/Utility/HtmlCompressor.php

<?php

/**
 * TomatoCMS
 * 
 * LICENSE
 *
 * This source file is subject to the GNU GENERAL PUBLIC LICENSE Version 2 
 * that is bundled with this package in the file LICENSE.txt.
 * It is also available through the world-wide-web at this URL:
 * http://www.gnu.org/licenses/gpl-2.0.txt
 * If you did not receive a copy of the license and are unable to
 * obtain it through the world-wide-web, please send an email
 * to license@tomatocms.com so we can send you a copy immediately.
 * 
 * @copyright	Copyright (c) 2009-2010 TIG Corporation (http://www.tig.vn)
 * @license		http://www.gnu.org/licenses/gpl-2.0.txt GNU GENERAL PUBLIC LICENSE Version 2
 * @version 	$Id: HtmlCompressor.php 3986 2010-07-25 16:32:46Z huuphuoc $
 * @since		2.0.0
 */


/**
 * Inspired from the set of functions created by Oliver Lillie
 * @see http://php100.wordpress.com/2006/10/30/html-compact/#comment-12700
 */
class Zrt_Utility_HtmlCompressor
    {


    public static function compress( $html )
        {
        $html = self::_removeHtmlComments( $html );
        $ret = self::_compressHorizontally( $html );
        $ret = self::_compressVertically( $ret[0] , $ret[1] );
        $html = self::_removeSpacesInScriptAndStyleTags( $ret[0] );

        return $html;
        }


    private static function _removeHtmlComments( $html )
        {
        /**
         * Check that the opening browser is Internet Explorer
         */
        $msie = "/msie\s(.*).*(win)/i";
        $keepCond = (isset( $_SERVER['HTTP_USER_AGENT'] ) && preg_match( $msie ,
                                                                         $_SERVER['HTTP_USER_AGENT'] ));
        if ( $keepCond )
            {
            $html = str_replace( array( '<!–[if' , '' ) ,
                                 array( '–**@@IECOND-OPEN@@**–' , '–**@@IECOND-CLOSE@@**–' ) ,
                                 $html );
            }

        /**
         * Remove comments
         */
        $html = preg_replace( '//' , '' , $html );

        /**
         * Re sub-in the conditionals if required.
         */
        if ( $keepCond )
            {
            $html = str_replace( array( '–**@@IECOND-OPEN@@**–' , '–**@@IECOND-CLOSE@@**–' ) ,
                                 array( '<!–[if' , '' ) , $html );
            }
        return $html;
        }


    /**
     * Compresses white space horizontally (ie spaces, tabs etc) whilst preserving
     * textarea and pre content.
     * Idea and partial code borrowed from smarty.
     * http://smarty.net/contribs/plugins/view.php/outputfilter.trimwhitespace.php
     *
     * @return array
     */
    private static function _compressHorizontally( $html ,
                                                   $preservedBlocks = false )
        {
        $flag = true;
        if ( !$preservedBlocks )
            {
            $flag = false;
            /**
             * Get the textarea matches
             */
            preg_match_all( '!]*>.*?!is' , $html , $preservedAreaMatch );
            $preservedBlocks = $preservedAreaMatch[0];

            /**
             * Replace the textareas inerds with markers
             */
            $html = preg_replace( '!]*>.*?!is' , '@@@HTMLCOMPRESSION@@@' , $html );
            }

        /**
         * Remove the white space
         */
        $html = preg_replace( '/((?)\n)[\s]+/m' , '\1' , $html );

        /**
         * Reinsert the textareas inners
         */
        if ( $flag )
            {
            foreach ( $preservedBlocks as $currBlock )
                {
                $html = preg_replace( '!@@@HTMLCOMPRESSION@@@!' , $currBlock ,
                                      $html , 1 );
                }
            }
        return array( $html , $preservedBlocks );
        }


    /**
     * Compresses white space vertically (ie line breaks) whilst preserving
     * textarea and pre content.
     *
     * @param mixed $preservedBlocks false if no textarea blocks have already been taken out, otherwise an array.
     * @return array
     */
    private static function _compressVertically( $html ,
                                                 $preservedBlocks = false )
        {
        $flag = true;
        if ( !$preservedBlocks )
            {
            $flag = false;
            /**
             * Get the textarea matches
             */
            preg_match_all( '!]*>.*?!is' , $html , $preservedAreaMatch );
            $preservedBlocks = $preservedAreaMatch[0];

            /**
             * Replace the textareas inerds with markers
             */
            $html = preg_replace( '!]*>.*?!is' , '@@@HTMLCOMPRESSION@@@' , $html );
            }
        $html = str_replace( "\n" , '' , $html );

        /**
         * Reinsert the textareas inerds
         */
        if ( $flag )
            {
            foreach ( $preservedBlocks as $currBlock )
                {
                $html = preg_replace( '!@@@HTMLCOMPRESSION@@@!' , $currBlock ,
                                      $html , 1 );
                }
            }
        return array( $html , $preservedBlocks );
        }


    private static function _removeSpacesInScriptAndStyleTags( $html )
        {
        preg_match_all( '!(]*>(?:\\s*\\s*)?)!is' , $html , $scripts );
        /**
         * Collect and compress the parts
         */
        $compressed = array( );
        $parts = array( );
        for ( $i = 0; $i < count( $scripts[0] ); $i++ )
            {
            array_push( $parts , $scripts[0][$i] );
            array_push( $compressed ,
                        self::_removeSpacesInJsAndCss( $scripts[0][$i] ) );
            }

        /**
         * Do the replacements and return
         */
        $html = str_replace( $parts , $compressed , $html );
        return $html;
        }


    private static function _removeSpacesInJsAndCss( $code )
        {
        /**
         * Remove multiline comment
         */
        $mulLineComment = '/\/\*(?!-)[\x00-\xff]*?\*\//';
        $code = preg_replace( $mulLineComment , '' , $code );

        /**
         * Remove single line comment
         */
        $singLineComment = '/[^:]\/\/.*/';
        $code = preg_replace( $singLineComment , '' , $code );

        /**
         * Remove extra spaces
         */
        $extraSpace = '/\s+/';
        $code = preg_replace( $extraSpace , ' ' , $code );

        /**
         * Remove spaces that can be removed
         */
        $removableSpace = '/\s?([\{\};\=\(\)\\\/\+\*-])\s?/';
        $code = preg_replace( '/\s?([\{\};\=\(\)\/\+\*-])\s?/' , '\\1' , $code );

        return $code;
        }


    }