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