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// Copyright 2011 Google Inc. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package uuid
import (
"bytes"
"crypto/rand"
"fmt"
"io"
"strings"
)
// A UUID is a 128 bit (16 byte) Universal Unique IDentifier as defined in RFC
// 4122.
type UUID []byte
// A Version represents a UUIDs version.
type Version byte
// A Variant represents a UUIDs variant.
type Variant byte
// Constants returned by Variant.
const (
Invalid = Variant(iota) // Invalid UUID
RFC4122 // The variant specified in RFC4122
Reserved // Reserved, NCS backward compatibility.
Microsoft // Reserved, Microsoft Corporation backward compatibility.
Future // Reserved for future definition.
)
var rander = rand.Reader // random function
// New returns a new random (version 4) UUID as a string. It is a convenience
// function for NewRandom().String().
func New() string {
return NewRandom().String()
}
// Parse decodes s into a UUID or returns nil. Both the UUID form of
// xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx and
// urn:uuid:xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx are decoded.
func Parse(s string) UUID {
if len(s) == 36+9 {
if strings.ToLower(s[:9]) != "urn:uuid:" {
return nil
}
s = s[9:]
} else if len(s) != 36 {
return nil
}
if s[8] != '-' || s[13] != '-' || s[18] != '-' || s[23] != '-' {
return nil
}
uuid := make([]byte, 16)
for i, x := range []int{
0, 2, 4, 6,
9, 11,
14, 16,
19, 21,
24, 26, 28, 30, 32, 34} {
if v, ok := xtob(s[x:]); !ok {
return nil
} else {
uuid[i] = v
}
}
return uuid
}
// Equal returns true if uuid1 and uuid2 are equal.
func Equal(uuid1, uuid2 UUID) bool {
return bytes.Equal(uuid1, uuid2)
}
// String returns the string form of uuid, xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx
// , or "" if uuid is invalid.
func (uuid UUID) String() string {
if uuid == nil || len(uuid) != 16 {
return ""
}
b := []byte(uuid)
return fmt.Sprintf("%08x-%04x-%04x-%04x-%012x",
b[:4], b[4:6], b[6:8], b[8:10], b[10:])
}
// URN returns the RFC 2141 URN form of uuid,
// urn:uuid:xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx, or "" if uuid is invalid.
func (uuid UUID) URN() string {
if uuid == nil || len(uuid) != 16 {
return ""
}
b := []byte(uuid)
return fmt.Sprintf("urn:uuid:%08x-%04x-%04x-%04x-%012x",
b[:4], b[4:6], b[6:8], b[8:10], b[10:])
}
// Variant returns the variant encoded in uuid. It returns Invalid if
// uuid is invalid.
func (uuid UUID) Variant() Variant {
if len(uuid) != 16 {
return Invalid
}
switch {
case (uuid[8] & 0xc0) == 0x80:
return RFC4122
case (uuid[8] & 0xe0) == 0xc0:
return Microsoft
case (uuid[8] & 0xe0) == 0xe0:
return Future
default:
return Reserved
}
panic("unreachable")
}
// Version returns the verison of uuid. It returns false if uuid is not
// valid.
func (uuid UUID) Version() (Version, bool) {
if len(uuid) != 16 {
return 0, false
}
return Version(uuid[6] >> 4), true
}
func (v Version) String() string {
if v > 15 {
return fmt.Sprintf("BAD_VERSION_%d", v)
}
return fmt.Sprintf("VERSION_%d", v)
}
func (v Variant) String() string {
switch v {
case RFC4122:
return "RFC4122"
case Reserved:
return "Reserved"
case Microsoft:
return "Microsoft"
case Future:
return "Future"
case Invalid:
return "Invalid"
}
return fmt.Sprintf("BadVariant%d", int(v))
}
// SetRand sets the random number generator to r, which implents io.Reader.
// If r.Read returns an error when the package requests random data then
// a panic will be issued.
//
// Calling SetRand with nil sets the random number generator to the default
// generator.
func SetRand(r io.Reader) {
if r == nil {
rander = rand.Reader
return
}
rander = r
}
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