codenothing/CSSCompressor

/**
 * 
 * Strip Empty Branches
 * 
 * @author: Corey Hart <http://www.codenothing.com>
 * @description: Removes all branches with no rules
 * 
 * @before:
 *     .example {
 *         color: red;
 *     }
 *
 *     .example {}
 * 
 *     body {
 *         font: Helvetica;
 *     }
 * 
 * @after:
 *     .example {
 *         color: red;
 *     }
 * 
 *     body {
 *         font: Helvetica;
 *     }
 * 
 */

var CSSCompressor = global.CSSCompressor;

CSSCompressor.rule({

    name: 'Strip Empty Branches',
    type: CSSCompressor.RULE_TYPE_SHEET,
    group: 'Trim',
    description: "Removes all branches with no rules",
    priority: CSSCompressor.PRIORITY_LOWEST,

    callback: function( branches, compressor ) {
        function strip( array ) {
            for ( var i = -1, branch; ++i < array.length; ) {
                branch = array[ i ];

                if ( branch.branches ) {
                    strip( branch.branches );

                    if ( ! branch.branches.length ) {
                        delete branch.branches;

                        if ( ! branch.rules || ! branch.rules.length ) {
                            compressor.log( "Removing Empty Atrule", branch.position );
                            CSSCompressor.removeItem( array, branch );
                            i--;
                        }
                    }
                }
                else if ( branch.selector && ( ! branch.rules || ! branch.rules.length ) ) {
                    compressor.log( "Removing Empty Rule Set", branch.position );
                    CSSCompressor.removeItem( array, branch );
                    i--;
                }
                else if ( branch.atrule && CSSCompressor.isArray( branch.rules ) && branch.rules.length === 0 ) {
                    compressor.log( "Removing Empty At Rule", branch.position );
                    CSSCompressor.removeItem( array, branch );
                    i--;
                }
            }
        }

        // Start with root branches
        strip( branches );
    }

});