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std.uuid

A UUID, or Universally unique identifier, is intended to uniquely identify information in a distributed environment without significant central coordination. It can be used to tag objects with very short lifetimes, or to reliably identify very persistent objects across a network.

Category Functions
Parsing UUIDs parseUUID UUID UUIDParsingException uuidRegex
Generating UUIDs sha1UUID randomUUID md5UUID
Using UUIDs UUID.uuidVersion UUID.variant UUID.toString UUID.data UUID.swap UUID.opEquals UUID.opCmp UUID.toHash
UUID namespaces dnsNamespace urlNamespace oidNamespace x500Namespace

UUIDs have many applications. Some examples follow: Databases may use UUIDs to identify rows or records in order to ensure that they are unique across different databases, or for publication/subscription services. Network messages may be identified with a UUID to ensure that different parts of a message are put back together again. Distributed computing may use UUIDs to identify a remote procedure call. Transactions and classes involved in serialization may be identified by UUIDs. Microsoft's component object model (COM) uses UUIDs to distinguish different software component interfaces. UUIDs are inserted into documents from Microsoft Office programs. UUIDs identify audio or video streams in the Advanced Systems Format (ASF). UUIDs are also a basis for OIDs (object identifiers), and URNs (uniform resource name).

An attractive feature of UUIDs when compared to alternatives is their relative small size, of 128 bits, or 16 bytes. Another is that the creation of UUIDs does not require a centralized authority.

When UUIDs are generated by one of the defined mechanisms, they are either guaranteed to be unique, different from all other generated UUIDs (that is, it has never been generated before and it will never be generated again), or it is extremely likely to be unique (depending on the mechanism).

For efficiency, UUID is implemented as a struct. UUIDs are therefore empty if not explicitly initialized. An UUID is empty if `UUID.empty` is true. Empty UUIDs are equal to UUID.init, which is a UUID with all 16 bytes set to 0. Use UUID's constructors or the UUID generator functions to get an initialized UUID.

This is a port of boost.uuid from the Boost project with some minor additions and API changes for a more D-like API.

Standards:
RFC 4122
See Also:
http://en.wikipedia.org/wiki/Universally_unique_identifier
License:
Boost License 1.0.
Authors:
Johannes Pfau
Source
std/uuid.d
Examples:
import std.uuid;

UUID[] ids;
ids ~= randomUUID();
ids ~= md5UUID("test.name.123");
ids ~= sha1UUID("test.name.123");

foreach (entry; ids)
{
    writeln(entry.variant); // UUID.Variant.rfc4122
}
writeln(ids[0].uuidVersion); // UUID.Version.randomNumberBased
writeln(ids[1].toString()); // "22390768-cced-325f-8f0f-cfeaa19d0ccd"
assert(ids[1].data == [34, 57, 7, 104, 204, 237, 50, 95, 143, 15, 207,
    234, 161, 157, 12, 205]);
UUID id;
assert(id.empty);
struct UUID;
Examples:
UUID id;
assert(id.empty);

id = randomUUID;
assert(!id.empty);

id = UUID(cast(ubyte[16]) [138, 179, 6, 14, 44, 186, 79,
    35, 183, 76, 181, 45, 179, 189, 251, 70]);
writeln(id.toString()); // "8ab3060e-2cba-4f23-b74c-b52db3bdfb46"
enum Variant: int;

RFC 4122 defines different internal data layouts for UUIDs. These are the UUID formats supported by this module. It's possible to read, compare and use all these Variants, but UUIDs generated by this module will always be in rfc4122 format.

Note
Do not confuse this with std.variant.Variant.
ncs

NCS backward compatibility

rfc4122

Defined in RFC 4122 document

microsoft

Microsoft Corporation backward compatibility

future

Reserved for future use

enum Version: int;

RFC 4122 defines different UUID versions. The version shows how a UUID was generated, e.g. a version 4 UUID was generated from a random number, a version 3 UUID from an MD5 hash of a name.

Note
All of these UUID versions can be read and processed by std.uuid, but only version 3, 4 and 5 UUIDs can be generated.
unknown

Unknown version

timeBased

Version 1

dceSecurity

Version 2

nameBasedMD5

Version 3 (Name based + MD5)

randomNumberBased

Version 4 (Random)

nameBasedSHA1

Version 5 (Name based + SHA-1)

ubyte[16] data;

It is sometimes useful to get or set the 16 bytes of a UUID directly.

Note
UUID uses a 16-ubyte representation for the UUID data. RFC 4122 defines a UUID as a special structure in big-endian format. These 16-ubytes always equal the big-endian structure defined in RFC 4122.
Example
auto rawData = uuid.data; //get data
rawData[0] = 1; //modify
uuid.data = rawData; //set data
uuid.data[1] = 2; //modify directly
pure nothrow @nogc @safe this(ref ubyte[16] uuidData);

pure nothrow @nogc @safe this(in ubyte[16] uuidData);

Construct a UUID struct from the 16 byte representation of a UUID.

Examples:
enum ubyte[16] data = [0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15];
auto uuid = UUID(data);
enum ctfe = UUID(data);
writeln(uuid.data); // data
writeln(ctfe.data); // data
pure @safe this(T...)(T uuidData)
Constraints: if (uuidData.length == 16 && allSatisfy!(isIntegral, T));

Construct a UUID struct from the 16 byte representation of a UUID. Variadic constructor to allow a simpler syntax, see examples. You need to pass exactly 16 ubytes.

Examples:
auto tmp = UUID(0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15);
assert(tmp.data == cast(ubyte[16])[0,1,2,3,4,5,6,7,8,9,10,11,
    12,13,14,15]);
this(T)(in T[] uuid)
Constraints: if (isSomeChar!(Unqual!T));

Parse a UUID from its canonical string form. An UUID in its canonical form looks like this: 8ab3060e-2cba-4f23-b74c-b52db3bdfb46

Throws:
UUIDParsingException if the input is invalid
CTFE
This function is supported in CTFE code. Note that error messages caused by a malformed UUID parsed at compile time can be cryptic, but errors are detected and reported at compile time.
Note
This is a strict parser. It only accepts the pattern above. It doesn't support any leading or trailing characters. It only accepts characters used for hex numbers and the string must have hyphens exactly like above.
For a less strict parser, see parseUUID
Examples:
auto id = UUID("8AB3060E-2cba-4f23-b74c-b52db3bdfb46");
assert(id.data == [138, 179, 6, 14, 44, 186, 79, 35, 183, 76,
   181, 45, 179, 189, 251, 70]);
writeln(id.toString()); // "8ab3060e-2cba-4f23-b74c-b52db3bdfb46"

//Can also be used in CTFE, for example as UUID literals:
enum ctfeID = UUID("8ab3060e-2cba-4f23-b74c-b52db3bdfb46");
//here parsing is done at compile time, no runtime overhead!
const pure nothrow @nogc @property @trusted bool empty();

Returns true if and only if the UUID is equal to {00000000-0000-0000-0000-000000000000}

Examples:
UUID id;
assert(id.empty);
id = UUID("00000000-0000-0000-0000-000000000001");
assert(!id.empty);
const pure nothrow @nogc @property @safe Variant variant();

RFC 4122 defines different internal data layouts for UUIDs. Returns the format used by this UUID.

Note
Do not confuse this with std.variant.Variant. The type of this property is `std.uuid.UUID.Variant`.
See Also:
`UUID.Variant`
Examples:
assert(UUID("8ab3060e-2cba-4f23-b74c-b52db3bdfb46").variant
   == UUID.Variant.rfc4122);
const pure nothrow @nogc @property @safe Version uuidVersion();

RFC 4122 defines different UUID versions. The version shows how a UUID was generated, e.g. a version 4 UUID was generated from a random number, a version 3 UUID from an MD5 hash of a name. Returns the version used by this UUID.

See Also:
`UUID.Version`
Examples:
assert(UUID("8ab3060e-2cba-4f23-b74c-b52db3bdfb46").uuidVersion
    == UUID.Version.randomNumberBased);
pure nothrow @nogc @safe void swap(ref UUID rhs);

Swap the data of this UUID with the data of rhs.

Examples:
immutable ubyte[16] data = [0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15];
UUID u1;
UUID u2 = UUID(data);
u1.swap(u2);

writeln(u1); // UUID(data)
writeln(u2); // UUID.init
const pure nothrow @nogc @safe bool opEquals(in UUID s);

const pure nothrow @nogc @safe bool opEquals(ref UUID s);

const pure nothrow @nogc @safe int opCmp(in UUID s);

const pure nothrow @nogc @safe int opCmp(ref UUID s);

pure nothrow @nogc @safe UUID opAssign(in UUID s);

pure nothrow @nogc @safe UUID opAssign(ref UUID s);

const pure nothrow @nogc @safe size_t toHash();

All of the standard numeric operators are defined for the UUID struct.

Examples:
//compare UUIDs
writeln(UUID("00000000-0000-0000-0000-000000000000")); // UUID.init

//UUIDs in associative arrays:
int[UUID] test = [UUID("8a94f585-d180-44f7-8929-6fca0189c7d0") : 1,
    UUID("7c351fd4-b860-4ee3-bbdc-7f79f3dfb00a") : 2,
    UUID("9ac0a4e5-10ee-493a-86fc-d29eeb82ecc1") : 3];

writeln(test[UUID("9ac0a4e5-10ee-493a-86fc-d29eeb82ecc1")]); // 3

//UUIDS can be sorted:
import std.algorithm;
UUID[] ids = [UUID("8a94f585-d180-44f7-8929-6fca0189c7d0"),
              UUID("7c351fd4-b860-4ee3-bbdc-7f79f3dfb00a"),
              UUID("9ac0a4e5-10ee-493a-86fc-d29eeb82ecc1")];
sort(ids);
const void toString(Writer)(scope Writer sink);

Write the UUID into sink as an ASCII string in the canonical form, which is 36 characters in the form "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx"

Parameters:
Writer sink OutputRange or writeable array at least 36 entries long
const pure nothrow @trusted string toString();

Return the UUID as a string in the canonical form.

Examples:
immutable str = "8ab3060e-2cba-4f23-b74c-b52db3bdfb46";
auto id = UUID(str);
writeln(id.toString()); // str
pure nothrow @nogc @safe UUID md5UUID(const(char[]) name, const UUID namespace = UUID.init);

pure nothrow @nogc @safe UUID md5UUID(const(ubyte[]) data, const UUID namespace = UUID.init);

This function generates a name based (Version 3) UUID from a namespace UUID and a name. If no namespace UUID was passed, the empty UUID UUID.init is used.

Note
The default namespaces (dnsNamespace, ...) defined by this module should be used when appropriate.
RFC 4122 recommends to use Version 5 UUIDs (SHA-1) instead of Version 3 UUIDs (MD5) for new applications.
CTFE
CTFE is not supported.
Note
RFC 4122 isn't very clear on how UUIDs should be generated from names. It is possible that different implementations return different UUIDs for the same input, so be warned. The implementation for UTF-8 strings and byte arrays used by std.uuid is compatible with Boost's implementation. std.uuid guarantees that the same input to this function will generate the same output at any time, on any system (this especially means endianness doesn't matter).
Note
This function does not provide overloads for wstring and dstring, as there's no clear answer on how that should be implemented. It could be argued, that string, wstring and dstring input should have the same output, but that wouldn't be compatible with Boost, which generates different output for strings and wstrings. It's always possible to pass wstrings and dstrings by using the ubyte[] function overload (but be aware of endianness issues!).
Examples:
//Use default UUID.init namespace
auto simpleID = md5UUID("test.uuid.any.string");

//use a name-based id as namespace
auto namespace = md5UUID("my.app");
auto id = md5UUID("some-description", namespace);
pure nothrow @nogc @safe UUID sha1UUID(scope const(char)[] name, scope const UUID namespace = UUID.init);

pure nothrow @nogc @safe UUID sha1UUID(scope const(ubyte)[] data, scope const UUID namespace = UUID.init);

This function generates a name based (Version 5) UUID from a namespace UUID and a name. If no namespace UUID was passed, the empty UUID UUID.init is used.

Note
The default namespaces (dnsNamespace, ...) defined by this module should be used when appropriate.
CTFE
CTFE is not supported.
Note
RFC 4122 isn't very clear on how UUIDs should be generated from names. It is possible that different implementations return different UUIDs for the same input, so be warned. The implementation for UTF-8 strings and byte arrays used by std.uuid is compatible with Boost's implementation. std.uuid guarantees that the same input to this function will generate the same output at any time, on any system (this especially means endianness doesn't matter).
Note
This function does not provide overloads for wstring and dstring, as there's no clear answer on how that should be implemented. It could be argued, that string, wstring and dstring input should have the same output, but that wouldn't be compatible with Boost, which generates different output for strings and wstrings. It's always possible to pass wstrings and dstrings by using the ubyte[] function overload (but be aware of endianness issues!).
Examples:
//Use default UUID.init namespace
auto simpleID = sha1UUID("test.uuid.any.string");

//use a name-based id as namespace
auto namespace = sha1UUID("my.app");
auto id = sha1UUID("some-description", namespace);
@safe UUID randomUUID();

UUID randomUUID(RNG)(ref RNG randomGen)
Constraints: if (isInputRange!RNG && isIntegral!(ElementType!RNG));

This function generates a random number based UUID from a random number generator.

This function is not supported at compile time.

Parameters:
RNG randomGen uniform RNG
See Also:
std.random.isUniformRNG
Examples:
import std.random : Xorshift192, unpredictableSeed;

//simple call
auto uuid = randomUUID();

//provide a custom RNG. Must be seeded manually.
Xorshift192 gen;

gen.seed(unpredictableSeed);
auto uuid3 = randomUUID(gen);
UUID parseUUID(T)(T uuidString)
Constraints: if (isSomeString!T);

UUID parseUUID(Range)(ref Range uuidRange)
Constraints: if (isInputRange!Range && is(Unqual!(ElementType!Range) == dchar));

This is a less strict parser compared to the parser used in the UUID constructor. It enforces the following rules:

  • hex numbers are always two hexdigits([0-9a-fA-F])
  • there must be exactly 16 such pairs in the input, not less, not more
  • there can be exactly one dash between two hex-pairs, but not more
  • there can be multiple characters enclosing the 16 hex pairs, as long as these characters do not contain [0-9a-fA-F]
Note
Like most parsers, it consumes its argument. This means: 
string s = "8AB3060E-2CBA-4F23-b74c-B52Db3BDFB46";
parseUUID(s);
assert(s == "");
Throws:
UUIDParsingException if the input is invalid
CTFE
This function is supported in CTFE code. Note that error messages caused by a malformed UUID parsed at compile time can be cryptic, but errors are detected and reported at compile time.
Examples:
auto id = parseUUID("8AB3060E-2CBA-4F23-b74c-B52Db3BDFB46");
//no dashes
id = parseUUID("8ab3060e2cba4f23b74cb52db3bdfb46");
//dashes at different positions
id = parseUUID("8a-b3-06-0e2cba4f23b74c-b52db3bdfb-46");
//leading / trailing characters
id = parseUUID("{8ab3060e-2cba-4f23-b74c-b52db3bdfb46}");
//unicode
id = parseUUID("ü8ab3060e2cba4f23b74cb52db3bdfb46ü");
//multiple trailing/leading characters
id = parseUUID("///8ab3060e2cba4f23b74cb52db3bdfb46||");

//Can also be used in CTFE, for example as UUID literals:
enum ctfeID = parseUUID("8ab3060e-2cba-4f23-b74c-b52db3bdfb46");
//here parsing is done at compile time, no runtime overhead!
enum UUID dnsNamespace;

Default namespace from RFC 4122

Name string is a fully-qualified domain name

enum UUID urlNamespace;

Default namespace from RFC 4122

Name string is a URL

enum UUID oidNamespace;

Default namespace from RFC 4122

Name string is an ISO OID

enum UUID x500Namespace;

Default namespace from RFC 4122

Name string is an X.500 DN (in DER or a text output format)

enum string uuidRegex;

Regex string to extract UUIDs from text.

Examples:
import std.algorithm;
import std.regex;

string test = "Lorem ipsum dolor sit amet, consetetur "~
"6ba7b814-9dad-11d1-80b4-00c04fd430c8 sadipscing \n"~
"elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore \r\n"~
"magna aliquyam erat, sed diam voluptua. "~
"8ab3060e-2cba-4f23-b74c-b52db3bdfb46 At vero eos et accusam et "~
"justo duo dolores et ea rebum.";

auto r = regex(uuidRegex, "g");
UUID[] found;
foreach (c; match(test, r))
{
    found ~= UUID(c.hit);
}
assert(found == [
    UUID("6ba7b814-9dad-11d1-80b4-00c04fd430c8"),
    UUID("8ab3060e-2cba-4f23-b74c-b52db3bdfb46"),
]);
class UUIDParsingException: object.Exception;

This exception is thrown if an error occurs when parsing a UUID from a string.

Examples:
import std.exception : collectException;

const inputUUID = "this-is-an-invalid-uuid";
auto ex = collectException!UUIDParsingException(UUID(inputUUID));
assert(ex !is null); // check that exception was thrown
writeln(ex.input); // inputUUID
writeln(ex.position); // 0
writeln(ex.reason); // UUIDParsingException.Reason.tooLittle
enum Reason: int;

Reason reason;

The reason why parsing the UUID string failed (if known)

unknown
tooLittle

The passed in input was correct, but more input was expected.

tooMuch

The input data is too long (There's no guarantee the first part of the data is valid)

invalidChar

Encountered an invalid character

string input;

The original input string which should have been parsed.

size_t position;

The position in the input string where the error occurred.

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Licensed under the Boost License 1.0.
https://dlang.org/phobos/std_uuid.html