summaryrefslogtreecommitdiffstats
path: root/includes/unicode.inc
blob: 81a0a4dfe2dcdc1d6af0eeb5ba65b37af96c64ea (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
<?php

/**
 * Indicates an error during check for PHP unicode support.
 */
define('UNICODE_ERROR', -1);

/**
 * Indicates that standard PHP (emulated) unicode support is being used.
 */
define('UNICODE_SINGLEBYTE', 0);

/**
 * Indicates that full unicode support with the PHP mbstring extension is being
 * used.
 */
define('UNICODE_MULTIBYTE', 1);

/**
 * Matches Unicode characters that are word boundaries.
 *
 * @see http://unicode.org/glossary
 *
 * Characters with the following General_category (gc) property values are used
 * as word boundaries. While this does not fully conform to the Word Boundaries
 * algorithm described in http://unicode.org/reports/tr29, as PCRE does not
 * contain the Word_Break property table, this simpler algorithm has to do.
 * - Cc, Cf, Cn, Co, Cs: Other.
 * - Pc, Pd, Pe, Pf, Pi, Po, Ps: Punctuation.
 * - Sc, Sk, Sm, So: Symbols.
 * - Zl, Zp, Zs: Separators.
 *
 * Non-boundary characters include the following General_category (gc) property
 * values:
 * - Ll, Lm, Lo, Lt, Lu: Letters.
 * - Mc, Me, Mn: Combining Marks.
 * - Nd, Nl, No: Numbers.
 *
 * Note that the PCRE property matcher is not used because we wanted to be
 * compatible with Unicode 5.2.0 regardless of the PCRE version used (and any
 * bugs in PCRE property tables).
 */
define('PREG_CLASS_UNICODE_WORD_BOUNDARY',
  '\x{0}-\x{2F}\x{3A}-\x{40}\x{5B}-\x{60}\x{7B}-\x{A9}\x{AB}-\x{B1}\x{B4}' .
  '\x{B6}-\x{B8}\x{BB}\x{BF}\x{D7}\x{F7}\x{2C2}-\x{2C5}\x{2D2}-\x{2DF}' .
  '\x{2E5}-\x{2EB}\x{2ED}\x{2EF}-\x{2FF}\x{375}\x{37E}-\x{385}\x{387}\x{3F6}' .
  '\x{482}\x{55A}-\x{55F}\x{589}-\x{58A}\x{5BE}\x{5C0}\x{5C3}\x{5C6}' .
  '\x{5F3}-\x{60F}\x{61B}-\x{61F}\x{66A}-\x{66D}\x{6D4}\x{6DD}\x{6E9}' .
  '\x{6FD}-\x{6FE}\x{700}-\x{70F}\x{7F6}-\x{7F9}\x{830}-\x{83E}' .
  '\x{964}-\x{965}\x{970}\x{9F2}-\x{9F3}\x{9FA}-\x{9FB}\x{AF1}\x{B70}' .
  '\x{BF3}-\x{BFA}\x{C7F}\x{CF1}-\x{CF2}\x{D79}\x{DF4}\x{E3F}\x{E4F}' .
  '\x{E5A}-\x{E5B}\x{F01}-\x{F17}\x{F1A}-\x{F1F}\x{F34}\x{F36}\x{F38}' .
  '\x{F3A}-\x{F3D}\x{F85}\x{FBE}-\x{FC5}\x{FC7}-\x{FD8}\x{104A}-\x{104F}' .
  '\x{109E}-\x{109F}\x{10FB}\x{1360}-\x{1368}\x{1390}-\x{1399}\x{1400}' .
  '\x{166D}-\x{166E}\x{1680}\x{169B}-\x{169C}\x{16EB}-\x{16ED}' .
  '\x{1735}-\x{1736}\x{17B4}-\x{17B5}\x{17D4}-\x{17D6}\x{17D8}-\x{17DB}' .
  '\x{1800}-\x{180A}\x{180E}\x{1940}-\x{1945}\x{19DE}-\x{19FF}' .
  '\x{1A1E}-\x{1A1F}\x{1AA0}-\x{1AA6}\x{1AA8}-\x{1AAD}\x{1B5A}-\x{1B6A}' .
  '\x{1B74}-\x{1B7C}\x{1C3B}-\x{1C3F}\x{1C7E}-\x{1C7F}\x{1CD3}\x{1FBD}' .
  '\x{1FBF}-\x{1FC1}\x{1FCD}-\x{1FCF}\x{1FDD}-\x{1FDF}\x{1FED}-\x{1FEF}' .
  '\x{1FFD}-\x{206F}\x{207A}-\x{207E}\x{208A}-\x{208E}\x{20A0}-\x{20B8}' .
  '\x{2100}-\x{2101}\x{2103}-\x{2106}\x{2108}-\x{2109}\x{2114}' .
  '\x{2116}-\x{2118}\x{211E}-\x{2123}\x{2125}\x{2127}\x{2129}\x{212E}' .
  '\x{213A}-\x{213B}\x{2140}-\x{2144}\x{214A}-\x{214D}\x{214F}' .
  '\x{2190}-\x{244A}\x{249C}-\x{24E9}\x{2500}-\x{2775}\x{2794}-\x{2B59}' .
  '\x{2CE5}-\x{2CEA}\x{2CF9}-\x{2CFC}\x{2CFE}-\x{2CFF}\x{2E00}-\x{2E2E}' .
  '\x{2E30}-\x{3004}\x{3008}-\x{3020}\x{3030}\x{3036}-\x{3037}' .
  '\x{303D}-\x{303F}\x{309B}-\x{309C}\x{30A0}\x{30FB}\x{3190}-\x{3191}' .
  '\x{3196}-\x{319F}\x{31C0}-\x{31E3}\x{3200}-\x{321E}\x{322A}-\x{3250}' .
  '\x{3260}-\x{327F}\x{328A}-\x{32B0}\x{32C0}-\x{33FF}\x{4DC0}-\x{4DFF}' .
  '\x{A490}-\x{A4C6}\x{A4FE}-\x{A4FF}\x{A60D}-\x{A60F}\x{A673}\x{A67E}' .
  '\x{A6F2}-\x{A716}\x{A720}-\x{A721}\x{A789}-\x{A78A}\x{A828}-\x{A82B}' .
  '\x{A836}-\x{A839}\x{A874}-\x{A877}\x{A8CE}-\x{A8CF}\x{A8F8}-\x{A8FA}' .
  '\x{A92E}-\x{A92F}\x{A95F}\x{A9C1}-\x{A9CD}\x{A9DE}-\x{A9DF}' .
  '\x{AA5C}-\x{AA5F}\x{AA77}-\x{AA79}\x{AADE}-\x{AADF}\x{ABEB}' .
  '\x{E000}-\x{F8FF}\x{FB29}\x{FD3E}-\x{FD3F}\x{FDFC}-\x{FDFD}' .
  '\x{FE10}-\x{FE19}\x{FE30}-\x{FE6B}\x{FEFF}-\x{FF0F}\x{FF1A}-\x{FF20}' .
  '\x{FF3B}-\x{FF40}\x{FF5B}-\x{FF65}\x{FFE0}-\x{FFFD}');

/**
 * Wrapper around _unicode_check().
 */
function unicode_check() {
  list($GLOBALS['multibyte']) = _unicode_check();
}

/**
 * Perform checks about Unicode support in PHP, and set the right settings if
 * needed.
 *
 * Because Drupal needs to be able to handle text in various encodings, we do
 * not support mbstring function overloading. HTTP input/output conversion must
 * be disabled for similar reasons.
 *
 * @param $errors
 *   Whether to report any fatal errors with form_set_error().
 */
function _unicode_check() {
  // Ensure translations don't break during installation.
  $t = get_t();

  // Check for mbstring extension
  if (!function_exists('mb_strlen')) {
    return array(UNICODE_SINGLEBYTE, $t('Operations on Unicode strings are emulated on a best-effort basis. Install the <a href="@url">PHP mbstring extension</a> for improved Unicode support.', array('@url' => 'http://www.php.net/mbstring')));
  }

  // Check mbstring configuration
  if (ini_get('mbstring.func_overload') != 0) {
    return array(UNICODE_ERROR, $t('Multibyte string function overloading in PHP is active and must be disabled. Check the php.ini <em>mbstring.func_overload</em> setting. Please refer to the <a href="@url">PHP mbstring documentation</a> for more information.', array('@url' => 'http://www.php.net/mbstring')));
  }
  if (ini_get('mbstring.encoding_translation') != 0) {
    return array(UNICODE_ERROR, $t('Multibyte string input conversion in PHP is active and must be disabled. Check the php.ini <em>mbstring.encoding_translation</em> setting. Please refer to the <a href="@url">PHP mbstring documentation</a> for more information.', array('@url' => 'http://www.php.net/mbstring')));
  }
  if (ini_get('mbstring.http_input') != 'pass') {
    return array(UNICODE_ERROR, $t('Multibyte string input conversion in PHP is active and must be disabled. Check the php.ini <em>mbstring.http_input</em> setting. Please refer to the <a href="@url">PHP mbstring documentation</a> for more information.', array('@url' => 'http://www.php.net/mbstring')));
  }
  if (ini_get('mbstring.http_output') != 'pass') {
    return array(UNICODE_ERROR, $t('Multibyte string output conversion in PHP is active and must be disabled. Check the php.ini <em>mbstring.http_output</em> setting. Please refer to the <a href="@url">PHP mbstring documentation</a> for more information.', array('@url' => 'http://www.php.net/mbstring')));
  }

  // Set appropriate configuration
  mb_internal_encoding('utf-8');
  mb_language('uni');
  return array(UNICODE_MULTIBYTE, '');
}

/**
 * Return Unicode library status and errors.
 */
function unicode_requirements() {
  // Ensure translations don't break during installation.
  $t = get_t();

  $libraries = array(
    UNICODE_SINGLEBYTE => $t('Standard PHP'),
    UNICODE_MULTIBYTE => $t('PHP Mbstring Extension'),
    UNICODE_ERROR => $t('Error'),
  );
  $severities = array(
    UNICODE_SINGLEBYTE => REQUIREMENT_WARNING,
    UNICODE_MULTIBYTE => REQUIREMENT_OK,
    UNICODE_ERROR => REQUIREMENT_ERROR,
  );
  list($library, $description) = _unicode_check();

  $requirements['unicode'] = array(
    'title' => $t('Unicode library'),
    'value' => $libraries[$library],
  );
  if ($description) {
    $requirements['unicode']['description'] = $description;
  }

  $requirements['unicode']['severity'] = $severities[$library];

  return $requirements;
}

/**
 * Prepare a new XML parser.
 *
 * This is a wrapper around xml_parser_create() which extracts the encoding from
 * the XML data first and sets the output encoding to UTF-8. This function should
 * be used instead of xml_parser_create(), because PHP 4's XML parser doesn't
 * check the input encoding itself. "Starting from PHP 5, the input encoding is
 * automatically detected, so that the encoding parameter specifies only the
 * output encoding."
 *
 * This is also where unsupported encodings will be converted. Callers should
 * take this into account: $data might have been changed after the call.
 *
 * @param $data
 *   The XML data which will be parsed later.
 *
 * @return
 *   An XML parser object or FALSE on error.
 *
 * @ingroup php_wrappers
 */
function drupal_xml_parser_create(&$data) {
  // Default XML encoding is UTF-8
  $encoding = 'utf-8';
  $bom = FALSE;

  // Check for UTF-8 byte order mark (PHP5's XML parser doesn't handle it).
  if (!strncmp($data, "\xEF\xBB\xBF", 3)) {
    $bom = TRUE;
    $data = substr($data, 3);
  }

  // Check for an encoding declaration in the XML prolog if no BOM was found.
  if (!$bom && preg_match('/^<\?xml[^>]+encoding="(.+?)"/', $data, $match)) {
    $encoding = $match[1];
  }

  // Unsupported encodings are converted here into UTF-8.
  $php_supported = array('utf-8', 'iso-8859-1', 'us-ascii');
  if (!in_array(strtolower($encoding), $php_supported)) {
    $out = drupal_convert_to_utf8($data, $encoding);
    if ($out !== FALSE) {
      $encoding = 'utf-8';
      $data = preg_replace('/^(<\?xml[^>]+encoding)="(.+?)"/', '\\1="utf-8"', $out);
    }
    else {
      watchdog('php', 'Could not convert XML encoding %s to UTF-8.', array('%s' => $encoding), WATCHDOG_WARNING);
      return FALSE;
    }
  }

  $xml_parser = xml_parser_create($encoding);
  xml_parser_set_option($xml_parser, XML_OPTION_TARGET_ENCODING, 'utf-8');
  return $xml_parser;
}

/**
 * Convert data to UTF-8
 *
 * Requires the iconv, GNU recode or mbstring PHP extension.
 *
 * @param $data
 *   The data to be converted.
 * @param $encoding
 *   The encoding that the data is in.
 *
 * @return
 *   Converted data or FALSE.
 */
function drupal_convert_to_utf8($data, $encoding) {
  if (function_exists('iconv')) {
    $out = @iconv($encoding, 'utf-8', $data);
  }
  elseif (function_exists('mb_convert_encoding')) {
    $out = @mb_convert_encoding($data, 'utf-8', $encoding);
  }
  elseif (function_exists('recode_string')) {
    $out = @recode_string($encoding . '..utf-8', $data);
  }
  else {
    watchdog('php', 'Unsupported encoding %s. Please install iconv, GNU recode or mbstring for PHP.', array('%s' => $encoding), WATCHDOG_ERROR);
    return FALSE;
  }

  return $out;
}

/**
 * Truncate a UTF-8-encoded string safely to a number of bytes.
 *
 * If the end position is in the middle of a UTF-8 sequence, it scans backwards
 * until the beginning of the byte sequence.
 *
 * Use this function whenever you want to chop off a string at an unsure
 * location. On the other hand, if you're sure that you're splitting on a
 * character boundary (e.g. after using strpos() or similar), you can safely use
 * substr() instead.
 *
 * @param $string
 *   The string to truncate.
 * @param $len
 *   An upper limit on the returned string length.
 *
 * @return
 *   The truncated string.
 */
function drupal_truncate_bytes($string, $len) {
  if (strlen($string) <= $len) {
    return $string;
  }
  if ((ord($string[$len]) < 0x80) || (ord($string[$len]) >= 0xC0)) {
    return substr($string, 0, $len);
  }
  // Scan backwards to beginning of the byte sequence.
  while (--$len >= 0 && ord($string[$len]) >= 0x80 && ord($string[$len]) < 0xC0);

  return substr($string, 0, $len);
}

/**
 * Truncates a UTF-8-encoded string safely to a number of characters.
 *
 * @param $string
 *   The string to truncate.
 * @param $max_length
 *   An upper limit on the returned string length, including trailing ellipsis
 *   if $add_ellipsis is TRUE.
 * @param $wordsafe
 *   If TRUE, attempt to truncate on a word boundary. Word boundaries are
 *   spaces, punctuation, and Unicode characters used as word boundaries in
 *   non-Latin languages; see PREG_CLASS_UNICODE_WORD_BOUNDARY for more
 *   information. If a word boundary cannot be found that would make the length
 *   of the returned string fall within length guidelines (see parameters
 *   $max_length and $min_wordsafe_length), word boundaries are ignored.
 * @param $add_ellipsis
 *   If TRUE, add t('...') to the end of the truncated string (defaults to
 *   FALSE). The string length will still fall within $max_length.
 * @param $min_wordsafe_length
 *   If $wordsafe is TRUE, the minimum acceptable length for truncation (before
 *   adding an ellipsis, if $add_ellipsis is TRUE). Has no effect if $wordsafe
 *   is FALSE. This can be used to prevent having a very short resulting string
 *   that will not be understandable. For instance, if you are truncating the
 *   string "See myverylongurlexample.com for more information" to a word-safe
 *   return length of 20, the only available word boundary within 20 characters
 *   is after the word "See", which wouldn't leave a very informative string. If
 *   you had set $min_wordsafe_length to 10, though, the function would realise
 *   that "See" alone is too short, and would then just truncate ignoring word
 *   boundaries, giving you "See myverylongurl..." (assuming you had set
 *   $add_ellipses to TRUE).
 *
 * @return
 *   The truncated string.
 */
function truncate_utf8($string, $max_length, $wordsafe = FALSE, $add_ellipsis = FALSE, $min_wordsafe_length = 1) {
  $ellipsis = '';
  $max_length = max($max_length, 0);
  $min_wordsafe_length = max($min_wordsafe_length, 0);

  if (drupal_strlen($string) <= $max_length) {
    // No truncation needed, so don't add ellipsis, just return.
    return $string;
  }

  if ($add_ellipsis) {
    // Truncate ellipsis in case $max_length is small.
    $ellipsis = drupal_substr(t('...'), 0, $max_length);
    $max_length -= drupal_strlen($ellipsis);
    $max_length = max($max_length, 0);
  }

  if ($max_length <= $min_wordsafe_length) {
    // Do not attempt word-safe if lengths are bad.
    $wordsafe = FALSE;
  }

  if ($wordsafe) {
    $matches = array();
    // Find the last word boundary, if there is one within $min_wordsafe_length
    // to $max_length characters. preg_match() is always greedy, so it will
    // find the longest string possible.
    $found = preg_match('/^(.{' . $min_wordsafe_length . ',' . $max_length . '})[' . PREG_CLASS_UNICODE_WORD_BOUNDARY . ']/u', $string, $matches);
    if ($found) {
      $string = $matches[1];
    }
    else {
      $string = drupal_substr($string, 0, $max_length);
    }
  }
  else {
    $string = drupal_substr($string, 0, $max_length);
  }

  if ($add_ellipsis) {
    $string .= $ellipsis;
  }

  return $string;
}

/**
 * Encodes MIME/HTTP header values that contain non-ASCII, UTF-8 encoded
 * characters.
 *
 * For example, mime_header_encode('t├ęst.txt') returns "=?UTF-8?B?dMOpc3QudHh0?=".
 *
 * See http://www.rfc-editor.org/rfc/rfc2047.txt for more information.
 *
 * Notes:
 * - Only encode strings that contain non-ASCII characters.
 * - We progressively cut-off a chunk with truncate_utf8(). This is to ensure
 *   each chunk starts and ends on a character boundary.
 * - Using \n as the chunk separator may cause problems on some systems and may
 *   have to be changed to \r\n or \r.
 */
function mime_header_encode($string) {
  if (preg_match('/[^\x20-\x7E]/', $string)) {
    $chunk_size = 47; // floor((75 - strlen("=?UTF-8?B??=")) * 0.75);
    $len = strlen($string);
    $output = '';
    while ($len > 0) {
      $chunk = drupal_truncate_bytes($string, $chunk_size);
      $output .= ' =?UTF-8?B?' . base64_encode($chunk) . "?=\n";
      $c = strlen($chunk);
      $string = substr($string, $c);
      $len -= $c;
    }
    return trim($output);
  }
  return $string;
}

/**
 * Complement to mime_header_encode
 */
function mime_header_decode($header) {
  // First step: encoded chunks followed by other encoded chunks (need to collapse whitespace)
  $header = preg_replace_callback('/=\?([^?]+)\?(Q|B)\?([^?]+|\?(?!=))\?=\s+(?==\?)/', '_mime_header_decode', $header);
  // Second step: remaining chunks (do not collapse whitespace)
  return preg_replace_callback('/=\?([^?]+)\?(Q|B)\?([^?]+|\?(?!=))\?=/', '_mime_header_decode', $header);
}

/**
 * Helper function to mime_header_decode
 */
function _mime_header_decode($matches) {
  // Regexp groups:
  // 1: Character set name
  // 2: Escaping method (Q or B)
  // 3: Encoded data
  $data = ($matches[2] == 'B') ? base64_decode($matches[3]) : str_replace('_', ' ', quoted_printable_decode($matches[3]));
  if (strtolower($matches[1]) != 'utf-8') {
    $data = drupal_convert_to_utf8($data, $matches[1]);
  }
  return $data;
}

/**
 * Decodes all HTML entities (including numerical ones) to regular UTF-8 bytes.
 *
 * Double-escaped entities will only be decoded once ("&amp;lt;" becomes "&lt;",
 * not "<"). Be careful when using this function, as decode_entities can revert
 * previous sanitization efforts (&lt;script&gt; will become <script>).
 *
 * @param $text
 *   The text to decode entities in.
 *
 * @return
 *   The input $text, with all HTML entities decoded once.
 */
function decode_entities($text) {
  return html_entity_decode($text, ENT_QUOTES, 'UTF-8');
}

/**
 * Count the amount of characters in a UTF-8 string. This is less than or
 * equal to the byte count.
 *
 * @ingroup php_wrappers
 */
function drupal_strlen($text) {
  global $multibyte;
  if ($multibyte == UNICODE_MULTIBYTE) {
    return mb_strlen($text);
  }
  else {
    // Do not count UTF-8 continuation bytes.
    return strlen(preg_replace("/[\x80-\xBF]/", '', $text));
  }
}

/**
 * Uppercase a UTF-8 string.
 *
 * @ingroup php_wrappers
 */
function drupal_strtoupper($text) {
  global $multibyte;
  if ($multibyte == UNICODE_MULTIBYTE) {
    return mb_strtoupper($text);
  }
  else {
    // Use C-locale for ASCII-only uppercase
    $text = strtoupper($text);
    // Case flip Latin-1 accented letters
    $text = preg_replace_callback('/\xC3[\xA0-\xB6\xB8-\xBE]/', '_unicode_caseflip', $text);
    return $text;
  }
}

/**
 * Lowercase a UTF-8 string.
 *
 * @ingroup php_wrappers
 */
function drupal_strtolower($text) {
  global $multibyte;
  if ($multibyte == UNICODE_MULTIBYTE) {
    return mb_strtolower($text);
  }
  else {
    // Use C-locale for ASCII-only lowercase
    $text = strtolower($text);
    // Case flip Latin-1 accented letters
    $text = preg_replace_callback('/\xC3[\x80-\x96\x98-\x9E]/', '_unicode_caseflip', $text);
    return $text;
  }
}

/**
 * Helper function for case conversion of Latin-1.
 * Used for flipping U+C0-U+DE to U+E0-U+FD and back.
 */
function _unicode_caseflip($matches) {
  return $matches[0][0] . chr(ord($matches[0][1]) ^ 32);
}

/**
 * Capitalize the first letter of a UTF-8 string.
 *
 * @ingroup php_wrappers
 */
function drupal_ucfirst($text) {
  // Note: no mbstring equivalent!
  return drupal_strtoupper(drupal_substr($text, 0, 1)) . drupal_substr($text, 1);
}

/**
 * Cut off a piece of a string based on character indices and counts. Follows
 * the same behavior as PHP's own substr() function.
 *
 * Note that for cutting off a string at a known character/substring
 * location, the usage of PHP's normal strpos/substr is safe and
 * much faster.
 *
 * @ingroup php_wrappers
 */
function drupal_substr($text, $start, $length = NULL) {
  global $multibyte;
  if ($multibyte == UNICODE_MULTIBYTE) {
    return $length === NULL ? mb_substr($text, $start) : mb_substr($text, $start, $length);
  }
  else {
    $strlen = strlen($text);
    // Find the starting byte offset.
    $bytes = 0;
    if ($start > 0) {
      // Count all the continuation bytes from the start until we have found
      // $start characters or the end of the string.
      $bytes = -1; $chars = -1;
      while ($bytes < $strlen - 1 && $chars < $start) {
        $bytes++;
        $c = ord($text[$bytes]);
        if ($c < 0x80 || $c >= 0xC0) {
          $chars++;
        }
      }
    }
    elseif ($start < 0) {
      // Count all the continuation bytes from the end until we have found
      // abs($start) characters.
      $start = abs($start);
      $bytes = $strlen; $chars = 0;
      while ($bytes > 0 && $chars < $start) {
        $bytes--;
        $c = ord($text[$bytes]);
        if ($c < 0x80 || $c >= 0xC0) {
          $chars++;
        }
      }
    }
    $istart = $bytes;

    // Find the ending byte offset.
    if ($length === NULL) {
      $iend = $strlen;
    }
    elseif ($length > 0) {
      // Count all the continuation bytes from the starting index until we have
      // found $length characters or reached the end of the string, then
      // backtrace one byte.
      $iend = $istart - 1;
      $chars = -1;
      $last_real = FALSE;
      while ($iend < $strlen - 1 && $chars < $length) {
        $iend++;
        $c = ord($text[$iend]);
        $last_real = FALSE;
        if ($c < 0x80 || $c >= 0xC0) {
          $chars++;
          $last_real = TRUE;
        }
      }
      // Backtrace one byte if the last character we found was a real character
      // and we don't need it.
      if ($last_real && $chars >= $length) {
        $iend--;
      }
    }
    elseif ($length < 0) {
      // Count all the continuation bytes from the end until we have found
      // abs($start) characters, then backtrace one byte.
      $length = abs($length);
      $iend = $strlen; $chars = 0;
      while ($iend > 0 && $chars < $length) {
        $iend--;
        $c = ord($text[$iend]);
        if ($c < 0x80 || $c >= 0xC0) {
          $chars++;
        }
      }
      // Backtrace one byte if we are not at the beginning of the string.
      if ($iend > 0) {
        $iend--;
      }
    }
    else {
      // $length == 0, return an empty string.
      return '';
    }

    return substr($text, $istart, max(0, $iend - $istart + 1));
  }
}