Update to last common bleve (#3986)

vendor/github.com/Smerity/govarint/govarint.go

@@ -0,0 +1,229 @@
+package govarint
+
+import "encoding/binary"
+import "io"
+
+type U32VarintEncoder interface {
+	PutU32(x uint32) int
+	Close()
+}
+
+type U32VarintDecoder interface {
+	GetU32() (uint32, error)
+}
+
+///
+
+type U64VarintEncoder interface {
+	PutU64(x uint64) int
+	Close()
+}
+
+type U64VarintDecoder interface {
+	GetU64() (uint64, error)
+}
+
+///
+
+type U32GroupVarintEncoder struct {
+	w     io.Writer
+	index int
+	store [4]uint32
+	temp  [17]byte
+}
+
+func NewU32GroupVarintEncoder(w io.Writer) *U32GroupVarintEncoder { return &U32GroupVarintEncoder{w: w} }
+
+func (b *U32GroupVarintEncoder) Flush() (int, error) {
+	// TODO: Is it more efficient to have a tailored version that's called only in Close()?
+	// If index is zero, there are no integers to flush
+	if b.index == 0 {
+		return 0, nil
+	}
+	// In the case we're flushing (the group isn't of size four), the non-values should be zero
+	// This ensures the unused entries are all zero in the sizeByte
+	for i := b.index; i < 4; i++ {
+		b.store[i] = 0
+	}
+	length := 1
+	// We need to reset the size byte to zero as we only bitwise OR into it, we don't overwrite it
+	b.temp[0] = 0
+	for i, x := range b.store {
+		size := byte(0)
+		shifts := []byte{24, 16, 8, 0}
+		for _, shift := range shifts {
+			// Always writes at least one byte -- the first one (shift = 0)
+			// Will write more bytes until the rest of the integer is all zeroes
+			if (x>>shift) != 0 || shift == 0 {
+				size += 1
+				b.temp[length] = byte(x >> shift)
+				length += 1
+			}
+		}
+		// We store the size in two of the eight bits in the first byte (sizeByte)
+		// 0 means there is one byte in total, hence why we subtract one from size
+		b.temp[0] |= (size - 1) << (uint8(3-i) * 2)
+	}
+	// If we're flushing without a full group of four, remove the unused bytes we computed
+	// This enables us to realize it's a partial group on decoding thanks to EOF
+	if b.index != 4 {
+		length -= 4 - b.index
+	}
+	_, err := b.w.Write(b.temp[:length])
+	return length, err
+}
+
+func (b *U32GroupVarintEncoder) PutU32(x uint32) (int, error) {
+	bytesWritten := 0
+	b.store[b.index] = x
+	b.index += 1
+	if b.index == 4 {
+		n, err := b.Flush()
+		if err != nil {
+			return n, err
+		}
+		bytesWritten += n
+		b.index = 0
+	}
+	return bytesWritten, nil
+}
+
+func (b *U32GroupVarintEncoder) Close() {
+	// On Close, we flush any remaining values that might not have been in a full group
+	b.Flush()
+}
+
+///
+
+type U32GroupVarintDecoder struct {
+	r        io.ByteReader
+	group    [4]uint32
+	pos      int
+	finished bool
+	capacity int
+}
+
+func NewU32GroupVarintDecoder(r io.ByteReader) *U32GroupVarintDecoder {
+	return &U32GroupVarintDecoder{r: r, pos: 4, capacity: 4}
+}
+
+func (b *U32GroupVarintDecoder) getGroup() error {
+	// We should always receive a sizeByte if there are more values to read
+	sizeByte, err := b.r.ReadByte()
+	if err != nil {
+		return err
+	}
+	// Calculate the size of the four incoming 32 bit integers
+	// 0b00 means 1 byte to read, 0b01 = 2, etc
+	b.group[0] = uint32((sizeByte >> 6) & 3)
+	b.group[1] = uint32((sizeByte >> 4) & 3)
+	b.group[2] = uint32((sizeByte >> 2) & 3)
+	b.group[3] = uint32(sizeByte & 3)
+	//
+	for index, size := range b.group {
+		b.group[index] = 0
+		// Any error that occurs in earlier byte reads should be repeated at the end one
+		// Hence we only catch and report the final ReadByte's error
+		var err error
+		switch size {
+		case 0:
+			var x byte
+			x, err = b.r.ReadByte()
+			b.group[index] = uint32(x)
+		case 1:
+			var x, y byte
+			x, _ = b.r.ReadByte()
+			y, err = b.r.ReadByte()
+			b.group[index] = uint32(x)<<8 | uint32(y)
+		case 2:
+			var x, y, z byte
+			x, _ = b.r.ReadByte()
+			y, _ = b.r.ReadByte()
+			z, err = b.r.ReadByte()
+			b.group[index] = uint32(x)<<16 | uint32(y)<<8 | uint32(z)
+		case 3:
+			var x, y, z, zz byte
+			x, _ = b.r.ReadByte()
+			y, _ = b.r.ReadByte()
+			z, _ = b.r.ReadByte()
+			zz, err = b.r.ReadByte()
+			b.group[index] = uint32(x)<<24 | uint32(y)<<16 | uint32(z)<<8 | uint32(zz)
+		}
+		if err != nil {
+			if err == io.EOF {
+				// If we hit EOF here, we have found a partial group
+				// We've return any valid entries we have read and return EOF once we run out
+				b.capacity = index
+				b.finished = true
+				break
+			} else {
+				return err
+			}
+		}
+	}
+	// Reset the pos pointer to the beginning of the read values
+	b.pos = 0
+	return nil
+}
+
+func (b *U32GroupVarintDecoder) GetU32() (uint32, error) {
+	// Check if we have any more values to give out - if not, let's get them
+	if b.pos == b.capacity {
+		// If finished is set, there is nothing else to do
+		if b.finished {
+			return 0, io.EOF
+		}
+		err := b.getGroup()
+		if err != nil {
+			return 0, err
+		}
+	}
+	// Increment pointer and return the value stored at that point
+	b.pos += 1
+	return b.group[b.pos-1], nil
+}
+
+///
+
+type Base128Encoder struct {
+	w        io.Writer
+	tmpBytes []byte
+}
+
+func NewU32Base128Encoder(w io.Writer) *Base128Encoder {
+	return &Base128Encoder{w: w, tmpBytes: make([]byte, binary.MaxVarintLen32)}
+}
+func NewU64Base128Encoder(w io.Writer) *Base128Encoder {
+	return &Base128Encoder{w: w, tmpBytes: make([]byte, binary.MaxVarintLen64)}
+}
+
+func (b *Base128Encoder) PutU32(x uint32) (int, error) {
+	writtenBytes := binary.PutUvarint(b.tmpBytes, uint64(x))
+	return b.w.Write(b.tmpBytes[:writtenBytes])
+}
+
+func (b *Base128Encoder) PutU64(x uint64) (int, error) {
+	writtenBytes := binary.PutUvarint(b.tmpBytes, x)
+	return b.w.Write(b.tmpBytes[:writtenBytes])
+}
+
+func (b *Base128Encoder) Close() {
+}
+
+///
+
+type Base128Decoder struct {
+	r io.ByteReader
+}
+
+func NewU32Base128Decoder(r io.ByteReader) *Base128Decoder { return &Base128Decoder{r: r} }
+func NewU64Base128Decoder(r io.ByteReader) *Base128Decoder { return &Base128Decoder{r: r} }
+
+func (b *Base128Decoder) GetU32() (uint32, error) {
+	v, err := binary.ReadUvarint(b.r)
+	return uint32(v), err
+}
+
+func (b *Base128Decoder) GetU64() (uint64, error) {
+	return binary.ReadUvarint(b.r)
+}