Typography.php

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<?php  if ( ! defined('BASEPATH')) exit('No direct script access allowed');
/**
 * CodeIgniter
 *
 * An open source application development framework for PHP 4.3.2 or newer
 *
 * @package             CodeIgniter
 * @author              ExpressionEngine Dev Team
 * @copyright   Copyright (c) 2008, EllisLab, Inc.
 * @license             http://codeigniter.com/user_guide/license.html
 * @link                http://codeigniter.com
 * @since               Version 1.0
 * @filesource
 */

// ------------------------------------------------------------------------

/**
 * Typography Class
 *
 *
 * @access              private
 * @category    Helpers
 * @author              ExpressionEngine Dev Team
 * @link                http://codeigniter.com/user_guide/helpers/
 */
class CI_Typography {

        // Block level elements that should not be wrapped inside <p> tags
        var $block_elements = 'address|blockquote|div|dl|fieldset|form|h\d|hr|noscript|object|ol|p|pre|script|table|ul';
        
        // Elements that should not have <p> and <br /> tags within them.
        var $skip_elements      = 'p|pre|ol|ul|dl|object|table';
        
        // Tags we want the parser to completely ignore when splitting the string.
        var $inline_elements = 'a|abbr|acronym|b|bdo|br|button|cite|code|del|dfn|em|i|img|ins|input|label|map|kbd|samp|select|span|strong|sub|sup|textarea|var';

        // whether or not to protect quotes within { curly braces }
        var $protect_braced_quotes = FALSE;
        
        /**
         * Nothing to do here...
         *
         */
        function CI_Typography()
        {
        }

        /**
         * Auto Typography
         *
         * This function converts text, making it typographically correct:
         *      - Converts double spaces into paragraphs.
         *      - Converts single line breaks into <br /> tags
         *      - Converts single and double quotes into correctly facing curly quote entities.
         *      - Converts three dots into ellipsis.
         *      - Converts double dashes into em-dashes.
         *  - Converts two spaces into entities
         *
         * @access      public
         * @param       string
         * @param       bool    whether to strip javascript event handlers for security
         * @param       bool    whether to reduce more then two consecutive newlines to two
         * @return      string
         */
        function auto_typography($str, $strip_js_event_handlers = TRUE, $reduce_linebreaks = FALSE)
        {
                if ($str == '')
                {
                        return '';
                }

                // Standardize Newlines to make matching easier
                if (strpos($str, "\r") !== FALSE)
                {
                        $str = str_replace(array("\r\n", "\r"), "\n", $str);                    
                }
                        
                // Reduce line breaks.  If there are more than two consecutive linebreaks
                // we'll compress them down to a maximum of two since there's no benefit to more.
                if ($reduce_linebreaks === TRUE)
                {
                        $str = preg_replace("/\n\n+/", "\n\n", $str);
                }
                
                 // Do we allow JavaScript event handlers? If not, we strip them from within all tags
                if ($strip_js_event_handlers === TRUE)
                {
                        $str = preg_replace("#<([^><]+?)([^a-z_\-]on\w*|xmlns)(\s*=\s*[^><]*)([><]*)#i", "<\\1\\4", $str);
                }       

                // Convert quotes within tags to temporary markers. We don't want quotes converted 
                // within tags so we'll temporarily convert them to {@DQ} and {@SQ}
                if (preg_match_all("#<.+?>#si", $str, $matches))
                {
                        for ($i = 0; $i < count($matches['0']); $i++)
                        {
                                $str = str_replace($matches['0'][$i],
                                                                        str_replace(array("'",'"'), array('{@SQ}', '{@DQ}'), $matches['0'][$i]),
                                                                        $str);
                        }
                }

                if ($this->protect_braced_quotes === TRUE)
                {
                        if (preg_match_all("#\{.+?}#si", $str, $matches))
                        {
                                for ($i = 0; $i < count($matches['0']); $i++)
                                {
                                        $str = str_replace($matches['0'][$i],
                                                                                str_replace(array("'",'"'), array('{@SQ}', '{@DQ}'), $matches['0'][$i]),
                                                                                $str);
                                }
                        }                       
                }
                        
                // Convert "ignore" tags to temporary marker.  The parser splits out the string at every tag 
                // it encounters.  Certain inline tags, like image tags, links, span tags, etc. will be 
                // adversely affected if they are split out so we'll convert the opening bracket < temporarily to: {@TAG}
                $str = preg_replace("#<(/*)(".$this->inline_elements.")([ >])#i", "{@TAG}\\1\\2\\3", $str);

                // Split the string at every tag.  This expression creates an array with this prototype:
                // 
                //      [array]
                //      {
                //              [0] = <opening tag>
                //              [1] = Content...
                //              [2] = <closing tag>
                //              Etc...
                //      }       
                $chunks = preg_split('/(<(?:[^<>]+(?:"[^"]*"|\'[^\']*\')?)+>)/', $str, -1, PREG_SPLIT_DELIM_CAPTURE|PREG_SPLIT_NO_EMPTY);
                
                // Build our finalized string.  We cycle through the array, skipping tags, and processing the contained text    
                $str = '';
                $process = TRUE;
                $paragraph = FALSE;
                foreach ($chunks as $chunk)
                {
                        // Are we dealing with a tag? If so, we'll skip the processing for this cycle.
                        // Well also set the "process" flag which allows us to skip <pre> tags and a few other things.
                        if (preg_match("#<(/*)(".$this->block_elements.").*?>#", $chunk, $match))
                        {
                                if (preg_match("#".$this->skip_elements."#", $match[2]))
                                {
                                        $process =  ($match[1] == '/') ? TRUE : FALSE;
                                }
                                
                                $str .= $chunk;
                                continue;
                        }

                        if ($process == FALSE)
                        {
                                $str .= $chunk;
                                continue;
                        }
                        
                        //  Convert Newlines into <p> and <br /> tags
                        $str .= $this->_format_newlines($chunk);
                }

                // is the whole of the content inside a block level element?
                if ( ! preg_match("/^<(?:".$this->block_elements.")/i", $str, $match))
                {
                        $str = "<p>{$str}</p>";
                }

                // Convert quotes, elipsis, and em-dashes
                $str = $this->format_characters($str);
        
                // Final clean up
                $table = array(
                
                                                // If the user submitted their own paragraph tags within the text
                                                // we will retain them instead of using our tags.
                                                '/(<p.*?>)<p>/'         => '$1', // <?php BBEdit syntax coloring bug fix
                                                
                                                // Reduce multiple instances of opening/closing paragraph tags to a single one
                                                '#(</p>)+#'                     => '</p>',
                                                '/(<p><p>)+/'           => '<p>',
                                                
                                                // Clean up stray paragraph tags that appear before block level elements
                                                '#<p></p><('.$this->block_elements.')#' => '<$1',
                        
                                                // Replace the temporary markers we added earlier
                                                '/\{@TAG\}/'            => '<',
                                                '/\{@DQ\}/'                     => '"',
                                                '/\{@SQ\}/'                     => "'"

                                                );
        
                // Do we need to reduce empty lines?
                if ($reduce_linebreaks === TRUE)
                {
                        $table['#<p>\n*</p>#'] = '';
                }
                else
                {
                        // If we have empty paragraph tags we add a non-breaking space
                        // otherwise most browsers won't treat them as true paragraphs
                        $table['#<p></p>#'] = '<p>&nbsp;</p>';
                }
        
                return preg_replace(array_keys($table), $table, $str);

        }
        
        // --------------------------------------------------------------------

        /**
         * Format Characters
         *
         * This function mainly converts double and single quotes
         * to curly entities, but it also converts em-dashes,
         * double spaces, and ampersands
         *
         * @access      public
         * @param       string
         * @return      string
         */
        function format_characters($str)
        {
                static $table;
                
                if ( ! isset($table))
                {
                $table = array(                                 
                                                        // nested smart quotes, opening and closing
                                                        // note that rules for grammar (English) allow only for two levels deep
                                                        // and that single quotes are _supposed_ to always be on the outside
                                                        // but we'll accommodate both
                                                        '/(^|\W|\s)\'"/'                                => '$1&#8216;&#8220;',
                                                        '/\'"(\s|\W|$)/'                                => '&#8217;&#8221;$1',
                                                        '/(^|\W|\s)"\'/'                                => '$1&#8220;&#8216;',
                                                        '/"\'(\s|\W|$)/'                                => '&#8221;&#8217;$1',

                                                        // single quote smart quotes
                                                        '/\'(\s|\W|$)/'                                 => '&#8217;$1',
                                                        '/(^|\W|\s)\'/'                                 => '$1&#8216;',

                                                        // double quote smart quotes
                                                        '/"(\s|\W|$)/'                                  => '&#8221;$1',
                                                        '/(^|\W|\s)"/'                                  => '$1&#8220;',

                                                        // apostrophes
                                                        "/(\w)'(\w)/"                   => '$1&#8217;$2',

                                                        // Em dash and ellipses dots
                                                        '/\s?\-\-\s?/'                                  => '&#8212;',
                                                        '/(\w)\.{3}/'                                   => '$1&#8230;',

                                                        // double space after sentences
                                                        '/(\W)  /'                                              => '$1&nbsp; ',

                                                        // ampersands, if not a character entity
                                                        '/&(?!#?[a-zA-Z0-9]{2,};)/'             => '&amp;'
                                        );                      
                }       

                return preg_replace(array_keys($table), $table, $str);
        }
        
        // --------------------------------------------------------------------

        /**
         * Format Newlines
         *
         * Converts newline characters into either <p> tags or <br />
         *
         * @access      public
         * @param       string
         * @return      string
         */     
        function _format_newlines($str)
        {
                if ($str == '')
                {
                        return $str;
                }

                if (strpos($str, "\n") === FALSE)
                {
                        return $str;
                }
                
                // Convert two consecutive newlines to paragraphs
                $str = str_replace("\n\n", "</p>\n\n<p>", $str);
                
                // Convert single spaces to <br /> tags
                $str = preg_replace("/([^\n])(\n)([^\n])/", "\\1<br />\\2\\3", $str);
                
                // Wrap the whole enchilada in enclosing paragraphs
                if ($str != "\n")
                {
                        $str =  '<p>'.$str.'</p>';
                }

                // Remove empty paragraphs if they are on the first line, as this
                // is a potential unintended consequence of the previous code
                $str = preg_replace("/<p><\/p>(.*)/", "\\1", $str, 1);
                
                return $str;
        }
        
        // ------------------------------------------------------------------------
        
        /**
         * Convert newlines to HTML line breaks except within PRE tags
         *
         * @access      public
         * @param       string
         * @return      string
         */             
        function nl2br_except_pre($str)
        {
                $ex = explode("pre>",$str);
                $ct = count($ex);
        
                $newstr = "";
                for ($i = 0; $i < $ct; $i++)
                {
                        if (($i % 2) == 0)
                        {
                                $newstr .= nl2br($ex[$i]);
                        }
                        else
                        {
                                $newstr .= $ex[$i];
                        }
                
                        if ($ct - 1 != $i)
                                $newstr .= "pre>";
                }
        
                return $newstr;
        }
        
}
// END Typography Class

/* End of file Typography.php */
/* Location: ./system/libraries/Typography.php */