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yap-6.3/pl/atoms.yap

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2014-04-06 17:05:17 +01:00
/*************************************************************************
* *
* YAP Prolog *
* *
* Yap Prolog was developed at NCCUP - Universidade do Porto *
* *
* Copyright L.Damas, V.S.Costa and Universidade do Porto 1985-2014 *
* *
*************************************************************************/
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:- system_module( '$_atoms', [
atom_concat/2,
string_concat/2,
atomic_list_concat/2,
atomic_list_concat/3,
current_atom/1], []).
:- use_system_module( '$_errors', ['$do_error'/2]).
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/**
* @short: Atom, and Atomic manipulation predicates in YAP
*
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*/
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atom_concat(Xs,At) :-
( var(At) ->
'$atom_concat'(Xs, At )
;
'$atom_concat_constraints'(Xs, 0, At, Unbound),
'$process_atom_holes'(Unbound)
).
% the constraints are of the form hole: HoleAtom, Begin, Atom, End
'$atom_concat_constraints'([At], 0, At, []) :- !.
'$atom_concat_constraints'([At0], mid(Next, At), At, [hole(At0, Next, At, end)]) :- !.
% just slice first atom
'$atom_concat_constraints'([At0|Xs], 0, At, Unbound) :-
atom(At0), !,
sub_atom(At, 0, Sz, L, At0 ),
sub_atom(At, _, L, 0, Atr ), %remainder
'$atom_concat_constraints'(Xs, 0, Atr, Unbound).
% first hole: Follow says whether we have two holes in a row, At1 will be our atom
'$atom_concat_constraints'([At0|Xs], 0, At, [hole(At0, 0, At, Next)|Unbound]) :-
'$atom_concat_constraints'(Xs, mid(Next,At1), At, Unbound).
% end of a run
'$atom_concat_constraints'([At0|Xs], mid(end, At1), At, Unbound) :-
atom(At0), !,
sub_atom(At, Next, Sz, L, At0),
sub_atom(At, 0, Next, Next, At1),
sub_atom(At, _, L, 0, Atr), %remainder
'$atom_concat_constraints'(Xs, 0, Atr, Unbound).
'$atom_concat_constraints'([At0|Xs], mid(Next,At1), At, Next, [hole(At0, Next, At, Follow)|Unbound]) :-
'$atom_concat_constraints'(Xs, mid(NextFollow, At1), At, Unbound).
'$process_atom_holes'([]).
'$process_atom_holes'([hole(At0, Next, At1, End)|Unbound]) :- End == end, !,
sub_atom(At1, Next, _, 0, At0),
'$process_atom_holes'(Unbound).
'$process_atom_holes'([hole(At0, Next, At1, Follow)|Unbound]) :-
sub_atom(At1, Next, Sz, _Left, At0),
Follow is Next+Sz,
'$process_atom_holes'(Unbound).
atomic_list_concat(L,At) :-
atomic_concat(L, At).
atomic_list_concat(L, El, At) :-
var(El), !,
'$do_error'(instantiation_error,atom_list_concat(L,El,At)).
atomic_list_concat(L, El, At) :-
nonvar(L), !,
'$add_els'(L,El,LEl),
atomic_concat(LEl, At).
atomic_list_concat(L, El, At) :-
nonvar(At), !,
atom_codes(At, S),
atom_codes(El, [ElS]),
'$split_elements'(S, ElS, SubS),
'$atomify_list'(SubS, L).
'$add_els'([A,B|L],El,[A,El|NL]) :- !,
'$add_els'([B|L],El,NL).
'$add_els'(L,_,L).
'$split_elements'(E.S, E, SubS) :- !,
'$split_elements'(S, E, SubS).
'$split_elements'(E1.S, E, [E1|L].SubS) :- !,
'$split_elements'(S, E, L, SubS).
'$split_elements'([], _, []).
'$split_elements'([], _, [], []).
'$split_elements'(E.S, E, [], SubS) :- !,
'$split_elements'(S, E, SubS).
'$split_elements'(E1.S, E, E1.L, SubS) :-
'$split_elements'(S, E, L, SubS).
'$atomify_list'([], []).
'$atomify_list'(S.SubS, A.L) :-
atom_codes(A, S),
'$atomify_list'(SubS, L).
%
% small compatibility hack
'$singletons_in_term'(T,VL) :-
'$variables_in_term'(T,[],V10),
'$sort'(V10, V1),
'$non_singletons_in_term'(T,[],V20),
'$sort'(V20, V2),
'$subtract_lists_of_variables'(V2,V1,VL).
'$subtract_lists_of_variables'([],VL,VL).
'$subtract_lists_of_variables'([_|_],[],[]) :- !.
'$subtract_lists_of_variables'([V1|VL1],[V2|VL2],VL) :-
V1 == V2, !,
'$subtract_lists_of_variables'(VL1,VL2,VL).
'$subtract_lists_of_variables'([V1|VL1],[V2|VL2],[V2|VL]) :-
'$subtract_lists_of_variables'([V1|VL1],VL2,VL).
current_atom(A) :- % check
atom(A), !.
current_atom(A) :- % generate
'$current_atom'(A).
current_atom(A) :- % generate
'$current_wide_atom'(A).
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string_concat(Xs,At) :-
( var(At) ->
'$string_concat'(Xs, At )
;
'$string_concat_constraints'(Xs, 0, At, Unbound),
'$process_string_holes'(Unbound)
).
% the constraints are of the form hole: HoleString, Begin, String, End
'$string_concat_constraints'([At], 0, At, []) :- !.
'$string_concat_constraints'([At0], mid(Next, At), At, [hole(At0, Next, At, end)]) :- !.
% just slice first string
'$string_concat_constraints'([At0|Xs], 0, At, Unbound) :-
string(At0), !,
sub_string(At, 0, Sz, L, At0 ),
sub_string(At, _, L, 0, Atr ), %remainder
'$string_concat_constraints'(Xs, 0, Atr, Unbound).
% first hole: Follow says whether we have two holes in a row, At1 will be our string
'$string_concat_constraints'([At0|Xs], 0, At, [hole(At0, 0, At, Next)|Unbound]) :-
'$string_concat_constraints'(Xs, mid(Next,At1), At, Unbound).
% end of a run
'$string_concat_constraints'([At0|Xs], mid(end, At1), At, Unbound) :-
string(At0), !,
sub_string(At, Next, Sz, L, At0),
sub_string(At, 0, Next, Next, At1),
sub_string(At, _, L, 0, Atr), %remainder
'$string_concat_constraints'(Xs, 0, Atr, Unbound).
'$string_concat_constraints'([At0|Xs], mid(Next,At1), At, Next, [hole(At0, Next, At, Follow)|Unbound]) :-
'$string_concat_constraints'(Xs, mid(NextFollow, At1), At, Unbound).
'$process_string_holes'([]).
'$process_string_holes'([hole(At0, Next, At1, End)|Unbound]) :- End == end, !,
sub_string(At1, Next, _, 0, At0),
'$process_string_holes'(Unbound).
'$process_string_holes'([hole(At0, Next, At1, Follow)|Unbound]) :-
sub_string(At1, Next, Sz, _Left, At0),
Follow is Next+Sz,
'$process_string_holes'(Unbound).