PHP - Highlight Search Query terms.php

<? 
############################################################################################# 
############################### BOLD KEYWORD SEARCH ENGINE LIKE ############################ 
############################################################################################# 

/* Usage calling function:
 * 
 * echo str_highlight($searched_title, $search_keyword);
*/



/** 
* Perform a simple text replace 
* This should be used when the string does not contain HTML 
* (off by default) 
*/ 
define('STR_HIGHLIGHT_SIMPLE', 1); 

/** 
* Only match whole words in the string 
* (off by default) 
*/ 
define('STR_HIGHLIGHT_WHOLEWD', 2); 

/** 
* Case sensitive matching 
* (off by default) 
*/ 
define('STR_HIGHLIGHT_CASESENS', 4); 

/** 
* Overwrite links if matched 
* This should be used when the replacement string is a link 
* (off by default) 
*/ 
define('STR_HIGHLIGHT_STRIPLINKS', 8); 

/** 
* Highlight a string in text without corrupting HTML tags 
* 
* @author Aidan Lister 
* @version 3.1.1 
* @link http://aidanlister.com/repos/v/function.str_highlight.php 
* @param string $text Haystack - The text to search 
* @param array|string $needle Needle - The string to highlight 
* @param bool $options Bitwise set of options 
* @param array $highlight Replacement string 
* @return Text with needle highlighted 
*/ 
function str_highlight($text, $needle, $options = null, $highlight = null) 
{ 
// Default highlighting 
if ($highlight === null) { 
$highlight = '1'; 
} 

// Select pattern to use 
if ($options & STR_HIGHLIGHT_SIMPLE) { 
$pattern = '#(%s)#'; 
$sl_pattern = '#(%s)#'; 
} else { 
$pattern = '#(?!<.*?)(%s)(?![^<>]*?>)#'; 
$sl_pattern = '#(%s)#'; 
} 

// Case sensitivity 
if (!($options & STR_HIGHLIGHT_CASESENS)) { 
$pattern .= 'i'; 
$sl_pattern .= 'i'; 
} 

$needle = (array) $needle; 
foreach ($needle as $needle_s) { 
$needle_s = preg_quote($needle_s); 

// Escape needle with optional whole word check 
if ($options & STR_HIGHLIGHT_WHOLEWD) { 
$needle_s = 'b' . $needle_s . 'b'; 
} 

// Strip links 
if ($options & STR_HIGHLIGHT_STRIPLINKS) { 
$sl_regex = sprintf($sl_pattern, $needle_s); 
$text = preg_replace($sl_regex, '1', $text); 
} 

$regex = sprintf($pattern, $needle_s); 
$text = preg_replace($regex, $highlight, $text); 
} 

return $text; 
} 
?>