codenothing/CSSCompressor

/**
 * 
 * Comma Repeats
 * 
 * @author: Corey Hart <http://www.codenothing.com>
 * @description: Removes repeated selectors separated by commas
 * 
 * @before:
 *     html body, html body {
 *         color: red;
 *     }
 * 
 * @after:
 *     html body {
 *         color: red;
 *     }
 * 
 */

var CSSCompressor = global.CSSCompressor;

CSSCompressor.rule({

    name: 'Comma Repeats',
    type: CSSCompressor.RULE_TYPE_BLOCK,
    group: 'Selector',
    description: "Removes repeated selectors separated by commas",
    priority: CSSCompressor.PRIORITY_LOW,

    callback: function( branch, compressor ) {
        if ( ! branch.selector || ! branch.parts || ! branch.parts.length ) {
            return;
        }

        // Break selectors across commas
        var parts = [], current = [], newparts = [], i = -1, l, j;
        branch.parts.forEach(function( part ) {
            if ( part === ',' ) {
                parts.push( current );
                current = [];
            }
            else {
                current.push( part );
            }
        });

        // Catch last comma
        if ( current.length ) {
            parts.push( current );
        }

        // Skip over matching selector queries
        for ( l = parts.length; ++i < l; ) {
            for ( j = i; ++j < l; ) {
                if ( CSSCompressor.objectsMatch( parts[ i ], parts[ j ] ) ) {
                    parts.splice( j, 1 );
                    l = parts.length;
                    j--;
                }
            }
        }


        // Join the parts back together, and inject commas back in
        parts.forEach(function( a, i ) {
            newparts.push.apply( newparts, a );

            if ( i < parts.length - 1 ) {
                newparts.push( ',' );
            }
        });

        // Mark updated branch
        if ( ! CSSCompressor.objectsMatch( branch.parts, newparts ) ) {
            compressor.log(
                "Removing a repeated selector separated by a comma",
                branch.position
            );

            branch.parts = newparts;
        }
    }

});