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fix DCGs to be closer to standard. 

git-svn-id: https://yap.svn.sf.net/svnroot/yap/trunk@1173 b08c6af1-5177-4d33-ba66-4b1c6b8b522a
This commit is contained in:
vsc 2004-11-05 03:03:54 +00:00
parent 6853d8eecd
commit 6edf6f1dd3
1 changed files with 32 additions and 14 deletions
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46
pl/grammar.yap
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@ -21,24 +21,40 @@
Also, phrase/2-3 check their first argument.
*/
'$translate_rule'((LP-->RP), H) :-
RP == [],
!,
'$t_head'(LP, S, S, H).
'$translate_rule'((LP-->RP), (H:-B)):-
'$t_head'(LP, S, SR, H),
'$t_body'(RP, _, last, S, SR, B1),
'$translate_rule'((LP-->RP), (NH:-B)) :-
'$t_head'(LP, NH, NGs, S, SR, (LP-->RP)),
(var(NGs) ->
'$t_body'(RP, _, last, S, SR, B1)
;
'$t_body'((RP,{NGs}), _, last, S, SR, B1)
),
'$t_tidy'(B1, B).
'$t_head'((LP,List), S, SR, H):- !,
'$append'(List, SR, List2),
'$extend'([S,List2], LP, H).
'$t_head'(M:LP, S, SR, M:H) :- !,
'$extend'([S,SR], LP, H).
'$t_head'(LP, S, SR, H) :-
'$extend'([S,SR], LP, H).
'$t_head'(V, _, _, _, _, G0) :- var(V), !,
'$do_error'(instantiation_error,G0).
'$t_head'((H,List), NH, NGs, S, S1, G0) :- !,
'$t_hgoal'(H, NH, S, SR, G0),
'$t_hlist'(List, S1, SR, NGs, G0).
'$t_head'(H, NH, _, S, SR, G0) :-
'$t_hgoal'(H, NH, S, SR, G0).
'$t_hgoal'(V, _, _, _, G0) :- var(V), !,
'$do_error'(instantiation_error,G0).
'$t_hgoal'(M:H, M:NH, S, SR, G0) :- !,
'$t_hgoal'(H, NH, S, SR, G0).
'$t_hgoal'(H, NH, S, SR, _) :-
'$extend'([S,SR],H,NH).
'$t_hlist'(V, _, _, _, G0) :- var(V), !,
'$do_error'(instantiation_error,G0).
'$t_hlist'([], S0, SR, true, _).
'$t_hlist'([H], S0, SR, ('C'(SR,H,S0)), _) :- !.
'$t_hlist'([H|List], S0, SR, ('C'(SR,H,S1),G0), Goal) :- !,
'$t_hlist'(List, S0, S1, G0, Goal).
'$t_hlist'(T, _, _, _, Goal) :-
'$do_error'(type_error(list,T),Goal).
%
% Two extra variables:
@ -64,6 +80,8 @@
'$t_body'((T->R), ToFill, Last, S, SR, (Tt->Rt)) :- !,
'$t_body'(T, ToFill, not_last, S, SR1, Tt),
'$t_body'(R, ToFill, Last, SR1, SR, Rt).
'$t_body'(\+T, ToFill, Last, S, SR, (Tt->fail ; S=SR)) :- !,
'$t_body'(T, ToFill, not_last, S, _, Tt).
'$t_body'((T;R), _ToFill, _, S, SR, (Tt;Rt)) :- !,
'$t_body'(T, _, last, S, SR, Tt),
'$t_body'(R, _, last, S, SR, Rt).