codenothing/CSSCompressor

/**
 * 
 * Border Combinations
 * 
 * @author: Corey Hart <http://www.codenothing.com>
 * @description: Combines border directionals into single border property
 * 
 * @before:
 *     .example {
 *         border-top: 1px solid red;
 *         border-left: 1px solid red;
 *         border-right: 1px solid red;
 *         border-bottom: 1px solid red;
 *     }
 * 
 * @after:
 *     .example {
 *         border: 1px solid red;
 *     }
 * 
 */

var CSSCompressor = global.CSSCompressor;

CSSCompressor.rule({

    name: 'Border Combinations',
    type: CSSCompressor.RULE_TYPE_BLOCK,
    group: 'Border',
    description: "Combines border directionals into single border property",

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

        var hash = {}, i, l, rule,
            used = [],
            parts = [],
            first = null,
            matchKeys = [
                'border-top',
                'border-right',
                'border-bottom',
                'border-left'
            ];

        // Build hash table of directionals
        branch.rules.forEach(function( rule ) {
            if ( rule.property == 'border' || matchKeys.indexOf( rule.property ) > -1 ) {
                used.push( rule );
                hash[ rule.property ] = rule;
            }
        });

        // Either all four directionals have to exist, or the shorthand property has to exist
        if ( ( hash.border && used.length > 1 ) || CSSCompressor.keysInHash( matchKeys, hash ) ) {
            first = used[ 0 ];

            // All property values have to match for combination to work
            for ( i = -1, l = used.length; ++i < l; ) {
                rule = used[ i ];

                if ( ! CSSCompressor.objectsMatch( first.parts, rule.parts ) ) {
                    return;
                }
            }

            // Log the compression of each rule
            used.forEach(function( rule ) {
                if ( rule !== first && rule.position && first.position ) {
                    compressor.log(
                        "Combining '" + rule.property + "' on line " + rule.position.start.line +
                        " with '" + first.property + "' on line " + first.position.start.line,
                        [ rule.position, first.position ]
                    );
                }
            });

            // Override the first property
            first.property = 'border';
            used.shift();
            CSSCompressor.removeItems( branch.rules, used );
        }
    }

});