includes/Html.php

   1 <?php
   2 # Copyright © 2009 Aryeh Gregor
   3 # http://www.mediawiki.org/
   4 #
   5 # This program is free software; you can redistribute it and/or modify
   6 # it under the terms of the GNU General Public License as published by
   7 # the Free Software Foundation; either version 2 of the License, or
   8 # (at your option) any later version.
   9 #
  10 # This program is distributed in the hope that it will be useful,
  11 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13 # GNU General Public License for more details.
  14 #
  15 # You should have received a copy of the GNU General Public License along
  16 # with this program; if not, write to the Free Software Foundation, Inc.,
  17 # 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18 # http://www.gnu.org/copyleft/gpl.html
  19
  20 /**
  21  * This class is a collection of static functions that serve two purposes:
  22  *
  23  * 1) Implement any algorithms specified by HTML5, or other HTML
  24  * specifications, in a convenient and self-contained way.
  25  *
  26  * 2) Allow HTML elements to be conveniently and safely generated, like the
  27  * current Xml class but a) less confused (Xml supports HTML-specific things,
  28  * but only sometimes!) and b) not necessarily confined to XML-compatible
  29  * output.
  30  *
  31  * There are two important configuration options this class uses:
  32  *
  33  * $wgHtml5: If this is set to false, then all output should be valid XHTML 1.0
  34  *     Transitional.
  35  * $wgWellFormedXml: If this is set to true, then all output should be
  36  *     well-formed XML (quotes on attributes, self-closing tags, etc.).
  37  *
  38  * This class is meant to be confined to utility functions that are called from
  39  * trusted code paths.  It does not do enforcement of policy like not allowing
  40  * <a> elements.
  41  *
  42  * @since 1.16
  43  */
  44 class Html {
  45         # List of void elements from HTML5, section 9.1.2 as of 2009-08-10
  46         private static $voidElements = array(
  47                 'area',
  48                 'base',
  49                 'br',
  50                 'col',
  51                 'command',
  52                 'embed',
  53                 'hr',
  54                 'img',
  55                 'input',
  56                 'keygen',
  57                 'link',
  58                 'meta',
  59                 'param',
  60                 'source',
  61         );
  62
  63         # Boolean attributes, which may have the value omitted entirely.  Manually
  64         # collected from the HTML5 spec as of 2010-06-07.
  65         private static $boolAttribs = array(
  66                 'async',
  67                 'autofocus',
  68                 'autoplay',
  69                 'checked',
  70                 'controls',
  71                 'defer',
  72                 'disabled',
  73                 'formnovalidate',
  74                 'hidden',
  75                 'ismap',
  76                 'itemscope',
  77                 'loop',
  78                 'multiple',
  79                 'novalidate',
  80                 'open',
  81                 'pubdate',
  82                 'readonly',
  83                 'required',
  84                 'reversed',
  85                 'scoped',
  86                 'seamless',
  87                 'selected',
  88         );
  89
  90         /**
  91          * Returns an HTML element in a string.  The major advantage here over
  92          * manually typing out the HTML is that it will escape all attribute
  93          * values.  If you're hardcoding all the attributes, or there are none, you
  94          * should probably type out the string yourself.
  95          *
  96          * This is quite similar to Xml::tags(), but it implements some useful
  97          * HTML-specific logic.  For instance, there is no $allowShortTag
  98          * parameter: the closing tag is magically omitted if $element has an empty
  99          * content model.  If $wgWellFormedXml is false, then a few bytes will be
 100          * shaved off the HTML output as well.  In the future, other HTML-specific
 101          * features might be added, like allowing arrays for the values of
 102          * attributes like class= and media=.
 103          *
 104          * @param $element  string The element's name, e.g., 'a'
 105          * @param $attribs  array  Associative array of attributes, e.g., array(
 106          *   'href' => 'http://www.mediawiki.org/' ).  See expandAttributes() for
 107          *   further documentation.
 108          * @param $contents string The raw HTML contents of the element: *not*
 109          *   escaped!
 110          * @return string Raw HTML
 111          */
 112         public static function rawElement( $element, $attribs = array(), $contents = '' ) {
 113                 global $wgWellFormedXml;
 114                 $start = self::openElement( $element, $attribs );
 115                 if ( in_array( $element, self::$voidElements ) ) {
 116                         if ( $wgWellFormedXml ) {
 117                                 # Silly XML.
 118                                 return substr( $start, 0, -1 ) . ' />';
 119                         }
 120                         return $start;
 121                 } else {
 122                         return "$start$contents" . self::closeElement( $element );
 123                 }
 124         }
 125
 126         /**
 127          * Identical to rawElement(), but HTML-escapes $contents (like
 128          * Xml::element()).
 129          */
 130         public static function element( $element, $attribs = array(), $contents = '' ) {
 131                 return self::rawElement( $element, $attribs, strtr( $contents, array(
 132                         # There's no point in escaping quotes, >, etc. in the contents of
 133                         # elements.
 134                         '&' => '&amp;',
 135                         '<' => '&lt;'
 136                 ) ) );
 137         }
 138
 139         /**
 140          * Identical to rawElement(), but has no third parameter and omits the end
 141          * tag (and the self-closing '/' in XML mode for empty elements).
 142          */
 143         public static function openElement( $element, $attribs = array() ) {
 144                 global $wgHtml5, $wgWellFormedXml;
 145                 $attribs = (array)$attribs;
 146                 # This is not required in HTML5, but let's do it anyway, for
 147                 # consistency and better compression.
 148                 $element = strtolower( $element );
 149
 150                 # In text/html, initial <html> and <head> tags can be omitted under
 151                 # pretty much any sane circumstances, if they have no attributes.  See:
 152                 # <http://www.whatwg.org/specs/web-apps/current-work/multipage/syntax.html#optional-tags>
 153                 if ( !$wgWellFormedXml && !$attribs
 154                 && in_array( $element, array( 'html', 'head' ) ) ) {
 155                         return '';
 156                 }
 157
 158                 # Remove HTML5-only attributes if we aren't doing HTML5
 159                 if ( !$wgHtml5 ) {
 160                         if ( $element == 'input' ) {
 161                                 # Whitelist of valid XHTML1 types
 162                                 $validTypes = array(
 163                                         'hidden',
 164                                         'text',
 165                                         'password',
 166                                         'checkbox',
 167                                         'radio',
 168                                         'file',
 169                                         'submit',
 170                                         'image',
 171                                         'reset',
 172                                         'button',
 173                                 );
 174                                 if ( isset( $attribs['type'] )
 175                                 && !in_array( $attribs['type'], $validTypes ) ) {
 176                                         # Fall back to type=text, the default
 177                                         unset( $attribs['type'] );
 178                                 }
 179                         }
 180                         if ( $element == 'textarea' && isset( $attribs['maxlength'] ) ) {
 181                                 unset( $attribs['maxlength'] );
 182                         }
 183                         # Here we're blacklisting some HTML5-only attributes...
 184                         $html5attribs = array(
 185                                 'autocomplete',
 186                                 'autofocus',
 187                                 'max',
 188                                 'min',
 189                                 'multiple',
 190                                 'pattern',
 191                                 'placeholder',
 192                                 'required',
 193                                 'step',
 194                                 'spellcheck',
 195                         );
 196                         foreach ( $html5attribs as $badAttr ) {
 197                                 unset( $attribs[$badAttr] );
 198                         }
 199                 }
 200
 201                 return "<$element" . self::expandAttributes(
 202                         self::dropDefaults( $element, $attribs ) ) . '>';
 203         }
 204
 205         /**
 206          * Returns "</$element>", except if $wgWellFormedXml is off, in which case
 207          * it returns the empty string when that's guaranteed to be safe.
 208          *
 209          * @param $element string Name of the element, e.g., 'a'
 210          * @return string A closing tag, if required
 211          */
 212         public static function closeElement( $element ) {
 213                 global $wgWellFormedXml;
 214
 215                 $element = strtolower( $element );
 216
 217                 # Reference:
 218                 # http://www.whatwg.org/specs/web-apps/current-work/multipage/syntax.html#optional-tags
 219                 if ( !$wgWellFormedXml && in_array( $element, array(
 220                         'html',
 221                         'head',
 222                         'body',
 223                         'li',
 224                         'dt',
 225                         'dd',
 226                         'tr',
 227                         'td',
 228                         'th',
 229                 ) ) ) {
 230                         return '';
 231                 }
 232                 return "</$element>";
 233         }
 234
 235         /**
 236          * Given an element name and an associative array of element attributes,
 237          * return an array that is functionally identical to the input array, but
 238          * possibly smaller.  In particular, attributes might be stripped if they
 239          * are given their default values.
 240          *
 241          * This method is not guaranteed to remove all redundant attributes, only
 242          * some common ones and some others selected arbitrarily at random.  It
 243          * only guarantees that the output array should be functionally identical
 244          * to the input array (currently per the HTML 5 draft as of 2009-09-06).
 245          *
 246          * @param $element string Name of the element, e.g., 'a'
 247          * @param $attribs array  Associative array of attributes, e.g., array(
 248          *   'href' => 'http://www.mediawiki.org/' ).  See expandAttributes() for
 249          *   further documentation.
 250          * @return array An array of attributes functionally identical to $attribs
 251          */
 252         private static function dropDefaults( $element, $attribs ) {
 253                 # Don't bother doing anything if we aren't outputting HTML5; it's too
 254                 # much of a pain to maintain two sets of defaults.
 255                 global $wgHtml5;
 256                 if ( !$wgHtml5 ) {
 257                         return $attribs;
 258                 }
 259
 260                 static $attribDefaults = array(
 261                         'area' => array( 'shape' => 'rect' ),
 262                         'button' => array(
 263                                 'formaction' => 'GET',
 264                                 'formenctype' => 'application/x-www-form-urlencoded',
 265                                 'type' => 'submit',
 266                         ),
 267                         'canvas' => array(
 268                                 'height' => '150',
 269                                 'width' => '300',
 270                         ),
 271                         'command' => array( 'type' => 'command' ),
 272                         'form' => array(
 273                                 'action' => 'GET',
 274                                 'autocomplete' => 'on',
 275                                 'enctype' => 'application/x-www-form-urlencoded',
 276                         ),
 277                         'input' => array(
 278                                 'formaction' => 'GET',
 279                                 'type' => 'text',
 280                                 'value' => '',
 281                         ),
 282                         'keygen' => array( 'keytype' => 'rsa' ),
 283                         'link' => array( 'media' => 'all' ),
 284                         'menu' => array( 'type' => 'list' ),
 285                         # Note: the use of text/javascript here instead of other JavaScript
 286                         # MIME types follows the HTML5 spec.
 287                         'script' => array( 'type' => 'text/javascript' ),
 288                         'style' => array(
 289                                 'media' => 'all',
 290                                 'type' => 'text/css',
 291                         ),
 292                         'textarea' => array( 'wrap' => 'soft' ),
 293                 );
 294
 295                 $element = strtolower( $element );
 296
 297                 foreach ( $attribs as $attrib => $value ) {
 298                         $lcattrib = strtolower( $attrib );
 299                         $value = strval( $value );
 300
 301                         # Simple checks using $attribDefaults
 302                         if ( isset( $attribDefaults[$element][$lcattrib] ) &&
 303                         $attribDefaults[$element][$lcattrib] == $value ) {
 304                                 unset( $attribs[$attrib] );
 305                         }
 306
 307                         if ( $lcattrib == 'class' && $value == '' ) {
 308                                 unset( $attribs[$attrib] );
 309                         }
 310                 }
 311
 312                 # More subtle checks
 313                 if ( $element === 'link' && isset( $attribs['type'] )
 314                 && strval( $attribs['type'] ) == 'text/css' ) {
 315                         unset( $attribs['type'] );
 316                 }
 317                 if ( $element === 'select' && isset( $attribs['size'] ) ) {
 318                         if ( in_array( 'multiple', $attribs )
 319                                 || ( isset( $attribs['multiple'] ) && $attribs['multiple'] !== false )
 320                         ) {
 321                                 # A multi-select
 322                                 if ( strval( $attribs['size'] ) == '4' ) {
 323                                         unset( $attribs['size'] );
 324                                 }
 325                         } else {
 326                                 # Single select
 327                                 if ( strval( $attribs['size'] ) == '1' ) {
 328                                         unset( $attribs['size'] );
 329                                 }
 330                         }
 331                 }
 332
 333                 return $attribs;
 334         }
 335
 336         /**
 337          * Given an associative array of element attributes, generate a string
 338          * to stick after the element name in HTML output.  Like array( 'href' =>
 339          * 'http://www.mediawiki.org/' ) becomes something like
 340          * ' href="http://www.mediawiki.org"'.  Again, this is like
 341          * Xml::expandAttributes(), but it implements some HTML-specific logic.
 342          * For instance, it will omit quotation marks if $wgWellFormedXml is false,
 343          * and will treat boolean attributes specially.
 344          *
 345          * @param $attribs array Associative array of attributes, e.g., array(
 346          *   'href' => 'http://www.mediawiki.org/' ).  Values will be HTML-escaped.
 347          *   A value of false means to omit the attribute.  For boolean attributes,
 348          *   you can omit the key, e.g., array( 'checked' ) instead of
 349          *   array( 'checked' => 'checked' ) or such.
 350          * @return string HTML fragment that goes between element name and '>'
 351          *   (starting with a space if at least one attribute is output)
 352          */
 353         public static function expandAttributes( $attribs ) {
 354                 global $wgHtml5, $wgWellFormedXml;
 355
 356                 $ret = '';
 357                 $attribs = (array)$attribs;
 358                 foreach ( $attribs as $key => $value ) {
 359                         if ( $value === false ) {
 360                                 continue;
 361                         }
 362
 363                         # For boolean attributes, support array( 'foo' ) instead of
 364                         # requiring array( 'foo' => 'meaningless' ).
 365                         if ( is_int( $key )
 366                         && in_array( strtolower( $value ), self::$boolAttribs ) ) {
 367                                 $key = $value;
 368                         }
 369
 370                         # Not technically required in HTML5, but required in XHTML 1.0,
 371                         # and we'd like consistency and better compression anyway.
 372                         $key = strtolower( $key );
 373
 374                         # Bug 23769: Blacklist all form validation attributes for now.  Current
 375                         # (June 2010) WebKit has no UI, so the form just refuses to submit
 376                         # without telling the user why, which is much worse than failing
 377                         # server-side validation.  Opera is the only other implementation at
 378                         # this time, and has ugly UI, so just kill the feature entirely until
 379                         # we have at least one good implementation.
 380                         if ( in_array( $key, array( 'max', 'min', 'pattern', 'required', 'step' ) ) ) {
 381                                 continue;
 382                         }
 383
 384                         # See the "Attributes" section in the HTML syntax part of HTML5,
 385                         # 9.1.2.3 as of 2009-08-10.  Most attributes can have quotation
 386                         # marks omitted, but not all.  (Although a literal " is not
 387                         # permitted, we don't check for that, since it will be escaped
 388                         # anyway.)
 389                         #
 390                         # See also research done on further characters that need to be
 391                         # escaped: http://code.google.com/p/html5lib/issues/detail?id=93
 392                         $badChars = "\\x00- '=<>`/\x{00a0}\x{1680}\x{180e}\x{180F}\x{2000}\x{2001}"
 393                                 . "\x{2002}\x{2003}\x{2004}\x{2005}\x{2006}\x{2007}\x{2008}\x{2009}"
 394                                 . "\x{200A}\x{2028}\x{2029}\x{202F}\x{205F}\x{3000}";
 395                         if ( $wgWellFormedXml || $value === ''
 396                         || preg_match( "![$badChars]!u", $value ) ) {
 397                                 $quote = '"';
 398                         } else {
 399                                 $quote = '';
 400                         }
 401
 402                         if ( in_array( $key, self::$boolAttribs ) ) {
 403                                 # In XHTML 1.0 Transitional, the value needs to be equal to the
 404                                 # key.  In HTML5, we can leave the value empty instead.  If we
 405                                 # don't need well-formed XML, we can omit the = entirely.
 406                                 if ( !$wgWellFormedXml ) {
 407                                         $ret .= " $key";
 408                                 } elseif ( $wgHtml5 ) {
 409                                         $ret .= " $key=\"\"";
 410                                 } else {
 411                                         $ret .= " $key=\"$key\"";
 412                                 }
 413                         } else {
 414                                 # Apparently we need to entity-encode \n, \r, \t, although the
 415                                 # spec doesn't mention that.  Since we're doing strtr() anyway,
 416                                 # and we don't need <> escaped here, we may as well not call
 417                                 # htmlspecialchars().  FIXME: verify that we actually need to
 418                                 # escape \n\r\t here, and explain why, exactly.
 419                                 #
 420                                 # We could call Sanitizer::encodeAttribute() for this, but we
 421                                 # don't because we're stubborn and like our marginal savings on
 422                                 # byte size from not having to encode unnecessary quotes.
 423                                 $map = array(
 424                                         '&' => '&amp;',
 425                                         '"' => '&quot;',
 426                                         "\n" => '&#10;',
 427                                         "\r" => '&#13;',
 428                                         "\t" => '&#9;'
 429                                 );
 430                                 if ( $wgWellFormedXml ) {
 431                                         # This is allowed per spec: <http://www.w3.org/TR/xml/#NT-AttValue>
 432                                         # But reportedly it breaks some XML tools?  FIXME: is this
 433                                         # really true?
 434                                         $map['<'] = '&lt;';
 435                                 }
 436                                 $ret .= " $key=$quote" . strtr( $value, $map ) . $quote;
 437                         }
 438                 }
 439                 return $ret;
 440         }
 441
 442         /**
 443          * Output a <script> tag with the given contents.  TODO: do some useful
 444          * escaping as well, like if $contents contains literal '</script>' or (for
 445          * XML) literal "]]>".
 446          *
 447          * @param $contents string JavaScript
 448          * @return string Raw HTML
 449          */
 450         public static function inlineScript( $contents ) {
 451                 global $wgHtml5, $wgJsMimeType, $wgWellFormedXml;
 452
 453                 $attrs = array();
 454                 if ( !$wgHtml5 ) {
 455                         $attrs['type'] = $wgJsMimeType;
 456                 }
 457                 if ( $wgWellFormedXml && preg_match( '/[<&]/', $contents ) ) {
 458                         $contents = "/*<![CDATA[*/$contents/*]]>*/";
 459                 }
 460                 return self::rawElement( 'script', $attrs, $contents );
 461         }
 462
 463         /**
 464          * Output a <script> tag linking to the given URL, e.g.,
 465          * <script src=foo.js></script>.
 466          *
 467          * @param $url string
 468          * @return string Raw HTML
 469          */
 470         public static function linkedScript( $url ) {
 471                 global $wgHtml5, $wgJsMimeType;
 472
 473                 $attrs = array( 'src' => $url );
 474                 if ( !$wgHtml5 ) {
 475                         $attrs['type'] = $wgJsMimeType;
 476                 }
 477                 return self::element( 'script', $attrs );
 478         }
 479
 480         /**
 481          * Output a <style> tag with the given contents for the given media type
 482          * (if any).  TODO: do some useful escaping as well, like if $contents
 483          * contains literal '</style>' (admittedly unlikely).
 484          *
 485          * @param $contents string CSS
 486          * @param $media mixed A media type string, like 'screen'
 487          * @return string Raw HTML
 488          */
 489         public static function inlineStyle( $contents, $media = 'all' ) {
 490                 global $wgWellFormedXml;
 491
 492                 if ( $wgWellFormedXml && preg_match( '/[<&]/', $contents ) ) {
 493                         $contents = "/*<![CDATA[*/$contents/*]]>*/";
 494                 }
 495                 return self::rawElement( 'style', array(
 496                         'type' => 'text/css',
 497                         'media' => $media,
 498                 ), $contents );
 499         }
 500
 501         /**
 502          * Output a <link rel=stylesheet> linking to the given URL for the given
 503          * media type (if any).
 504          *
 505          * @param $url string
 506          * @param $media mixed A media type string, like 'screen'
 507          * @return string Raw HTML
 508          */
 509         public static function linkedStyle( $url, $media = 'all' ) {
 510                 return self::element( 'link', array(
 511                         'rel' => 'stylesheet',
 512                         'href' => $url,
 513                         'type' => 'text/css',
 514                         'media' => $media,
 515                 ) );
 516         }
 517
 518         /**
 519          * Convenience function to produce an <input> element.  This supports the
 520          * new HTML5 input types and attributes, and will silently strip them if
 521          * $wgHtml5 is false.
 522          *
 523          * @param $name    string name attribute
 524          * @param $value   mixed  value attribute
 525          * @param $type    string type attribute
 526          * @param $attribs array  Associative array of miscellaneous extra
 527          *   attributes, passed to Html::element()
 528          * @return string Raw HTML
 529          */
 530         public static function input( $name, $value = '', $type = 'text', $attribs = array() ) {
 531                 $attribs['type'] = $type;
 532                 $attribs['value'] = $value;
 533                 $attribs['name'] = $name;
 534
 535                 return self::element( 'input', $attribs );
 536         }
 537
 538         /**
 539          * Convenience function to produce an input element with type=hidden, like
 540          * Xml::hidden.
 541          *
 542          * @param $name    string name attribute
 543          * @param $value   string value attribute
 544          * @param $attribs array  Associative array of miscellaneous extra
 545          *   attributes, passed to Html::element()
 546          * @return string Raw HTML
 547          */
 548         public static function hidden( $name, $value, $attribs = array() ) {
 549                 return self::input( $name, $value, 'hidden', $attribs );
 550         }
 551
 552         /**
 553          * Convenience function to produce an <input> element.  This supports leaving
 554          * out the cols= and rows= which Xml requires and are required by HTML4/XHTML
 555          * but not required by HTML5 and will silently set cols="" and rows="" if
 556          * $wgHtml5 is false and cols and rows are omitted (HTML4 validates present
 557          * but empty cols="" and rows="" as valid).
 558          *
 559          * @param $name    string name attribute
 560          * @param $value   string value attribute
 561          * @param $attribs array  Associative array of miscellaneous extra
 562          *   attributes, passed to Html::element()
 563          * @return string Raw HTML
 564          */
 565         public static function textarea( $name, $value = '', $attribs = array() ) {
 566                 global $wgHtml5;
 567                 $attribs['name'] = $name;
 568                 if ( !$wgHtml5 ) {
 569                         if ( !isset( $attribs['cols'] ) )
 570                                 $attribs['cols'] = "";
 571                         if ( !isset( $attribs['rows'] ) )
 572                                 $attribs['rows'] = "";
 573                 }
 574                 return self::element( 'textarea', $attribs, $value );
 575         }
 576
 577         /**
 578          * Constructs the opening html-tag with necessary doctypes depending on
 579          * global variables.
 580          *
 581          * @param $attribs array  Associative array of miscellaneous extra
 582          *   attributes, passed to Html::element() of html tag.
 583          * @return string  Raw HTML
 584          */
 585         public static function htmlHeader( $attribs = array() ) {
 586                 $ret = '';
 587
 588                 global $wgMimeType, $wgOutputEncoding;
 589                 if ( self::isXmlMimeType( $wgMimeType ) ) {
 590                         $ret .= "<?xml version=\"1.0\" encoding=\"$wgOutputEncoding\" ?" . ">\n";
 591                 }
 592
 593                 global $wgHtml5, $wgHtml5Version, $wgWellFormedXml, $wgDocType, $wgDTD;
 594                 global $wgXhtmlNamespaces, $wgXhtmlDefaultNamespace;
 595                 if ( $wgHtml5 ) {
 596                         if ( $wgWellFormedXml ) {
 597                                 # Unknown elements and attributes are okay in XML, but unknown
 598                                 # named entities are well-formedness errors and will break XML
 599                                 # parsers.  Thus we need a doctype that gives us appropriate
 600                                 # entity definitions.  The HTML5 spec permits four legacy
 601                                 # doctypes as obsolete but conforming, so let's pick one of
 602                                 # those, although it makes our pages look like XHTML1 Strict.
 603                                 # Isn't compatibility great?
 604                                 $ret .= "<!DOCTYPE html PUBLIC \"-//W3C//DTD XHTML 1.0 Strict//EN\" \"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd\">\n";
 605                         } else {
 606                                 # Much saner.
 607                                 $ret .= "<!doctype html>\n";
 608                         }
 609                         if ( $wgHtml5Version ) {
 610                                 $attribs['version'] = $wgHtml5Version;
 611                         }
 612                 } else {
 613                         $ret .= "<!DOCTYPE html PUBLIC \"$wgDocType\" \"$wgDTD\">\n";
 614                         $attribs['xmlns'] = $wgXhtmlDefaultNamespace;
 615                         foreach ( $wgXhtmlNamespaces as $tag => $ns ) {
 616                                 $attribs["xmlns:$tag"] = $ns;
 617                         }
 618                 }
 619                 return $ret . Html::openElement( 'html', $attribs ) . "\n";
 620         }
 621
 622         /**
 623          * Determines if the given mime type is xml.
 624          *
 625          * @param $mimetype    string MimeType
 626          * @return Boolean
 627          */
 628         public static function isXmlMimeType( $mimetype ) {
 629                 switch ( $mimetype ) {
 630                 case 'text/xml':
 631                 case 'application/xhtml+xml':
 632                 case 'application/xml':
 633                         return true;
 634                 default:
 635                         return false;
 636                 }
 637         }
 638 }