Method ReadFrom

roaring64/roaring64.go:133–175

ReadFrom reads a serialized version of this bitmap from stream. The format is compatible with other 64-bit RoaringBitmap implementations (Java, Go, C++) and it has a specification : https://github.com/RoaringBitmap/RoaringFormatSpec#extention-for-64-bit-implementations

(stream io.Reader)

// implementations (Java, Go, C++) and it has a specification :
// https://github.com/RoaringBitmap/RoaringFormatSpec#extention-for-64-bit-implementations
func (rb *Bitmap) ReadFrom(stream io.Reader) (p int64, err error) {
	sizeBuf := make([]byte, 8)
	var n int
	n, err = io.ReadFull(stream, sizeBuf)
	if err != nil {
		return int64(n), err
	}
	p += int64(n)
	size := binary.LittleEndian.Uint64(sizeBuf)
	rb.highlowcontainer.resize(0)
	if cap(rb.highlowcontainer.keys) >= int(size) {
		rb.highlowcontainer.keys = rb.highlowcontainer.keys[:size]
	} else {
		rb.highlowcontainer.keys = make([]uint32, size)
	}
	if cap(rb.highlowcontainer.containers) >= int(size) {
		rb.highlowcontainer.containers = rb.highlowcontainer.containers[:size]
	} else {
		rb.highlowcontainer.containers = make([]*roaring.Bitmap, size)
	}
	if cap(rb.highlowcontainer.needCopyOnWrite) >= int(size) {
		rb.highlowcontainer.needCopyOnWrite = rb.highlowcontainer.needCopyOnWrite[:size]
	} else {
		rb.highlowcontainer.needCopyOnWrite = make([]bool, size)
	}
	keyBuf := sizeBuf[:4]
	for i := uint64(0); i < size; i++ {
		n, err = io.ReadFull(stream, keyBuf)
		if err != nil {
			return int64(n), fmt.Errorf("error in bitmap.readFrom: could not read key #%d: %s", i, err)
		}
		p += int64(n)
		rb.highlowcontainer.keys[i] = binary.LittleEndian.Uint32(keyBuf)
		rb.highlowcontainer.containers[i] = roaring.NewBitmap()
		n, err := rb.highlowcontainer.containers[i].ReadFrom(stream)

		if n == 0 || err != nil {
			return n, fmt.Errorf("Could not deserialize bitmap for key #%d: %s", i, err)
		}
		p += n
	}
	return p, nil
}

// MarshalBinary implements the encoding.BinaryMarshaler interface for the bitmap
// (same as ToBytes)