uuid

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Published: Aug 11, 2020 License: Apache-2.0 Imports: 20 Imported by: 3

Documentation

Index

Constants

View Source
const (
	V1 byte // Version 1 (date-time and MAC address)

	V3 // Version 3 (namespace name-based)
	V4 // Version 4 (random)
	V5 // Version 5 (namespace name-based)
)

UUID versions.

View Source
const (
	VariantNCS byte = iota
	VariantRFC4122
	VariantMicrosoft
	VariantFuture
)

UUID layout variants.

View Source
const Size = 16

Size of a UUID in bytes.

Variables

View Source
var (
	NamespaceDNS  = Must(FromString("6ba7b810-9dad-11d1-80b4-00c04fd430c8"))
	NamespaceURL  = Must(FromString("6ba7b811-9dad-11d1-80b4-00c04fd430c8"))
	NamespaceOID  = Must(FromString("6ba7b812-9dad-11d1-80b4-00c04fd430c8"))
	NamespaceX500 = Must(FromString("6ba7b814-9dad-11d1-80b4-00c04fd430c8"))
)

Predefined namespace UUIDs.

View Source
var Nil = UUID{}

Nil is the nil UUID, as specified in RFC-4122, that has all 128 bits set to zero.

Functions

This section is empty.

Types

type Gen

type Gen struct {
	// contains filtered or unexported fields
}

Gen is a reference UUID generator based on the specifications laid out in RFC-4122 and DCE 1.1: Authentication and Security Services. This type satisfies the Generator interface as defined in this package.

For consumers who are generating V1 UUIDs, but don't want to expose the MAC address of the node generating the UUIDs, the NewGenWithHWAF() function has been provided as a convenience. See the function's documentation for more info.

The authors of this package do not feel that the majority of users will need to obfuscate their MAC address, and so we recommend using NewGen() to create a new generator.

func NewGen

func NewGen() *Gen

NewGen returns a new instance of Gen with some default values set. Most people should use this. NewGen by default uses crypto/rand.Reader as its source of randomness.

func NewGenWithHWAF

func NewGenWithHWAF(hwaf HWAddrFunc) *Gen

NewGenWithHWAF builds a new UUID generator with the HWAddrFunc provided. Most consumers should use NewGen() instead.

This is used so that consumers can generate their own MAC addresses, for use in the generated UUIDs, if there is some concern about exposing the physical address of the machine generating the UUID.

The Gen generator will only invoke the HWAddrFunc once, and cache that MAC address for all the future UUIDs generated by it. If you'd like to switch the MAC address being used, you'll need to create a new generator using this function.

func NewGenWithReader

func NewGenWithReader(r io.Reader) *Gen

NewGenWithReader returns a new instance of gen which uses r as its source of randomness.

func (*Gen) NewV1

func (g *Gen) NewV1() (UUID, error)

NewV1 returns a UUID based on the current timestamp and MAC address.

func (*Gen) NewV3

func (g *Gen) NewV3(ns UUID, name string) UUID

NewV3 returns a UUID based on the MD5 hash of the namespace UUID and name.

func (*Gen) NewV4

func (g *Gen) NewV4() (UUID, error)

NewV4 returns a randomly generated UUID.

func (*Gen) NewV5

func (g *Gen) NewV5(ns UUID, name string) UUID

NewV5 returns a UUID based on SHA-1 hash of the namespace UUID and name.

type Generator

type Generator interface {
	NewV1() (UUID, error)
	// NewV2(domain byte) (UUID, error) // CRL: Removed support for V2.
	NewV3(ns UUID, name string) UUID
	NewV4() (UUID, error)
	NewV5(ns UUID, name string) UUID
}

Generator provides an interface for generating UUIDs.

var DefaultGenerator Generator = NewGen()

DefaultGenerator is the default UUID Generator used by this package.

type HWAddrFunc

type HWAddrFunc func() (net.HardwareAddr, error)

HWAddrFunc is the function type used to provide hardware (MAC) addresses.

type NullUUID

type NullUUID struct {
	UUID  UUID
	Valid bool
}

NullUUID can be used with the standard sql package to represent a UUID value that can be NULL in the database.

func (NullUUID) MarshalJSON

func (u NullUUID) MarshalJSON() ([]byte, error)

MarshalJSON marshals the NullUUID as null or the nested UUID

func (*NullUUID) Scan

func (u *NullUUID) Scan(src interface{}) error

Scan implements the sql.Scanner interface.

func (*NullUUID) UnmarshalJSON

func (u *NullUUID) UnmarshalJSON(b []byte) error

UnmarshalJSON unmarshals a NullUUID

func (NullUUID) Value

func (u NullUUID) Value() (driver.Value, error)

Value implements the driver.Valuer interface.

type ShortStringer

type ShortStringer UUID

ShortStringer implements fmt.Stringer to output Short() on String().

func (ShortStringer) String

func (s ShortStringer) String() string

String is part of fmt.Stringer.

type Timestamp

type Timestamp uint64

Timestamp is the count of 100-nanosecond intervals since 00:00:00.00, 15 October 1582 within a V1 UUID. This type has no meaning for V2-V5 UUIDs since they don't have an embedded timestamp.

func TimestampFromV1

func TimestampFromV1(u UUID) (Timestamp, error)

TimestampFromV1 returns the Timestamp embedded within a V1 UUID. Returns an error if the UUID is any version other than 1.

func (Timestamp) Time

func (t Timestamp) Time() (time.Time, error)

Time returns the UTC time.Time representation of a Timestamp

type UUID

type UUID [Size]byte

UUID is an array type to represent the value of a UUID, as defined in RFC-4122.

func FastMakeV4

func FastMakeV4() UUID

FastMakeV4 generates a UUID using a fast but not cryptographically secure source of randomness.

func FromBytes

func FromBytes(input []byte) (UUID, error)

FromBytes returns a UUID generated from the raw byte slice input. It will return an error if the slice isn't 16 bytes long.

func FromBytesOrNil

func FromBytesOrNil(input []byte) UUID

FromBytesOrNil returns a UUID generated from the raw byte slice input. Same behavior as FromBytes(), but returns uuid.Nil instead of an error.

func FromString

func FromString(input string) (UUID, error)

FromString returns a UUID parsed from the input string. Input is expected in a form accepted by UnmarshalText.

func FromStringOrNil

func FromStringOrNil(input string) UUID

FromStringOrNil returns a UUID parsed from the input string. Same behavior as FromString(), but returns uuid.Nil instead of an error.

func FromUint128

func FromUint128(input uint128.Uint128) UUID

FromUint128 delegates to FromBytes and wraps the result in a UUID.

func MakeV4

func MakeV4() UUID

MakeV4 calls Must(NewV4)

func Must

func Must(u UUID, err error) UUID

Must is a helper that wraps a call to a function returning (UUID, error) and panics if the error is non-nil. It is intended for use in variable initializations such as

var packageUUID = uuid.Must(uuid.FromString("123e4567-e89b-12d3-a456-426655440000"))

func NewPopulatedUUID

func NewPopulatedUUID(r interface {
	Int63() int64
}) *UUID

NewPopulatedUUID returns a populated UUID.

func NewV1

func NewV1() (UUID, error)

NewV1 returns a UUID based on the current timestamp and MAC address.

func NewV3

func NewV3(ns UUID, name string) UUID

NewV3 returns a UUID based on the MD5 hash of the namespace UUID and name.

func NewV4

func NewV4() (UUID, error)

NewV4 returns a randomly generated UUID.

func NewV5

func NewV5(ns UUID, name string) UUID

NewV5 returns a UUID based on SHA-1 hash of the namespace UUID and name.

func (*UUID) DeterministicV4

func (u *UUID) DeterministicV4(i, n uint64)

DeterministicV4 overwrites this UUID with one computed deterministically to evenly fill the space of possible V4 UUIDs. `n` represents how many UUIDs will fill the space and `i` is an index into these `n` (and thus must be in the range `[0,n)`). The resulting UUIDs will be unique, evenly-spaced, and sorted.

func (UUID) Equal

func (u UUID) Equal(t UUID) bool

Equal returns true iff the receiver equals the argument.

This method exists only to conform to the API expected by gogoproto's generated Equal implementations.

func (UUID) GetBytes

func (u UUID) GetBytes() []byte

GetBytes returns the UUID as a byte slice. It incurs an allocation if the return value escapes.

func (*UUID) GetBytesMut

func (u *UUID) GetBytesMut() []byte

GetBytesMut returns the UUID as a mutable byte slice. Unlike GetBytes, it does not necessarily incur an allocation if the return value escapes. Instead, the return value escaping will cause the method's receiver (and any struct that it is a part of) to escape. Use only if GetBytes is causing an allocation and the UUID is already on the heap.

func (UUID) MarshalBinary

func (u UUID) MarshalBinary() ([]byte, error)

MarshalBinary implements the encoding.BinaryMarshaler interface.

func (UUID) MarshalJSON

func (u UUID) MarshalJSON() ([]byte, error)

MarshalJSON returns the JSON encoding of u.

func (UUID) MarshalText

func (u UUID) MarshalText() ([]byte, error)

MarshalText implements the encoding.TextMarshaler interface. The encoding is the same as returned by the String() method.

func (UUID) MarshalTo

func (u UUID) MarshalTo(data []byte) (int, error)

MarshalTo marshals u to data.

func (*UUID) Scan

func (u *UUID) Scan(src interface{}) error

Scan implements the sql.Scanner interface. A 16-byte slice will be handled by UnmarshalBinary, while a longer byte slice or a string will be handled by UnmarshalText.

func (*UUID) SetVariant

func (u *UUID) SetVariant(v byte)

SetVariant sets the variant bits.

func (*UUID) SetVersion

func (u *UUID) SetVersion(v byte)

SetVersion sets the version bits.

func (UUID) Short

func (u UUID) Short() string

Short returns the first eight characters of the output of String().

func (UUID) Size

func (u UUID) Size() int

Size returns the marshaled size of u, in bytes.

func (UUID) String

func (u UUID) String() string

String returns a canonical RFC-4122 string representation of the UUID: xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx.

func (UUID) StringBytes

func (u UUID) StringBytes(buf []byte)

StringBytes writes the result of String directly into a buffer, which must have a length of at least 36.

func (UUID) ToUint128

func (u UUID) ToUint128() uint128.Uint128

ToUint128 returns the UUID as a Uint128.

func (*UUID) Unmarshal

func (u *UUID) Unmarshal(data []byte) error

Unmarshal unmarshals data to u.

func (*UUID) UnmarshalBinary

func (u *UUID) UnmarshalBinary(data []byte) error

UnmarshalBinary implements the encoding.BinaryUnmarshaler interface. It will return an error if the slice isn't 16 bytes long.

func (*UUID) UnmarshalJSON

func (u *UUID) UnmarshalJSON(data []byte) error

UnmarshalJSON unmarshals the JSON encoded data into u.

func (*UUID) UnmarshalText

func (u *UUID) UnmarshalText(text []byte) error

UnmarshalText implements the encoding.TextUnmarshaler interface. Following formats are supported:

"6ba7b810-9dad-11d1-80b4-00c04fd430c8",
"{6ba7b810-9dad-11d1-80b4-00c04fd430c8}",
"urn:uuid:6ba7b810-9dad-11d1-80b4-00c04fd430c8"
"6ba7b8109dad11d180b400c04fd430c8"
"{6ba7b8109dad11d180b400c04fd430c8}",
"urn:uuid:6ba7b8109dad11d180b400c04fd430c8"

ABNF for supported UUID text representation follows:

URN := 'urn'
UUID-NID := 'uuid'

hexdig := '0' | '1' | '2' | '3' | '4' | '5' | '6' | '7' | '8' | '9' |
          'a' | 'b' | 'c' | 'd' | 'e' | 'f' |
          'A' | 'B' | 'C' | 'D' | 'E' | 'F'

hexoct := hexdig hexdig
2hexoct := hexoct hexoct
4hexoct := 2hexoct 2hexoct
6hexoct := 4hexoct 2hexoct
12hexoct := 6hexoct 6hexoct

hashlike := 12hexoct
canonical := 4hexoct '-' 2hexoct '-' 2hexoct '-' 6hexoct

plain := canonical | hashlike
uuid := canonical | hashlike | braced | urn

braced := '{' plain '}' | '{' hashlike  '}'
urn := URN ':' UUID-NID ':' plain

func (UUID) Value

func (u UUID) Value() (driver.Value, error)

Value implements the driver.Valuer interface.

func (UUID) Variant

func (u UUID) Variant() byte

Variant returns the UUID layout variant.

func (UUID) Version

func (u UUID) Version() byte

Version returns the algorithm version used to generate the UUID.

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