/
fixed_size.go
213 lines (187 loc) · 3.98 KB
/
fixed_size.go
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package longbits
import (
"bytes"
"errors"
"io"
"github.com/insolar/vanilla/throw"
)
type Foldable interface {
FoldToUint64() uint64
}
//go:generate minimock -i github.com/insolar/vanilla/longbits.FixedReader -o . -s _mock.go -g
type FixedReader interface {
io.WriterTo
CopyTo(p []byte) int
AsByteString() ByteString
FixedByteSize() int
}
//go:generate minimock -i github.com/insolar/vanilla/longbits.FoldableReader -o . -s _mock.go -g
type FoldableReader interface {
FixedReader
Foldable
}
func FoldUint64(v uint64) uint32 {
return uint32(v) ^ uint32(v>>32)
}
func Equal(t, o FixedReader) bool {
switch {
case t == nil || o == nil:
return false
case t.FixedByteSize() == 0:
return o.FixedByteSize() == 0
}
return (&writerToComparer{}).compare(t, o)
}
func EqualToBytes(t FixedReader, o []byte) bool {
switch {
case t == nil:
return false
case t.FixedByteSize() == 0:
return len(o) == 0
case len(o) == 0:
return false
}
return (&writerToComparer{}).compareBytes(o, t)
}
type writerToComparer struct {
thisValue *[]byte
other io.WriterTo
result bool
}
func (c *writerToComparer) compareBytes(this []byte, other FixedReader) bool {
if other == nil || len(this) != other.FixedByteSize() {
return false
}
c.thisValue = &this
c.other = other
_, _ = other.WriteTo(c)
return c.other == nil && c.result
}
func (c *writerToComparer) compare(this, other FixedReader) bool {
c.thisValue = nil
if this == nil || other == nil || this.FixedByteSize() != other.FixedByteSize() {
return false
}
c.other = other
_, _ = this.WriteTo(c)
return c.other == nil && c.result
}
func (c *writerToComparer) Write(otherValue []byte) (int, error) {
if c.other == nil {
panic("content of FixedReader must be read/written all at once")
}
if c.thisValue == nil {
c.thisValue = &otherValue
_, err := c.other.WriteTo(c)
if err != nil {
return 0, err
}
} else {
c.other = nil // mark "done"
c.result = bytes.Equal(*c.thisValue, otherValue)
}
return len(otherValue), nil
}
type fixedSize struct {
data []byte
}
func (c fixedSize) AsByteString() ByteString {
return ByteString(c.data)
}
func (c fixedSize) String() string {
return ByteString(c.data).String()
}
func (c fixedSize) WriteTo(w io.Writer) (n int64, err error) {
n32, err := w.Write(c.data)
return int64(n32), err
}
func (c fixedSize) CopyTo(p []byte) (n int) {
return copy(p, c.data)
}
func (c fixedSize) FoldToUint64() uint64 {
return FoldToUint64(c.data)
}
func (c fixedSize) CutOutUint64() uint64 {
return CutOutUint64(c.data)
}
func (c fixedSize) FixedByteSize() int {
return len(c.data)
}
func AsBytes(v FixedReader) []byte {
if v == nil {
return nil
}
n := v.FixedByteSize()
if n == 0 {
return nil
}
data := make([]byte, n)
if v.CopyTo(data) != len(data) {
panic(throw.Impossible())
}
return data
}
func WrapBytes(data []byte) FoldableReader {
return fixedSize{data}
}
func CopyFixed(v FixedReader) FoldableReader {
if v == nil {
return EmptyByteString
}
if bs, ok := v.(ByteString); ok {
return bs
}
switch n := v.FixedByteSize(); n*8 {
case 0:
return EmptyByteString
case 64:
dst := Bits64{}
v.CopyTo(dst[:])
return dst
case 128:
dst := Bits128{}
v.CopyTo(dst[:])
return dst
case 224:
dst := Bits224{}
v.CopyTo(dst[:])
return dst
case 256:
dst := Bits256{}
v.CopyTo(dst[:])
return dst
case 512:
dst := Bits512{}
v.CopyTo(dst[:])
return dst
default:
data := make([]byte, n)
if v.CopyTo(data) != n {
panic(throw.Impossible())
}
return WrapBytes(data)
}
}
func Copy(to []byte, from FixedReader) error {
if n := from.FixedByteSize(); n != len(to) {
if n < len(to) {
return io.ErrShortBuffer
}
return io.ErrShortWrite
}
from.CopyTo(to)
return nil
}
func VerifyReadAt(b []byte, off int64, max int) (n int, err error) {
switch {
case off < 0:
return 0, errors.New("negative offset")
case off > int64(max):
return 0, io.ErrUnexpectedEOF
case len(b) == 0:
return 0, nil
case max == int(off):
return 0, io.EOF
}
return len(b), nil
}