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package roaring
import (
"encoding/binary"
"io"
)
type byteInput interface {
// next returns a slice containing the next n bytes from the buffer,
// advancing the buffer as if the bytes had been returned by Read.
next(n int) ([]byte, error)
// readUInt32 reads uint32 with LittleEndian order
readUInt32() (uint32, error)
// readUInt16 reads uint16 with LittleEndian order
readUInt16() (uint16, error)
// getReadBytes returns read bytes
getReadBytes() int64
// skipBytes skips exactly n bytes
skipBytes(n int) error
}
func newByteInputFromReader(reader io.Reader) byteInput {
return &byteInputAdapter{
r: reader,
readBytes: 0,
}
}
func newByteInput(buf []byte) byteInput {
return &byteBuffer{
buf: buf,
off: 0,
}
}
type byteBuffer struct {
buf []byte
off int
}
// next returns a slice containing the next n bytes from the reader
// If there are fewer bytes than the given n, io.ErrUnexpectedEOF will be returned
func (b *byteBuffer) next(n int) ([]byte, error) {
m := len(b.buf) - b.off
if n > m {
return nil, io.ErrUnexpectedEOF
}
data := b.buf[b.off : b.off+n]
b.off += n
return data, nil
}
// readUInt32 reads uint32 with LittleEndian order
func (b *byteBuffer) readUInt32() (uint32, error) {
if len(b.buf)-b.off < 4 {
return 0, io.ErrUnexpectedEOF
}
v := binary.LittleEndian.Uint32(b.buf[b.off:])
b.off += 4
return v, nil
}
// readUInt16 reads uint16 with LittleEndian order
func (b *byteBuffer) readUInt16() (uint16, error) {
if len(b.buf)-b.off < 2 {
return 0, io.ErrUnexpectedEOF
}
v := binary.LittleEndian.Uint16(b.buf[b.off:])
b.off += 2
return v, nil
}
// getReadBytes returns read bytes
func (b *byteBuffer) getReadBytes() int64 {
return int64(b.off)
}
// skipBytes skips exactly n bytes
func (b *byteBuffer) skipBytes(n int) error {
m := len(b.buf) - b.off
if n > m {
return io.ErrUnexpectedEOF
}
b.off += n
return nil
}
// reset resets the given buffer with a new byte slice
func (b *byteBuffer) reset(buf []byte) {
b.buf = buf
b.off = 0
}
type byteInputAdapter struct {
r io.Reader
readBytes int
}
// next returns a slice containing the next n bytes from the buffer,
// advancing the buffer as if the bytes had been returned by Read.
func (b *byteInputAdapter) next(n int) ([]byte, error) {
buf := make([]byte, n)
m, err := io.ReadAtLeast(b.r, buf, n)
b.readBytes += m
if err != nil {
return nil, err
}
return buf, nil
}
// readUInt32 reads uint32 with LittleEndian order
func (b *byteInputAdapter) readUInt32() (uint32, error) {
buf, err := b.next(4)
if err != nil {
return 0, err
}
return binary.LittleEndian.Uint32(buf), nil
}
// readUInt16 reads uint16 with LittleEndian order
func (b *byteInputAdapter) readUInt16() (uint16, error) {
buf, err := b.next(2)
if err != nil {
return 0, err
}
return binary.LittleEndian.Uint16(buf), nil
}
// getReadBytes returns read bytes
func (b *byteInputAdapter) getReadBytes() int64 {
return int64(b.readBytes)
}
// skipBytes skips exactly n bytes
func (b *byteInputAdapter) skipBytes(n int) error {
_, err := b.next(n)
return err
}
// reset resets the given buffer with a new stream
func (b *byteInputAdapter) reset(stream io.Reader) {
b.r = stream
b.readBytes = 0
}
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