codenothing/CSSCompressor

/**
 * 
 * Common Rules
 * 
 * @author: Corey Hart <http://www.codenothing.com>
 * @description: Combines rule sets with matching rules
 * 
 * @before:
 *     .example {
 *         color: red;
 *         font-size: 2px;
 *     }
 *
 *     .match {
 *         color: red;
 *         font-size: 2px;
 *     }
 *
 * 
 * @after:
 *     .example, .match {
 *         color: red;
 *         font-size: 2px;
 *     }
 * 
 */

var CSSCompressor = global.CSSCompressor,
    rulesMatch = function( a, b ) {
        if ( ! a || ! b || a.length !== b.length ) {
            return false;
        }

        for ( var i = -1, l = a.length; ++i < l; ) {
            if ( a[ i ].property !== b[ i ].property || ! CSSCompressor.objectsMatch( a[ i ].parts, b[ i ].parts ) ) {
                return false;
            }
        }

        return true;
    };

CSSCompressor.rule({

    name: 'Common Rules',
    type: CSSCompressor.RULE_TYPE_SHEET,
    group: 'Common Groupings',
    description: "Combines rule sets with matching rules",
    priority: CSSCompressor.PRIORITY_LOWER,

    callback: function( branches, compressor ) {
        var index = -1, subindex = -1, branch, next;

        for ( ; ++index < branches.length; ) {
            branch = branches[ index ];
            if ( ! branch.selector ) {
                continue;
            }

            for ( subindex = index; ++subindex < branches.length; ) {
                next = branches[ subindex ];
                if ( ! next.selector ) {
                    continue;
                }

                if ( rulesMatch( branch.rules, next.rules ) ) {
                    compressor.rerun = true;
                    branch.parts.push( ',' );
                    branch.parts.push.apply( branch.parts, next.parts );
                    CSSCompressor.removeItem( branches, next );

                    if ( next.position && branch.position ) {
                        compressor.log(
                            "Combining rule set on line " + next.position.start.line +
                            " with ruleset on line " + branch.position.start.line +
                            " as they share the same rules.",
                            [ next.position, branch.position ]
                        );
                    }
                }
            }
        }
    }

});