// Restore restores the pool to the previously captured state. ErrMismatchedNetwork
// is returned if the provided port range doesn't exactly match the previous range.
func (r *Allocator) Restore(into *uid.Range, data []byte) error {
	if into.String() != r.r.String() {
		return ErrMismatchedRange
	}
	snapshottable, ok := r.alloc.(allocator.Snapshottable)
	if !ok {
		return fmt.Errorf("not a snapshottable allocator")
	}
	return snapshottable.Restore(into.String(), data)
}

// DefaultMCSAllocation returns a label from the MCS range that matches the offset
// within the overall range. blockSize must be a positive integer representing the
// number of labels to jump past in the category space (if 1, range == label, if 2
// each range will have two labels).
func DefaultMCSAllocation(from *uid.Range, to *mcs.Range, blockSize int) MCSAllocationFunc {
	return func(block uid.Block) *mcs.Label {
		ok, offset := from.Offset(block)
		if !ok {
			return nil
		}
		if blockSize > 0 {
			offset = offset * uint32(blockSize)
		}
		label, _ := to.LabelAt(uint64(offset))
		return label
	}
}

// New creates a Allocator over a UID range, calling factory to construct the backing store.
func New(r *uid.Range, factory allocator.AllocatorFactory) *Allocator {
	return &Allocator{
		r:     r,
		alloc: factory(int(r.Size()), r.String()),
	}
}