codenothing/CSSCompressor

/**
 * 
 * Border Radius Shorthand
 * 
 * @author: Corey Hart <http://www.codenothing.com>
 * @description: Converts shorthand border radius properties
 * 
 * @before:
 *     .example {
 *         border-radius: 10px 10px 10px 10px;
 *     }
 * 
 * @after:
 *     .example {
 *         border-radius: 10px;
 *     }
 * 
 */

var CSSCompressor = global.CSSCompressor,
    rshortradiusprop = /^(-webkit-|-moz-)?border-radius$/;

CSSCompressor.rule({

    name: 'Border Radius Shorthand',
    type: CSSCompressor.RULE_TYPE_RULE,
    group: 'Border Radius',
    description: "Converts shorthand border radius properties",

    callback: function( rule, branch, compressor ) {
        if ( ! rshortradiusprop.exec( rule.property ) || ! rule.parts || ! rule.parts.length ) {
            return;
        }

        // Locals
        var section = [], sections = [ section ];

        // Build up sections for compression
        rule.parts.forEach(function( part ) {
            if ( part == '/' ) {
                sections.push( section = [] );
            }
            else {
                section.push( part );
            }
        });

        // Compress both sections if possible
        sections.forEach(function( section, index ) {
            if ( ! section.length ) {
                return;
            }

            // Keep record
            var before = section.slice( 0 );

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

            // Log combination
            if ( before.length != section.length ) {
                sections[ index ] = section;
                compressor.log(
                    "Combining " + rule.property + " directionals " + 
                    " '" + before.join( ' ' ) + "' => '" + section.join( ' ' ) + "'",
                    rule.position
                );
            }
        });

        // Apply compression back to rule block
        if ( sections.length == 2 ) {
            rule.parts = [];
            rule.parts.push.apply( rule.parts, sections[ 0 ] );
            rule.parts.push( '/' );
            rule.parts.push.apply( rule.parts, sections[ 1 ] );
        }
        else if ( sections.length == 1 ) {
            rule.parts = sections[ 0 ];
        }
    }

});