lib/html2text.php

   1 <?php
   2
   3 /*************************************************************************
   4  *                                                                       *
   5  * class.html2text.inc                                                   *
   6  *                                                                       *
   7  *************************************************************************
   8  *                                                                       *
   9  * Converts HTML to formatted plain text                                 *
  10  *                                                                       *
  11  * Copyright (c) 2005-2007 Jon Abernathy <jon@chuggnutt.com>             *
  12  * All rights reserved.                                                  *
  13  *                                                                       *
  14  * This script is free software; you can redistribute it and/or modify   *
  15  * it under the terms of the GNU General Public License as published by  *
  16  * the Free Software Foundation; either version 2 of the License, or     *
  17  * (at your option) any later version.                                   *
  18  *                                                                       *
  19  * The GNU General Public License can be found at                        *
  20  * http://www.gnu.org/copyleft/gpl.html.                                 *
  21  *                                                                       *
  22  * This script is distributed in the hope that it will be useful,        *
  23  * but WITHOUT ANY WARRANTY; without even the implied warranty of        *
  24  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the          *
  25  * GNU General Public License for more details.                          *
  26  *                                                                       *
  27  * Author(s): Jon Abernathy <jon@chuggnutt.com>                          *
  28  *                                                                       *
  29  * Last modified: 08/08/07                                               *
  30  *                                                                       *
  31  *************************************************************************/
  32
  33 if (!defined('RCMAIL_CHARSET')) {
  34     define('RCMAIL_CHARSET', 'UTF-8');
  35 }
  36
  37 /**
  38  *  Takes HTML and converts it to formatted, plain text.
  39  *
  40  *  Thanks to Alexander Krug (http://www.krugar.de/) to pointing out and
  41  *  correcting an error in the regexp search array. Fixed 7/30/03.
  42  *
  43  *  Updated set_html() function's file reading mechanism, 9/25/03.
  44  *
  45  *  Thanks to Joss Sanglier (http://www.dancingbear.co.uk/) for adding
  46  *  several more HTML entity codes to the $search and $replace arrays.
  47  *  Updated 11/7/03.
  48  *
  49  *  Thanks to Darius Kasperavicius (http://www.dar.dar.lt/) for
  50  *  suggesting the addition of $allowed_tags and its supporting function
  51  *  (which I slightly modified). Updated 3/12/04.
  52  *
  53  *  Thanks to Justin Dearing for pointing out that a replacement for the
  54  *  <TH> tag was missing, and suggesting an appropriate fix.
  55  *  Updated 8/25/04.
  56  *
  57  *  Thanks to Mathieu Collas (http://www.myefarm.com/) for finding a
  58  *  display/formatting bug in the _build_link_list() function: email
  59  *  readers would show the left bracket and number ("[1") as part of the
  60  *  rendered email address.
  61  *  Updated 12/16/04.
  62  *
  63  *  Thanks to Wojciech Bajon (http://histeria.pl/) for submitting code
  64  *  to handle relative links, which I hadn't considered. I modified his
  65  *  code a bit to handle normal HTTP links and MAILTO links. Also for
  66  *  suggesting three additional HTML entity codes to search for.
  67  *  Updated 03/02/05.
  68  *
  69  *  Thanks to Jacob Chandler for pointing out another link condition
  70  *  for the _build_link_list() function: "https".
  71  *  Updated 04/06/05.
  72  *
  73  *  Thanks to Marc Bertrand (http://www.dresdensky.com/) for
  74  *  suggesting a revision to the word wrapping functionality; if you
  75  *  specify a $width of 0 or less, word wrapping will be ignored.
  76  *  Updated 11/02/06.
  77  *
  78  *  *** Big housecleaning updates below:
  79  *
  80  *  Thanks to Colin Brown (http://www.sparkdriver.co.uk/) for
  81  *  suggesting the fix to handle </li> and blank lines (whitespace).
  82  *  Christian Basedau (http://www.movetheweb.de/) also suggested the
  83  *  blank lines fix.
  84  *
  85  *  Special thanks to Marcus Bointon (http://www.synchromedia.co.uk/),
  86  *  Christian Basedau, Norbert Laposa (http://ln5.co.uk/),
  87  *  Bas van de Weijer, and Marijn van Butselaar
  88  *  for pointing out my glaring error in the <th> handling. Marcus also
  89  *  supplied a host of fixes.
  90  *
  91  *  Thanks to Jeffrey Silverman (http://www.newtnotes.com/) for pointing
  92  *  out that extra spaces should be compressed--a problem addressed with
  93  *  Marcus Bointon's fixes but that I had not yet incorporated.
  94  *
  95  *      Thanks to Daniel Schledermann (http://www.typoconsult.dk/) for
  96  *  suggesting a valuable fix with <a> tag handling.
  97  *
  98  *  Thanks to Wojciech Bajon (again!) for suggesting fixes and additions,
  99  *  including the <a> tag handling that Daniel Schledermann pointed
 100  *  out but that I had not yet incorporated. I haven't (yet)
 101  *  incorporated all of Wojciech's changes, though I may at some
 102  *  future time.
 103  *
 104  *  *** End of the housecleaning updates. Updated 08/08/07.
 105  *
 106  *  @author Jon Abernathy <jon@chuggnutt.com>
 107  *  @version 1.0.0
 108  *  @since PHP 4.0.2
 109  */
 110 class html2text
 111 {
 112
 113     /**
 114      *  Contains the HTML content to convert.
 115      *
 116      *  @var string $html
 117      *  @access public
 118      */
 119     var $html;
 120
 121     /**
 122      *  Contains the converted, formatted text.
 123      *
 124      *  @var string $text
 125      *  @access public
 126      */
 127     var $text;
 128
 129     /**
 130      *  Maximum width of the formatted text, in columns.
 131      *
 132      *  Set this value to 0 (or less) to ignore word wrapping
 133      *  and not constrain text to a fixed-width column.
 134      *
 135      *  @var integer $width
 136      *  @access public
 137      */
 138     var $width = 70;
 139
 140     /**
 141      *  List of preg* regular expression patterns to search for,
 142      *  used in conjunction with $replace.
 143      *
 144      *  @var array $search
 145      *  @access public
 146      *  @see $replace
 147      */
 148     var $search = array(
 149         "/\r/",                                  // Non-legal carriage return
 150         "/[\n\t]+/",                             // Newlines and tabs
 151         '/<script[^>]*>.*?<\/script>/i',         // <script>s -- which strip_tags supposedly has problems with
 152         '/<style[^>]*>.*?<\/style>/i',           // <style>s -- which strip_tags supposedly has problems with
 153         '/<p[^>]*>/i',                           // <P>
 154         '/<br[^>]*>/i',                          // <br>
 155         '/<i[^>]*>(.*?)<\/i>/i',                 // <i>
 156         '/<em[^>]*>(.*?)<\/em>/i',               // <em>
 157         '/(<ul[^>]*>|<\/ul>)/i',                 // <ul> and </ul>
 158         '/(<ol[^>]*>|<\/ol>)/i',                 // <ol> and </ol>
 159         '/<li[^>]*>(.*?)<\/li>/i',               // <li> and </li>
 160         '/<li[^>]*>/i',                          // <li>
 161         '/<hr[^>]*>/i',                          // <hr>
 162         '/<div[^>]*>/i',                         // <div>
 163         '/(<table[^>]*>|<\/table>)/i',           // <table> and </table>
 164         '/(<tr[^>]*>|<\/tr>)/i',                 // <tr> and </tr>
 165         '/<td[^>]*>(.*?)<\/td>/i',               // <td> and </td>
 166     );
 167
 168     /**
 169      *  List of pattern replacements corresponding to patterns searched.
 170      *
 171      *  @var array $replace
 172      *  @access public
 173      *  @see $search
 174      */
 175     var $replace = array(
 176         '',                                     // Non-legal carriage return
 177         ' ',                                    // Newlines and tabs
 178         '',                                     // <script>s -- which strip_tags supposedly has problems with
 179         '',                                     // <style>s -- which strip_tags supposedly has problems with
 180         "\n\n",                                 // <P>
 181         "\n",                                   // <br>
 182         '_\\1_',                                // <i>
 183         '_\\1_',                                // <em>
 184         "\n\n",                                 // <ul> and </ul>
 185         "\n\n",                                 // <ol> and </ol>
 186         "\t* \\1\n",                            // <li> and </li>
 187         "\n\t* ",                               // <li>
 188         "\n-------------------------\n",        // <hr>
 189         "<div>\n",                              // <div>
 190         "\n\n",                                 // <table> and </table>
 191         "\n",                                   // <tr> and </tr>
 192         "\t\t\\1\n",                            // <td> and </td>
 193     );
 194
 195     /**
 196      *  List of preg* regular expression patterns to search for,
 197      *  used in conjunction with $ent_replace.
 198      *
 199      *  @var array $ent_search
 200      *  @access public
 201      *  @see $ent_replace
 202      */
 203     var $ent_search = array(
 204         '/&(nbsp|#160);/i',                      // Non-breaking space
 205         '/&(quot|rdquo|ldquo|#8220|#8221|#147|#148);/i',
 206         // Double quotes
 207         '/&(apos|rsquo|lsquo|#8216|#8217);/i',   // Single quotes
 208         '/&gt;/i',                               // Greater-than
 209         '/&lt;/i',                               // Less-than
 210         '/&(copy|#169);/i',                      // Copyright
 211         '/&(trade|#8482|#153);/i',               // Trademark
 212         '/&(reg|#174);/i',                       // Registered
 213         '/&(mdash|#151|#8212);/i',               // mdash
 214         '/&(ndash|minus|#8211|#8722);/i',        // ndash
 215         '/&(bull|#149|#8226);/i',                // Bullet
 216         '/&(pound|#163);/i',                     // Pound sign
 217         '/&(euro|#8364);/i',                     // Euro sign
 218         '/&(amp|#38);/i',                        // Ampersand: see _converter()
 219         '/[ ]{2,}/',                             // Runs of spaces, post-handling
 220     );
 221
 222     /**
 223      *  List of pattern replacements corresponding to patterns searched.
 224      *
 225      *  @var array $ent_replace
 226      *  @access public
 227      *  @see $ent_search
 228      */
 229     var $ent_replace = array(
 230         ' ',                                    // Non-breaking space
 231         '"',                                    // Double quotes
 232         "'",                                    // Single quotes
 233         '>',
 234         '<',
 235         '(c)',
 236         '(tm)',
 237         '(R)',
 238         '--',
 239         '-',
 240         '*',
 241         '£',
 242         'EUR',                                  // Euro sign. € ?
 243         '|+|amp|+|',                            // Ampersand: see _converter()
 244         ' ',                                    // Runs of spaces, post-handling
 245     );
 246
 247     /**
 248      *  List of preg* regular expression patterns to search for
 249      *  and replace using callback function.
 250      *
 251      *  @var array $callback_search
 252      *  @access public
 253      */
 254     var $callback_search = array(
 255         '/<(a) [^>]*href=("|\')([^"\']+)\2[^>]*>(.*?)<\/a>/i',
 256         // <a href="">
 257         '/<(h)[123456][^>]*>(.*?)<\/h[123456]>/i', // H1 - H3
 258         '/<(b)[^>]*>(.*?)<\/b>/i',                 // <b>
 259         '/<(strong)[^>]*>(.*?)<\/strong>/i',       // <strong>
 260         '/<(th)[^>]*>(.*?)<\/th>/i',               // <th> and </th>
 261         '/<(img)[^>]*alt=\"([^>"]+)\"[^>]*>/i',    // <img> with alt
 262     );
 263
 264     /**
 265      *  List of preg* regular expression patterns to search for in PRE body,
 266      *  used in conjunction with $pre_replace.
 267      *
 268      *  @var array $pre_search
 269      *  @access public
 270      *  @see $pre_replace
 271      */
 272     var $pre_search = array(
 273         "/\n/",
 274         "/\t/",
 275         '/ /',
 276         '/<pre[^>]*>/',
 277         '/<\/pre>/'
 278     );
 279
 280     /**
 281      *  List of pattern replacements corresponding to patterns searched for PRE body.
 282      *
 283      *  @var array $pre_replace
 284      *  @access public
 285      *  @see $pre_search
 286      */
 287     var $pre_replace = array(
 288         '<br>',
 289         '&nbsp;&nbsp;&nbsp;&nbsp;',
 290         '&nbsp;',
 291         '',
 292         ''
 293     );
 294
 295     /**
 296      *  Contains a list of HTML tags to allow in the resulting text.
 297      *
 298      *  @var string $allowed_tags
 299      *  @access public
 300      *  @see set_allowed_tags()
 301      */
 302     var $allowed_tags = '';
 303
 304     /**
 305      *  Contains the base URL that relative links should resolve to.
 306      *
 307      *  @var string $url
 308      *  @access public
 309      */
 310     var $url;
 311
 312     /**
 313      *  Indicates whether content in the $html variable has been converted yet.
 314      *
 315      *  @var boolean $_converted
 316      *  @access private
 317      *  @see $html, $text
 318      */
 319     var $_converted = false;
 320
 321     /**
 322      *  Contains URL addresses from links to be rendered in plain text.
 323      *
 324      *  @var array $_link_list
 325      *  @access private
 326      *  @see _build_link_list()
 327      */
 328     var $_link_list = array();
 329
 330     /**
 331      * Boolean flag, true if a table of link URLs should be listed after the text.
 332      *
 333      * @var boolean $_do_links
 334      * @access private
 335      * @see html2text()
 336      */
 337     var $_do_links = true;
 338
 339     /**
 340      *  Constructor.
 341      *
 342      *  If the HTML source string (or file) is supplied, the class
 343      *  will instantiate with that source propagated, all that has
 344      *  to be done it to call get_text().
 345      *
 346      *  @param string $source HTML content
 347      *  @param boolean $from_file Indicates $source is a file to pull content from
 348      *  @param boolean $do_links Indicate whether a table of link URLs is desired
 349      *  @param integer $width Maximum width of the formatted text, 0 for no limit
 350      *  @access public
 351      *  @return void
 352      */
 353     function html2text( $source = '', $from_file = false, $do_links = true, $width = 75 )
 354     {
 355         if ( $source !== '' ) {
 356             $this->set_html($source, $from_file);
 357         }
 358
 359         $this->set_base_url();
 360         $this->_do_links = $do_links;
 361         $this->width = $width;
 362     }
 363
 364     /**
 365      *  Loads source HTML into memory, either from $source string or a file.
 366      *
 367      *  @param string $source HTML content
 368      *  @param boolean $from_file Indicates $source is a file to pull content from
 369      *  @access public
 370      *  @return void
 371      */
 372     function set_html( $source, $from_file = false )
 373     {
 374         if ( $from_file && file_exists($source) ) {
 375             $this->html = file_get_contents($source);
 376         }
 377         else
 378             $this->html = $source;
 379
 380         $this->_converted = false;
 381     }
 382
 383     /**
 384      *  Returns the text, converted from HTML.
 385      *
 386      *  @access public
 387      *  @return string
 388      */
 389     function get_text()
 390     {
 391         if ( !$this->_converted ) {
 392             $this->_convert();
 393         }
 394
 395         return $this->text;
 396     }
 397
 398     /**
 399      *  Prints the text, converted from HTML.
 400      *
 401      *  @access public
 402      *  @return void
 403      */
 404     function print_text()
 405     {
 406         print $this->get_text();
 407     }
 408
 409     /**
 410      *  Alias to print_text(), operates identically.
 411      *
 412      *  @access public
 413      *  @return void
 414      *  @see print_text()
 415      */
 416     function p()
 417     {
 418         print $this->get_text();
 419     }
 420
 421     /**
 422      *  Sets the allowed HTML tags to pass through to the resulting text.
 423      *
 424      *  Tags should be in the form "<p>", with no corresponding closing tag.
 425      *
 426      *  @access public
 427      *  @return void
 428      */
 429     function set_allowed_tags( $allowed_tags = '' )
 430     {
 431         if ( !empty($allowed_tags) ) {
 432             $this->allowed_tags = $allowed_tags;
 433         }
 434     }
 435
 436     /**
 437      *  Sets a base URL to handle relative links.
 438      *
 439      *  @access public
 440      *  @return void
 441      */
 442     function set_base_url( $url = '' )
 443     {
 444         if ( empty($url) ) {
 445             if ( !empty($_SERVER['HTTP_HOST']) ) {
 446                 $this->url = 'http://' . $_SERVER['HTTP_HOST'];
 447             } else {
 448                 $this->url = '';
 449             }
 450         } else {
 451             // Strip any trailing slashes for consistency (relative
 452             // URLs may already start with a slash like "/file.html")
 453             if ( substr($url, -1) == '/' ) {
 454                 $url = substr($url, 0, -1);
 455             }
 456             $this->url = $url;
 457         }
 458     }
 459
 460     /**
 461      *  Workhorse function that does actual conversion (calls _converter() method).
 462      *
 463      *  @access private
 464      *  @return void
 465      */
 466     function _convert()
 467     {
 468         // Variables used for building the link list
 469         $this->_link_list = array();
 470
 471         $text = trim($this->html);
 472
 473         // Convert HTML to TXT
 474         $this->_converter($text);
 475
 476         // Add link list
 477         if (!empty($this->_link_list)) {
 478             $text .= "\n\nLinks:\n------\n";
 479             foreach ($this->_link_list as $idx => $url) {
 480                 $text .= '[' . ($idx+1) . '] ' . $url . "\n";
 481             }
 482         }
 483
 484         $this->text = $text;
 485
 486         $this->_converted = true;
 487     }
 488
 489     /**
 490      *  Workhorse function that does actual conversion.
 491      *
 492      *  First performs custom tag replacement specified by $search and
 493      *  $replace arrays. Then strips any remaining HTML tags, reduces whitespace
 494      *  and newlines to a readable format, and word wraps the text to
 495      *  $width characters.
 496      *
 497      *  @param string Reference to HTML content string
 498      *
 499      *  @access private
 500      *  @return void
 501      */
 502     function _converter(&$text)
 503     {
 504         // Convert <BLOCKQUOTE> (before PRE!)
 505         $this->_convert_blockquotes($text);
 506
 507         // Convert <PRE>
 508         $this->_convert_pre($text);
 509
 510         // Run our defined tags search-and-replace
 511         $text = preg_replace($this->search, $this->replace, $text);
 512
 513         // Run our defined tags search-and-replace with callback
 514         $text = preg_replace_callback($this->callback_search, array('html2text', '_preg_callback'), $text);
 515
 516         // Strip any other HTML tags
 517         $text = strip_tags($text, $this->allowed_tags);
 518
 519         // Run our defined entities/characters search-and-replace
 520         $text = preg_replace($this->ent_search, $this->ent_replace, $text);
 521
 522         // Replace known html entities
 523         $text = html_entity_decode($text, ENT_COMPAT, 'UTF-8');
 524
 525         // Remove unknown/unhandled entities (this cannot be done in search-and-replace block)
 526         $text = preg_replace('/&([a-zA-Z0-9]{2,6}|#[0-9]{2,4});/', '', $text);
 527
 528         // Convert "|+|amp|+|" into "&", need to be done after handling of unknown entities
 529         // This properly handles situation of "&amp;quot;" in input string
 530         $text = str_replace('|+|amp|+|', '&', $text);
 531
 532         // Bring down number of empty lines to 2 max
 533         $text = preg_replace("/\n\s+\n/", "\n\n", $text);
 534         $text = preg_replace("/[\n]{3,}/", "\n\n", $text);
 535
 536         // remove leading empty lines (can be produced by eg. P tag on the beginning)
 537         $text = ltrim($text, "\n");
 538
 539         // Wrap the text to a readable format
 540         // for PHP versions >= 4.0.2. Default width is 75
 541         // If width is 0 or less, don't wrap the text.
 542         if ( $this->width > 0 ) {
 543             $text = wordwrap($text, $this->width);
 544         }
 545     }
 546
 547     /**
 548      *  Helper function called by preg_replace() on link replacement.
 549      *
 550      *  Maintains an internal list of links to be displayed at the end of the
 551      *  text, with numeric indices to the original point in the text they
 552      *  appeared. Also makes an effort at identifying and handling absolute
 553      *  and relative links.
 554      *
 555      *  @param string $link URL of the link
 556      *  @param string $display Part of the text to associate number with
 557      *  @access private
 558      *  @return string
 559      */
 560     function _build_link_list( $link, $display )
 561     {
 562         if (!$this->_do_links || empty($link)) {
 563             return $display;
 564         }
 565
 566         // Ignored link types
 567         if (preg_match('!^(javascript|mailto|#):!i', $link)) {
 568             return $display;
 569         }
 570
 571         if (preg_match('!^(https?://)!i', $link)) {
 572             $url = $link;
 573         }
 574         else {
 575             $url = $this->url;
 576             if (substr($link, 0, 1) != '/') {
 577                 $url .= '/';
 578             }
 579             $url .= "$link";
 580         }
 581
 582         if (($index = array_search($url, $this->_link_list)) === false) {
 583             $this->_link_list[] = $url;
 584             $index = count($this->_link_list);
 585         }
 586
 587         return $display . ' [' . ($index+1) . ']';
 588     }
 589
 590     /**
 591      *  Helper function for PRE body conversion.
 592      *
 593      *  @param string HTML content
 594      *  @access private
 595      */
 596     function _convert_pre(&$text)
 597     {
 598         // get the content of PRE element
 599         while (preg_match('/<pre[^>]*>(.*)<\/pre>/ismU', $text, $matches)) {
 600             // convert the content
 601             $this->pre_content = sprintf('<div><br>%s<br></div>',
 602                 preg_replace($this->pre_search, $this->pre_replace, $matches[1]));
 603             // replace the content (use callback because content can contain $0 variable)
 604             $text = preg_replace_callback('/<pre[^>]*>.*<\/pre>/ismU',
 605                 array('html2text', '_preg_pre_callback'), $text, 1);
 606             // free memory
 607             $this->pre_content = '';
 608         }
 609     }
 610
 611     /**
 612      *  Helper function for BLOCKQUOTE body conversion.
 613      *
 614      *  @param string HTML content
 615      *  @access private
 616      */
 617     function _convert_blockquotes(&$text)
 618     {
 619         if (preg_match_all('/<\/*blockquote[^>]*>/i', $text, $matches, PREG_OFFSET_CAPTURE)) {
 620             $level = 0;
 621             $diff = 0;
 622             foreach ($matches[0] as $m) {
 623                 if ($m[0][0] == '<' && $m[0][1] == '/') {
 624                     $level--;
 625                     if ($level < 0) {
 626                         $level = 0; // malformed HTML: go to next blockquote
 627                     }
 628                     else if ($level > 0) {
 629                         // skip inner blockquote
 630                     }
 631                     else {
 632                         $end  = $m[1];
 633                         $len  = $end - $taglen - $start;
 634                         // Get blockquote content
 635                         $body = substr($text, $start + $taglen - $diff, $len);
 636
 637                         // Set text width
 638                         $p_width = $this->width;
 639                         if ($this->width > 0) $this->width -= 2;
 640                         // Convert blockquote content
 641                         $body = trim($body);
 642                         $this->_converter($body);
 643                         // Add citation markers and create PRE block
 644                         $body = preg_replace('/((^|\n)>*)/', '\\1> ', trim($body));
 645                         $body = '<pre>' . htmlspecialchars($body) . '</pre>';
 646                         // Re-set text width
 647                         $this->width = $p_width;
 648                         // Replace content
 649                         $text = substr($text, 0, $start - $diff)
 650                             . $body . substr($text, $end + strlen($m[0]) - $diff);
 651
 652                         $diff = $len + $taglen + strlen($m[0]) - strlen($body);
 653                         unset($body);
 654                     }
 655                 }
 656                 else {
 657                     if ($level == 0) {
 658                         $start = $m[1];
 659                         $taglen = strlen($m[0]);
 660                     }
 661                     $level ++;
 662                 }
 663             }
 664         }
 665     }
 666
 667     /**
 668      *  Callback function for preg_replace_callback use.
 669      *
 670      *  @param  array PREG matches
 671      *  @return string
 672      */
 673     private function _preg_callback($matches)
 674     {
 675         switch($matches[1]) {
 676             case 'b':
 677             case 'strong':
 678                 return $this->_toupper($matches[2]);
 679             case 'th':
 680                 return $this->_toupper("\t\t". $matches[2] ."\n");
 681             case 'h':
 682                 return $this->_toupper("\n\n". $matches[2] ."\n\n");
 683             case 'a':
 684                 // Remove spaces in URL (#1487805)
 685                 $url = str_replace(' ', '', $matches[3]);
 686                 return $this->_build_link_list($url, $matches[4]);
 687             case 'img':
 688                 return '[' . $matches[2] . ']';
 689         }
 690     }
 691
 692     /**
 693      *  Callback function for preg_replace_callback use in PRE content handler.
 694      *
 695      *  @param  array PREG matches
 696      *  @return string
 697      */
 698     private function _preg_pre_callback($matches)
 699     {
 700         return $this->pre_content;
 701     }
 702
 703     /**
 704      * Strtoupper function with HTML tags and entities handling.
 705      *
 706      * @param string $str Text to convert
 707      * @return string Converted text
 708      */
 709     private function _toupper($str)
 710     {
 711         // string can containg HTML tags
 712         $chunks = preg_split('/(<[^>]*>)/', $str, null, PREG_SPLIT_NO_EMPTY | PREG_SPLIT_DELIM_CAPTURE);
 713
 714         // convert toupper only the text between HTML tags
 715         foreach ($chunks as $idx => $chunk) {
 716             if ($chunk[0] != '<') {
 717                 $chunks[$idx] = $this->_strtoupper($chunk);
 718             }
 719         }
 720
 721         return implode($chunks);
 722     }
 723
 724     /**
 725      * Strtoupper multibyte wrapper function with HTML entities handling.
 726      *
 727      * @param string $str Text to convert
 728      * @return string Converted text
 729      */
 730     private function _strtoupper($str)
 731     {
 732         $str = html_entity_decode($str, ENT_COMPAT, RCMAIL_CHARSET);
 733
 734         if (class_exists('textlib'))
 735             $str = textlib::strtoupper($str);
 736         else if (function_exists('mb_strtoupper'))
 737             $str = mb_strtoupper($str);
 738         else
 739             $str = strtoupper($str);
 740
 741         $str = htmlspecialchars($str, ENT_COMPAT, RCMAIL_CHARSET);
 742
 743         return $str;
 744     }
 745 }