includes/Html.php

   1 <?php
   2 # Copyright (C) 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 HTML 5, 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 class Html {
  43         # List of void elements from HTML 5, section 9.1.2 as of 2009-08-10
  44         private static $voidElements = array(
  45                 'area',
  46                 'base',
  47                 'br',
  48                 'col',
  49                 'command',
  50                 'embed',
  51                 'hr',
  52                 'img',
  53                 'input',
  54                 'keygen',
  55                 'link',
  56                 'meta',
  57                 'param',
  58                 'source',
  59         );
  60
  61         # Boolean attributes, which may have the value omitted entirely.  Manually
  62         # collected from the HTML 5 spec as of 2009-08-10.
  63         private static $boolAttribs = array(
  64                 'async',
  65                 'autobuffer',
  66                 'autofocus',
  67                 'autoplay',
  68                 'checked',
  69                 'controls',
  70                 'defer',
  71                 'disabled',
  72                 'formnovalidate',
  73                 'hidden',
  74                 'ismap',
  75                 'loop',
  76                 'multiple',
  77                 'novalidate',
  78                 'open',
  79                 'readonly',
  80                 'required',
  81                 'reversed',
  82                 'scoped',
  83                 'seamless',
  84         );
  85
  86         /**
  87          * Returns an HTML element in a string.  The major advantage here over
  88          * manually typing out the HTML is that it will escape all attribute
  89          * values.  If you're hardcoding all the attributes, or there are none, you
  90          * should probably type out the string yourself.
  91          *
  92          * This is quite similar to Xml::element(), but it implements some useful
  93          * HTML-specific logic.  For instance, there is no $allowShortTag
  94          * parameter: the closing tag is magically omitted if $element has an empty
  95          * content model.  If $wgWellFormedXml is false, then a few bytes will be
  96          * shaved off the HTML output as well.  In the future, other HTML-specific
  97          * features might be added, like allowing arrays for the values of
  98          * attributes like class= and media=.
  99          *
 100          * One notable difference to Xml::element() is that $contents is *not*
 101          * escaped.  This means that Html::element() can be usefully nested, rather
 102          * than using the rather clumsy Xml::openElement() and Xml::closeElement().
 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/' ).  Values will be HTML-escaped.
 107          * @param $contents string The raw HTML contents of the element: *not*
 108          *   escaped!
 109          * @return string Raw HTML
 110          */
 111         public static function rawElement( $element, $attribs = array(), $contents = '' ) {
 112                 global $wgWellFormedXml;
 113                 $element = strtolower( $element );
 114                 $start = "<$element" . self::expandAttributes( $attribs );
 115                 if ( in_array( $element, self::$voidElements ) ) {
 116                         if ( $wgWellFormedXml ) {
 117                                 return "$start />";
 118                         }
 119                         return "$start>";
 120                 } else {
 121                         return "$start>$contents</$element>";
 122                 }
 123         }
 124
 125         /**
 126          * Identical to rawElement(), but HTML-escapes $contents.
 127          */
 128         public static function element( $element, $attribs = array(), $contents = '' ) {
 129                 return self::rawElement( $element, $attribs, strtr( $contents, array(
 130                         # There's no point in escaping quotes, >, etc. in the contents of
 131                         # elements.
 132                         '&' => '&amp;',
 133                         '<' => '&lt;'
 134                 ) ) );
 135         }
 136
 137         /**
 138          * Given an associative array of element attributes, generate a string
 139          * to stick after the element name in HTML output.  Like array( 'href' =>
 140          * 'http://www.mediawiki.org/' ) becomes something like
 141          * ' href="http://www.mediawiki.org"'.  Again, this is like
 142          * Xml::expandAttributes(), but it implements some HTML-specific logic.
 143          * For instance, it will omit quotation marks if $wgWellFormedXml is false,
 144          * and will treat boolean attributes specially.
 145          *
 146          * @param $attribs array Associative array of attributes, e.g., array(
 147          *   'href' => 'http://www.mediawiki.org/' ).  Values will be HTML-escaped.
 148          * @return string HTML fragment that goes between element name and '>'
 149          *   (starting with a space if at least one attribute is output)
 150          */
 151         public static function expandAttributes( $attribs ) {
 152                 global $wgHtml5, $wgWellFormedXml;
 153
 154                 $ret = '';
 155                 foreach ( $attribs as $key => $value ) {
 156                         # See the "Attributes" section in the HTML syntax part of HTML 5,
 157                         # 9.1.2.3 as of 2009-08-10.  Most attributes can have quotation
 158                         # marks omitted, but not all.  (Although a literal " is not
 159                         # permitted, we don't check for that, since it will be escaped
 160                         # anyway.)
 161                         if ( $wgWellFormedXml || $value == ''
 162                         || preg_match( "/[ '=<>]/", $value ) ) {
 163                                 $quote = '"';
 164                         } else {
 165                                 $quote = '';
 166                         }
 167
 168                         if ( in_array( $key, self::$boolAttribs ) ) {
 169                                 # In XHTML 1.0 Transitional, the value needs to be equal to the
 170                                 # key.  In HTML 5, we can leave the value empty instead.  If we
 171                                 # don't need well-formed XML, we can omit the = entirely.
 172                                 if ( !$wgWellFormedXml ) {
 173                                         $ret .= " $key";
 174                                 } elseif ( $wgHtml5 ) {
 175                                         $ret .= " $key=\"\"";
 176                                 } else {
 177                                         $ret .= " $key=\"$key\"";
 178                                 }
 179                         } else {
 180                                 # Apparently we need to entity-encode \n, \r, \t, although the
 181                                 # spec doesn't mention that.  Since we're doing strtr() anyway,
 182                                 # and we don't need <> escaped here, we may as well not call
 183                                 # htmlspecialchars().  FIXME: verify that we actually need to
 184                                 # escape \n\r\t here, and explain why, exactly.
 185                                 $ret .= " $key=$quote" . strtr( $value, array(
 186                                         '&' => '&amp;',
 187                                         '"' => '&quot;',
 188                                         "\n" => '&#10;',
 189                                         "\r" => '&#13;',
 190                                         "\t" => '&#9;'
 191                                 ) ) . $quote;
 192                         }
 193                 }
 194                 return $ret;
 195         }
 196
 197         /**
 198          * Output a <script> tag with the given contents.  TODO: do some useful
 199          * escaping as well, like if $contents contains literal '</script>' or (for
 200          * XML) literal "]]>".
 201          *
 202          * @param $contents string JavaScript
 203          * @return string Raw HTML
 204          */
 205         public static function inlineScript( $contents ) {
 206                 global $wgHtml5, $wgJsMimeType;
 207
 208                 $attrs = array();
 209                 if ( !$wgHtml5 ) {
 210                         $attrs['type'] = $wgJsMimeType;
 211                         $contents = "/*<![CDATA[*/$contents/*]]>*/";
 212                 }
 213                 return self::rawElement( 'script', $attrs, $contents );
 214         }
 215
 216         /**
 217          * Output a <script> tag linking to the given URL, e.g.,
 218          * <script src=foo.js></script>.
 219          *
 220          * @param $url string
 221          * @return string Raw HTML
 222          */
 223         public static function linkedScript( $url ) {
 224                 global $wgHtml5, $wgJsMimeType;
 225
 226                 $attrs = array( 'src' => $url );
 227                 if ( !$wgHtml5 ) {
 228                         $attrs['type'] = $wgJsMimeType;
 229                 }
 230                 return self::element( 'script', $attrs );
 231         }
 232
 233         /**
 234          * Output a <style> tag with the given contents for the given media type
 235          * (if any).  TODO: do some useful escaping as well, like if $contents
 236          * contains literal '</style>' (admittedly unlikely).
 237          *
 238          * @param $contents string CSS
 239          * @param $media mixed A media type string, like 'screen', or null for all
 240          *   media
 241          * @return string Raw HTML
 242          */
 243         public static function inlineStyle( $contents, $media = null ) {
 244                 global $wgHtml5;
 245
 246                 $attrs = array();
 247                 if ( !$wgHtml5 ) {
 248                         # Technically we should probably add CDATA stuff here like with
 249                         # scripts, but in practice, stylesheets tend not to have
 250                         # problematic characters anyway.
 251                         $attrs['type'] = 'text/css';
 252                 }
 253                 if ( $media !== null ) {
 254                         $attrs['media'] = $media;
 255                 }
 256                 return self::rawElement( 'style', $attrs, $contents );
 257         }
 258
 259         /**
 260          * Output a <link rel=stylesheet> linking to the given URL for the given
 261          * media type (if any).
 262          *
 263          * @param $url string
 264          * @param $media mixed A media type string, like 'screen', or null for all
 265          *   media
 266          * @return string Raw HTML
 267          */
 268         public static function linkedStyle( $url, $media = null ) {
 269                 global $wgHtml5;
 270
 271                 $attrs = array( 'rel' => 'stylesheet', 'href' => $url );
 272                 if ( !$wgHtml5 ) {
 273                         $attrs['type'] = 'text/css';
 274                 }
 275                 if ( $media !== null ) {
 276                         $attrs['media'] = $media;
 277                 }
 278                 return self::element( 'link', $attrs );
 279         }
 280
 281         /**
 282          * Convenience function to produce an <input> element.  This supports the
 283          * new HTML 5 input types and attributes, and will silently strip them if
 284          * $wgHtml5 is false.
 285          *
 286          * @param $name    string name attribute
 287          * @param $value   mixed  value attribute (null = omit)
 288          * @param $type    string type attribute
 289          * @param $attribs array  Assocative array of miscellaneous extra attributes,
 290          *   passed to Html::element()
 291          * @return string Raw HTML
 292          */
 293         public static function input( $name, $value = null, $type = 'text', $attribs = array() ) {
 294                 global $wgHtml5;
 295
 296                 if ( !$wgHtml5 ) {
 297                         // With $wgHtml5 off we want to validate as XHTML 1, so we
 298                         // strip out any fancy HTML 5-only input types for now.
 299                         //
 300                         // Whitelist of valid types:
 301                         $validTypes = array(
 302                                 'hidden',
 303                                 'text',
 304                                 'password',
 305                                 'checkbox',
 306                                 'radio',
 307                                 'file',
 308                                 'submit',
 309                                 'image',
 310                                 'reset',
 311                                 'button',
 312                         );
 313                         if ( !in_array( $type, $validTypes ) ) {
 314                                 $type = 'text';
 315                         }
 316                         // Here we're blacklisting some HTML5-only attributes...
 317                         $html5attribs = array(
 318                                 'autocomplete',
 319                                 'autofocus',
 320                                 'max',
 321                                 'min',
 322                                 'multiple',
 323                                 'pattern',
 324                                 'placeholder',
 325                                 'required',
 326                                 'step',
 327                         );
 328                         foreach ( $html5attribs as $badAttr ) {
 329                                 unset( $attribs[$badAttr] );
 330                         }
 331                 }
 332                 if ( $type != 'text' ) {
 333                         $attribs['type'] = $type;
 334                 }
 335                 if ( $value !== null ) {
 336                         $attribs['value'] = $value;
 337                 }
 338                 $attribs['name'] = $name;
 339
 340                 return self::element( 'input', $attribs );
 341         }
 342 }