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uuid.go
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uuid.go
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package uuid
import (
"bytes"
"crypto/md5"
"crypto/rand"
"encoding/hex"
"errors"
)
var (
byteGroups = []int{8, 4, 4, 4, 12}
ErrorInvalidID = errors.New("Invalid ID.")
)
type UUID [16]byte
func (this *UUID) String() string {
return bytesToString(this.Bytes())
}
func (this *UUID) Bytes() []byte {
return this[:]
}
func (this *UUID) Equals(another *UUID) bool {
if this == nil && another == nil {
return true
}
if this == nil || another == nil {
return false
}
return bytes.Equal(this.Bytes(), another.Bytes())
}
// Next generates a deterministic random UUID based on this UUID.
func (this *UUID) Next() *UUID {
md5hash := md5.New()
md5hash.Write(this.Bytes())
md5hash.Write([]byte("16167dc8-16b6-4e6d-b8bb-65dd68113a81"))
newid := new(UUID)
for {
md5hash.Sum(newid[:0])
if !newid.Equals(this) {
return newid
}
md5hash.Write([]byte("533eff8a-4113-4b10-b5ce-0f5d76b98cd2"))
}
}
func bytesToString(bytes []byte) string {
result := hex.EncodeToString(bytes[0 : byteGroups[0]/2])
start := byteGroups[0] / 2
for i := 1; i < len(byteGroups); i++ {
nBytes := byteGroups[i] / 2
result += "-"
result += hex.EncodeToString(bytes[start : start+nBytes])
start += nBytes
}
return result
}
func New() *UUID {
uuid := new(UUID)
rand.Read(uuid.Bytes())
return uuid
}
func ParseBytes(b []byte) (*UUID, error) {
if len(b) != 16 {
return nil, ErrorInvalidID
}
uuid := new(UUID)
copy(uuid[:], b)
return uuid, nil
}
func ParseString(str string) (*UUID, error) {
text := []byte(str)
if len(text) < 32 {
return nil, ErrorInvalidID
}
uuid := new(UUID)
b := uuid.Bytes()
for _, byteGroup := range byteGroups {
if text[0] == '-' {
text = text[1:]
}
_, err := hex.Decode(b[:byteGroup/2], text[:byteGroup])
if err != nil {
return nil, err
}
text = text[byteGroup:]
b = b[byteGroup/2:]
}
return uuid, nil
}