html-minify-process.php

<?php

	class WP_HTML_Compression {
		// Variables
		protected $html;
		public function __construct($html) {
		  if (!empty($html)) {
				$this->parseHTML($html);
			}
		}
		public function __toString() {
			return $this->html;
		}
		protected function bottomComment($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 '.$compressed.' bytes-->';
		}
		protected function minifyHTML($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;
			// Variable reused for output
			$html = '';
			foreach ($matches as $token) {
				$tag = (isset($token['tag'])) ? strtolower($token['tag']) : null;
				$content = $token[0];
				if (is_null($tag)) {
					if ( !empty($token['script']) ) {
						$strip = html_minify_get_ignore_js();
					}
					else if ( !empty($token['style']) ) {
						$strip = html_minify_get_ignore_css();
					}
					else if ($content == '<!--wp-html-compression no compression-->') {
						$overriding = !$overriding;
						// Don't print the comment
						continue;
					}
					else if ( html_minify_get_ignore_comments() ) {
						if (!$overriding && $raw_tag != 'textarea') {
							// Remove any HTML comments, except MSIE conditional comments
							$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;
							// Remove any empty attributes, except:
							// action, alt, content, src
							$content = preg_replace('/(\s+)(\w++(?<!\baction|\balt|\bcontent|\bsrc)="")/', '$1', $content);
							// Remove any space before the end of self-closing XHTML tags
							// JavaScript excluded
							$content = str_replace(' />', '/>', $content);
						}
					}
				}
				if ($strip) {
					$content = $this->removeWhiteSpace($content);
				}
				$html .= $content;
			}
			return $html;
		}
		public function parseHTML($html) {
			$this->html = $this->minifyHTML($html);
			$this->html .= "\n" . $this->bottomComment($html, $this->html);
		}
		protected function removeWhiteSpace($str) {
			$str = str_replace("\t", ' ', $str);
			$str = str_replace("\n",  '', $str);
			$str = str_replace("\r",  '', $str);
			while (stristr($str, '  ')) {
				$str = str_replace('  ', ' ', $str);
			}
			return $str;
		}
	}
	function wp_html_compression_finish($html) {
		return new WP_HTML_Compression($html);
	}
	function wp_html_compression_start() {
		ob_start('wp_html_compression_finish');
	}
	add_action('get_header', 'wp_html_compression_start');