xesite/vendor/github.com/xtgo/uuid/uuid.go

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2018-08-22 03:17:59 +00:00
// Copyright (c) 2012 The gocql Authors. 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 can be used to generate and parse universally unique
// identifiers, a standardized format in the form of a 128 bit number.
//
// http://tools.ietf.org/html/rfc4122
package uuid
import (
"crypto/rand"
"encoding/hex"
"errors"
"io"
"net"
"strconv"
"time"
)
type UUID [16]byte
var hardwareAddr []byte
const (
VariantNCSCompat = 0
VariantIETF = 2
VariantMicrosoft = 6
VariantFuture = 7
)
func init() {
if interfaces, err := net.Interfaces(); err == nil {
for _, i := range interfaces {
if i.Flags&net.FlagLoopback == 0 && len(i.HardwareAddr) > 0 {
hardwareAddr = i.HardwareAddr
break
}
}
}
if hardwareAddr == nil {
// If we failed to obtain the MAC address of the current computer,
// we will use a randomly generated 6 byte sequence instead and set
// the multicast bit as recommended in RFC 4122.
hardwareAddr = make([]byte, 6)
_, err := io.ReadFull(rand.Reader, hardwareAddr)
if err != nil {
panic(err)
}
hardwareAddr[0] = hardwareAddr[0] | 0x01
}
}
// Parse parses a 32 digit hexadecimal number (that might contain hyphens)
// representing an UUID.
func Parse(input string) (UUID, error) {
var u UUID
j := 0
for i := 0; i < len(input); i++ {
b := input[i]
switch {
default:
fallthrough
case j == 32:
goto err
case b == '-':
continue
case '0' <= b && b <= '9':
b -= '0'
case 'a' <= b && b <= 'f':
b -= 'a' - 10
case 'A' <= b && b <= 'F':
b -= 'A' - 10
}
u[j/2] |= b << byte(^j&1<<2)
j++
}
if j == 32 {
return u, nil
}
err:
return UUID{}, errors.New("invalid UUID " + strconv.Quote(input))
}
// FromBytes converts a raw byte slice to an UUID. It will panic if the slice
// isn't exactly 16 bytes long.
func FromBytes(input []byte) UUID {
var u UUID
if len(input) != 16 {
panic("UUIDs must be exactly 16 bytes long")
}
copy(u[:], input)
return u
}
// NewRandom generates a totally random UUID (version 4) as described in
// RFC 4122.
func NewRandom() UUID {
var u UUID
io.ReadFull(rand.Reader, u[:])
u[6] &= 0x0F // clear version
u[6] |= 0x40 // set version to 4 (random uuid)
u[8] &= 0x3F // clear variant
u[8] |= 0x80 // set to IETF variant
return u
}
var timeBase = time.Date(1582, time.October, 15, 0, 0, 0, 0, time.UTC).Unix()
// NewTime generates a new time based UUID (version 1) as described in RFC
// 4122. This UUID contains the MAC address of the node that generated the
// UUID, a timestamp and a sequence number.
func NewTime() UUID {
var u UUID
now := time.Now().In(time.UTC)
t := uint64(now.Unix()-timeBase)*10000000 + uint64(now.Nanosecond()/100)
u[0], u[1], u[2], u[3] = byte(t>>24), byte(t>>16), byte(t>>8), byte(t)
u[4], u[5] = byte(t>>40), byte(t>>32)
u[6], u[7] = byte(t>>56)&0x0F, byte(t>>48)
var clockSeq [2]byte
io.ReadFull(rand.Reader, clockSeq[:])
u[8] = clockSeq[1]
u[9] = clockSeq[0]
copy(u[10:], hardwareAddr)
u[6] |= 0x10 // set version to 1 (time based uuid)
u[8] &= 0x3F // clear variant
u[8] |= 0x80 // set to IETF variant
return u
}
// String returns the UUID in it's canonical form, a 32 digit hexadecimal
// number in the form of xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx.
func (u UUID) String() string {
buf := [36]byte{8: '-', 13: '-', 18: '-', 23: '-'}
hex.Encode(buf[0:], u[0:4])
hex.Encode(buf[9:], u[4:6])
hex.Encode(buf[14:], u[6:8])
hex.Encode(buf[19:], u[8:10])
hex.Encode(buf[24:], u[10:])
return string(buf[:])
}
// Bytes returns the raw byte slice for this UUID. A UUID is always 128 bits
// (16 bytes) long.
func (u UUID) Bytes() []byte {
return u[:]
}
// Variant returns the variant of this UUID. This package will only generate
// UUIDs in the IETF variant.
func (u UUID) Variant() int {
x := u[8]
switch byte(0) {
case x & 0x80:
return VariantNCSCompat
case x & 0x40:
return VariantIETF
case x & 0x20:
return VariantMicrosoft
}
return VariantFuture
}
// Version extracts the version of this UUID variant. The RFC 4122 describes
// five kinds of UUIDs.
func (u UUID) Version() int {
return int(u[6] & 0xF0 >> 4)
}
// Node extracts the MAC address of the node who generated this UUID. It will
// return nil if the UUID is not a time based UUID (version 1).
func (u UUID) Node() []byte {
if u.Version() != 1 {
return nil
}
return u[10:]
}
// Timestamp extracts the timestamp information from a time based UUID
// (version 1).
func (u UUID) Timestamp() uint64 {
if u.Version() != 1 {
return 0
}
return uint64(u[0])<<24 + uint64(u[1])<<16 + uint64(u[2])<<8 +
uint64(u[3]) + uint64(u[4])<<40 + uint64(u[5])<<32 +
uint64(u[7])<<48 + uint64(u[6]&0x0F)<<56
}
// Time is like Timestamp, except that it returns a time.Time.
func (u UUID) Time() time.Time {
t := u.Timestamp()
if t == 0 {
return time.Time{}
}
sec := t / 10000000
nsec := t - sec
return time.Unix(int64(sec)+timeBase, int64(nsec))
}