1/*  Part of SWI-Prolog
    2
    3    Author:        Jan Wielemaker
    4    E-mail:        J.Wielemaker@vu.nl
    5    WWW:           http://www.swi-prolog.org
    6    Copyright (c)  2012-2024, VU University Amsterdam
    7                              SWI-Prolog Solutions b.v.
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   35
   36:- module(uuid,
   37          [ uuid/1,                     % -UUID
   38            uuid/2,                     % -UUID, +Options
   39            is_uuid/1,                  % @UUID
   40            uuid_property/2             % +UUID, ?Property
   41          ]).   42:- autoload(library(apply), [maplist/2]).

?- uuid(X).
X = 'ea6589fa-19dd-11e2-8a49-001d92e1879d'.

?- uuid(X, [url('http://www.swi-prolog.org')]).
X = '73a07870-6a90-3f2e-ae2b-ffa538dc7c2c'.

   63link_uuid :-
   64    catch(load_foreign_library(foreign(uuid)), _, true).
   65
   66:- initialization(link_uuid, now).

 uuid(-UUID) is det

UUID is an atom representing a new UUID. This is the same as calling uuid(UUID, []). See uuid/2 for options.

   73uuid(UUID) :-
   74    uuid(UUID, []).

 uuid(-UUID, +Options) is det

Create a new UUID according to Options. The following options are defined:

version(+Versions)

Integer in the range 1..5, which specifies the UUID version that is created. Default is 1.

dns(DNS)

url(URL)

oid(OID)

x500(X500)

Provide additional context information for UUIDs using version 3 or 5. If there is no explicit version option, UUID version 3 is used.

format(+Format)

Representation of the UUID. Default is atom, yielding atoms such as 8304efdd-bd6e-5b7c-a27f-83f3f05c64e0. The alternative is integer, returning a large integer that represents the 128 bits of the UUID.

If SWI-Prolog was not built with the OSSP UUID dependency library a simple Prolog alternative that only implements version 4 random UUIDs is provided. In this case the default version is 4 and the only admissible options are version(4) and format(Format).

  104:- if(current_predicate(ossp_uuid/2)).  105uuid(UUID, Options) :-
  106    ossp_uuid(UUID, Options).
  107
  108:- else.  109
  110uuid(UUID, []) :-
  111    !,
  112    random_uuid(UUID).
  113uuid(UUID, Options) :-
  114    option(version(4), Options, 4),
  115    option(format(Format), Options, atom),
  116    (   Format == atom
  117    ->  !, random_uuid(UUID)
  118    ;   Format == integer
  119    ->  !, random_int_uuid(UUID)
  120    ).
  121uuid(_UUID, Options) :-
  122    domain_error(uuid_options, Options).
  123
  124random_uuid(UUID) :-
  125    Version = 4,
  126    A is random(0xffffffff),
  127    B is random(0xffff),
  128    C is random(0x0fff) \/ Version<<12,
  129    D is random(0x3fff) \/ 0x8000,
  130    E is random(0xffffffffffff),
  131    format(atom(UUID),
  132           '~`0t~16r~8+-~|\c
  133            ~`0t~16r~4+-~|\c
  134            ~`0t~16r~4+-~|\c
  135            ~`0t~16r~4+-~|\c
  136            ~`0t~16r~12+', [A,B,C,D,E]).
  137
  138random_int_uuid(UUID) :-
  139    Version = 4,
  140    A is random(0xffffffff),
  141    B is random(0xffff),
  142    C is random(0x0fff) \/ Version<<12,
  143    D is random(0x3fff) \/ 0x8000,
  144    E is random(0xffffffffffff),
  145    UUID is (A<<96)+(B<<80)+(C<<84)+(D<<48)+E.
  146
  147:- endif.

 uuid_property(+UUID, ?Property)

True when UUID is a property of the given UUID. Supported properties are:

version(V)

Return the version of the UUID (1..5)

time(-Stamp)

Time using SWI-Prolog's time stamp (float with seconds since January 1, 1970, UTC). Only for version 1 and 2 UUIDs

To be done

- Implement more properties.

  163uuid_property(UUID, P) :-
  164    property_uuid(P, UUID).
  165
  166property_uuid(version(V), UUID) :-
  167    split_string(UUID, "-", "", [_A,_B,C,_D,_E]),
  168    sub_string(C, 0, 1, _, F),
  169    char_type(F, xdigit(V)).
  170property_uuid(time(Time), UUID) :-
  171    split_string(UUID, "-", "", [A,B,C,_D,_E]),
  172    sub_atom(C, 0, 1, _, F),
  173    has_time(F),
  174    sub_string(C, 1, _, 0, T),
  175    atomics_to_string(["0x",T,B,A], Hex),
  176    number_string(Nanos, Hex),
  177    Offset is 24*60*60*141427*10 000 000,
  178    Time is (Nanos-Offset)/10000000.0.
  179
  180has_time('1').
  181has_time('2').

 is_uuid(@UUID) is semidet

True when UUID is a UUID represented as an atom. It merely validates that the length is 36 characters, there are - at the right place and all other characters are hexadecimal.

  189is_uuid(UUID) :-
  190    atom(UUID),
  191    atom_length(UUID, 36),
  192    atom_codes(UUID, Codes),
  193    Codes = [ _,_,_,_,_,_,_,_, 0'-,
  194              _,_,_,_, 0'-,
  195              _,_,_,_, 0'-,
  196              _,_,_,_, 0'-,
  197              _,_,_,_,_,_,_,_,_,_,_,_
  198            ],
  199    maplist(hex_or_minus, Codes).
  200
  201hex_or_minus(0'-) :-
  202    !.
  203hex_or_minus(Code) :-
  204    code_type(Code, xdigit(_))