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::tags(), 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          * @param $element  string The element's name, e.g., 'a'
 101          * @param $attribs  array  Associative array of attributes, e.g., array(
 102          *   'href' => 'http://www.mediawiki.org/' ).  Values will be HTML-escaped.
 103          *   A value of false means to omit the attribute.
 104          * @param $contents string The raw HTML contents of the element: *not*
 105          *   escaped!
 106          * @return string Raw HTML
 107          */
 108         public static function rawElement( $element, $attribs = array(), $contents = '' ) {
 109                 global $wgHtml5, $wgWellFormedXml;
 110                 # This is not required in HTML 5, but let's do it anyway, for
 111                 # consistency and better compression.
 112                 $element = strtolower( $element );
 113
 114                 # Element-specific hacks to slim down output and ensure validity
 115                 if ( $element == 'input' ) {
 116                         if ( !$wgHtml5 ) {
 117                                 # With $wgHtml5 off we want to validate as XHTML 1, so we
 118                                 # strip out any fancy HTML 5-only input types for now.
 119                                 #
 120                                 # Whitelist of valid types:
 121                                 $validTypes = array(
 122                                         'hidden',
 123                                         'text',
 124                                         'password',
 125                                         'checkbox',
 126                                         'radio',
 127                                         'file',
 128                                         'submit',
 129                                         'image',
 130                                         'reset',
 131                                         'button',
 132                                 );
 133                                 if ( isset( $attribs['type'] )
 134                                 && !in_array( $attribs['type'], $validTypes ) ) {
 135                                         # Fall back to type=text, the default
 136                                         unset( $attribs['type'] );
 137                                 }
 138                                 # Here we're blacklisting some HTML5-only attributes...
 139                                 $html5attribs = array(
 140                                         'autocomplete',
 141                                         'autofocus',
 142                                         'max',
 143                                         'min',
 144                                         'multiple',
 145                                         'pattern',
 146                                         'placeholder',
 147                                         'required',
 148                                         'step',
 149                                 );
 150                                 foreach ( $html5attribs as $badAttr ) {
 151                                         unset( $attribs[$badAttr] );
 152                                 }
 153                         }
 154                 }
 155
 156                 $start = "<$element" . self::expandAttributes( $attribs );
 157                 if ( in_array( $element, self::$voidElements ) ) {
 158                         if ( $wgWellFormedXml ) {
 159                                 return "$start />";
 160                         }
 161                         return "$start>";
 162                 } else {
 163                         return "$start>$contents</$element>";
 164                 }
 165         }
 166
 167         /**
 168          * Identical to rawElement(), but HTML-escapes $contents (like
 169          * Xml::element()).
 170          */
 171         public static function element( $element, $attribs = array(), $contents = '' ) {
 172                 return self::rawElement( $element, $attribs, strtr( $contents, array(
 173                         # There's no point in escaping quotes, >, etc. in the contents of
 174                         # elements.
 175                         '&' => '&amp;',
 176                         '<' => '&lt;'
 177                 ) ) );
 178         }
 179
 180         /**
 181          * Given an associative array of element attributes, generate a string
 182          * to stick after the element name in HTML output.  Like array( 'href' =>
 183          * 'http://www.mediawiki.org/' ) becomes something like
 184          * ' href="http://www.mediawiki.org"'.  Again, this is like
 185          * Xml::expandAttributes(), but it implements some HTML-specific logic.
 186          * For instance, it will omit quotation marks if $wgWellFormedXml is false,
 187          * and will treat boolean attributes specially.
 188          *
 189          * @param $attribs array Associative array of attributes, e.g., array(
 190          *   'href' => 'http://www.mediawiki.org/' ).  Values will be HTML-escaped.
 191          *   A value of false means to omit the attribute.
 192          * @return string HTML fragment that goes between element name and '>'
 193          *   (starting with a space if at least one attribute is output)
 194          */
 195         public static function expandAttributes( $attribs ) {
 196                 global $wgHtml5, $wgWellFormedXml;
 197
 198                 $ret = '';
 199                 foreach ( $attribs as $key => $value ) {
 200                         if ( $value === false ) {
 201                                 continue;
 202                         }
 203
 204                         # For boolean attributes, support array( 'foo' ) instead of
 205                         # requiring array( 'foo' => 'meaningless' ).
 206                         if ( is_int( $key )
 207                         && in_array( strtolower( $value ), self::$boolAttribs ) ) {
 208                                 $key = $value;
 209                         }
 210
 211                         # Not technically required in HTML 5, but required in XHTML 1.0,
 212                         # and we'd like consistency and better compression anyway.
 213                         $key = strtolower( $key );
 214
 215                         # See the "Attributes" section in the HTML syntax part of HTML 5,
 216                         # 9.1.2.3 as of 2009-08-10.  Most attributes can have quotation
 217                         # marks omitted, but not all.  (Although a literal " is not
 218                         # permitted, we don't check for that, since it will be escaped
 219                         # anyway.)
 220                         if ( $wgWellFormedXml || $value == ''
 221                         || preg_match( "/[ '=<>]/", $value ) ) {
 222                                 $quote = '"';
 223                         } else {
 224                                 $quote = '';
 225                         }
 226
 227                         if ( in_array( $key, self::$boolAttribs ) ) {
 228                                 # In XHTML 1.0 Transitional, the value needs to be equal to the
 229                                 # key.  In HTML 5, we can leave the value empty instead.  If we
 230                                 # don't need well-formed XML, we can omit the = entirely.
 231                                 if ( !$wgWellFormedXml ) {
 232                                         $ret .= " $key";
 233                                 } elseif ( $wgHtml5 ) {
 234                                         $ret .= " $key=\"\"";
 235                                 } else {
 236                                         $ret .= " $key=\"$key\"";
 237                                 }
 238                         } else {
 239                                 # Apparently we need to entity-encode \n, \r, \t, although the
 240                                 # spec doesn't mention that.  Since we're doing strtr() anyway,
 241                                 # and we don't need <> escaped here, we may as well not call
 242                                 # htmlspecialchars().  FIXME: verify that we actually need to
 243                                 # escape \n\r\t here, and explain why, exactly.
 244                                 $ret .= " $key=$quote" . strtr( $value, array(
 245                                         '&' => '&amp;',
 246                                         '"' => '&quot;',
 247                                         "\n" => '&#10;',
 248                                         "\r" => '&#13;',
 249                                         "\t" => '&#9;'
 250                                 ) ) . $quote;
 251                         }
 252                 }
 253                 return $ret;
 254         }
 255
 256         /**
 257          * Output a <script> tag with the given contents.  TODO: do some useful
 258          * escaping as well, like if $contents contains literal '</script>' or (for
 259          * XML) literal "]]>".
 260          *
 261          * @param $contents string JavaScript
 262          * @return string Raw HTML
 263          */
 264         public static function inlineScript( $contents ) {
 265                 global $wgHtml5, $wgJsMimeType, $wgWellFormedXml;
 266
 267                 $attrs = array();
 268                 if ( !$wgHtml5 ) {
 269                         $attrs['type'] = $wgJsMimeType;
 270                 }
 271                 if ( $wgWellFormedXml && preg_match( '/[<&]/', $contents ) ) {
 272                         $contents = "/*<![CDATA[*/$contents/*]]>*/";
 273                 }
 274                 return self::rawElement( 'script', $attrs, $contents );
 275         }
 276
 277         /**
 278          * Output a <script> tag linking to the given URL, e.g.,
 279          * <script src=foo.js></script>.
 280          *
 281          * @param $url string
 282          * @return string Raw HTML
 283          */
 284         public static function linkedScript( $url ) {
 285                 global $wgHtml5, $wgJsMimeType;
 286
 287                 $attrs = array( 'src' => $url );
 288                 if ( !$wgHtml5 ) {
 289                         $attrs['type'] = $wgJsMimeType;
 290                 }
 291                 return self::element( 'script', $attrs );
 292         }
 293
 294         /**
 295          * Output a <style> tag with the given contents for the given media type
 296          * (if any).  TODO: do some useful escaping as well, like if $contents
 297          * contains literal '</style>' (admittedly unlikely).
 298          *
 299          * @param $contents string CSS
 300          * @param $media mixed A media type string, like 'screen', or null for all
 301          *   media
 302          * @return string Raw HTML
 303          */
 304         public static function inlineStyle( $contents, $media = null ) {
 305                 global $wgHtml5, $wgWellFormedXml;
 306
 307                 $attrs = array();
 308                 if ( !$wgHtml5 ) {
 309                         $attrs['type'] = 'text/css';
 310                 }
 311                 if ( $wgWellFormedXml && preg_match( '/[<&]/', $contents ) ) {
 312                         $contents = "/*<![CDATA[*/$contents/*]]>*/";
 313                 }
 314                 if ( $media !== null ) {
 315                         $attrs['media'] = $media;
 316                 }
 317                 return self::rawElement( 'style', $attrs, $contents );
 318         }
 319
 320         /**
 321          * Output a <link rel=stylesheet> linking to the given URL for the given
 322          * media type (if any).
 323          *
 324          * @param $url string
 325          * @param $media mixed A media type string, like 'screen', or null for all
 326          *   media
 327          * @return string Raw HTML
 328          */
 329         public static function linkedStyle( $url, $media = null ) {
 330                 global $wgHtml5;
 331
 332                 $attrs = array( 'rel' => 'stylesheet', 'href' => $url );
 333                 if ( !$wgHtml5 ) {
 334                         $attrs['type'] = 'text/css';
 335                 }
 336                 if ( $media !== null ) {
 337                         $attrs['media'] = $media;
 338                 }
 339                 return self::element( 'link', $attrs );
 340         }
 341
 342         /**
 343          * Convenience function to produce an <input> element.  This supports the
 344          * new HTML 5 input types and attributes, and will silently strip them if
 345          * $wgHtml5 is false.
 346          *
 347          * @param $name    string name attribute
 348          * @param $value   mixed  value attribute (null = omit)
 349          * @param $type    string type attribute
 350          * @param $attribs array  Associative array of miscellaneous extra
 351          *   attributes, passed to Html::element()
 352          * @return string Raw HTML
 353          */
 354         public static function input( $name, $value = null, $type = 'text', $attribs = array() ) {
 355                 if ( $type != 'text' ) {
 356                         $attribs['type'] = $type;
 357                 }
 358                 if ( $value !== null && $value !== '' ) {
 359                         $attribs['value'] = $value;
 360                 }
 361                 $attribs['name'] = $name;
 362
 363                 return self::element( 'input', $attribs );
 364         }
 365
 366         /**
 367          * Convenience function to produce an input element with type=hidden, like
 368          * Xml::hidden.
 369          *
 370          * @param $name    string name attribute
 371          * @param $value   string value attribute
 372          * @param $attribs array  Associative array of miscellaneous extra
 373          *   attributes, passed to Html::element()
 374          * @return string Raw HTML
 375          */
 376         public static function hidden( $name, $value, $attribs = array() ) {
 377                 return self::input( $name, $value, 'hidden', $attribs );
 378         }
 379 }