summaryrefslogtreecommitdiff
path: root/includes/Html.php
blob: d312e0a6e9cde5ae5083c11a8706be673be1c963 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
<?php
/**
 * Collection of methods to generate HTML content
 *
 * Copyright © 2009 Aryeh Gregor
 * http://www.mediawiki.org/
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 * http://www.gnu.org/copyleft/gpl.html
 *
 * @file
 */

/**
 * This class is a collection of static functions that serve two purposes:
 *
 * 1) Implement any algorithms specified by HTML5, or other HTML
 * specifications, in a convenient and self-contained way.
 *
 * 2) Allow HTML elements to be conveniently and safely generated, like the
 * current Xml class but a) less confused (Xml supports HTML-specific things,
 * but only sometimes!) and b) not necessarily confined to XML-compatible
 * output.
 *
 * There are two important configuration options this class uses:
 *
 * $wgMimeType: If this is set to an xml MIME type then output should be
 *     valid XHTML5.
 * $wgWellFormedXml: If this is set to true, then all output should be
 *     well-formed XML (quotes on attributes, self-closing tags, etc.).
 *
 * This class is meant to be confined to utility functions that are called from
 * trusted code paths.  It does not do enforcement of policy like not allowing
 * <a> elements.
 *
 * @since 1.16
 */
class Html {
	// List of void elements from HTML5, section 8.1.2 as of 2011-08-12
	private static $voidElements = array(
		'area',
		'base',
		'br',
		'col',
		'command',
		'embed',
		'hr',
		'img',
		'input',
		'keygen',
		'link',
		'meta',
		'param',
		'source',
		'track',
		'wbr',
	);

	// Boolean attributes, which may have the value omitted entirely.  Manually
	// collected from the HTML5 spec as of 2011-08-12.
	private static $boolAttribs = array(
		'async',
		'autofocus',
		'autoplay',
		'checked',
		'controls',
		'default',
		'defer',
		'disabled',
		'formnovalidate',
		'hidden',
		'ismap',
		'itemscope',
		'loop',
		'multiple',
		'muted',
		'novalidate',
		'open',
		'pubdate',
		'readonly',
		'required',
		'reversed',
		'scoped',
		'seamless',
		'selected',
		'truespeed',
		'typemustmatch',
		// HTML5 Microdata
		'itemscope',
	);

	/**
	 * Modifies a set of attributes meant for button elements
	 * and apply a set of default attributes when $wgUseMediaWikiUIEverywhere enabled.
	 * @param array $attrs
	 * @param string[] $modifiers to add to the button
	 * @see https://tools.wmflabs.org/styleguide/desktop/index.html for guidance on available modifiers
	 * @return array $attrs A modified attribute array
	 */
	public static function buttonAttributes( $attrs, $modifiers = array() ) {
		global $wgUseMediaWikiUIEverywhere;
		if ( $wgUseMediaWikiUIEverywhere ) {
			if ( isset( $attrs['class'] ) ) {
				if ( is_array( $attrs['class'] ) ) {
					$attrs['class'][] = 'mw-ui-button';
					$attrs = array_merge( $attrs, $modifiers );
					// ensure compatibility with Xml
					$attrs['class'] = implode( ' ', $attrs['class'] );
				} else {
					$attrs['class'] .= ' mw-ui-button ' . implode( ' ', $modifiers );
				}
			} else {
				$attrs['class'] = array( 'mw-ui-button' );
				// ensure compatibility with Xml
				$attrs['class'] = implode( ' ', array_merge( $attrs['class'], $modifiers ) );
			}
		}
		return $attrs;
	}

	/**
	 * Modifies a set of attributes meant for text input elements
	 * and apply a set of default attributes.
	 * Removes size attribute when $wgUseMediaWikiUIEverywhere enabled.
	 * @param array $attrs An attribute array.
	 * @return array $attrs A modified attribute array
	 */
	public static function getTextInputAttributes( $attrs ) {
		global $wgUseMediaWikiUIEverywhere;
		if ( !$attrs ) {
			$attrs = array();
		}
		if ( $wgUseMediaWikiUIEverywhere ) {
			if ( isset( $attrs['class'] ) ) {
				if ( is_array( $attrs['class'] ) ) {
					$attrs['class'][] = 'mw-ui-input';
				} else {
					$attrs['class'] .= ' mw-ui-input';
				}
			} else {
				$attrs['class'] = 'mw-ui-input';
			}
		}
		return $attrs;
	}

	/**
	 * Returns an HTML link element in a string styled as a button
	 * (when $wgUseMediaWikiUIEverywhere is enabled).
	 *
	 * @param string $contents The raw HTML contents of the element: *not*
	 *   escaped!
	 * @param array $attrs Associative array of attributes, e.g., array(
	 *   'href' => 'http://www.mediawiki.org/' ). See expandAttributes() for
	 *   further documentation.
	 * @param string[] $modifiers to add to the button
	 * @see http://tools.wmflabs.org/styleguide/desktop/index.html for guidance on available modifiers
	 * @return string Raw HTML
	 */
	public static function linkButton( $contents, $attrs, $modifiers = array() ) {
		return self::element( 'a',
			self::buttonAttributes( $attrs, $modifiers ),
			$contents
		);
	}

	/**
	 * Returns an HTML link element in a string styled as a button
	 * (when $wgUseMediaWikiUIEverywhere is enabled).
	 *
	 * @param string $contents The raw HTML contents of the element: *not*
	 *   escaped!
	 * @param array $attrs Associative array of attributes, e.g., array(
	 *   'href' => 'http://www.mediawiki.org/' ). See expandAttributes() for
	 *   further documentation.
	 * @param string[] $modifiers to add to the button
	 * @see http://tools.wmflabs.org/styleguide/desktop/index.html for guidance on available modifiers
	 * @return string Raw HTML
	 */
	public static function submitButton( $contents, $attrs, $modifiers = array() ) {
		$attrs['type'] = 'submit';
		$attrs['value'] = $contents;
		return self::element( 'input', self::buttonAttributes( $attrs, $modifiers ) );
	}

	/**
	 * Returns an HTML element in a string.  The major advantage here over
	 * manually typing out the HTML is that it will escape all attribute
	 * values.
	 *
	 * This is quite similar to Xml::tags(), but it implements some useful
	 * HTML-specific logic.  For instance, there is no $allowShortTag
	 * parameter: the closing tag is magically omitted if $element has an empty
	 * content model.  If $wgWellFormedXml is false, then a few bytes will be
	 * shaved off the HTML output as well.
	 *
	 * @param string $element The element's name, e.g., 'a'
	 * @param array $attribs Associative array of attributes, e.g., array(
	 *   'href' => 'http://www.mediawiki.org/' ). See expandAttributes() for
	 *   further documentation.
	 * @param string $contents The raw HTML contents of the element: *not*
	 *   escaped!
	 * @return string Raw HTML
	 */
	public static function rawElement( $element, $attribs = array(), $contents = '' ) {
		global $wgWellFormedXml;
		$start = self::openElement( $element, $attribs );
		if ( in_array( $element, self::$voidElements ) ) {
			if ( $wgWellFormedXml ) {
				// Silly XML.
				return substr( $start, 0, -1 ) . ' />';
			}
			return $start;
		} else {
			return "$start$contents" . self::closeElement( $element );
		}
	}

	/**
	 * Identical to rawElement(), but HTML-escapes $contents (like
	 * Xml::element()).
	 *
	 * @param string $element
	 * @param array $attribs
	 * @param string $contents
	 *
	 * @return string
	 */
	public static function element( $element, $attribs = array(), $contents = '' ) {
		return self::rawElement( $element, $attribs, strtr( $contents, array(
			// There's no point in escaping quotes, >, etc. in the contents of
			// elements.
			'&' => '&amp;',
			'<' => '&lt;'
		) ) );
	}

	/**
	 * Identical to rawElement(), but has no third parameter and omits the end
	 * tag (and the self-closing '/' in XML mode for empty elements).
	 *
	 * @param string $element
	 * @param array $attribs
	 *
	 * @return string
	 */
	public static function openElement( $element, $attribs = array() ) {
		$attribs = (array)$attribs;
		// This is not required in HTML5, but let's do it anyway, for
		// consistency and better compression.
		$element = strtolower( $element );

		// Remove invalid input types
		if ( $element == 'input' ) {
			$validTypes = array(
				'hidden',
				'text',
				'password',
				'checkbox',
				'radio',
				'file',
				'submit',
				'image',
				'reset',
				'button',

				// HTML input types
				'datetime',
				'datetime-local',
				'date',
				'month',
				'time',
				'week',
				'number',
				'range',
				'email',
				'url',
				'search',
				'tel',
				'color',
			);
			if ( isset( $attribs['type'] ) && !in_array( $attribs['type'], $validTypes ) ) {
				unset( $attribs['type'] );
			}
		}

		// According to standard the default type for <button> elements is "submit".
		// Depending on compatibility mode IE might use "button", instead.
		// We enforce the standard "submit".
		if ( $element == 'button' && !isset( $attribs['type'] ) ) {
			$attribs['type'] = 'submit';
		}

		return "<$element" . self::expandAttributes(
			self::dropDefaults( $element, $attribs ) ) . '>';
	}

	/**
	 * Returns "</$element>"
	 *
	 * @since 1.17
	 * @param string $element Name of the element, e.g., 'a'
	 * @return string A closing tag
	 */
	public static function closeElement( $element ) {
		$element = strtolower( $element );

		return "</$element>";
	}

	/**
	 * Given an element name and an associative array of element attributes,
	 * return an array that is functionally identical to the input array, but
	 * possibly smaller.  In particular, attributes might be stripped if they
	 * are given their default values.
	 *
	 * This method is not guaranteed to remove all redundant attributes, only
	 * some common ones and some others selected arbitrarily at random.  It
	 * only guarantees that the output array should be functionally identical
	 * to the input array (currently per the HTML 5 draft as of 2009-09-06).
	 *
	 * @param string $element Name of the element, e.g., 'a'
	 * @param array $attribs Associative array of attributes, e.g., array(
	 *   'href' => 'http://www.mediawiki.org/' ).  See expandAttributes() for
	 *   further documentation.
	 * @return array An array of attributes functionally identical to $attribs
	 */
	private static function dropDefaults( $element, $attribs ) {

		// Whenever altering this array, please provide a covering test case
		// in HtmlTest::provideElementsWithAttributesHavingDefaultValues
		static $attribDefaults = array(
			'area' => array( 'shape' => 'rect' ),
			'button' => array(
				'formaction' => 'GET',
				'formenctype' => 'application/x-www-form-urlencoded',
			),
			'canvas' => array(
				'height' => '150',
				'width' => '300',
			),
			'command' => array( 'type' => 'command' ),
			'form' => array(
				'action' => 'GET',
				'autocomplete' => 'on',
				'enctype' => 'application/x-www-form-urlencoded',
			),
			'input' => array(
				'formaction' => 'GET',
				'type' => 'text',
			),
			'keygen' => array( 'keytype' => 'rsa' ),
			'link' => array( 'media' => 'all' ),
			'menu' => array( 'type' => 'list' ),
			// Note: the use of text/javascript here instead of other JavaScript
			// MIME types follows the HTML5 spec.
			'script' => array( 'type' => 'text/javascript' ),
			'style' => array(
				'media' => 'all',
				'type' => 'text/css',
			),
			'textarea' => array( 'wrap' => 'soft' ),
		);

		$element = strtolower( $element );

		foreach ( $attribs as $attrib => $value ) {
			$lcattrib = strtolower( $attrib );
			if ( is_array( $value ) ) {
				$value = implode( ' ', $value );
			} else {
				$value = strval( $value );
			}

			// Simple checks using $attribDefaults
			if ( isset( $attribDefaults[$element][$lcattrib] )
				&& $attribDefaults[$element][$lcattrib] == $value
			) {
				unset( $attribs[$attrib] );
			}

			if ( $lcattrib == 'class' && $value == '' ) {
				unset( $attribs[$attrib] );
			}
		}

		// More subtle checks
		if ( $element === 'link'
			&& isset( $attribs['type'] ) && strval( $attribs['type'] ) == 'text/css'
		) {
			unset( $attribs['type'] );
		}
		if ( $element === 'input' ) {
			$type = isset( $attribs['type'] ) ? $attribs['type'] : null;
			$value = isset( $attribs['value'] ) ? $attribs['value'] : null;
			if ( $type === 'checkbox' || $type === 'radio' ) {
				// The default value for checkboxes and radio buttons is 'on'
				// not ''. By stripping value="" we break radio boxes that
				// actually wants empty values.
				if ( $value === 'on' ) {
					unset( $attribs['value'] );
				}
			} elseif ( $type === 'submit' ) {
				// The default value for submit appears to be "Submit" but
				// let's not bother stripping out localized text that matches
				// that.
			} else {
				// The default value for nearly every other field type is ''
				// The 'range' and 'color' types use different defaults but
				// stripping a value="" does not hurt them.
				if ( $value === '' ) {
					unset( $attribs['value'] );
				}
			}
		}
		if ( $element === 'select' && isset( $attribs['size'] ) ) {
			if ( in_array( 'multiple', $attribs )
				|| ( isset( $attribs['multiple'] ) && $attribs['multiple'] !== false )
			) {
				// A multi-select
				if ( strval( $attribs['size'] ) == '4' ) {
					unset( $attribs['size'] );
				}
			} else {
				// Single select
				if ( strval( $attribs['size'] ) == '1' ) {
					unset( $attribs['size'] );
				}
			}
		}

		return $attribs;
	}

	/**
	 * Given an associative array of element attributes, generate a string
	 * to stick after the element name in HTML output.  Like array( 'href' =>
	 * 'http://www.mediawiki.org/' ) becomes something like
	 * ' href="http://www.mediawiki.org"'.  Again, this is like
	 * Xml::expandAttributes(), but it implements some HTML-specific logic.
	 * For instance, it will omit quotation marks if $wgWellFormedXml is false,
	 * and will treat boolean attributes specially.
	 *
	 * Attributes that can contain space-separated lists ('class', 'accesskey' and 'rel') array
	 * values are allowed as well, which will automagically be normalized
	 * and converted to a space-separated string. In addition to a numerical
	 * array, the attribute value may also be an associative array. See the
	 * example below for how that works.
	 *
	 * @par Numerical array
	 * @code
	 *     Html::element( 'em', array(
	 *         'class' => array( 'foo', 'bar' )
	 *     ) );
	 *     // gives '<em class="foo bar"></em>'
	 * @endcode
	 *
	 * @par Associative array
	 * @code
	 *     Html::element( 'em', array(
	 *         'class' => array( 'foo', 'bar', 'foo' => false, 'quux' => true )
	 *     ) );
	 *     // gives '<em class="bar quux"></em>'
	 * @endcode
	 *
	 * @param array $attribs Associative array of attributes, e.g., array(
	 *   'href' => 'http://www.mediawiki.org/' ).  Values will be HTML-escaped.
	 *   A value of false means to omit the attribute.  For boolean attributes,
	 *   you can omit the key, e.g., array( 'checked' ) instead of
	 *   array( 'checked' => 'checked' ) or such.
	 *
	 * @throws MWException If an attribute that doesn't allow lists is set to an array
	 * @return string HTML fragment that goes between element name and '>'
	 *   (starting with a space if at least one attribute is output)
	 */
	public static function expandAttributes( $attribs ) {
		global $wgWellFormedXml;

		$ret = '';
		$attribs = (array)$attribs;
		foreach ( $attribs as $key => $value ) {
			// Support intuitive array( 'checked' => true/false ) form
			if ( $value === false || is_null( $value ) ) {
				continue;
			}

			// For boolean attributes, support array( 'foo' ) instead of
			// requiring array( 'foo' => 'meaningless' ).
			if ( is_int( $key ) && in_array( strtolower( $value ), self::$boolAttribs ) ) {
				$key = $value;
			}

			// Not technically required in HTML5 but we'd like consistency
			// and better compression anyway.
			$key = strtolower( $key );

			// Bug 23769: Blacklist all form validation attributes for now.  Current
			// (June 2010) WebKit has no UI, so the form just refuses to submit
			// without telling the user why, which is much worse than failing
			// server-side validation.  Opera is the only other implementation at
			// this time, and has ugly UI, so just kill the feature entirely until
			// we have at least one good implementation.

			// As the default value of "1" for "step" rejects decimal
			// numbers to be entered in 'type="number"' fields, allow
			// the special case 'step="any"'.

			if ( in_array( $key, array( 'max', 'min', 'pattern', 'required' ) )
				|| $key === 'step' && $value !== 'any' ) {
				continue;
			}

			// http://www.w3.org/TR/html401/index/attributes.html ("space-separated")
			// http://www.w3.org/TR/html5/index.html#attributes-1 ("space-separated")
			$spaceSeparatedListAttributes = array(
				'class', // html4, html5
				'accesskey', // as of html5, multiple space-separated values allowed
				// html4-spec doesn't document rel= as space-separated
				// but has been used like that and is now documented as such
				// in the html5-spec.
				'rel',
			);

			// Specific features for attributes that allow a list of space-separated values
			if ( in_array( $key, $spaceSeparatedListAttributes ) ) {
				// Apply some normalization and remove duplicates

				// Convert into correct array. Array can contain space-separated
				// values. Implode/explode to get those into the main array as well.
				if ( is_array( $value ) ) {
					// If input wasn't an array, we can skip this step
					$newValue = array();
					foreach ( $value as $k => $v ) {
						if ( is_string( $v ) ) {
							// String values should be normal `array( 'foo' )`
							// Just append them
							if ( !isset( $value[$v] ) ) {
								// As a special case don't set 'foo' if a
								// separate 'foo' => true/false exists in the array
								// keys should be authoritative
								$newValue[] = $v;
							}
						} elseif ( $v ) {
							// If the value is truthy but not a string this is likely
							// an array( 'foo' => true ), falsy values don't add strings
							$newValue[] = $k;
						}
					}
					$value = implode( ' ', $newValue );
				}
				$value = explode( ' ', $value );

				// Normalize spacing by fixing up cases where people used
				// more than 1 space and/or a trailing/leading space
				$value = array_diff( $value, array( '', ' ' ) );

				// Remove duplicates and create the string
				$value = implode( ' ', array_unique( $value ) );
			} elseif ( is_array( $value ) ) {
				throw new MWException( "HTML attribute $key can not contain a list of values" );
			}

			// See the "Attributes" section in the HTML syntax part of HTML5,
			// 9.1.2.3 as of 2009-08-10.  Most attributes can have quotation
			// marks omitted, but not all.  (Although a literal " is not
			// permitted, we don't check for that, since it will be escaped
			// anyway.)

			// See also research done on further characters that need to be
			// escaped: http://code.google.com/p/html5lib/issues/detail?id=93
			$badChars = "\\x00- '=<>`/\x{00a0}\x{1680}\x{180e}\x{180F}\x{2000}\x{2001}"
				. "\x{2002}\x{2003}\x{2004}\x{2005}\x{2006}\x{2007}\x{2008}\x{2009}"
				. "\x{200A}\x{2028}\x{2029}\x{202F}\x{205F}\x{3000}";
			if ( $wgWellFormedXml || $value === '' || preg_match( "![$badChars]!u", $value ) ) {
				$quote = '"';
			} else {
				$quote = '';
			}

			if ( in_array( $key, self::$boolAttribs ) ) {
				// In HTML5, we can leave the value empty. If we don't need
				// well-formed XML, we can omit the = entirely.
				if ( !$wgWellFormedXml ) {
					$ret .= " $key";
				} else {
					$ret .= " $key=\"\"";
				}
			} else {
				// Apparently we need to entity-encode \n, \r, \t, although the
				// spec doesn't mention that.  Since we're doing strtr() anyway,
				// we may as well not call htmlspecialchars().
				// @todo FIXME: Verify that we actually need to
				// escape \n\r\t here, and explain why, exactly.
				#
				// We could call Sanitizer::encodeAttribute() for this, but we
				// don't because we're stubborn and like our marginal savings on
				// byte size from not having to encode unnecessary quotes.
				// The only difference between this transform and the one by
				// Sanitizer::encodeAttribute() is '<' is only encoded here if
				// $wgWellFormedXml is set, and ' is not encoded.
				$map = array(
					'&' => '&amp;',
					'"' => '&quot;',
					'>' => '&gt;',
					"\n" => '&#10;',
					"\r" => '&#13;',
					"\t" => '&#9;'
				);
				if ( $wgWellFormedXml ) {
					// This is allowed per spec: <http://www.w3.org/TR/xml/#NT-AttValue>
					// But reportedly it breaks some XML tools?
					// @todo FIXME: Is this really true?
					$map['<'] = '&lt;';
				}
				$ret .= " $key=$quote" . strtr( $value, $map ) . $quote;
			}
		}
		return $ret;
	}

	/**
	 * Output a "<script>" tag with the given contents.
	 *
	 * @todo do some useful escaping as well, like if $contents contains
	 * literal "</script>" or (for XML) literal "]]>".
	 *
	 * @param string $contents JavaScript
	 * @return string Raw HTML
	 */
	public static function inlineScript( $contents ) {
		global $wgWellFormedXml;

		$attrs = array();

		if ( $wgWellFormedXml && preg_match( '/[<&]/', $contents ) ) {
			$contents = "/*<![CDATA[*/$contents/*]]>*/";
		}

		return self::rawElement( 'script', $attrs, $contents );
	}

	/**
	 * Output a "<script>" tag linking to the given URL, e.g.,
	 * "<script src=foo.js></script>".
	 *
	 * @param string $url
	 * @return string Raw HTML
	 */
	public static function linkedScript( $url ) {
		$attrs = array( 'src' => $url );

		return self::element( 'script', $attrs );
	}

	/**
	 * Output a "<style>" tag with the given contents for the given media type
	 * (if any).  TODO: do some useful escaping as well, like if $contents
	 * contains literal "</style>" (admittedly unlikely).
	 *
	 * @param string $contents CSS
	 * @param string $media A media type string, like 'screen'
	 * @return string Raw HTML
	 */
	public static function inlineStyle( $contents, $media = 'all' ) {
		global $wgWellFormedXml;

		if ( $wgWellFormedXml && preg_match( '/[<&]/', $contents ) ) {
			$contents = "/*<![CDATA[*/$contents/*]]>*/";
		}

		return self::rawElement( 'style', array(
			'type' => 'text/css',
			'media' => $media,
		), $contents );
	}

	/**
	 * Output a "<link rel=stylesheet>" linking to the given URL for the given
	 * media type (if any).
	 *
	 * @param string $url
	 * @param string $media A media type string, like 'screen'
	 * @return string Raw HTML
	 */
	public static function linkedStyle( $url, $media = 'all' ) {
		return self::element( 'link', array(
			'rel' => 'stylesheet',
			'href' => $url,
			'type' => 'text/css',
			'media' => $media,
		) );
	}

	/**
	 * Convenience function to produce an "<input>" element.  This supports the
	 * new HTML5 input types and attributes.
	 *
	 * @param string $name Name attribute
	 * @param string $value Value attribute
	 * @param string $type Type attribute
	 * @param array $attribs Associative array of miscellaneous extra
	 *   attributes, passed to Html::element()
	 * @return string Raw HTML
	 */
	public static function input( $name, $value = '', $type = 'text', $attribs = array() ) {
		$attribs['type'] = $type;
		$attribs['value'] = $value;
		$attribs['name'] = $name;
		if ( in_array( $type, array( 'text', 'search', 'email', 'password', 'number' ) ) ) {
			$attribs = self::getTextInputAttributes( $attribs );
		}
		return self::element( 'input', $attribs );
	}

	/**
	 * Convenience function to produce a checkbox (input element with type=checkbox)
	 *
	 * @param string $name Name attribute
	 * @param bool $checked Whether the checkbox is checked or not
	 * @param array $attribs Array of additional attributes
	 * @return string Raw HTML
	 */
	public static function check( $name, $checked = false, array $attribs = array() ) {
		if ( isset( $attribs['value'] ) ) {
			$value = $attribs['value'];
			unset( $attribs['value'] );
		} else {
			$value = 1;
		}

		if ( $checked ) {
			$attribs[] = 'checked';
		}

		return self::input( $name, $value, 'checkbox', $attribs );
	}

	/**
	 * Convenience function to produce a checkbox (input element with type=checkbox)
	 *
	 * @param string $name Name attribute
	 * @param bool $checked Whether the checkbox is checked or not
	 * @param array $attribs Array of additional attributes
	 * @return string Raw HTML
	 */
	public static function radio( $name, $checked = false, array $attribs = array() ) {
		if ( isset( $attribs['value'] ) ) {
			$value = $attribs['value'];
			unset( $attribs['value'] );
		} else {
			$value = 1;
		}

		if ( $checked ) {
			$attribs[] = 'checked';
		}

		return self::input( $name, $value, 'radio', $attribs );
	}

	/**
	 * Convenience function for generating a label for inputs.
	 *
	 * @param string $label Contents of the label
	 * @param string $id ID of the element being labeled
	 * @param array $attribs Additional attributes
	 * @return string Raw HTML
	 */
	public static function label( $label, $id, array $attribs = array() ) {
		$attribs += array(
			'for' => $id
		);
		return self::element( 'label', $attribs, $label );
	}

	/**
	 * Convenience function to produce an input element with type=hidden
	 *
	 * @param string $name Name attribute
	 * @param string $value Value attribute
	 * @param array $attribs Associative array of miscellaneous extra
	 *   attributes, passed to Html::element()
	 * @return string Raw HTML
	 */
	public static function hidden( $name, $value, $attribs = array() ) {
		return self::input( $name, $value, 'hidden', $attribs );
	}

	/**
	 * Convenience function to produce a <textarea> element.
	 *
	 * This supports leaving out the cols= and rows= which Xml requires and are
	 * required by HTML4/XHTML but not required by HTML5.
	 *
	 * @param string $name Name attribute
	 * @param string $value Value attribute
	 * @param array $attribs Associative array of miscellaneous extra
	 *   attributes, passed to Html::element()
	 * @return string Raw HTML
	 */
	public static function textarea( $name, $value = '', $attribs = array() ) {
		$attribs['name'] = $name;

		if ( substr( $value, 0, 1 ) == "\n" ) {
			// Workaround for bug 12130: browsers eat the initial newline
			// assuming that it's just for show, but they do keep the later
			// newlines, which we may want to preserve during editing.
			// Prepending a single newline
			$spacedValue = "\n" . $value;
		} else {
			$spacedValue = $value;
		}
		return self::element( 'textarea', self::getTextInputAttributes( $attribs ), $spacedValue );
	}

	/**
	 * Build a drop-down box for selecting a namespace
	 *
	 * @param array $params Params to set.
	 * - selected: [optional] Id of namespace which should be pre-selected
	 * - all: [optional] Value of item for "all namespaces". If null or unset,
	 *   no "<option>" is generated to select all namespaces.
	 * - label: text for label to add before the field.
	 * - exclude: [optional] Array of namespace ids to exclude.
	 * - disable: [optional] Array of namespace ids for which the option should
	 *   be disabled in the selector.
	 * @param array $selectAttribs HTML attributes for the generated select element.
	 * - id:   [optional], default: 'namespace'.
	 * - name: [optional], default: 'namespace'.
	 * @return string HTML code to select a namespace.
	 */
	public static function namespaceSelector( array $params = array(),
		array $selectAttribs = array()
	) {
		global $wgContLang;

		ksort( $selectAttribs );

		// Is a namespace selected?
		if ( isset( $params['selected'] ) ) {
			// If string only contains digits, convert to clean int. Selected could also
			// be "all" or "" etc. which needs to be left untouched.
			// PHP is_numeric() has issues with large strings, PHP ctype_digit has other issues
			// and returns false for already clean ints. Use regex instead..
			if ( preg_match( '/^\d+$/', $params['selected'] ) ) {
				$params['selected'] = intval( $params['selected'] );
			}
			// else: leaves it untouched for later processing
		} else {
			$params['selected'] = '';
		}

		if ( !isset( $params['exclude'] ) || !is_array( $params['exclude'] ) ) {
			$params['exclude'] = array();
		}
		if ( !isset( $params['disable'] ) || !is_array( $params['disable'] ) ) {
			$params['disable'] = array();
		}

		// Associative array between option-values and option-labels
		$options = array();

		if ( isset( $params['all'] ) ) {
			// add an option that would let the user select all namespaces.
			// Value is provided by user, the name shown is localized for the user.
			$options[$params['all']] = wfMessage( 'namespacesall' )->text();
		}
		// Add all namespaces as options (in the content language)
		$options += $wgContLang->getFormattedNamespaces();

		// Convert $options to HTML and filter out namespaces below 0
		$optionsHtml = array();
		foreach ( $options as $nsId => $nsName ) {
			if ( $nsId < NS_MAIN || in_array( $nsId, $params['exclude'] ) ) {
				continue;
			}
			if ( $nsId === NS_MAIN ) {
				// For other namespaces use the namespace prefix as label, but for
				// main we don't use "" but the user message describing it (e.g. "(Main)" or "(Article)")
				$nsName = wfMessage( 'blanknamespace' )->text();
			} elseif ( is_int( $nsId ) ) {
				$nsName = $wgContLang->convertNamespace( $nsId );
			}
			$optionsHtml[] = self::element(
				'option', array(
					'disabled' => in_array( $nsId, $params['disable'] ),
					'value' => $nsId,
					'selected' => $nsId === $params['selected'],
				), $nsName
			);
		}

		if ( !array_key_exists( 'id', $selectAttribs ) ) {
			$selectAttribs['id'] = 'namespace';
		}

		if ( !array_key_exists( 'name', $selectAttribs ) ) {
			$selectAttribs['name'] = 'namespace';
		}

		$ret = '';
		if ( isset( $params['label'] ) ) {
			$ret .= self::element(
				'label', array(
					'for' => isset( $selectAttribs['id'] ) ? $selectAttribs['id'] : null,
				), $params['label']
			) . '&#160;';
		}

		// Wrap options in a <select>
		$ret .= self::openElement( 'select', $selectAttribs )
			. "\n"
			. implode( "\n", $optionsHtml )
			. "\n"
			. self::closeElement( 'select' );

		return $ret;
	}

	/**
	 * Constructs the opening html-tag with necessary doctypes depending on
	 * global variables.
	 *
	 * @param array $attribs Associative array of miscellaneous extra
	 *   attributes, passed to Html::element() of html tag.
	 * @return string Raw HTML
	 */
	public static function htmlHeader( $attribs = array() ) {
		$ret = '';

		global $wgHtml5Version, $wgMimeType, $wgXhtmlNamespaces;

		$isXHTML = self::isXmlMimeType( $wgMimeType );

		if ( $isXHTML ) { // XHTML5
			// XML MIME-typed markup should have an xml header.
			// However a DOCTYPE is not needed.
			$ret .= "<?xml version=\"1.0\" encoding=\"UTF-8\" ?" . ">\n";

			// Add the standard xmlns
			$attribs['xmlns'] = 'http://www.w3.org/1999/xhtml';

			// And support custom namespaces
			foreach ( $wgXhtmlNamespaces as $tag => $ns ) {
				$attribs["xmlns:$tag"] = $ns;
			}
		} else { // HTML5
			// DOCTYPE
			$ret .= "<!DOCTYPE html>\n";
		}

		if ( $wgHtml5Version ) {
			$attribs['version'] = $wgHtml5Version;
		}

		$html = self::openElement( 'html', $attribs );

		if ( $html ) {
			$html .= "\n";
		}

		$ret .= $html;

		return $ret;
	}

	/**
	 * Determines if the given MIME type is xml.
	 *
	 * @param string $mimetype MIME type
	 * @return bool
	 */
	public static function isXmlMimeType( $mimetype ) {
		# http://www.whatwg.org/html/infrastructure.html#xml-mime-type
		# * text/xml
		# * application/xml
		# * Any MIME type with a subtype ending in +xml (this implicitly includes application/xhtml+xml)
		return (bool)preg_match( '!^(text|application)/xml$|^.+/.+\+xml$!', $mimetype );
	}

	/**
	 * Get HTML for an info box with an icon.
	 *
	 * @param string $text Wikitext, get this with wfMessage()->plain()
	 * @param string $icon Path to icon file (used as 'src' attribute)
	 * @param string $alt Alternate text for the icon
	 * @param string $class Additional class name to add to the wrapper div
	 *
	 * @return string
	 */
	static function infoBox( $text, $icon, $alt, $class = '' ) {
		$s = self::openElement( 'div', array( 'class' => "mw-infobox $class" ) );

		$s .= self::openElement( 'div', array( 'class' => 'mw-infobox-left' ) ) .
				self::element( 'img',
					array(
						'src' => $icon,
						'alt' => $alt,
					)
				) .
				self::closeElement( 'div' );

		$s .= self::openElement( 'div', array( 'class' => 'mw-infobox-right' ) ) .
				$text .
				self::closeElement( 'div' );
		$s .= self::element( 'div', array( 'style' => 'clear: left;' ), ' ' );

		$s .= self::closeElement( 'div' );

		$s .= self::element( 'div', array( 'style' => 'clear: left;' ), ' ' );

		return $s;
	}

	/**
	 * Generate a srcset attribute value.
	 *
	 * Generates a srcset attribute value from an array mapping pixel densities
	 * to URLs. A trailing 'x' in pixel density values is optional.
	 *
	 * @note srcset width and height values are not supported.
	 *
	 * @see http://www.whatwg.org/html/embedded-content-1.html#attr-img-srcset
	 *
	 * @par Example:
	 * @code
	 *     Html::srcSet( array(
	 *         '1x'   => 'standard.jpeg',
	 *         '1.5x' => 'large.jpeg',
	 *         '3x'   => 'extra-large.jpeg',
	 *     ) );
	 *     // gives 'standard.jpeg 1x, large.jpeg 1.5x, extra-large.jpeg 2x'
	 * @endcode
	 *
	 * @param string[] $urls
	 * @return string
	 */
	static function srcSet( $urls ) {
		$candidates = array();
		foreach ( $urls as $density => $url ) {
			// Cast density to float to strip 'x'.
			$candidates[] = $url . ' ' . (float)$density . 'x';
		}
		return implode( ", ", $candidates );
	}
}