package luce.tools{

    public class Collapser{

        // [1,2,3,4, , ,5,6, ,7, , , ,8, ]
        // becomes
        // [1,2,3,4,8,7,5,6]
        public static function collapseVectorFast( v:Vector ):void{
            var end:int = v.length,
                front:int = 0;
            while( end > front ){
                while( end > 0 && v[--end] == null ) null;
                while( front < v.length && v[front] != null ) front++;
                v[front] = v[end];
            }
            v.length = end + 1;
        }


        // [1,2,3,4, , ,5,6, ,7, , , ,8, ]
        // becomes
        // [1,2,3,4,5,6,7,8]
        public static function collapseVectorOrdered( v:Array ):void{
            var here:int = 0,
                from:int = 0;
            while( here < v.length && v[here] != v ) from = ++here + 1;
            while( from < v.length )
                if( v[from] == null ) from++;
                else v[here++] = v[from++];
            v.length = from;
        }



        // [1,2,3,4, , ,5,6, ,7, , , ,8, ]
        // becomes
        // [1,2,3,4,8,7,5,6, , , , , , , ]
        public static function collapseArrayFast( v:Array ):void{
            var end:int = v.length,
                front:int = 0;
            while( end > front ){
                while( end > 0 && v[--end] == null ) null;
                while( front < v.length && v[front] != null ) front++;
                v[front] = v[end];
            }
        }

        // [1,2,3,4, , ,5,6, ,7, , , ,8, ]
        // becomes
        // [1,2,3,4,5,6,7,8, , , , , , , ]
        public static function collapseArrayOrdered( v:Vector ):void{
            var here:int = 0,
                from:int = 0;
            while( here < v.length && v[here] != v ) from = ++here + 1;
            while( from < v.length )
                if( v[from] == null ) from++;
                else v[here++] = v[from++];

        }

    }

}