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/*************************************************************************
* *
* YAP Prolog *
* *
* Yap Prolog was developed at NCCUP - Universidade do Porto *
* *
* Copyright L.Damas, V.S.Costa and Universidade do Porto 1985-1997 *
* *
**************************************************************************
* *
* File: sbaunify.h *
* Last rev: *
* mods: *
* comments: Basic abstract machine operations, such as *
* dereferencing, binding, trailing, and unification *
* in the SBA model. *
* *
*************************************************************************/
#ifdef SCCS
static char SccsId[] = "%W% %G%";
#endif /* SCCS */
/************************************************************
Unification Routines
*************************************************************/
static inline
Int bind_variable(Term t0, Term t1)
{
tr_fr_ptr TR0 = TR;
if (Yap_IUnify(t0,t1)) {
return(TRUE);
} else {
while(TR != TR0) {
CELL *p = (CELL *)TrailTerm(--TR);
RESET_VARIABLE(p);
}
return(FALSE);
}
}
EXTERN inline
/*
Int unify(Term t0, Term t1)
*/
Int unify(Term t0, Term t1)
{
tr_fr_ptr TR0 = TR;
if (Yap_IUnify(t0,t1)) {
return(TRUE);
} else {
while(TR != TR0) {
CELL *p = (CELL *)TrailTerm(--TR);
RESET_VARIABLE(p);
}
return(FALSE);
}
}
EXTERN inline Int unify_constant(register Term a, register Term cons)
{
CELL *pt;
deref_head(a,unify_cons_unk);
unify_cons_nonvar:
{
if (a == cons) return(TRUE);
else if (IsApplTerm(a) && IsExtensionFunctor(FunctorOfTerm(a))) {
Functor fun = FunctorOfTerm(a);
if (fun == FunctorDouble)
return(IsFloatTerm(cons) && FloatOfTerm(a) == FloatOfTerm(cons));
else if (fun == FunctorLongInt) {
return(IsLongIntTerm(cons) && LongIntOfTerm(a) == LongIntOfTerm(cons));
#ifdef TERM_EXTENSIONS
} else if (IsAttachFunc(fun)) {
return(attas[ExtFromFunctor(fun)].bind_op(SBIND,a,cons));
#endif /* TERM_EXTENSIONS */
} else
return(FALSE);
/* no other factors are accepted as arguments */
} else return(FALSE);
}
deref_body(a,pt,unify_cons_unk,unify_cons_nonvar);
Bind(pt,cons);
return(TRUE);
}
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