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update dcgs to handle ; and ->

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This commit is contained in:
Mark Thom
2018-10-27 20:56:23 -06:00
parent a4e882756e
commit 81f4128bc6
2 changed files with 34 additions and 9 deletions
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30
src/prolog/lib/dcgs.pl
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@@ -1,6 +1,7 @@
:- module(dcgs, [(-->)/2, phrase/2, phrase/3]).
:- use_module(library(lists), [append/3]).
:- use_module(library(terms)).
:- op(1200, xfx, -->).
@@ -19,40 +20,51 @@ phrase(G, Ls0, Ls2) :-
phrase(G, Ls0, Ls1) :-
call(G, Ls0, Ls1).
term_expansion(Term0, (ModHead :- ModBody)) :-
term_expansion(Term0, Term) :-
numbervars(Term0, 0, N),
expand_dcgs(Term0, N, Term).
expand_dcgs(Term0, N, (ModHead :- ModBody)) :-
nonvar(Term0),
Term0 = (Head, [SC | SCs] --> Body),
!,
nonvar(Head),
Head =.. [RuleName | Args],
append([SC | SCs], '$VAR'(N), SemiContextArgs),
append(Args, ['$VAR'(0), SemiContextArgs], ModArgs),
append([SC | SCs], '$VAR'(N1), SemiContextArgs),
append(Args, ['$VAR'(N), SemiContextArgs], ModArgs),
ModHead =.. [RuleName | ModArgs],
nonvar(Body),
expand_body(Body, ModBody, 0, N).
term_expansion(Term0, (ModHead :- ModBody)) :-
expand_body(Body, ModBody, 0, N1).
expand_dcgs(Term0, N, (ModHead :- ModBody)) :-
nonvar(Term0),
Term0 = (Head --> Body),
nonvar(Head),
Head =.. [RuleName | Args],
append(Args, ['$VAR'(0), '$VAR'(N)], ModArgs),
append(Args, ['$VAR'(N), '$VAR'(N1)], ModArgs),
ModHead =.. [RuleName | ModArgs],
nonvar(Body),
expand_body(Body, ModBody, 0, N).
expand_body(Body, ModBody, N, N1).
expand_body(Term0, (ModTerm, ModTerms), N0, N) :-
nonvar(Term0), Term0 = (Term, Terms), !,
nonvar(Term),
expand_body_term(Term, ModTerm, N0, N1),
expand_body(Terms, ModTerms, N1, N).
expand_body(Term0, ModTerm, N0, N) :-
nonvar(Term0), expand_body_term(Term0, ModTerm, N0, N).
expand_body(Term0, ModTerm, N0, N) :-
nonvar(Term0),
expand_body_term(Term0, ModTerm, N0, N).
expand_body_term([], true, N, N) :- !.
expand_body_term([Arg|Args], ModTerm, N0, N) :-
!, N is N0 + 1,
append([Arg|Args], '$VAR'(N), ModArgs),
ModTerm = ('$VAR'(N0) = ModArgs).
expand_body_term((P -> Q), (PModTerm -> QModTerm), N0, N) :-
!, expand_body(P, PModTerm, N0, N1),
expand_body(Q, QModTerm, N1, N).
expand_body_term((P ; Q), (PModTerm ; QModTerm), N0, N) :-
!, expand_body(P, PModTerm, N0, N),
expand_body(Q, QModTerm, N0, N).
expand_body_term(CommaTerm, ModTerm, N, N) :-
CommaTerm =.. [{} | BodyTerms], !,
comma_ify(BodyTerms, ModTerm).