PHP class to Minify HTML, CSS and JavaScript

OutputmodMinify.php

<?php

/**
 * Class OutputmodMinify
 * 
 * include_once 'OutputmodMinify.php';
 * $html = \OutputmodMinify::minify($html);
 */
/**
 * -----------------------------------------------------------------------------------------
 * Based on `https://github.com/mecha-cms/mecha-cms/blob/master/system/kernel/converter.php`
 * -----------------------------------------------------------------------------------------
 * GitHub Rodrigo54/php-html-css-js-minifier.php
 */

Class OutputmodMinify
{
    protected $processCSS;
    protected $processJS;

    public static function minify($source, $processCSS = false, $processJS = false){
        $outputMinifier = new self($processCSS, $processJS);
        return $outputMinifier->minify_html($source);
    }

    public function __construct($processCSS = false, $processJS = false) {
        $this->processCSS = $processCSS;
        $this->processJS = $processJS;
    }

    // HTML Minifier
    public function minify_html($input) {
        if(trim($input) === "") return $input;
        // Remove extra white-space(s) between HTML attribute(s)
        $input = preg_replace_callback('#<([^\/\s<>!]+)(?:\s+([^<>]*?)\s*|\s*)(\/?)>#s', function($matches) {
            return '<' . $matches[1] . preg_replace('#([^\s=]+)(\=([\'"]?)(.*?)\3)?(\s+|$)#s', ' $1$2', $matches[2]) . $matches[3] . '>';
        }, str_replace("\r", "", $input));
        
        // Minify inline CSS declaration(s)
        if ($this->processCSS){
            if(strpos($input, ' style=') !== false) {
                $input = preg_replace_callback('#<([^<]+?)\s+style=([\'"])(.*?)\2(?=[\/\s>])#s', function($matches) {
                    return '<' . $matches[1] . ' style=' . $matches[2] . $this->minify_css($matches[3]) . $matches[2];
                }, $input);
            }
            if(strpos($input, '</style>') !== false) {
                $input = preg_replace_callback('#<style(.*?)>(.*?)</style>#is', function($matches) {
                    return '<style' . $matches[1] .'>'. $this->minify_css($matches[2]) . '</style>';
                }, $input);
            }
        }
        
        if ($this->processJS){
            if(strpos($input, '</script>') !== false) {
                $input = preg_replace_callback('#<script(.*?)>(.*?)</script>#is', function($matches) {
                    return '<script' . $matches[1] .'>'. $this->minify_js($matches[2]) . '</script>';
                }, $input);
            }
        }

        return preg_replace(
            array(
                // t = text
                // o = tag open
                // c = tag close
                // Keep important white-space(s) after self-closing HTML tag(s)
                '#<(img|input)(>| .*?>)#s',
                // Remove a line break and two or more white-space(s) between tag(s)
                '#(<!--.*?-->)|(>)(?:\n*|\s{2,})(<)|^\s*|\s*$#s',
                '#(<!--.*?-->)|(?<!\>)\s+(<\/.*?>)|(<[^\/]*?>)\s+(?!\<)#s', // t+c || o+t
                '#(<!--.*?-->)|(<[^\/]*?>)\s+(<[^\/]*?>)|(<\/.*?>)\s+(<\/.*?>)#s', // o+o || c+c
                '#(<!--.*?-->)|(<\/.*?>)\s+(\s)(?!\<)|(?<!\>)\s+(\s)(<[^\/]*?\/?>)|(<[^\/]*?\/?>)\s+(\s)(?!\<)#s', // c+t || t+o || o+t -- separated by long white-space(s)
                '#(<!--.*?-->)|(<[^\/]*?>)\s+(<\/.*?>)#s', // empty tag
                '#<(img|input)(>| .*?>)<\/\1>#s', // reset previous fix
                '#(&nbsp;)&nbsp;(?![<\s])#', // clean up ...
                '#(?<=\>)(&nbsp;)(?=\<)#', // --ibid
                // Remove HTML comment(s) except IE and noindex comment(s)
                '#\s*<!--(?!(\[if\s)|(noindex)|(\/noindex)).*?-->\s*|(?<!\>)\n+(?=\<[^!])#s', //'#\s*<!--(?!\[if\s).*?-->\s*|(?<!\>)\n+(?=\<[^!])#s' - noindex fix
            ),
            array(
                '<$1$2</$1>',
                '$1$2$3',
                '$1$2$3',
                '$1$2$3$4$5',
                '$1$2$3$4$5$6$7',
                '$1$2$3',
                '<$1$2',
                '$1 ',
                '$1',
                ""
            ),
        $input);
    }

    // CSS Minifier => http://ideone.com/Q5USEF + improvement(s)
    public function minify_css($input) {
        if(trim($input) === "") return $input;
        $replaced = preg_replace(
            array(
                // Remove comment(s)
                '#("(?:[^"\\\]++|\\\.)*+"|\'(?:[^\'\\\\]++|\\\.)*+\')|\/\*(?!\!)(?>.*?\*\/)|^\s*|\s*$#s',
                // Remove unused white-space(s)
                '#("(?:[^"\\\]++|\\\.)*+"|\'(?:[^\'\\\\]++|\\\.)*+\'|\/\*(?>.*?\*\/))|\s*+;\s*+(})\s*+|\s*+([*$~^|]?+=|[{};,>~]|\s(?![0-9\.])|!important\b)\s*+|([[(:])\s++|\s++([])])|\s++(:)\s*+(?!(?>[^{}"\']++|"(?:[^"\\\]++|\\\.)*+"|\'(?:[^\'\\\\]++|\\\.)*+\')*+{)|^\s++|\s++\z|(\s)\s+#si',
                // Replace `0(cm|em|ex|in|mm|pc|pt|px|vh|vw|%)` with `0`
                '#(?<=[\s:])(0)(cm|em|ex|in|mm|pc|pt|px|vh|vw|%)#si',
                // Replace `:0 0 0 0` with `:0`
                '#:(0\s+0|0\s+0\s+0\s+0)(?=[;\}]|\!important)#i',
                // Replace `background-position:0` with `background-position:0 0`
                '#(background-position):0(?=[;\}])#si',
                // Replace `0.6` with `.6`, but only when preceded by `:`, `,`, `-` or a white-space
                '#(?<=[\s:,\-])0+\.(\d+)#s',
                // Minify string value
                '#(\/\*(?>.*?\*\/))|(?<!content\:)([\'"])([a-z_][a-z0-9\-_]*?)\2(?=[\s\{\}\];,])#si',
                '#(\/\*(?>.*?\*\/))|(\burl\()([\'"])([^\s]+?)\3(\))#si',
                // Minify HEX color code
                '#(?<=[\s:,\-]\#)([a-f0-6]+)\1([a-f0-6]+)\2([a-f0-6]+)\3#i',
                // Replace `(border|outline):none` with `(border|outline):0`
                '#(?<=[\{;])(border|outline):none(?=[;\}\!])#',
                // Remove empty selector(s)
                '#(\/\*(?>.*?\*\/))|(^|[\{\}])(?:[^\s\{\}]+)\{\}#s'
            ),
            array(
                '$1',
                '$1$2$3$4$5$6$7',
                '$1',
                ':0',
                '$1:0 0',
                '.$1',
                '$1$3',
                '$1$2$4$5',
                '$1$2$3',
                '$1:0',
                '$1$2'
            ),
        $input);
        return str_replace('fill=none', '', $replaced); // fix for url("data:image/svg+xml,%3Csvg ...  fill='none'
    }

    // JavaScript Minifier
    public function minify_js($input) {
        if(trim($input) === "") return $input;
        return preg_replace(
            array(
                // Remove comment(s)
                '#\s*("(?:[^"\\\]++|\\\.)*+"|\'(?:[^\'\\\\]++|\\\.)*+\')\s*|\s*\/\*(?!\!|@cc_on)(?>[\s\S]*?\*\/)\s*|\s*(?<![\:\=])\/\/.*(?=[\n\r]|$)|^\s*|\s*$#',
                // Remove white-space(s) outside the string and regex
                '#("(?:[^"\\\]++|\\\.)*+"|\'(?:[^\'\\\\]++|\\\.)*+\'|\/\*(?>.*?\*\/)|\/(?!\/)[^\n\r]*?\/(?=[\s.,;]|[gimuy]|$))|\s*([!%&*\(\)\-=+\[\]\{\}|;:,.<>?\/])\s*#s',
                // Remove the last semicolon
                '#;+\}#',
                // Minify object attribute(s) except JSON attribute(s). From `{'foo':'bar'}` to `{foo:'bar'}`
                '#([\{,])([\'])(\d+|[a-z_][a-z0-9_]*)\2(?=\:)#i',
                // --ibid. From `foo['bar']` to `foo.bar`
                '#([a-z0-9_\)\]])\[([\'"])([a-z_][a-z0-9_]*)\2\]#i'
            ),
            array(
                '$1',
                '$1$2',
                '}',
                '$1$3',
                '$1.$3'
            ),
        $input);
    }

}