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]).   43:- if(exists_source(library(shlib))).   44:- autoload(library(shlib), [load_foreign_library/1]).   45:- endif.

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

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

   66link_uuid :-
   67    catch(load_foreign_library(foreign(uuid)), error(_,_), true).
   68
   69:- 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.

   76uuid(UUID) :-
   77    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).

  107:- if(current_predicate(ossp_uuid/2)).  108uuid(UUID, Options) :-
  109    ossp_uuid(UUID, Options).
  110
  111:- else.  112
  113uuid(UUID, []) :-
  114    !,
  115    random_uuid(UUID).
  116uuid(UUID, Options) :-
  117    option(version(4), Options, 4),
  118    option(format(Format), Options, atom),
  119    (   Format == atom
  120    ->  !, random_uuid(UUID)
  121    ;   Format == integer
  122    ->  !, random_int_uuid(UUID)
  123    ).
  124uuid(_UUID, Options) :-
  125    domain_error(uuid_options, Options).
  126
  127random_uuid(UUID) :-
  128    Version = 4,
  129    A is random(0xffffffff),
  130    B is random(0xffff),
  131    C is random(0x0fff) \/ Version<<12,
  132    D is random(0x3fff) \/ 0x8000,
  133    E is random(0xffffffffffff),
  134    format(atom(UUID),
  135           '~`0t~16r~8+-~|\c
  136            ~`0t~16r~4+-~|\c
  137            ~`0t~16r~4+-~|\c
  138            ~`0t~16r~4+-~|\c
  139            ~`0t~16r~12+', [A,B,C,D,E]).
  140
  141random_int_uuid(UUID) :-
  142    Version = 4,
  143    A is random(0xffffffff),
  144    B is random(0xffff),
  145    C is random(0x0fff) \/ Version<<12,
  146    D is random(0x3fff) \/ 0x8000,
  147    E is random(0xffffffffffff),
  148    UUID is (A<<96)+(B<<80)+(C<<84)+(D<<48)+E.
  149
  150:- 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.

  166uuid_property(UUID, P) :-
  167    property_uuid(P, UUID).
  168
  169property_uuid(version(V), UUID) :-
  170    split_string(UUID, "-", "", [_A,_B,C,_D,_E]),
  171    sub_string(C, 0, 1, _, F),
  172    char_type(F, xdigit(V)).
  173property_uuid(time(Time), UUID) :-
  174    split_string(UUID, "-", "", [A,B,C,_D,_E]),
  175    sub_atom(C, 0, 1, _, F),
  176    has_time(F),
  177    sub_string(C, 1, _, 0, T),
  178    atomics_to_string(["0x",T,B,A], Hex),
  179    number_string(Nanos, Hex),
  180    Offset is 24*60*60*141427*10 000 000,
  181    Time is (Nanos-Offset)/10000000.0.
  182
  183has_time('1').
  184has_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.

  192is_uuid(UUID) :-
  193    atom(UUID),
  194    atom_length(UUID, 36),
  195    atom_codes(UUID, Codes),
  196    Codes = [ _,_,_,_,_,_,_,_, 0'-,
  197              _,_,_,_, 0'-,
  198              _,_,_,_, 0'-,
  199              _,_,_,_, 0'-,
  200              _,_,_,_,_,_,_,_,_,_,_,_
  201            ],
  202    maplist(hex_or_minus, Codes).
  203
  204hex_or_minus(0'-) :-
  205    !.
  206hex_or_minus(Code) :-
  207    code_type(Code, xdigit(_))