codenothing/CSSCompressor

/**
 * 
 * Margin, Padding Shorthand
 * 
 * @author: Corey Hart <http://www.codenothing.com>
 * @description: Reduces Margin/Padding shorthand directionals
 * 
 * @before:
 *     .example {
 *         margin: 3px 3px 3px 3px;
 *     }
 * 
 * @after:
 *     .example {
 *         margin: 3px;
 *     }
 * 
 */

var CSSCompressor = global.CSSCompressor;

CSSCompressor.rule({

    name: 'Margin, Padding Shorthand',
    type: CSSCompressor.RULE_TYPE_RULE,
    group: 'Directionals',
    description: "Reduces Margin/Padding shorthand directionals",

    callback: function( rule, branch, compressor ) {
        if ( rule.property == 'margin' || rule.property == 'padding' ) {
            // Local copies
            var before = rule.parts.slice( 0 ),
                parts = rule.parts.slice( 0 );

            // 4 Direction
            if ( parts.length === 4 ) {
                // '3px 3px 3px 3px' => '3px'
                if ( parts[ 0 ] === parts[ 1 ] && parts[ 1 ] === parts[ 2 ] && parts[ 2 ] === parts[ 3 ] ) {
                    parts = [ parts[ 0 ] ];
                }
                // '3px 2px 3px 2px' => '3px 2px'
                else if ( parts [ 0 ] === parts[ 2 ] && parts[ 1 ] === parts[ 3 ] ) {
                    parts = [ parts[ 0 ], parts[ 1 ] ];
                }
                // '3px 2px 1px 2px' => '3px 2px 1px'
                else if ( parts[ 1 ] === parts[ 3 ] ) {
                    parts = [ parts[ 0 ], parts[ 1 ], parts[ 2 ] ];
                }
            }
            // 3 Direction
            else if ( parts.length === 3 ) {
                // '3px 3px 3px' => '3px'
                if ( parts[ 0 ] === parts[ 1 ] && parts[ 1 ] === parts[ 2 ] ) {
                    parts = [ parts[ 0 ] ];
                }
                // '3px 2px 3px' => '3px 2px'
                else if ( parts[ 0 ] === parts[ 2 ] ) {
                    parts = [ parts[ 0 ], parts[ 1 ] ];
                }
            }
            // 2 Direction
            // '3px 3px' => '3px'
            else if ( parts.length === 2 && parts[ 0 ] === parts[ 1 ] ) {
                parts = [ parts[ 0 ] ];
            }

            // Log combination
            if ( before.length !== parts.length ) {
                rule.parts = parts;
                compressor.log(
                    "Combining directionals for '" + rule.property + "'" + 
                    " '" + before.join( ' ' ) + "' => '" + parts.join( ' ' ) + "'",
                    rule.position
                );
            }
        }
    }

});