system/helpers/typography_helper.php

<?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) 2006, EllisLab, Inc.
 * @license		http://www.codeigniter.com/user_guide/license.html
 * @link		http://www.codeigniter.com
 * @since		Version 1.0
 * @filesource
 */

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

/**
 * CodeIgniter Typography Helpers
 *
 * @package		CodeIgniter
 * @subpackage	Helpers
 * @category	Helpers
 * @author		ExpressionEngine Dev Team
 * @link		http://www.codeigniter.com/user_guide/helpers/typography_helper.html
 */

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

/**
 * 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;
}
	
// ------------------------------------------------------------------------

/**
 * Auto Typography Wrapper Function
 *
 *
 * @access	public
 * @param	string
 * @return	string
 */
function auto_typography($str)
{
	$TYPE = new Auto_typography();
	return $TYPE->convert($str);
}
	
// ------------------------------------------------------------------------

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

	// Block level elements that should not be wrapped inside <p> tags
	var $block_elements = 'div|blockquote|pre|code|h\d|script|ol|ul';
	
	// Elements that should not have <p> and <br /> tags within them.
	var $skip_elements	= 'pre|ol|ul';
	
	// Tags we want the parser to completely ignore when splitting the string.
	var $ignore_elements = 'a|b|i|em|strong|span|img|li';	


	/**
	 * Main Processing Function
	 *
	 */
	function convert($str)
	{
		if ($str == '')
		{
			return '';
		}
		
		$str = ' '.$str.' ';
		
		// Standardize Newlines to make matching easier
		$str = preg_replace("/(\r\n|\r)/", "\n", $str);
		
		/*
		 * Reduce line breaks
		 *
		 * If there are more than two consecutive line
		 * breaks we'll compress them down to a maximum
		 * of two since there's no benefit to more.
		 *
		 */
		$str = preg_replace("/\n\n+/", "\n\n", $str);

		/*
		 * Convert quotes within tags to temporary marker
		 *
		 * 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);
			}
		}
	

		/*
		 * Add closing/opening paragraph tags before/after "block" elements
		 *
		 * Since block elements (like <blockquotes>, <pre>, etc.) do not get
		 * wrapped in paragraph tags we will add a closing </p> tag just before
		 * each block element starts and an opening <p> tag right after the block element
		 * ends.  Later on we'll do some further clean up.
		 *
		 */
		$str = preg_replace("#(<)(".$this->block_elements.")(.*?>)#", "</p>\\1\\2\\3", $str);
		$str = preg_replace("#(</)(".$this->block_elements.")(.*?>)#", "\\1\\2\\3<p>", $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 < temporarily to: {@TAG}
		 *
		 */		
		$str = preg_replace("#<(/*)(".$this->ignore_elements.")#i", "{@TAG}\\1\\2", $str);	
		
		/*
		 * Split the string at every tag
		 *
		 * This creates an array with this prototype:
		 *
		 *	[array]
		 *	{
		 *		[0] = <opening tag>
		 *		[1] = Content contained between the tags
		 *		[2] = <closing tag>
		 *		Etc...
		 *	}
		 *
		 */			
		$chunks = preg_split('/(<(?:[^<>]+(?:"[^"]*"|\'[^\']*\')?)+>)/', $str, -1, PREG_SPLIT_DELIM_CAPTURE|PREG_SPLIT_NO_EMPTY);
		
		/*
		 * Build our finalized string
		 *
		 * We'll cycle through the array, skipping tags,
		 * and processing the contained text
		 *
		 */			
		$str = '';
		$process = TRUE;
		foreach ($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);
		}

		// FINAL CLEAN UP
		// IMPORTANT:  DO NOT ALTER THE ORDER OF THE ITEMS BELOW!
		
		/*
		 * Clean up paragraph tags before/after "block" elements
		 *
		 * Earlier we added <p></p> tags before/after block level elements.
		 * Then, we added paragraph tags around double line breaks.  This
		 * potentially created incorrectly formatted paragraphs so we'll
		 * clean it up here.
		 *
		 */
		$str = preg_replace("#<p>({@TAG}.*?)(".$this->block_elements.")(.*?>)#", "\\1\\2\\3", $str);
		$str = preg_replace("#({@TAG}/.*?)(".$this->block_elements.")(.*?>)</p>#", "\\1\\2\\3", $str);

		// Convert Quotes and other characters
		$str = $this->format_characters($str);
		
		// Fix an artifact that happens during the paragraph replacement
		$str = preg_replace('#(<p>\n*</p>)#', '', $str);

		// If the user submitted their own paragraph tags with class data
		// in them we will retain them instead of using our tags.
		$str = preg_replace('#(<p.*?>)<p>#', "\\1", $str);

		// Final clean up
		$str = str_replace(
							array(
									'</p></p>',
									'</p><p>',
									'<p> ',
									' </p>',
									'{@TAG}',
									'{@DQ}',
									'{@SQ}',
									'<p></p>'
								),
							array(
									'</p>',
									'<p>',
									'<p>',
									'</p>',
									'<',
									'"',
									"'",
									''
								),
							$str
						);
		
		return $str;
	}
	
	// --------------------------------------------------------------------

	/**
	 * Format Characters
	 *
	 * This function mainly converts double and single quotes
	 * to entities, but since these are directional, it does
	 * it based on some rules.  It also converts em-dashes
	 * and a couple other things.
	 */
	function format_characters($str)
	{	
		$table = array(
						' "'		=> " &#8220;",
						'" '		=> "&#8221; ",
						" '"		=> " &#8216;",
						"' "		=> "&#8217; ",
						
						'>"'		=> ">&#8220;",
						'"<'		=> "&#8221;<",
						">'"		=> ">&#8216;",
						"'<"		=> "&#8217;<",

						"\"."		=> "&#8221;.",
						"\","		=> "&#8221;,",
						"\";"		=> "&#8221;;",
						"\":"		=> "&#8221;:",
						"\"!"		=> "&#8221;!",
						"\"?"		=> "&#8221;?",
						
						".  "		=> ".&nbsp; ",
						"?  "		=> "?&nbsp; ",
						"!  "		=> "!&nbsp; ",
						":  "		=> ":&nbsp; ",
					);

		// These deal with quotes within quotes, like:  "'hi here'"
		$start = 0;
		$space = array("\n", "\t", " ");
		
		while(TRUE)
		{
			$current = strpos(substr($str, $start), "\"'");
			
			if ($current === FALSE) break;
			
			$one_before = substr($str, $start+$current-1, 1);
			$one_after = substr($str, $start+$current+2, 1);
			
			if ( ! in_array($one_after, $space, TRUE) && $one_after != "<")
			{
				$str = str_replace(	$one_before."\"'".$one_after,
									$one_before."&#8220;&#8216;".$one_after,
									$str);
			}
			elseif ( ! in_array($one_before, $space, TRUE) && (in_array($one_after, $space, TRUE) OR $one_after == '<'))
			{
				$str = str_replace(	$one_before."\"'".$one_after,
									$one_before."&#8221;&#8217;".$one_after,
									$str);
			}
			
			$start = $start+$current+2;
		}
		
		$start = 0;
		
		while(TRUE)
		{
			$current = strpos(substr($str, $start), "'\"");
			
			if ($current === FALSE) break;
			
			$one_before = substr($str, $start+$current-1, 1);
			$one_after = substr($str, $start+$current+2, 1);
			
			if ( in_array($one_before, $space, TRUE) && ! in_array($one_after, $space, TRUE) && $one_after != "<")
			{
				$str = str_replace(	$one_before."'\"".$one_after,
									$one_before."&#8216;&#8220;".$one_after,
									$str);
			}
			elseif ( ! in_array($one_before, $space, TRUE) && $one_before != ">")
			{
				$str = str_replace(	$one_before."'\"".$one_after,
									$one_before."&#8217;&#8221;".$one_after,
									$str);
			}
			
			$start = $start+$current+2;
		}
		
		// Are there quotes within a word, as in:  ("something")
		if (preg_match_all("/(.)\"(\S+?)\"(.)/", $str, $matches))
		{
			for ($i=0, $s=sizeof($matches['0']); $i < $s; ++$i)
			{
				if ( ! in_array($matches['1'][$i], $space, TRUE) && ! in_array($matches['3'][$i], $space, TRUE))
				{
					$str = str_replace(	$matches['0'][$i],
										$matches['1'][$i]."&#8220;".$matches['2'][$i]."&#8221;".$matches['3'][$i],
										$str);
				}
			}
		}
		
		if (preg_match_all("/(.)\'(\S+?)\'(.)/", $str, $matches))
		{
			for ($i=0, $s=sizeof($matches['0']); $i < $s; ++$i)
			{
				if ( ! in_array($matches['1'][$i], $space, TRUE) && ! in_array($matches['3'][$i], $space, TRUE))
				{
					$str = str_replace(	$matches['0'][$i],
										$matches['1'][$i]."&#8216;".$matches['2'][$i]."&#8217;".$matches['3'][$i],
										$str);
				}
			}
		}
		
		// How about one apostrophe, as in Rick's
		$start = 0;
		
		while(TRUE)
		{
			$current = strpos(substr($str, $start), "'");
			
			if ($current === FALSE) break;
			
			$one_before = substr($str, $start+$current-1, 1);
			$one_after = substr($str, $start+$current+1, 1);
			
			if ( ! in_array($one_before, $space, TRUE) && ! in_array($one_after, $space, TRUE))
			{
				$str = str_replace(	$one_before."'".$one_after,
									$one_before."&#8217;".$one_after,
									$str);
			}
			
			$start = $start+$current+2;
		}

		// Em-dashes
		$start = 0;
		while(TRUE)
		{
			$current = strpos(substr($str, $start), "--");
			
			if ($current === FALSE) break;
			
			$one_before = substr($str, $start+$current-1, 1);
			$one_after = substr($str, $start+$current+2, 1);
			$two_before = substr($str, $start+$current-2, 1);
			$two_after = substr($str, $start+$current+3, 1);
			
			if (( ! in_array($one_before, $space, TRUE) && ! in_array($one_after, $space, TRUE))
				OR
				( ! in_array($two_before, $space, TRUE) && ! in_array($two_after, $space, TRUE) && $one_before == ' ' && $one_after == ' ')
				)
			{
				$str = str_replace(	$two_before.$one_before."--".$one_after.$two_after,
									$two_before.trim($one_before)."&#8212;".trim($one_after).$two_after,
									$str);
			}
			
			$start = $start+$current+2;
		}
		
		// Ellipsis
		$str = preg_replace("#(\w)\.\.\.(\s|<br />|</p>)#", "\\1&#8230;\\2", $str);
		$str = preg_replace("#(\s|<br />|</p>)\.\.\.(\w)#", "\\1&#8230;\\2", $str);
		
		// Run the translation array we defined above		
		$str = str_replace(array_keys($table), array_values($table), $str);
		
		// If there are any stray double quotes we'll catch them here
		
		$start = 0;
		
		while(TRUE)
		{
			$current = strpos(substr($str, $start), '"');
			
			if ($current === FALSE) break;
			
			$one_before = substr($str, $start+$current-1, 1);
			$one_after = substr($str, $start+$current+1, 1);
			
			if ( ! in_array($one_after, $space, TRUE))
			{
				$str = str_replace(	$one_before.'"'.$one_after,
									$one_before."&#8220;".$one_after,
									$str);
			}
			elseif( ! in_array($one_before, $space, TRUE))
			{
				$str = str_replace(	$one_before."'".$one_after,
									$one_before."&#8221;".$one_after,
									$str);
			}
			
			$start = $start+$current+2;
		}
		
		$start = 0;
		
		while(TRUE)
		{
			$current = strpos(substr($str, $start), "'");
			
			if ($current === FALSE) break;
			
			$one_before = substr($str, $start+$current-1, 1);
			$one_after = substr($str, $start+$current+1, 1);
			
			if ( ! in_array($one_after, $space, TRUE))
			{
				$str = str_replace(	$one_before."'".$one_after,
									$one_before."&#8216;".$one_after,
									$str);
			}
			elseif( ! in_array($one_before, $space, TRUE))
			{
				$str = str_replace(	$one_before."'".$one_after,
									$one_before."&#8217;".$one_after,
									$str);
			}
			
			$start = $start+$current+2;
		}
		
		return $str;
	}
	
	// --------------------------------------------------------------------

	/**
	 * Format Newlines
	 *
	 * Converts newline characters into either <p> tags or <br />
	 *
	 */	
	function format_newlines($str)
	{
		if ($str == '')
		{
			return $str;
		}

		if (strpos($str, "\n") === FALSE)
		{
			return '<p>'.$str.'</p>';
		}
			
		$str = str_replace("\n\n", "</p>\n\n<p>", $str);
		$str = preg_replace("/([^\n])(\n)([^\n])/", "\\1<br />\\2\\3", $str);
		
		return '<p>'.$str.'</p>';
	}	
}


?>