#WordPress Compression PHP - FLHM_HTML_Compression

functions.php

class FLHM_HTML_Compression{
	protected $flhm_compress_css = true;
	protected $flhm_compress_js = true;
	protected $flhm_info_comment = true;
	protected $flhm_remove_comments = true;
	protected $html;
	public function __construct($html){
		if (!empty($html)){
			$this->flhm_parseHTML($html);
		}
	}
	public function __toString(){
		return $this->html;
	}
	protected function flhm_bottomComment($raw, $compressed){
		$raw = strlen($raw);
		$compressed = strlen($compressed);
		$savings = ($raw-$compressed) / $raw * 100;
		$savings = round($savings, 2);
		return '<!--HTML compressed, size saved '.$savings.'%. From '.$raw.' bytes, now '.$compressed.' bytes-->';
	}

	protected function flhm_minifyHTML($html){
		$pattern = '/<(?<script>script).*?<\/script\s*>|<(?<style>style).*?<\/style\s*>|<!(?<comment>--).*?-->|<(?<tag>[\/\w.:-]*)(?:".*?"|\'.*?\'|[^\'">]+)*>|(?<text>((<[^!\/\w.:-])?[^<]*)+)|/si';
		preg_match_all($pattern, $html, $matches, PREG_SET_ORDER);
		$overriding = false;
		$raw_tag = false;
		$html = '';
		
		foreach ($matches as $token){
			$tag = (isset($token['tag'])) ? strtolower($token['tag']) : null;
			$content = $token[0];
			if (is_null($tag)){
				if ( !empty($token['script']) ){
					$strip = $this->flhm_compress_js;
				}else if ( !empty($token['style']) ){
					$strip = $this->flhm_compress_css;
				}else if ($content == '<!--wp-html-compression no compression-->'){
					$overriding = !$overriding; 
					continue;
				}else if ($this->flhm_remove_comments){
				if (!$overriding && $raw_tag != 'textarea'){
					$content = preg_replace('/<!--(?!\s*(?:\[if [^\]]+]|<!|>))(?:(?!-->).)*-->/s', '', $content);
				}
			}
		}else{
			if ($tag == 'pre' || $tag == 'textarea'){
				$raw_tag = $tag;
			}else if ($tag == '/pre' || $tag == '/textarea'){
				$raw_tag = false;
			}else{
				if ($raw_tag || $overriding){
					$strip = false;
				}else{
					$strip = true; 
					$content = preg_replace('/(\s+)(\w++(?<!\baction|\balt|\bcontent|\bsrc)="")/', '$1', $content); 
					$content = str_replace(' />', '/>', $content);
				}
			}
		}
	 
		if ($strip){
			$content = $this->flhm_removeWhiteSpace($content);
		}
		$html .= $content;
	
		} 
	
		return $html;
	} 
	public function flhm_parseHTML($html){
		$this->html = $this->flhm_minifyHTML($html);
		if ($this->flhm_info_comment){
			$this->html .= "\n" . $this->flhm_bottomComment($html, $this->html);
		}
	}
	protected function flhm_removeWhiteSpace($str){
		$str = str_replace("\t", ' ', $str);
		$str = str_replace("\n",  '', $str);
		$str = str_replace("\r",  '', $str);
		while (stristr($str, '  ')){
			$str = str_replace('  ', ' ', $str);
		}   
		return $str;
	}
}
function flhm_wp_html_compression_finish($html){
	return new FLHM_HTML_Compression($html);
}
function flhm_wp_html_compression_start(){
	ob_start('flhm_wp_html_compression_finish');
}
add_action('get_header', 'flhm_wp_html_compression_start');