. The
     *   caller is responsible for choosing the right escaping / sanitization. If
     *   the result is intended to be used as plain text, using
     *   PlainTextOutput::renderFromHtml() is recommended. If the result is just
     *   printed as part of a template relying on Twig autoescaping is possible,
     *   otherwise for example the result can be put into #markup, in which case
     *   it would be sanitized by Xss::filterAdmin().
     */
    public function replace($text, array $data = [], array $options = [], BubbleableMetadata $bubbleable_metadata = NULL) {
        $text_tokens = $this->scan($text);
        if (empty($text_tokens)) {
            return $text;
        }
        $bubbleable_metadata_is_passed_in = (bool) $bubbleable_metadata;
        $bubbleable_metadata = $bubbleable_metadata ?: new BubbleableMetadata();
        $replacements = [];
        foreach ($text_tokens as $type => $tokens) {
            $replacements += $this->generate($type, $tokens, $data, $options, $bubbleable_metadata);
            if (!empty($options['clear'])) {
                $replacements += array_fill_keys($tokens, '');
            }
        }
        // Escape the tokens, unless they are explicitly markup.
        foreach ($replacements as $token => $value) {
            $replacements[$token] = $value instanceof MarkupInterface ? $value : new HtmlEscapedText($value);
        }
        // Optionally alter the list of replacement values.
        if (!empty($options['callback'])) {
            $function = $options['callback'];
            $function($replacements, $data, $options, $bubbleable_metadata);
        }
        $tokens = array_keys($replacements);
        $values = array_values($replacements);
        // If a local $bubbleable_metadata object was created, apply the metadata
        // it collected to the renderer's currently active render context.
        if (!$bubbleable_metadata_is_passed_in && $this->renderer
            ->hasRenderContext()) {
            $build = [];
            $bubbleable_metadata->applyTo($build);
            $this->renderer
                ->render($build);
        }
        return str_replace($tokens, $values, $text);
    }
    
    /**
     * Builds a list of all token-like patterns that appear in the text.
     *
     * @param string $text
     *   The text to be scanned for possible tokens.
     *
     * @return array
     *   An associative array of discovered tokens, grouped by type.
     */
    public function scan($text) {
        // Matches tokens with the following pattern: [$type:$name]
        // $type and $name may not contain [ ] characters.
        // $type may not contain : or whitespace characters, but $name may.
        preg_match_all('/
      \\[             # [ - pattern start
      ([^\\s\\[\\]:]+)  # match $type not containing whitespace : [ or ]
      :              # : - separator
      ([^\\[\\]]+)     # match $name not containing [ or ]
      \\]             # ] - pattern end
      /x', $text, $matches);
        $types = $matches[1];
        $tokens = $matches[2];
        // Iterate through the matches, building an associative array containing
        // $tokens grouped by $types, pointing to the version of the token found in
        // the source text. For example, $results['node']['title'] = '[node:title]';
        $results = [];
        for ($i = 0; $i < count($tokens); $i++) {
            $results[$types[$i]][$tokens[$i]] = $matches[0][$i];
        }
        return $results;
    }
    
    /**
     * Generates replacement values for a list of tokens.
     *
     * @param string $type
     *   The type of token being replaced. 'node', 'user', and 'date' are common.
     * @param array $tokens
     *   An array of tokens to be replaced, keyed by the literal text of the token
     *   as it appeared in the source text.
     * @param array $data
     *   An array of keyed objects. For simple replacement scenarios: 'node',
     *   'user', and others are common keys, with an accompanying node or user
     *   object being the value. Some token types, like 'site', do not require
     *   any explicit information from $data and can be replaced even if it is
     *   empty.
     * @param array $options
     *   A keyed array of settings and flags to control the token replacement
     *   process. Supported options are:
     *   - langcode: A language code to be used when generating locale-sensitive
     *     tokens.
     *   - callback: A callback function that will be used to post-process the
     *     array of token replacements after they are generated. Can be used when
     *     modules require special formatting of token text, for example URL
     *     encoding or truncation to a specific length.
     * @param \Drupal\Core\Render\BubbleableMetadata $bubbleable_metadata
     *   The bubbleable metadata. This is passed to the token replacement
     *   implementations so that they can attach their metadata.
     *
     * @return array
     *   An associative array of replacement values, keyed by the original 'raw'
     *   tokens that were found in the source text. For example:
     *   $results['[node:title]'] = 'My new node';
     *
     * @see hook_tokens()
     * @see hook_tokens_alter()
     */
    public function generate($type, array $tokens, array $data, array $options, BubbleableMetadata $bubbleable_metadata) {
        foreach ($data as $object) {
            if ($object instanceof CacheableDependencyInterface || $object instanceof AttachmentsInterface) {
                $bubbleable_metadata->addCacheableDependency($object);
            }
        }
        $replacements = $this->moduleHandler
            ->invokeAll('tokens', [
            $type,
            $tokens,
            $data,
            $options,
            $bubbleable_metadata,
        ]);
        // Allow other modules to alter the replacements.
        $context = [
            'type' => $type,
            'tokens' => $tokens,
            'data' => $data,
            'options' => $options,
        ];
        $this->moduleHandler
            ->alter('tokens', $replacements, $context, $bubbleable_metadata);
        return $replacements;
    }
    
    /**
     * Returns a list of tokens that begin with a specific prefix.
     *
     * Used to extract a group of 'chained' tokens (such as [node:author:name])
     * from the full list of tokens found in text. For example:
     * @code
     *   $data = array(
     *     'author:name' => '[node:author:name]',
     *     'title'       => '[node:title]',
     *     'created'     => '[node:created]',
     *   );
     *   $results = Token::findWithPrefix($data, 'author');
     *   $results == array('name' => '[node:author:name]');
     * @endcode
     *
     * @param array $tokens
     *   A keyed array of tokens, and their original raw form in the source text.
     * @param string $prefix
     *   A textual string to be matched at the beginning of the token.
     * @param string $delimiter
     *   (optional) A string containing the character that separates the prefix from
     *   the rest of the token. Defaults to ':'.
     *
     * @return array
     *   An associative array of discovered tokens, with the prefix and delimiter
     *   stripped from the key.
     */
    public function findWithPrefix(array $tokens, $prefix, $delimiter = ':') {
        $results = [];
        foreach ($tokens as $token => $raw) {
            $parts = explode($delimiter, $token, 2);
            if (count($parts) == 2 && $parts[0] == $prefix) {
                $results[$parts[1]] = $raw;
            }
        }
        return $results;
    }
    
    /**
     * Returns metadata describing supported tokens.
     *
     * The metadata array contains token type, name, and description data as well
     * as an optional pointer indicating that the token chains to another set of
     * tokens.
     *
     * @return array
     *   An associative array of token information, grouped by token type. The
     *   array structure is identical to that of hook_token_info().
     *
     * @see hook_token_info()
     */
    public function getInfo() {
        if (is_null($this->tokenInfo)) {
            $cache_id = 'token_info:' . $this->languageManager
                ->getCurrentLanguage(LanguageInterface::TYPE_CONTENT)
                ->getId();
            $cache = $this->cache
                ->get($cache_id);
            if ($cache) {
                $this->tokenInfo = $cache->data;
            }
            else {
                $this->tokenInfo = $this->moduleHandler
                    ->invokeAll('token_info');
                $this->moduleHandler
                    ->alter('token_info', $this->tokenInfo);
                $this->cache
                    ->set($cache_id, $this->tokenInfo, CacheBackendInterface::CACHE_PERMANENT, [
                    static::TOKEN_INFO_CACHE_TAG,
                ]);
            }
        }
        return $this->tokenInfo;
    }
    
    /**
     * Sets metadata describing supported tokens.
     *
     * @param array $tokens
     *   Token metadata that has an identical structure to the return value of
     *   hook_token_info().
     *
     * @see hook_token_info()
     */
    public function setInfo(array $tokens) {
        $this->tokenInfo = $tokens;
    }
    
    /**
     * Resets metadata describing supported tokens.
     */
    public function resetInfo() {
        $this->tokenInfo = NULL;
        $this->cacheTagsInvalidator
            ->invalidateTags([
            static::TOKEN_INFO_CACHE_TAG,
        ]);
    }

}