codenothing/CSSCompressor

/**
 * 
 * Strict ID
 * 
 * @author: Corey Hart <http://www.codenothing.com>
 * @description: Removes entire selector before last ID selector
 * 
 * @before:
 *     html body #myid div {
 *         color: red;
 *     }
 * 
 * @after:
 *     #myid div {
 *         color: red;
 *     }
 * 
 */

var CSSCompressor = global.CSSCompressor;

CSSCompressor.rule({

    name: 'Strict ID',
    type: CSSCompressor.RULE_TYPE_BLOCK,
    group: 'Selector',
    description: "Removes entire selector before last ID selector",

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

        var commaParts = [],
            current = [],
            newCommaParts = [],
            parts = [];

        // Break selectors across commas
        branch.parts.forEach(function( part ) {
            if ( part === ',' ) {
                commaParts.push( current );
                current = [];
            }
            else {
                current.push( part );
            }
        });

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

        // Promote ID's on each selector
        commaParts.forEach(function( parts ) {
            var newparts = [], subparts = [],
                i = parts.length,
                found = false,
                part, subpart, j;

            while ( i-- ) {
                part = parts[ i ];

                if ( CSSCompressor.isArray( part ) ) {
                    j = part.length;
                    subparts = [];

                    while ( j-- ) {
                        subpart = part[ j ];
                        subparts.unshift( subpart );

                        if ( subpart[ 0 ] === '#' ) {
                            if ( j !== 0 && i !== 0 ) {
                                compressor.log(
                                    "Promoting nested ID to selector front",
                                    branch.position
                                );
                            }

                            found = true;
                            break;
                        }
                    }

                    newparts.unshift( subparts );
                    if ( found ) {
                        break;
                    }
                }
                else {
                    newparts.unshift( part );

                    if ( part[ 0 ] === '#' ) {
                        if ( i !== 0 ) {
                            compressor.log(
                                "Promoting nested ID to selector front",
                                branch.position
                            );
                        }

                        break;
                    }
                }
            }

            newCommaParts.push( newparts );
        });

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

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

        // Update branch
        branch.parts = parts;
    }

});