codenothing/CSSTree

var ratruleseek = /"|'|\(/,
    ratrulepart = /[\, ]/;


function AtRule( atrule, position ) {
    var self = this;

    if ( ! ( self instanceof AtRule ) ) {
        return new AtRule( atrule, position );
    }

    self.atrule = ( atrule || '' ).trim();
    self.position = position;
    self.parts = [];
    self.breakdown();
}

AtRule.prototype = {
    
    breakdown: function(){
        var self = this, atrule = self.atrule,
            parts = [], part = '',
            i = -1, l = atrule.length, c = '',
            seek;

        for ( ; ++i < l; ) {
            c = atrule[ i ];

            // Part separator
            if ( ratrulepart.exec( c ) ) {
                part = part.trim();

                if ( part.length ) {
                    parts.push( part );
                }

                if ( c != ' ' ) {
                    parts.push( c );
                }

                part = '';
            }
            // Read all characters in a seek sequence ((...), "...", '...', etc)
            else if ( ratruleseek.exec( c ) ) {
                part += c;
                seek = c == '(' ? ')' : c;

                // Find end char
                for ( ; ++i < l; ) {
                    c = atrule[ i ];
                    part += c;

                    // End char found, break off and attach part
                    if ( c == seek ) {
                        break;
                    }
                    // Skip over escaped values
                    else if ( c == "\\" && atrule[ i + 1 ] ) {
                        part += atrule[ ++i ];
                    }
                }
            }
            // Add to the current part
            else {
                part += c;
            }
        }

        // Catch the last part and add it
        if ( ( part = part.trim() ).length ) {
            parts.push( part );
        }

        self.parts = parts;
    }

};

global.CSSTree.AtRule = AtRule;