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, and disable
 159                 # form validation regardless (see bug 23769 and the more detailed
 160                 # comment in expandAttributes())
 161                 if ( $element == 'input' ) {
 162                         # Whitelist of types that don't cause validation.  All except
 163                         # 'search' are valid in XHTML1.
 164                         $validTypes = array(
 165                                 'hidden',
 166                                 'text',
 167                                 'password',
 168                                 'checkbox',
 169                                 'radio',
 170                                 'file',
 171                                 'submit',
 172                                 'image',
 173                                 'reset',
 174                                 'button',
 175                                 'search',
 176                         );
 177                         if ( isset( $attribs['type'] )
 178                         && !in_array( $attribs['type'], $validTypes ) ) {
 179                                 unset( $attribs['type'] );
 180                         }
 181                         if ( isset( $attribs['type'] ) && $attribs['type'] == 'search'
 182                         && !$wgHtml5 ) {
 183                                 unset( $attribs['type'] );
 184                         }
 185                 }
 186                 if ( !$wgHtml5 && $element == 'textarea' && isset( $attribs['maxlength'] ) ) {
 187                         unset( $attribs['maxlength'] );
 188                 }
 189
 190                 return "<$element" . self::expandAttributes(
 191                         self::dropDefaults( $element, $attribs ) ) . '>';
 192         }
 193
 194         /**
 195          * Returns "</$element>", except if $wgWellFormedXml is off, in which case
 196          * it returns the empty string when that's guaranteed to be safe.
 197          *
 198          * @param $element string Name of the element, e.g., 'a'
 199          * @return string A closing tag, if required
 200          */
 201         public static function closeElement( $element ) {
 202                 global $wgWellFormedXml;
 203
 204                 $element = strtolower( $element );
 205
 206                 # Reference:
 207                 # http://www.whatwg.org/specs/web-apps/current-work/multipage/syntax.html#optional-tags
 208                 if ( !$wgWellFormedXml && in_array( $element, array(
 209                         'html',
 210                         'head',
 211                         'body',
 212                         'li',
 213                         'dt',
 214                         'dd',
 215                         'tr',
 216                         'td',
 217                         'th',
 218                 ) ) ) {
 219                         return '';
 220                 }
 221                 return "</$element>";
 222         }
 223
 224         /**
 225          * Given an element name and an associative array of element attributes,
 226          * return an array that is functionally identical to the input array, but
 227          * possibly smaller.  In particular, attributes might be stripped if they
 228          * are given their default values.
 229          *
 230          * This method is not guaranteed to remove all redundant attributes, only
 231          * some common ones and some others selected arbitrarily at random.  It
 232          * only guarantees that the output array should be functionally identical
 233          * to the input array (currently per the HTML 5 draft as of 2009-09-06).
 234          *
 235          * @param $element string Name of the element, e.g., 'a'
 236          * @param $attribs array  Associative array of attributes, e.g., array(
 237          *   'href' => 'http://www.mediawiki.org/' ).  See expandAttributes() for
 238          *   further documentation.
 239          * @return array An array of attributes functionally identical to $attribs
 240          */
 241         private static function dropDefaults( $element, $attribs ) {
 242                 # Don't bother doing anything if we aren't outputting HTML5; it's too
 243                 # much of a pain to maintain two sets of defaults.
 244                 global $wgHtml5;
 245                 if ( !$wgHtml5 ) {
 246                         return $attribs;
 247                 }
 248
 249                 static $attribDefaults = array(
 250                         'area' => array( 'shape' => 'rect' ),
 251                         'button' => array(
 252                                 'formaction' => 'GET',
 253                                 'formenctype' => 'application/x-www-form-urlencoded',
 254                                 'type' => 'submit',
 255                         ),
 256                         'canvas' => array(
 257                                 'height' => '150',
 258                                 'width' => '300',
 259                         ),
 260                         'command' => array( 'type' => 'command' ),
 261                         'form' => array(
 262                                 'action' => 'GET',
 263                                 'autocomplete' => 'on',
 264                                 'enctype' => 'application/x-www-form-urlencoded',
 265                         ),
 266                         'input' => array(
 267                                 'formaction' => 'GET',
 268                                 'type' => 'text',
 269                                 'value' => '',
 270                         ),
 271                         'keygen' => array( 'keytype' => 'rsa' ),
 272                         'link' => array( 'media' => 'all' ),
 273                         'menu' => array( 'type' => 'list' ),
 274                         # Note: the use of text/javascript here instead of other JavaScript
 275                         # MIME types follows the HTML5 spec.
 276                         'script' => array( 'type' => 'text/javascript' ),
 277                         'style' => array(
 278                                 'media' => 'all',
 279                                 'type' => 'text/css',
 280                         ),
 281                         'textarea' => array( 'wrap' => 'soft' ),
 282                 );
 283
 284                 $element = strtolower( $element );
 285
 286                 foreach ( $attribs as $attrib => $value ) {
 287                         $lcattrib = strtolower( $attrib );
 288                         $value = strval( $value );
 289
 290                         # Simple checks using $attribDefaults
 291                         if ( isset( $attribDefaults[$element][$lcattrib] ) &&
 292                         $attribDefaults[$element][$lcattrib] == $value ) {
 293                                 unset( $attribs[$attrib] );
 294                         }
 295
 296                         if ( $lcattrib == 'class' && $value == '' ) {
 297                                 unset( $attribs[$attrib] );
 298                         }
 299                 }
 300
 301                 # More subtle checks
 302                 if ( $element === 'link' && isset( $attribs['type'] )
 303                 && strval( $attribs['type'] ) == 'text/css' ) {
 304                         unset( $attribs['type'] );
 305                 }
 306                 if ( $element === 'select' && isset( $attribs['size'] ) ) {
 307                         if ( in_array( 'multiple', $attribs )
 308                                 || ( isset( $attribs['multiple'] ) && $attribs['multiple'] !== false )
 309                         ) {
 310                                 # A multi-select
 311                                 if ( strval( $attribs['size'] ) == '4' ) {
 312                                         unset( $attribs['size'] );
 313                                 }
 314                         } else {
 315                                 # Single select
 316                                 if ( strval( $attribs['size'] ) == '1' ) {
 317                                         unset( $attribs['size'] );
 318                                 }
 319                         }
 320                 }
 321
 322                 return $attribs;
 323         }
 324
 325         /**
 326          * Given an associative array of element attributes, generate a string
 327          * to stick after the element name in HTML output.  Like array( 'href' =>
 328          * 'http://www.mediawiki.org/' ) becomes something like
 329          * ' href="http://www.mediawiki.org"'.  Again, this is like
 330          * Xml::expandAttributes(), but it implements some HTML-specific logic.
 331          * For instance, it will omit quotation marks if $wgWellFormedXml is false,
 332          * and will treat boolean attributes specially.
 333          *
 334          * @param $attribs array Associative array of attributes, e.g., array(
 335          *   'href' => 'http://www.mediawiki.org/' ).  Values will be HTML-escaped.
 336          *   A value of false means to omit the attribute.  For boolean attributes,
 337          *   you can omit the key, e.g., array( 'checked' ) instead of
 338          *   array( 'checked' => 'checked' ) or such.
 339          * @return string HTML fragment that goes between element name and '>'
 340          *   (starting with a space if at least one attribute is output)
 341          */
 342         public static function expandAttributes( $attribs ) {
 343                 global $wgHtml5, $wgWellFormedXml;
 344
 345                 $ret = '';
 346                 $attribs = (array)$attribs;
 347                 foreach ( $attribs as $key => $value ) {
 348                         if ( $value === false ) {
 349                                 continue;
 350                         }
 351
 352                         # For boolean attributes, support array( 'foo' ) instead of
 353                         # requiring array( 'foo' => 'meaningless' ).
 354                         if ( is_int( $key )
 355                         && in_array( strtolower( $value ), self::$boolAttribs ) ) {
 356                                 $key = $value;
 357                         }
 358
 359                         # Not technically required in HTML5, but required in XHTML 1.0,
 360                         # and we'd like consistency and better compression anyway.
 361                         $key = strtolower( $key );
 362
 363                         # Bug 23769: Blacklist all form validation attributes for now.  Current
 364                         # (June 2010) WebKit has no UI, so the form just refuses to submit
 365                         # without telling the user why, which is much worse than failing
 366                         # server-side validation.  Opera is the only other implementation at
 367                         # this time, and has ugly UI, so just kill the feature entirely until
 368                         # we have at least one good implementation.
 369                         if ( in_array( $key, array( 'max', 'min', 'pattern', 'required', 'step' ) ) ) {
 370                                 continue;
 371                         }
 372
 373                         # Here we're blacklisting some HTML5-only attributes...
 374                         if ( !$wgHtml5 && in_array( $key, array(
 375                                         'autocomplete',
 376                                         'autofocus',
 377                                         'max',
 378                                         'min',
 379                                         'multiple',
 380                                         'pattern',
 381                                         'placeholder',
 382                                         'required',
 383                                         'step',
 384                                         'spellcheck',
 385                         ) ) ) {
 386                                 continue;
 387                         }
 388
 389                         # See the "Attributes" section in the HTML syntax part of HTML5,
 390                         # 9.1.2.3 as of 2009-08-10.  Most attributes can have quotation
 391                         # marks omitted, but not all.  (Although a literal " is not
 392                         # permitted, we don't check for that, since it will be escaped
 393                         # anyway.)
 394                         #
 395                         # See also research done on further characters that need to be
 396                         # escaped: http://code.google.com/p/html5lib/issues/detail?id=93
 397                         $badChars = "\\x00- '=<>`/\x{00a0}\x{1680}\x{180e}\x{180F}\x{2000}\x{2001}"
 398                                 . "\x{2002}\x{2003}\x{2004}\x{2005}\x{2006}\x{2007}\x{2008}\x{2009}"
 399                                 . "\x{200A}\x{2028}\x{2029}\x{202F}\x{205F}\x{3000}";
 400                         if ( $wgWellFormedXml || $value === ''
 401                         || preg_match( "![$badChars]!u", $value ) ) {
 402                                 $quote = '"';
 403                         } else {
 404                                 $quote = '';
 405                         }
 406
 407                         if ( in_array( $key, self::$boolAttribs ) ) {
 408                                 # In XHTML 1.0 Transitional, the value needs to be equal to the
 409                                 # key.  In HTML5, we can leave the value empty instead.  If we
 410                                 # don't need well-formed XML, we can omit the = entirely.
 411                                 if ( !$wgWellFormedXml ) {
 412                                         $ret .= " $key";
 413                                 } elseif ( $wgHtml5 ) {
 414                                         $ret .= " $key=\"\"";
 415                                 } else {
 416                                         $ret .= " $key=\"$key\"";
 417                                 }
 418                         } else {
 419                                 # Apparently we need to entity-encode \n, \r, \t, although the
 420                                 # spec doesn't mention that.  Since we're doing strtr() anyway,
 421                                 # and we don't need <> escaped here, we may as well not call
 422                                 # htmlspecialchars().  FIXME: verify that we actually need to
 423                                 # escape \n\r\t here, and explain why, exactly.
 424                                 #
 425                                 # We could call Sanitizer::encodeAttribute() for this, but we
 426                                 # don't because we're stubborn and like our marginal savings on
 427                                 # byte size from not having to encode unnecessary quotes.
 428                                 $map = array(
 429                                         '&' => '&amp;',
 430                                         '"' => '&quot;',
 431                                         "\n" => '&#10;',
 432                                         "\r" => '&#13;',
 433                                         "\t" => '&#9;'
 434                                 );
 435                                 if ( $wgWellFormedXml ) {
 436                                         # This is allowed per spec: <http://www.w3.org/TR/xml/#NT-AttValue>
 437                                         # But reportedly it breaks some XML tools?  FIXME: is this
 438                                         # really true?
 439                                         $map['<'] = '&lt;';
 440                                 }
 441                                 $ret .= " $key=$quote" . strtr( $value, $map ) . $quote;
 442                         }
 443                 }
 444                 return $ret;
 445         }
 446
 447         /**
 448          * Output a <script> tag with the given contents.  TODO: do some useful
 449          * escaping as well, like if $contents contains literal '</script>' or (for
 450          * XML) literal "]]>".
 451          *
 452          * @param $contents string JavaScript
 453          * @return string Raw HTML
 454          */
 455         public static function inlineScript( $contents ) {
 456                 global $wgHtml5, $wgJsMimeType, $wgWellFormedXml;
 457
 458                 $attrs = array();
 459                 if ( !$wgHtml5 ) {
 460                         $attrs['type'] = $wgJsMimeType;
 461                 }
 462                 if ( $wgWellFormedXml && preg_match( '/[<&]/', $contents ) ) {
 463                         $contents = "/*<![CDATA[*/$contents/*]]>*/";
 464                 }
 465                 return self::rawElement( 'script', $attrs, $contents );
 466         }
 467
 468         /**
 469          * Output a <script> tag linking to the given URL, e.g.,
 470          * <script src=foo.js></script>.
 471          *
 472          * @param $url string
 473          * @return string Raw HTML
 474          */
 475         public static function linkedScript( $url ) {
 476                 global $wgHtml5, $wgJsMimeType;
 477
 478                 $attrs = array( 'src' => $url );
 479                 if ( !$wgHtml5 ) {
 480                         $attrs['type'] = $wgJsMimeType;
 481                 }
 482                 return self::element( 'script', $attrs );
 483         }
 484
 485         /**
 486          * Output a <style> tag with the given contents for the given media type
 487          * (if any).  TODO: do some useful escaping as well, like if $contents
 488          * contains literal '</style>' (admittedly unlikely).
 489          *
 490          * @param $contents string CSS
 491          * @param $media mixed A media type string, like 'screen'
 492          * @return string Raw HTML
 493          */
 494         public static function inlineStyle( $contents, $media = 'all' ) {
 495                 global $wgWellFormedXml;
 496
 497                 if ( $wgWellFormedXml && preg_match( '/[<&]/', $contents ) ) {
 498                         $contents = "/*<![CDATA[*/$contents/*]]>*/";
 499                 }
 500                 return self::rawElement( 'style', array(
 501                         'type' => 'text/css',
 502                         'media' => $media,
 503                 ), $contents );
 504         }
 505
 506         /**
 507          * Output a <link rel=stylesheet> linking to the given URL for the given
 508          * media type (if any).
 509          *
 510          * @param $url string
 511          * @param $media mixed A media type string, like 'screen'
 512          * @return string Raw HTML
 513          */
 514         public static function linkedStyle( $url, $media = 'all' ) {
 515                 return self::element( 'link', array(
 516                         'rel' => 'stylesheet',
 517                         'href' => $url,
 518                         'type' => 'text/css',
 519                         'media' => $media,
 520                 ) );
 521         }
 522
 523         /**
 524          * Convenience function to produce an <input> element.  This supports the
 525          * new HTML5 input types and attributes, and will silently strip them if
 526          * $wgHtml5 is false.
 527          *
 528          * @param $name    string name attribute
 529          * @param $value   mixed  value attribute
 530          * @param $type    string type attribute
 531          * @param $attribs array  Associative array of miscellaneous extra
 532          *   attributes, passed to Html::element()
 533          * @return string Raw HTML
 534          */
 535         public static function input( $name, $value = '', $type = 'text', $attribs = array() ) {
 536                 $attribs['type'] = $type;
 537                 $attribs['value'] = $value;
 538                 $attribs['name'] = $name;
 539
 540                 return self::element( 'input', $attribs );
 541         }
 542
 543         /**
 544          * Convenience function to produce an input element with type=hidden, like
 545          * Xml::hidden.
 546          *
 547          * @param $name    string name attribute
 548          * @param $value   string value attribute
 549          * @param $attribs array  Associative array of miscellaneous extra
 550          *   attributes, passed to Html::element()
 551          * @return string Raw HTML
 552          */
 553         public static function hidden( $name, $value, $attribs = array() ) {
 554                 return self::input( $name, $value, 'hidden', $attribs );
 555         }
 556
 557         /**
 558          * Convenience function to produce an <input> element.  This supports leaving
 559          * out the cols= and rows= which Xml requires and are required by HTML4/XHTML
 560          * but not required by HTML5 and will silently set cols="" and rows="" if
 561          * $wgHtml5 is false and cols and rows are omitted (HTML4 validates present
 562          * but empty cols="" and rows="" as valid).
 563          *
 564          * @param $name    string name attribute
 565          * @param $value   string value attribute
 566          * @param $attribs array  Associative array of miscellaneous extra
 567          *   attributes, passed to Html::element()
 568          * @return string Raw HTML
 569          */
 570         public static function textarea( $name, $value = '', $attribs = array() ) {
 571                 global $wgHtml5;
 572                 $attribs['name'] = $name;
 573                 if ( !$wgHtml5 ) {
 574                         if ( !isset( $attribs['cols'] ) ) {
 575                                 $attribs['cols'] = "";
 576                         }
 577                         if ( !isset( $attribs['rows'] ) ) {
 578                                 $attribs['rows'] = "";
 579                         }
 580                 }
 581                 return self::element( 'textarea', $attribs, $value );
 582         }
 583
 584         /**
 585          * Constructs the opening html-tag with necessary doctypes depending on
 586          * global variables.
 587          *
 588          * @param $attribs array  Associative array of miscellaneous extra
 589          *   attributes, passed to Html::element() of html tag.
 590          * @return string  Raw HTML
 591          */
 592         public static function htmlHeader( $attribs = array() ) {
 593                 $ret = '';
 594
 595                 global $wgMimeType, $wgOutputEncoding;
 596                 if ( self::isXmlMimeType( $wgMimeType ) ) {
 597                         $ret .= "<?xml version=\"1.0\" encoding=\"$wgOutputEncoding\" ?" . ">\n";
 598                 }
 599
 600                 global $wgHtml5, $wgHtml5Version, $wgDocType, $wgDTD;
 601                 global $wgXhtmlNamespaces, $wgXhtmlDefaultNamespace;
 602                 if ( $wgHtml5 ) {
 603                         $ret .= "<!DOCTYPE html>\n";
 604                         if ( $wgHtml5Version ) {
 605                                 $attribs['version'] = $wgHtml5Version;
 606                         }
 607                 } else {
 608                         $ret .= "<!DOCTYPE html PUBLIC \"$wgDocType\" \"$wgDTD\">\n";
 609                         $attribs['xmlns'] = $wgXhtmlDefaultNamespace;
 610                         foreach ( $wgXhtmlNamespaces as $tag => $ns ) {
 611                                 $attribs["xmlns:$tag"] = $ns;
 612                         }
 613                 }
 614                 $html = Html::openElement( 'html', $attribs );
 615                 if ( $html ) {
 616                         $html .= "\n";
 617                 }
 618                 $ret .= $html;
 619                 return $ret;
 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 }