A new function for converting HTML into text form

diff --git a/lib/html2text.php b/lib/html2text.php
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+<?php
+
+/***************************************************************
+ * Library to convert HTML into an approximate text equivalent *
+ ***************************************************************
+
+  Version: 1.0  (with modifications)
+  Copyright 2002 Mark Wilton-Jones
+  License: HowToCreate script license with written permission
+  URL: http://www.howtocreate.co.uk/php/
+  
+  For full details about the script and to get the latest version,
+  please see the HowToCreate web site above.
+  
+  This version contains modifications for Moodle.  In each case the 
+  original line has been commented out below and a new line has been
+  added, so it should be easy to see what has changed.
+  
+  --------------------------------------------------------------
+
+The reason this library was written was to convert HTML email contents into a text
+based email content, where the rendering does not have to be as accurate as with
+a text based browser. However, there must be many more uses for it.
+
+This library attempts to deal with non-standard HTML, but may occasionally suffer
+from problems with pages that are not properly written - most especially:
+Tags written as <tagName attribute=somethingWithA"or'InItButNotSurroundedByQuotes>,
+Closing </pre> or </textarea> tags without their corresponding opening tags,
+Tags within <textarea> </textarea> tags, which will be rendered, even though they
+should not be.
+
+Conversion requires a lot of preg_replace statements, so it can be quite slow with
+large HTML files.
+
+******
+To use
+******
+
+This library requires PHP 4+
+
+To use this library, put the following line in your script before the part that needs it:
+require('PATH_TO_THIS_FILE/html2text.php');
+
+To convert HTML/PHP to text:
+       $textVersion = html2text( $HTMLversion );
+
+************
+Further info
+************
+
+For the technically minded, this is the process I use for converting HTML to approx text:
+
+REMOVE php start and end tags
+REMOVE <!-- -->
+ensure HTML uses entities in the right places (like inside tags) so strip_tags works properly
+<STYLE|SCRIPT|OPTION>
+carefully remove everything between them
+strip_tags except the important ones
+replace all \s that are after the start or a </pre> and before <pre> or end with a single space
+</TITLE|HR>
+\n          --------------------
+<H1|H2|H3|H4|H5|H6|DIV|P|PRE>
+\n\n
+<SUP>
+^
+<UL|OL|BR|DL|DT|TABLE|CAPTION|TR->(TH|TD)>
+\n
+<LI>
+\n· 
+<DD>
+\n\t
+<TH|TD>
+\t
+<A|AREA href=(!javascript:&&!#)>
+[LINK:hrefWithout#]
+<IMG>
+[IMG:alt]
+<FORM>
+[FORM:action]
+<INPUT|TEXTAREA|BUTTON|SELECT>
+[INPUT]
+strip tags again, leaving nothing this time
+un-htmlspecialchars
+word wrap (this will also affect pre, but as this is intended for email use, I don't care)
+
+
+*/
+
+function html2text( $badStr ) {
+       //remove PHP if it exists
+       if( $andPHP ) { while( substr_count( $badStr, '<'.'?' ) && substr_count( $badStr, '?'.'>' ) && strpos( $badStr, '?'.'>' ) > strpos( $badStr, '<'.'?' ) ) {
+               $badStr = substr( $badStr, 0, strpos( $badStr, '<'.'?' ) ) . substr( $badStr, strpos( $badStr, '?'.'>' ) + 2 ); } }
+       //remove comments
+       while( substr_count( $badStr, '<!--' ) && substr_count( $badStr, '-->' ) && strpos( $badStr, '-->' ) > strpos( $badStr, '<!--' ) ) {
+               $badStr = substr( $badStr, 0, strpos( $badStr, '<!--' ) ) . substr( $badStr, strpos( $badStr, '-->' ) + 3 ); }
+       //now make sure all HTML tags are correctly written (> not in between quotes)
+       for( $x = 0, $goodStr = '', $is_open_tb = false, $is_open_sq = false, $is_open_sq = false; strlen( $chr = $badStr{$x} ); $x++ ) {
+               //take each letter in turn and check if that character is permitted there
+               switch( $chr ) {
+                       case '<':
+                               if( !$is_open_tb && strtolower( substr( $badStr, $x + 1, 5 ) ) == 'style' ) {
+                                       $badStr = substr( $badStr, 0, $x ) . substr( $badStr, strpos( strtolower( $badStr ), '</style>' ) + 7 ); $chr = '';
+                               } elseif( !$is_open_tb && strtolower( substr( $badStr, $x + 1, 6 ) ) == 'script' ) {
+                                       $badStr = substr( $badStr, 0, $x ) . substr( $badStr, strpos( strtolower( $badStr ), '</script>' ) + 8 ); $chr = '';
+                               } elseif( !$is_open_tb ) { $is_open_tb = true; } else { $chr = '&lt;'; }
+                               break;
+                       case '>':
+                               if( !$is_open_tb || $is_open_dq || $is_open_sq ) { $chr = '&gt;'; } else { $is_open_tb = false; }
+                               break;
+                       case '"':
+                               if( $is_open_tb && !$is_open_dq && !$is_open_sq ) { $is_open_dq = true; }
+                               elseif( $is_open_tb && $is_open_dq && !$is_open_sq ) { $is_open_dq = false; }
+                               else { $chr = '&quot;'; }
+                               break;
+                       case "'":
+                               if( $is_open_tb && !$is_open_dq && !$is_open_sq ) { $is_open_sq = true; }
+                               elseif( $is_open_tb && !$is_open_dq && $is_open_sq ) { $is_open_sq = false; }
+               } $goodStr .= $chr;
+       }
+       //now that the page is valid (I hope) for strip_tags, strip all unwanted tags
+       $goodStr = strip_tags( $goodStr, '<title><hr><h1><h2><h3><h4><h5><h6><div><p><pre><sup><ul><ol><br><dl><dt><table><caption><tr><li><dd><th><td><a><area><img><form><input><textarea><button><select><option>' );
+       //strip extra whitespace except between <pre> and <textarea> tags
+       $badStr = preg_split( "/<\/?pre[^>]*>/i", $goodStr );
+       for( $x = 0; is_string( $badStr[$x] ); $x++ ) {
+               if( $x % 2 ) { $badStr[$x] = '<pre>'.$badStr[$x].'</pre>'; } else {
+                       $goodStr = preg_split( "/<\/?textarea[^>]*>/i", $badStr[$x] );
+                       for( $z = 0; is_string( $goodStr[$z] ); $z++ ) {
+                               if( $z % 2 ) { $goodStr[$z] = '<textarea>'.$goodStr[$z].'</textarea>'; } else {
+                                       $goodStr[$z] = preg_replace( "/\s+/", ' ', $goodStr[$z] );
+                       } }
+                       $badStr[$x] = implode('',$goodStr);
+       } }
+       $goodStr = implode('',$badStr);
+       //remove all options from select inputs
+       $goodStr = preg_replace( "/<option[^>]*>[^<]*/i", '', $goodStr );
+       //replace all tags with their text equivalents
+       $goodStr = preg_replace( "/<(\/title|hr)[^>]*>/i", "\n          --------------------\n", $goodStr );
+       $goodStr = preg_replace( "/<(h|div|p)[^>]*>/i", "\n\n", $goodStr );
+       $goodStr = preg_replace( "/<sup[^>]*>/i", '^', $goodStr );
+       $goodStr = preg_replace( "/<(ul|ol|br|dl|dt|table|caption|\/textarea|tr[^>]*>\s*<(td|th))[^>]*>/i", "\n", $goodStr );
+       $goodStr = preg_replace( "/<li[^>]*>/i", "\n· ", $goodStr );
+       $goodStr = preg_replace( "/<dd[^>]*>/i", "\n\t", $goodStr );
+       $goodStr = preg_replace( "/<(th|td)[^>]*>/i", "\t", $goodStr );
+       ///$goodStr = preg_replace( "/<a[^>]* href=(\"((?!\"|#|javascript:)[^\"#]*)(\"|#)|'((?!'|#|javascript:)[^'#]*)('|#)|((?!'|\"|>|#|javascript:)[^#\"'> ]*))[^>]*>/i", "[LINK: $2$4$6] ", $goodStr ); /// Moodle
+       $goodStr = preg_replace( "/<a[^>]* href=(\"((?!\"|#|javascript:)[^\"#]*)(\"|#)|'((?!'|#|javascript:)[^'#]*)('|#)|((?!'|\"|>|#|javascript:)[^#\"'> ]*))[^>]*>/i", "[$2$4$6] ", $goodStr );
+       /// $goodStr = preg_replace( "/<img[^>]* alt=(\"([^\"]+)\"|'([^']+)'|([^\"'> ]+))[^>]*>/i", "[IMAGE: $2$3$4] ", $goodStr );/// Moodle
+       $goodStr = preg_replace( "/<img[^>]* alt=(\"([^\"]+)\"|'([^']+)'|([^\"'> ]+))[^>]*>/i", "{$2$3$4} ", $goodStr );
+       $goodStr = preg_replace( "/<form[^>]* action=(\"([^\"]+)\"|'([^']+)'|([^\"'> ]+))[^>]*>/i", "\n[FORM: $2$3$4] ", $goodStr );
+       $goodStr = preg_replace( "/<(input|textarea|button|select)[^>]*>/i", "[INPUT] ", $goodStr );
+       //strip all remaining tags (mostly closing tags)
+       $goodStr = strip_tags( $goodStr );
+       //convert HTML entities
+       $goodStr = strtr( $goodStr, array_flip( get_html_translation_table( HTML_ENTITIES ) ) );
+       preg_replace( "/&#(\d+);/me", "chr('$1')", $goodStr );
+       //wordwrap
+       ///$goodStr = wordwrap($goodStr);    /// Moodle
+       $goodStr = wordwrap($goodStr, 70);
+       //make sure there are no more than 3 linebreaks in a row and trim whitespace
+       return preg_replace( "/^\n*|\n*$/", '', preg_replace( "/[ \t]+(\n|$)/", "$1", preg_replace( "/\n(\s*\n){2}/", "\n\n\n", preg_replace( "/\r\n?|\f/", "\n", str_replace( chr(160), ' ', $goodStr ) ) ) ) );
+}
+
+?>