php search อยากทราบเกี่ยวกับการค้นหาแบบแสดงสีสันจากคำค้นใน keyword

<?php
	$text = 'Lorem ipsum dolor sit amet, consectetuer
adipiscing elit. Vestibulum blandit mollis risus.';
 
	class highlight
	{
		public $output_text;
 
		function __construct($text, $words)
		{
			$split_words = explode( " " , $words );
			foreach ($split_words as $word)
			{
				$color = self::generate_colors();
				$text = preg_replace("|($word)|Ui" ,
						   "<span style=\"background:".$color.";\"><b>$1</b></span>" , $text );
			}
			$this->output_text = $text;
		}
 
		private function rgbhex($red, $green, $blue)
		{
			return sprintf('#%02X%02X%02X', $red, $green, $blue);
		}
 
		private function generate_colors()
		{
			$red = rand( rand(60,100) , rand(200,252) );
			$green = rand( rand(60,100) , rand(200,252) );
			$blue = rand( rand(60,100) , rand(200,252) );
 
			$color = self::rgbhex( $red , $green , $blue );
			return $color;
		}
	}
 
	$highlight = new highlight($text , 'lorem dolor blandit');
	echo $highlight->output_text;
	
//Thank & Ref : http://www.php-help.ro/php-tutorials/php-highlight-search-keywords/
?>