138 lines
3.3 KiB
Prolog
138 lines
3.3 KiB
Prolog
/**
|
|
* @file bootlists.yap
|
|
* @author VITOR SANTOS COSTA <vsc@VITORs-MBP.lan>
|
|
* @date Thu Nov 19 09:54:00 2015
|
|
*
|
|
* @addtogroup lists
|
|
* @{
|
|
*/
|
|
|
|
:- set_prolog_flag(source, true). % source.
|
|
|
|
% memberchk(+Element, +Set)
|
|
% means the same thing, but may only be used to test whether a known
|
|
% Element occurs in a known Set. In return for this limited use, it
|
|
% is more efficient when it is applicable.
|
|
/** @pred memberchk(+ _Element_, + _Set_)
|
|
|
|
|
|
As member/2, but may only be used to test whether a known
|
|
_Element_ occurs in a known Set. In return for this limited use, it
|
|
is more efficient when it is applicable.
|
|
|
|
|
|
*/
|
|
lists:memberchk(X,[X|_]) :- !.
|
|
lists:memberchk(X,[_|L]) :-
|
|
lists:memberchk(X,L).
|
|
|
|
%% member(?Element, ?Set)
|
|
% is true when Set is a list, and Element occurs in it. It may be used
|
|
% to test for an element or to enumerate all the elements by backtracking.
|
|
% Indeed, it may be used to generate the Set!
|
|
|
|
/** @pred member(? _Element_, ? _Set_)
|
|
|
|
|
|
True when _Set_ is a list, and _Element_ occurs in it. It may be used
|
|
to test for an element or to enumerate all the elements by backtracking.
|
|
|
|
|
|
*/
|
|
lists:member(X,[X|_]).
|
|
lists:member(X,[_|L]) :-
|
|
lists:member(X,L).
|
|
|
|
%% @pred identical_member(?Element, ?Set) is nondet
|
|
%
|
|
% identical_member holds true when Set is a list, and Element is
|
|
% exactly identical to one of the elements that occurs in it.
|
|
|
|
lists:identical_member(X,[Y|M]) :-
|
|
(
|
|
X == Y
|
|
;
|
|
M \= [], lists:identical_member(X,M)
|
|
).
|
|
|
|
/** @pred append(? _List1_,? _List2_,? _List3_)
|
|
|
|
|
|
Succeeds when _List3_ unifies with the concatenation of _List1_
|
|
and _List2_. The predicate can be used with any instantiation
|
|
pattern (even three variables).
|
|
|
|
|
|
*/
|
|
lists:append([], L, L).
|
|
lists:append([H|T], L, [H|R]) :-
|
|
lists:append(T, L, R).
|
|
|
|
|
|
% lists:delete(List, Elem, Residue)
|
|
% is true when List is a list, in which Elem may or may not occur, and
|
|
% Residue is a copy of List with all elements identical to Elem lists:deleted.
|
|
|
|
/** @pred delete(+ _List_, ? _Element_, ? _Residue_)
|
|
|
|
True when _List_ is a list, in which _Element_ may or may not
|
|
occur, and _Residue_ is a copy of _List_ with all elements
|
|
identical to _Element_ deleted.
|
|
|
|
*/
|
|
lists:delete([], _, []).
|
|
lists:delete([Head|List], Elem, Residue) :-
|
|
( Head \= Elem
|
|
->
|
|
lists:delete(List, Elem, Residue)
|
|
;
|
|
Residue = [Head|MoreResidue],
|
|
lists:delete(List, Elem, MoreResidue)
|
|
).
|
|
|
|
|
|
|
|
|
|
% length of a list.
|
|
|
|
:- set_prolog_flag(source, false). % disable source.
|
|
|
|
/** @pred length(? _L_,? _S_)
|
|
|
|
|
|
Unify the well-defined list _L_ with its length. The procedure can
|
|
be used to find the length of a pre-defined list, or to build a list
|
|
of length _S_.
|
|
|
|
*/
|
|
|
|
prolog:length(L, M) :-
|
|
'$skip_list'(L, M, M0, R),
|
|
( var(R) -> '$$_length'(R, M, M0) ;
|
|
R == []
|
|
).
|
|
|
|
%
|
|
% in case A1 is unbound or a difference list, things get tricky
|
|
%
|
|
'$$_length'(R, M, M0) :-
|
|
( var(M) -> '$$_length1'(R,M,M0)
|
|
; M >= M0 -> '$$_length2'(R,M,M0) ).
|
|
|
|
%
|
|
% Size is unbound, generate lists
|
|
%
|
|
'$$_length1'([], M, M).
|
|
'$$_length1'([_|L], O, N) :-
|
|
M is N + 1,
|
|
'$$_length1'(L, O, M).
|
|
|
|
%
|
|
% Size is bound, generate single list
|
|
%
|
|
'$$_length2'(NL, O, N) :-
|
|
( N =:= O -> NL = [];
|
|
M is N + 1, NL = [_|L], '$$_length2'(L, O, M) ).
|
|
|
|
%% @}
|