struct SpawnLink {
    public int length;

    private Spawn attach;
    private thistype prev, next;

    public float operator x()      { return this.attach.x; }
    public float operator y()      { return this.attach.y; }
    public float operator charge() { return this.attach.charge; }

    private static thistype create(float x, float y, player owner, int level, int length, thistype prev) {
        thistype this = thistype.allocate();
        this.prev = prev;
        this.next = 0;
        this.attach = Spawn.create(x, y, owner, level);
        this.length = length;
        this.changeLength(1);
        return this;
    }

    private void destroy() {
        if (this.prev != 0) && (this.next != 0) {
            this.prev.next = this.next;
            this.next.prev = this.prev;
        } else {
            this.prev.next = 0;
            this.next.prev = 0;
        }
        this.attach.destroy();
        this.deallocate();
    }

    public thistype add(float x, float y, player owner, int level) {
        if (this == 0) {
            return thistype.create(x, y, owner, level, 0, 0);
        }
        this.next = thistype.create(x, y, owner, level, this.length, this);
        return this.next;
    }

    public thistype remove(thistype toRemove) {
        thistype temp = this;
        if (this == toRemove) {
            temp = this.prev;
        }
        this.changeLength(-1);
        toRemove.destroy();
        return temp;
    }

    public void removeFirst() {
        thistype iterated = this;
        while (iterated.prev != 0) {
            iterated = iterated.prev;
        }
        this.changeLength(-1);
        iterated.destroy();
    }

    public void removeAll() {
        thistype temp, iterated = this;
        while (iterated != 0) {
            temp = iterated.prev;
            iterated.destroy();
            iterated = temp;
        }
    }

    public thistype getNearest(float x, float y) {
        thistype nearest = this, iterated = this.prev;
        float tempDistSqr, nearestDistSqr = this.attach.distToSqr(x, y);
        while (iterated != 0) {
            tempDistSqr = iterated.attach.distToSqr(x, y);
            if (nearestDistSqr > tempDistSqr) {
                nearestDistSqr = tempDistSqr;
                nearest = iterated;
            }
            iterated = iterated.prev;
        }
        return nearest;
    }

    public unit getUnit() {
        return this.attach.getUnit();
    }

    private void changeLength(int howMuch) {
        thistype iterated = this;
        while (iterated != 0) {
            iterated.length += howMuch;
            iterated = iterated.prev;
        }
    }

    public void setLevel(int level) {
        thistype iterated = this;
        while (iterated != 0) {
            iterated.attach.setLevel(level);
            iterated = iterated.prev;
        }
    }
}