class Html

Same name in this branch

11.x core/lib/Drupal/Core/Render/Element/Html.php \Drupal\Core\Render\Element\Html

Same name in other branches

9 core/lib/Drupal/Core/Render/Element/Html.php \Drupal\Core\Render\Element\Html
9 core/lib/Drupal/Component/Utility/Html.php \Drupal\Component\Utility\Html
8.9.x core/lib/Drupal/Core/Render/Element/Html.php \Drupal\Core\Render\Element\Html
8.9.x core/lib/Drupal/Component/Utility/Html.php \Drupal\Component\Utility\Html
10 core/lib/Drupal/Core/Render/Element/Html.php \Drupal\Core\Render\Element\Html
10 core/lib/Drupal/Component/Utility/Html.php \Drupal\Component\Utility\Html

Provides DOMDocument helpers for parsing and serializing HTML strings.

Hierarchy

class \Drupal\Component\Utility\Html

Expanded class hierarchy of Html

File

core/lib/Drupal/Component/Utility/Html.php, line 13

Namespace

Drupal\Component\Utility

View source

class Html {
    
    /**
     * An array of previously cleaned HTML classes.
     *
     * @var array
     */
    protected static $classes = [];
    
    /**
     * An array of the initial IDs used in one request.
     *
     * @var array
     */
    protected static $seenIdsInit;
    
    /**
     * An array of IDs, including incremented versions when an ID is duplicated.
     * @var array
     */
    protected static $seenIds;
    
    /**
     * Stores whether the current request was sent via AJAX.
     *
     * @var bool
     */
    protected static $isAjax = FALSE;
    
    /**
     * All attributes that may contain URIs.
     *
     * - The attributes 'code' and 'codebase' are omitted, because they only exist
     *   for the <applet> tag. The time of Java applets has passed.
     * - The attribute 'icon' is omitted, because no browser implements the
     *   <command> tag anymore.
     *  See https://developer.mozilla.org/en-US/docs/Web/HTML/Element/command.
     * - The 'manifest' attribute is omitted because it only exists for the <html>
     *   tag. That tag only makes sense in an HTML-served-as-HTML context, in
     *   which case relative URLs are guaranteed to work.
     *
     * @var string[]
     *
     * @see https://developer.mozilla.org/en-US/docs/Web/HTML/Attributes
     * @see https://stackoverflow.com/questions/2725156/complete-list-of-html-tag-attributes-which-have-a-url-value
     */
    protected static $uriAttributes = [
        'href',
        'poster',
        'src',
        'cite',
        'data',
        'action',
        'formaction',
        'srcset',
        'about',
    ];
    
    /**
     * Prepares a string for use as a valid class name.
     *
     * Do not pass one string containing multiple classes as they will be
     * incorrectly concatenated with dashes, i.e. "one two" will become "one-two".
     *
     * @param mixed $class
     *   The class name to clean. It can be a string or anything that can be cast
     *   to string.
     *
     * @return string
     *   The cleaned class name.
     */
    public static function getClass($class) {
        $class = (string) $class;
        if (!isset(static::$classes[$class])) {
            static::$classes[$class] = static::cleanCssIdentifier(mb_strtolower($class));
        }
        return static::$classes[$class];
    }
    
    /**
     * Prepares a string for use as a CSS identifier (element, class, or ID name).
     *
     * Link below shows the syntax for valid CSS identifiers (including element
     * names, classes, and IDs in selectors).
     *
     * @see https://www.w3.org/TR/CSS21/syndata.html#characters
     *
     * @param string $identifier
     *   The identifier to clean.
     * @param array $filter
     *   An array of string replacements to use on the identifier.
     *
     * @return string
     *   The cleaned identifier.
     */
    public static function cleanCssIdentifier($identifier, array $filter = [
        ' ' => '-',
        '_' => '-',
        '/' => '-',
        '[' => '-',
        ']' => '',
    ]) {
        // We could also use strtr() here but its much slower than str_replace(). In
        // order to keep '__' to stay '__' we first replace it with a different
        // placeholder after checking that it is not defined as a filter.
        $double_underscore_replacements = 0;
        if (!isset($filter['__'])) {
            $identifier = str_replace('__', '##', $identifier, $double_underscore_replacements);
        }
        $identifier = str_replace(array_keys($filter), array_values($filter), $identifier);
        // Replace temporary placeholder '##' with '__' only if the original
        // $identifier contained '__'.
        if ($double_underscore_replacements > 0) {
            $identifier = str_replace('##', '__', $identifier);
        }
        // Valid characters in a CSS identifier are:
        // - the hyphen (U+002D)
        // - a-z (U+0030 - U+0039)
        // - A-Z (U+0041 - U+005A)
        // - the underscore (U+005F)
        // - 0-9 (U+0061 - U+007A)
        // - ISO 10646 characters U+00A1 and higher
        // We strip out any character not in the above list.
        $identifier = preg_replace('/[^\\x{002D}\\x{0030}-\\x{0039}\\x{0041}-\\x{005A}\\x{005F}\\x{0061}-\\x{007A}\\x{00A1}-\\x{FFFF}]/u', '', $identifier);
        // Identifiers cannot start with a digit, two hyphens, or a hyphen followed by a digit.
        $identifier = preg_replace([
            '/^[0-9]/',
            '/^(-[0-9])|^(--)/',
        ], [
            '_',
            '__',
        ], $identifier);
        return $identifier;
    }
    
    /**
     * Sets if this request is an Ajax request.
     *
     * @param bool $is_ajax
     *   TRUE if this request is an Ajax request, FALSE otherwise.
     */
    public static function setIsAjax($is_ajax) {
        static::$isAjax = $is_ajax;
    }
    
    /**
     * Prepares a string for use as a valid HTML ID and guarantees uniqueness.
     *
     * This function ensures that each passed HTML ID value only exists once on
     * the page. By tracking the already returned ids, this function enables
     * forms, blocks, and other content to be output multiple times on the same
     * page, without breaking HTML validation.
     *
     * For already existing IDs, a counter is appended to the ID string.
     * Therefore, JavaScript and CSS code should not rely on any value that was
     * generated by this function and instead should rely on manually added CSS
     * classes or similarly reliable constructs.
     *
     * Two consecutive hyphens separate the counter from the original ID. To
     * manage uniqueness across multiple Ajax requests on the same page, Ajax
     * requests POST an array of all IDs currently present on the page, which are
     * used to prime this function's cache upon first invocation.
     *
     * To allow reverse-parsing of IDs submitted via Ajax, any multiple
     * consecutive hyphens in the originally passed $id are replaced with a
     * single hyphen.
     *
     * @param string $id
     *   The ID to clean.
     *
     * @return string
     *   The cleaned ID.
     */
    public static function getUniqueId($id) {
        // If this is an Ajax request, then content returned by this page request
        // will be merged with content already on the base page. The HTML IDs must
        // be unique for the fully merged content. Therefore use unique IDs.
        if (static::$isAjax) {
            return static::getId($id) . '--' . Crypt::randomBytesBase64(8);
        }
        // @todo Remove all that code once we switch over to random IDs only,
        // see https://www.drupal.org/node/1090592.
        if (!isset(static::$seenIdsInit)) {
            static::$seenIdsInit = [];
        }
        if (!isset(static::$seenIds)) {
            static::$seenIds = static::$seenIdsInit;
        }
        $id = static::getId($id);
        // Ensure IDs are unique by appending a counter after the first occurrence.
        // The counter needs to be appended with a delimiter that does not exist in
        // the base ID. Requiring a unique delimiter helps ensure that we really do
        // return unique IDs and also helps us re-create the $seen_ids array during
        // Ajax requests.
        if (isset(static::$seenIds[$id])) {
            $id = $id . '--' . ++static::$seenIds[$id];
        }
        else {
            static::$seenIds[$id] = 1;
        }
        return $id;
    }
    
    /**
     * Prepares a string for use as a valid HTML ID.
     *
     * Only use this function when you want to intentionally skip the uniqueness
     * guarantee of self::getUniqueId().
     *
     * @param string $id
     *   The ID to clean.
     *
     * @return string
     *   The cleaned ID.
     *
     * @see self::getUniqueId()
     */
    public static function getId($id) {
        $id = str_replace([
            ' ',
            '_',
            '[',
            ']',
        ], [
            '-',
            '-',
            '-',
            '',
        ], mb_strtolower($id));
        // As defined in https://www.w3.org/TR/html4/types.html#type-name, HTML IDs can
        // only contain letters, digits ([0-9]), hyphens ("-"), underscores ("_"),
        // colons (":"), and periods ("."). We strip out any character not in that
        // list. Note that the CSS spec doesn't allow colons or periods in identifiers
        // (https://www.w3.org/TR/CSS21/syndata.html#characters), so we strip those two
        // characters as well.
        $id = preg_replace('/[^A-Za-z0-9\\-_]/', '', $id);
        // Removing multiple consecutive hyphens.
        $id = preg_replace('/\\-+/', '-', $id);
        return $id;
    }
    
    /**
     * Resets the list of seen IDs.
     */
    public static function resetSeenIds() {
        static::$seenIds = NULL;
    }
    
    /**
     * Normalizes an HTML snippet.
     *
     * This function is essentially \DOMDocument::normalizeDocument(), but
     * operates on an HTML string instead of a \DOMDocument.
     *
     * @param string $html
     *   The HTML string to normalize.
     *
     * @return string
     *   The normalized HTML string.
     */
    public static function normalize($html) {
        $document = static::load($html);
        return static::serialize($document);
    }
    
    /**
     * Parses an HTML snippet and returns it as a DOM object.
     *
     * This function loads the body part of a partial HTML document and returns a
     * full \DOMDocument object that represents this document.
     *
     * Use \Drupal\Component\Utility\Html::serialize() to serialize this
     * \DOMDocument back to a string.
     *
     * @param string $html
     *   The partial HTML snippet to load. Invalid markup will be corrected on
     *   import.
     *
     * @return \DOMDocument
     *   A \DOMDocument that represents the loaded HTML snippet.
     */
    public static function load($html) {
        // Instantiate the HTML5 parser, but without the HTML5 namespace being
        // added to the DOM document.
        $html5 = new HTML5([
            'disable_html_ns' => TRUE,
            'encoding' => 'UTF-8',
        ]);
        // Attach the provided HTML inside the body. Rely on the HTML5 parser to
        // close the body tag.
        return $html5->loadHTML('<body>' . $html);
    }
    
    /**
     * Converts the body of a \DOMDocument back to an HTML snippet.
     *
     * The function serializes the body part of a \DOMDocument back to an HTML
     * snippet. The resulting HTML snippet will be properly formatted to be
     * compatible with HTML user agents.
     *
     * @param \DOMDocument $document
     *   A \DOMDocument object to serialize, only the tags below the first <body>
     *   node will be converted.
     *
     * @return string
     *   A valid HTML snippet, as a string.
     */
    public static function serialize(\DOMDocument $document) {
        $body_node = $document->getElementsByTagName('body')
            ->item(0);
        $html = '';
        if ($body_node !== NULL) {
            foreach ($body_node->getElementsByTagName('script') as $node) {
                static::escapeCdataElement($node);
            }
            foreach ($body_node->getElementsByTagName('style') as $node) {
                static::escapeCdataElement($node, '/*', '*/');
            }
            // Serialize the body using our custom set of rules.
            // @see \Masterminds\HTML5::saveHTML()
            $stream = fopen('php://temp', 'wb');
            $rules = new HtmlSerializerRules($stream);
            foreach ($body_node->childNodes as $node) {
                $traverser = new Traverser($node, $stream, $rules);
                $traverser->walk();
            }
            $rules->unsetTraverser();
            $html = stream_get_contents($stream, -1, 0);
            fclose($stream);
        }
        // Normalize all newlines.
        $html = str_replace([
            "\r\n",
            "\r",
        ], "\n", $html);
        return $html;
    }
    
    /**
     * Adds comments around a <!CDATA section in a \DOMNode.
     *
     * \DOMDocument::loadHTML() in \Drupal\Component\Utility\Html::load() makes
     * CDATA sections from the contents of inline script and style tags. This can
     * cause HTML4 browsers to throw exceptions.
     *
     * This function attempts to solve the problem by creating a
     * \DOMDocumentFragment to comment the CDATA tag.
     *
     * @param \DOMNode $node
     *   The element potentially containing a CDATA node.
     * @param string $comment_start
     *   (optional) A string to use as a comment start marker to escape the CDATA
     *   declaration. Defaults to '//'.
     * @param string $comment_end
     *   (optional) A string to use as a comment end marker to escape the CDATA
     *   declaration. Defaults to an empty string.
     */
    public static function escapeCdataElement(\DOMNode $node, $comment_start = '//', $comment_end = '') {
        foreach ($node->childNodes as $child_node) {
            if ($child_node instanceof \DOMCdataSection) {
                $data = $child_node->data;
                if (!str_contains($child_node->data, 'CDATA')) {
                    $embed_prefix = "\n{$comment_start}<![CDATA[{$comment_end}\n";
                    $embed_suffix = "\n{$comment_start}]]>{$comment_end}\n";
                    $data = $embed_prefix . $data . $embed_suffix;
                }
                $fragment = $node->ownerDocument
                    ->createDocumentFragment();
                $fragment->appendXML($data);
                $node->appendChild($fragment);
                $node->removeChild($child_node);
            }
        }
    }
    
    /**
     * Decodes all HTML entities including numerical ones to regular UTF-8 bytes.
     *
     * Double-escaped entities will only be decoded once ("&amp;lt;" becomes
     * "&lt;", not "<"). Be careful when using this function, as it will revert
     * previous sanitization efforts (&lt;script&gt; will become <script>).
     *
     * This method is not the opposite of Html::escape(). For example, this method
     * will convert "&eacute;" to "é", whereas Html::escape() will not convert "é"
     * to "&eacute;".
     *
     * @param string $text
     *   The text to decode entities in.
     *
     * @return string
     *   The input $text, with all HTML entities decoded once.
     *
     * @see html_entity_decode()
     * @see \Drupal\Component\Utility\Html::escape()
     */
    public static function decodeEntities(string $text) : string {
        return html_entity_decode($text, ENT_QUOTES, 'UTF-8');
    }
    
    /**
     * Escapes text by converting special characters to HTML entities.
     *
     * This method escapes HTML for sanitization purposes by replacing the
     * following special characters with their HTML entity equivalents:
     * - & (ampersand) becomes &amp;
     * - " (double quote) becomes &quot;
     * - ' (single quote) becomes &#039;
     * - < (less than) becomes &lt;
     * - > (greater than) becomes &gt;
     * Special characters that have already been escaped will be double-escaped
     * (for example, "&lt;" becomes "&amp;lt;"), and invalid UTF-8 encoding
     * will be converted to the Unicode replacement character ("�").
     *
     * This method is not the opposite of Html::decodeEntities(). For example,
     * this method will not encode "é" to "&eacute;", whereas
     * Html::decodeEntities() will convert all HTML entities to UTF-8 bytes,
     * including "&eacute;" and "&lt;" to "é" and "<".
     *
     * When constructing @link theme_render render arrays @endlink passing the output of Html::escape() to
     * '#markup' is not recommended. Use the '#plain_text' key instead and the
     * renderer will autoescape the text.
     *
     * @param string $text
     *   The input text.
     *
     * @return string
     *   The text with all HTML special characters converted.
     *
     * @see htmlspecialchars()
     * @see \Drupal\Component\Utility\Html::decodeEntities()
     *
     * @ingroup sanitization
     */
    public static function escape(string $text) : string {
        return htmlspecialchars($text, ENT_QUOTES | ENT_SUBSTITUTE, 'UTF-8');
    }
    
    /**
     * Converts all root-relative URLs to absolute URLs.
     *
     * Does not change any existing protocol-relative or absolute URLs. Does not
     * change other relative URLs because they would result in different absolute
     * URLs depending on the current path. For example: when the same content
     * containing such a relative URL (for example 'image.png'), is served from
     * its canonical URL (for example 'http://example.com/some-article') or from
     * a listing or feed (for example 'http://example.com/all-articles') their
     * "current path" differs, resulting in different absolute URLs:
     * 'http://example.com/some-article/image.png' versus
     * 'http://example.com/all-articles/image.png'. Only one can be correct.
     * Therefore relative URLs that are not root-relative cannot be safely
     * transformed and should generally be avoided.
     *
     * Necessary for HTML that is served outside of a website, for example, RSS
     * and email.
     *
     * @param string $html
     *   The partial HTML snippet to load. Invalid markup will be corrected on
     *   import.
     * @param string $scheme_and_host
     *   The root URL, which has a URI scheme, host and optional port.
     *
     * @return string
     *   The updated HTML snippet.
     */
    public static function transformRootRelativeUrlsToAbsolute($html, $scheme_and_host) {
        assert(empty(array_diff(array_keys(parse_url($scheme_and_host)), [
            "scheme",
            "host",
            "port",
        ])), '$scheme_and_host contains scheme, host and port at most.');
        assert(isset(parse_url($scheme_and_host)["scheme"]), '$scheme_and_host is absolute and hence has a scheme.');
        assert(isset(parse_url($scheme_and_host)["host"]), '$base_url is absolute and hence has a host.');
        $html_dom = Html::load($html);
        $xpath = new \DOMXpath($html_dom);
        // Update all root-relative URLs to absolute URLs in the given HTML.
        // Perform on attributes that may contain a single URI.
        foreach (static::$uriAttributes as $attr) {
            foreach ($xpath->query("//*[starts-with(@{$attr}, '/') and not(starts-with(@{$attr}, '//'))]") as $node) {
                $node->setAttribute($attr, $scheme_and_host . $node->getAttribute($attr));
            }
        }
        // Perform on each URI within "srcset" attributes.
        foreach ($xpath->query("//*[@srcset]") as $node) {
            // @see https://html.spec.whatwg.org/multipage/embedded-content.html#attr-img-srcset
            // @see https://html.spec.whatwg.org/multipage/embedded-content.html#image-candidate-string
            $image_candidate_strings = explode(',', $node->getAttribute('srcset'));
            $image_candidate_strings = array_filter(array_map('trim', $image_candidate_strings));
            foreach ($image_candidate_strings as $key => $image_candidate_string) {
                if ($image_candidate_string[0] === '/' && $image_candidate_string[1] !== '/') {
                    $image_candidate_strings[$key] = $scheme_and_host . $image_candidate_string;
                }
            }
            $node->setAttribute('srcset', implode(', ', $image_candidate_strings));
        }
        return Html::serialize($html_dom);
    }

}

Members

Title Sort descending	Modifiers	Object type	Summary
Html::$classes	protected static	property	An array of previously cleaned HTML classes.
Html::$isAjax	protected static	property	Stores whether the current request was sent via AJAX.
Html::$seenIds	protected static	property	An array of IDs, including incremented versions when an ID is duplicated.
Html::$seenIdsInit	protected static	property	An array of the initial IDs used in one request.
Html::$uriAttributes	protected static	property	All attributes that may contain URIs.
Html::cleanCssIdentifier	public static	function	Prepares a string for use as a CSS identifier (element, class, or ID name).
Html::decodeEntities	public static	function	Decodes all HTML entities including numerical ones to regular UTF-8 bytes.
Html::escape	public static	function	Escapes text by converting special characters to HTML entities.
Html::escapeCdataElement	public static	function	Adds comments around a <!CDATA section in a \DOMNode.
Html::getClass	public static	function	Prepares a string for use as a valid class name.
Html::getId	public static	function	Prepares a string for use as a valid HTML ID.
Html::getUniqueId	public static	function	Prepares a string for use as a valid HTML ID and guarantees uniqueness.
Html::load	public static	function	Parses an HTML snippet and returns it as a DOM object.
Html::normalize	public static	function	Normalizes an HTML snippet.
Html::resetSeenIds	public static	function	Resets the list of seen IDs.
Html::serialize	public static	function	Converts the body of a \DOMDocument back to an HTML snippet.
Html::setIsAjax	public static	function	Sets if this request is an Ajax request.
Html::transformRootRelativeUrlsToAbsolute	public static	function	Converts all root-relative URLs to absolute URLs.

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class Html

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class Html

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