codenothing/CSSCompressor

/**
 * 
 * Gradient Compression
 * 
 * @author: Corey Hart
 * @authorLink: http://www.codenothing.com
 * @description: Breaks down gradient properties and runs compressions on individual parts
 * 
 * @before:
 *     .example {
 *         background: linear-gradient( top, black 0%, #dddddd 100% );
 *     }
 * 
 * @after:
 *     .example {
 *         background: linear-gradient(top,#000 0%,#ddd 100%);
 *     }
 * 
 */

var CSSCompressor = global.CSSCompressor,
    StringIterator = CSSCompressor.StringIterator,
    rwhitespace = /\r\n|\r|\n|\t|\s/,
    rgradient = /^(([\-a-z]*)gradient)\((.*?)\)$/i;

CSSCompressor.rule({

    name: 'Gradient Compression',
    type: CSSCompressor.RULE_TYPE_VALUE,
    group: 'Color',
    description: "Breaks down gradient properties and runs compressions on individual parts",

    callback: function( value, position, compressor ) {
        var m = rgradient.exec( value ),
            before = value,
            prefix = ( m || [] )[ 1 ] || '',
            iter = new StringIterator( ( m || [] )[ 3 ] || '' ),
            parts = [],
            string = '';

        if ( iter.length ) {
            iter.each(function( c ) {
                if ( c == "\\" ) {
                    string += c + iter.skip();
                }
                else if ( c == ',' ) {
                    parts.push( string.trim() );
                    string = '';
                }
                else if ( c == "'" || c == '"' || c == '(' ) {
                    string += c + iter.seek( c == '(' ? ')' : c );
                }
                else {
                    string += c;
                }
            });

            parts.push( string.trim() );
            parts.forEach(function( part, index ) {
                var iter = new StringIterator( part ),
                    subparts = [],
                    string = '';

                iter.each(function( c ) {
                    if ( c == "\\" ) {
                        string += c + iter.skip();
                    }
                    else if ( rwhitespace.exec( c ) ) {
                        subparts.push( string.trim() );
                        string = '';
                    }
                    else if ( c == "'" || c == '"' || c == '(' ) {
                        string += c + iter.seek( c == '(' ? ')' : c );
                    }
                    else {
                        string += c;
                    }
                });

                subparts.push( string.trim() );
                string = '';
                subparts.forEach(function( s ) {
                    if ( string.length ) {
                        string += ' ';
                    }

                    string += compressor.value( s, position );
                });

                parts[ index ] = string;
            });

            // Only mark if change occured
            string = prefix + '(' + parts.join( ',' ) + ')';
            if ( string !== value ) {
                compressor.log(
                    "Trimming gradient value '" + before + "' => '" + string + "'",
                    position
                );

                return string;
            }
        }
    }

});