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