mirror of
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297 lines
7.7 KiB
Go
297 lines
7.7 KiB
Go
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// This package provides RFC4122 UUIDs.
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//
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// NewV1, NewV3, NewV4, NewV5, for generating versions 1, 3, 4
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// and 5 UUIDs as specified in RFC-4122.
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//
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// New([]byte), unsafe; NewHex(string); and Parse(string) for
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// creating UUIDs from existing data.
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//
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// The original version was from Krzysztof Kowalik <chris@nu7hat.ch>
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// Unfortunately, that version was non compliant with RFC4122.
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// I forked it but have since heavily redesigned it.
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//
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// The example code in the specification was also used as reference
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// for design.
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//
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// Copyright (C) 2014 twinj@github.com 2014 MIT style licence
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package uuid
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/****************
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* Date: 31/01/14
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* Time: 3:35 PM
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***************/
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import (
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"encoding"
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"encoding/hex"
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"errors"
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"fmt"
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"hash"
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"regexp"
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"strings"
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"bytes"
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)
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const (
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ReservedNCS byte = 0x00
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ReservedRFC4122 byte = 0x80 // or and A0 if masked with 1F
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ReservedMicrosoft byte = 0xC0
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ReservedFuture byte = 0xE0
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TakeBack byte = 0xF0
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)
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const (
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// Pattern used to parse string representation of the UUID.
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// Current one allows to parse string where only one opening
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// or closing bracket or any of the hyphens are optional.
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// It is only used to extract the main bytes to create a UUID,
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// so these imperfections are of no consequence.
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hexPattern = `^(urn\:uuid\:)?[\{(\[]?([A-Fa-f0-9]{8})-?([A-Fa-f0-9]{4})-?([1-5][A-Fa-f0-9]{3})-?([A-Fa-f0-9]{4})-?([A-Fa-f0-9]{12})[\]\})]?$`
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)
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var (
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parseUUIDRegex = regexp.MustCompile(hexPattern)
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format string
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)
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func init() {
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SwitchFormat(CleanHyphen)
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}
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// ****************************************************** UUID
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// The main interface for UUIDs
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// Each implementation must also implement the UniqueName interface
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type UUID interface {
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encoding.BinaryMarshaler
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encoding.BinaryUnmarshaler
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// Marshals the UUID bytes or data
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Bytes() (data []byte)
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// Organises data into a new UUID
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Unmarshal(pData []byte)
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// Size is used where different implementations require
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// different sizes. Should return the number of bytes in
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// the implementation.
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// Enables unmarshal and Bytes to screen for size
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Size() int
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// Version returns a version number of the algorithm used
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// to generate the UUID.
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// This may may behave independently across non RFC4122 UUIDs
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Version() int
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// Variant returns the UUID Variant
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// This will be one of the constants:
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// ReservedRFC4122,
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// ReservedMicrosoft,
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// ReservedFuture,
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// ReservedNCS.
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// This may behave differently across non RFC4122 UUIDs
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Variant() byte
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// UUID can be used as a Name within a namespace
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// Is simply just a String() string method
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// Returns a formatted version of the UUID.
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String() string
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}
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// New creates a UUID from a slice of bytes.
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// Truncates any bytes past the default length of 16
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// Will panic if data slice is too small.
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func New(pData []byte) UUID {
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o := new(Array)
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o.Unmarshal(pData[:length])
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return o
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}
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// Creates a UUID from a hex string
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// Will panic if hex string is invalid - will panic even with hyphens and brackets
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// Expects a clean string use Parse otherwise.
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func NewHex(pUuid string) UUID {
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bytes, err := hex.DecodeString(pUuid)
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if err != nil {
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panic(err)
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}
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return New(bytes)
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}
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// Parse creates a UUID from a valid string representation.
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// Accepts UUID string in following formats:
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// 6ba7b8149dad11d180b400c04fd430c8
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// 6ba7b814-9dad-11d1-80b4-00c04fd430c8
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// {6ba7b814-9dad-11d1-80b4-00c04fd430c8}
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// urn:uuid:6ba7b814-9dad-11d1-80b4-00c04fd430c8
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// [6ba7b814-9dad-11d1-80b4-00c04fd430c8]
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//
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func Parse(pUUID string) (UUID, error) {
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md := parseUUIDRegex.FindStringSubmatch(pUUID)
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if md == nil {
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return nil, errors.New("uuid.Parse: invalid string")
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}
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return NewHex(md[2] + md[3] + md[4] + md[5] + md[6]), nil
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}
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// Digest a namespace UUID and a UniqueName, which then marshals to
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// a new UUID
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func Digest(o, pNs UUID, pName UniqueName, pHash hash.Hash) {
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// Hash writer never returns an error
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pHash.Write(pNs.Bytes())
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pHash.Write([]byte(pName.String()))
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o.Unmarshal(pHash.Sum(nil)[:o.Size()])
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}
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// Function provides a safe way to unmarshal bytes into an
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// existing UUID.
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// Checks for length.
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func UnmarshalBinary(o UUID, pData []byte) error {
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if len(pData) != o.Size() {
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return errors.New("uuid.UnmarshalBinary: invalid length")
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}
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o.Unmarshal(pData)
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return nil
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}
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// ********************************************** UUID Names
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// A UUID Name is a simple string which implements UniqueName
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// which satisfies the Stringer interface.
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type Name string
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// Returns the name as a string. Satisfies the Stringer interface.
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func (o Name) String() string {
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return string(o)
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}
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// NewName will create a unique name from several sources
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func NewName(salt string, pNames ...UniqueName) UniqueName {
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var s string
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for _, s2 := range pNames {
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s += s2.String()
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}
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return Name(s + salt)
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}
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// UniqueName is a Stinger interface
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// Made for easy passing of IPs, URLs, the several Address types,
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// Buffers and any other type which implements Stringer
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// string, []byte types and Hash sums will need to be cast to
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// the Name type or some other type which implements
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// Stringer or UniqueName
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type UniqueName interface {
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// Many go types implement this method for use with printing
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// Will convert the current type to its native string format
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String() string
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}
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// ********************************************** UUID Printing
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// A Format is a pattern used by the stringer interface with which to print
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// the UUID.
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type Format string
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const (
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Clean Format = "%x%x%x%x%x%x"
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Curly Format = "{%x%x%x%x%x%x}"
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Bracket Format = "(%x%x%x%x%x%x)"
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// This is the default format.
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CleanHyphen Format = "%x-%x-%x-%x%x-%x"
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CurlyHyphen Format = "{%x-%x-%x-%x%x-%x}"
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BracketHyphen Format = "(%x-%x-%x-%x%x-%x)"
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GoIdFormat Format = "[%X-%X-%x-%X%X-%x]"
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)
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// Gets the current default format pattern
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func GetFormat() string {
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return format
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}
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// Switches the default printing format for ALL UUID strings
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// A valid format will have 6 groups if the supplied Format does not
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func SwitchFormat(pFormat Format) {
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form := string(pFormat)
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if strings.Count(form, "%") != 6 {
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panic(errors.New("uuid.switchFormat: invalid formatting"))
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}
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format = form
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}
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// Same as SwitchFormat but will make it uppercase
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func SwitchFormatUpperCase(pFormat Format) {
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form := strings.ToUpper(string(pFormat))
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SwitchFormat(Format(form))
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}
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// Compares whether each UUID is the same
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func Equal(p1 UUID, p2 UUID) bool {
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return bytes.Equal(p1.Bytes(), p2.Bytes())
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}
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// Format a UUID into a human readable string which matches the given Format
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// Use this for one time formatting when setting the default using SwitchFormat
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// is overkill.
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func Formatter(pUUID UUID, pFormat Format) string {
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form := string(pFormat)
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if strings.Count(form, "%") != 6 {
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panic(errors.New("uuid.Formatter: invalid formatting"))
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}
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return formatter(pUUID, form)
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}
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// ********************************************** UUID Versions
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type UUIDVersion int
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const (
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NONE UUIDVersion = iota
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RFC4122v1
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DunnoYetv2
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RFC4122v3
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RFC4122v4
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RFC4122v5
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)
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// *************************************************** Helpers
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// Retrieves the variant from the given byte
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func variant(pVariant byte) byte {
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switch pVariant & variantGet {
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case ReservedRFC4122, 0xA0:
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return ReservedRFC4122
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case ReservedMicrosoft:
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return ReservedMicrosoft
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case ReservedFuture:
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return ReservedFuture
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}
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return ReservedNCS
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}
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// not strictly required
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func setVariant(pByte *byte, pVariant byte) {
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switch pVariant {
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case ReservedRFC4122:
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*pByte &= variantSet
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case ReservedFuture, ReservedMicrosoft:
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*pByte &= 0x1F
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case ReservedNCS:
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*pByte &= 0x7F
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default:
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panic(errors.New("uuid.setVariant: invalid variant mask"))
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}
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*pByte |= pVariant
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}
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// format a UUID into a human readable string
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func formatter(pUUID UUID, pFormat string) string {
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b := pUUID.Bytes()
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return fmt.Sprintf(pFormat, b[0:4], b[4:6], b[6:8], b[8:9], b[9:10], b[10:pUUID.Size()])
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}
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