574 lines
13 KiB
C
574 lines
13 KiB
C
/*************************************************************************
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* *
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* YAP Prolog *
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* *
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* Yap Prolog was developed at NCCUP - Universidade do Porto *
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* *
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* Copyright L.Damas, V.S.Costa and Universidade do Porto 1985-1997 *
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* *
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**************************************************************************
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* *
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* File: corout.c *
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* Last rev: *
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* mods: *
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* comments: Co-routining from within YAP *
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* *
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*************************************************************************/
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#ifdef SCCS
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static char SccsId[]="%W% %G%";
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#endif
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#include "Yap.h"
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#include "Yatom.h"
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#include "YapHeap.h"
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#include "heapgc.h"
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#include "attvar.h"
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#ifndef NULL
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#define NULL (void *)0
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#endif
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#ifdef COROUTINING
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/* check if variable was there */
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static Term AddVarIfNotThere(Term var , Term dest)
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{
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Term test = dest;
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while (test != TermNil) {
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if ((RepPair(test))[0] == var) return(dest);
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else test = (RepPair(test))[1];
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}
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return(MkPairTerm(var,dest));
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}
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/* This routine verifies whether two complex structures can unify. */
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static int can_unify_complex(register CELL *pt0,
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register CELL *pt0_end,
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register CELL *pt1,
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Term *Vars)
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{
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/* This is really just unification, folks */
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tr_fr_ptr saved_TR;
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CELL *saved_HB;
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choiceptr saved_B;
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register CELL **to_visit = (CELL **)Yap_PreAllocCodeSpace();
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CELL **to_visit_base = to_visit;
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/* make sure to trail all bindings */
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saved_TR = TR;
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saved_B = B;
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saved_HB = HB;
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HB = H;
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loop:
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while (pt0 < pt0_end) {
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register CELL d0, d1;
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++ pt0;
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++ pt1;
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d0 = Derefa(pt0);
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d1 = Derefa(pt1);
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if (IsVarTerm(d0)) {
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if (IsVarTerm(d1)) {
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if (d0 != d1) {
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/* we need to suspend on both variables ! */
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*Vars = AddVarIfNotThere(d0, AddVarIfNotThere(d1,*Vars));
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/* bind the two variables, we would have to do that to unify
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them */
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if (d1 > d0) { /* youngest */
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/* we don't want to wake up goals */
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Bind_Global((CELL *)d1, d0);
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} else {
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Bind_Global((CELL *)d0, d1);
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}
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}
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/* continue the loop */
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continue;
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}
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else {
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/* oh no, some more variables! */
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*Vars = AddVarIfNotThere(d0, *Vars);
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}
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/* now bind it */
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Bind_Global((CELL *)d0, d1);
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/* continue the loop */
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} else if (IsVarTerm(d1)) {
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*Vars = AddVarIfNotThere(d1, *Vars);
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/* and bind it */
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Bind_Global((CELL *)d1, d0);
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/* continue the loop */
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} else {
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if (d0 == d1) continue;
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if (IsAtomOrIntTerm(d0) || IsAtomOrIntTerm(d1)) {
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if (d0 != d1) goto comparison_failed;
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/* else continue the loop */
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}
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else if (IsPairTerm(d0)) {
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if (!IsPairTerm(d1)) goto comparison_failed;
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#ifdef RATIONAL_TREES
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to_visit[0] = pt0;
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to_visit[1] = pt0_end;
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to_visit[2] = pt1;
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to_visit[3] = (CELL *)*pt0;
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to_visit += 4;
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*pt0 = d1;
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#else
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/* store the terms to visit */
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if (pt0 < pt0_end) {
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to_visit[0] = pt0;
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to_visit[1] = pt0_end;
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to_visit[2] = pt1;
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to_visit += 3;
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}
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#endif
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pt0 = RepPair(d0) - 1;
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pt0_end = RepPair(d0) + 1;
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pt1 = RepPair(d1) - 1;
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continue;
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}
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else if (IsApplTerm(d0)) {
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register Functor f;
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register CELL *ap2, *ap3;
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if (!IsApplTerm(d1)) {
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goto comparison_failed;
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} else {
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/* store the terms to visit */
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ap2 = RepAppl(d0);
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ap3 = RepAppl(d1);
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f = (Functor)(*ap2);
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/* compare functors */
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if (f != (Functor)*ap3) {
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goto comparison_failed;
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}
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if (IsExtensionFunctor(f)) {
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switch((CELL)f) {
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case (CELL)FunctorDBRef:
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if (d0 == d1) continue;
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goto comparison_failed;
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case (CELL)FunctorLongInt:
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if (ap2[1] == ap3[1]) continue;
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goto comparison_failed;
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case (CELL)FunctorDouble:
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if (FloatOfTerm(d0) == FloatOfTerm(d1)) continue;
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goto comparison_failed;
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#ifdef USE_GMP
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case (CELL)FunctorBigInt:
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if (Yap_gmp_tcmp_big_big(d0,d1) == 0) continue;
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goto comparison_failed;
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#endif /* USE_GMP */
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default:
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goto comparison_failed;
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}
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}
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#ifdef RATIONAL_TREES
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to_visit[0] = pt0;
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to_visit[1] = pt0_end;
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to_visit[2] = pt1;
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to_visit[3] = (CELL *)*pt0;
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to_visit += 4;
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*pt0 = d1;
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#else
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/* store the terms to visit */
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if (pt0 < pt0_end) {
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to_visit[0] = pt0;
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to_visit[1] = pt0_end;
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to_visit[2] = pt1;
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to_visit += 3;
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}
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#endif
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d0 = ArityOfFunctor(f);
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pt0 = ap2;
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pt0_end = ap2 + d0;
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pt1 = ap3;
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continue;
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}
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}
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}
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}
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/* Do we still have compound terms to visit */
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if (to_visit > (CELL **)to_visit_base) {
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#ifdef RATIONAL_TREES
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to_visit -= 4;
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pt0 = to_visit[0];
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pt0_end = to_visit[1];
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pt1 = to_visit[2];
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*pt0 = (CELL)to_visit[3];
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#else
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to_visit -= 3;
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pt0 = to_visit[0];
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pt0_end = to_visit[1];
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pt1 = to_visit[2];
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#endif
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goto loop;
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}
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/* success */
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Yap_ReleasePreAllocCodeSpace((ADDR)to_visit);
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/* restore B, and later HB */
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B = saved_B;
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HB = saved_HB;
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/* untrail all bindings made by IUnify */
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while (TR != saved_TR) {
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pt1 = (CELL *)(TrailTerm(--TR));
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RESET_VARIABLE(pt1);
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}
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return(TRUE);
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comparison_failed:
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/* failure */
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Yap_ReleasePreAllocCodeSpace((ADDR)to_visit);
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#ifdef RATIONAL_TREES
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while (to_visit > (CELL **)to_visit_base) {
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to_visit -= 4;
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pt0 = to_visit[0];
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pt0_end = to_visit[1];
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pt1 = to_visit[2];
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*pt0 = (CELL)to_visit[3];
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}
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#endif
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/* restore B, and later HB */
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B = saved_B;
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HB = saved_HB;
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/* the system will take care of TR for me, no need to worry here! */
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return(FALSE);
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}
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static int
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can_unify(Term t1, Term t2, Term *Vars)
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{
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t1 = Deref(t1);
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t2 = Deref(t2);
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if (t1 == t2) {
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*Vars = TermNil;
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return TRUE;
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}
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if (IsVarTerm(t1)) {
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/* we know for sure they can't be different */
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if (IsVarTerm(t2)) {
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/* we need to suspend on both variables because otherwise
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Y = susp(_) would not wakeup susp ! */
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*Vars = MkPairTerm(t1,MkPairTerm(t2,TermNil));
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return TRUE;
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} else {
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*Vars = MkPairTerm(t1,TermNil);
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return TRUE;
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}
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} else if (IsVarTerm(t2)) {
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/* wait until t2 is bound */
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*Vars = MkPairTerm(t2,TermNil);
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return TRUE;
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}
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/* Two standard terms at last! */
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if (IsAtomOrIntTerm(t1) || IsAtomOrIntTerm(t2)) {
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/* Two primitive terms can only be equal if they are
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the same. If they are, $eq succeeds without further ado.
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*/
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if (t1 != t2)
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return FALSE;
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else {
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*Vars = TermNil;
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return TRUE;
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}
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} else if (IsPairTerm(t1)) {
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if (IsPairTerm(t2)) {
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return(can_unify_complex(RepPair(t1)-1, RepPair(t1)+1,
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RepPair(t2)-1, Vars));
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} else return FALSE;
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} else {
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Functor f = FunctorOfTerm(t1);
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if (f != FunctorOfTerm(t2))
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return FALSE;
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if (IsExtensionFunctor(f)) {
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switch((CELL)f) {
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case (CELL)FunctorDBRef:
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if (t1 == t2) return FALSE;
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return FALSE;
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case (CELL)FunctorLongInt:
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if (RepAppl(t1)[1] == RepAppl(t2)[1]) return(TRUE);
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return FALSE;
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case (CELL)FunctorDouble:
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if (FloatOfTerm(t1) == FloatOfTerm(t2)) return(TRUE);
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return FALSE;
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#ifdef USE_GMP
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case (CELL)FunctorBigInt:
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if (Yap_gmp_tcmp_big_big(t1,t2) == 0) return(TRUE);
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return(FALSE);
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#endif /* USE_GMP */
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default:
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return FALSE;
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}
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}
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/* Two complex terms with the same functor */
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return can_unify_complex(RepAppl(t1),
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RepAppl(t1)+ArityOfFunctor(f),
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RepAppl(t2), Vars);
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}
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}
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/* This routine verifies whether a complex has variables. */
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static int non_ground_complex(register CELL *pt0,
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register CELL *pt0_end,
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Term *Var)
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{
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register CELL **to_visit = (CELL **)Yap_PreAllocCodeSpace();
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CELL **to_visit_base = to_visit;
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loop:
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while (pt0 < pt0_end) {
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register CELL d0;
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++ pt0;
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d0 = Derefa(pt0);
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if (IsVarTerm(d0)) {
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*Var = d0;
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goto var_found;
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}
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if (IsPairTerm(d0)) {
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if (to_visit + 1024 >= (CELL **)AuxSp) {
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goto aux_overflow;
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}
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#ifdef RATIONAL_TREES
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to_visit[0] = pt0;
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to_visit[1] = pt0_end;
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to_visit[2] = (CELL *)*pt0;
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to_visit += 3;
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*pt0 = TermNil;
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#else
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/* store the terms to visit */
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if (pt0 < pt0_end) {
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to_visit[0] = pt0;
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to_visit[1] = pt0_end;
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to_visit += 2;
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}
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#endif
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pt0 = RepPair(d0) - 1;
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pt0_end = RepPair(d0) + 1;
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}
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else if (IsApplTerm(d0)) {
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register Functor f;
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register CELL *ap2;
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/* store the terms to visit */
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ap2 = RepAppl(d0);
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f = (Functor)(*ap2);
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if (IsExtensionFunctor(f)) {
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continue;
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}
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if (to_visit + 1024 >= (CELL **)AuxSp) {
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goto aux_overflow;
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}
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#ifdef RATIONAL_TREES
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to_visit[0] = pt0;
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to_visit[1] = pt0_end;
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to_visit[2] = (CELL *)*pt0;
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to_visit += 3;
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*pt0 = TermNil;
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#else
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/* store the terms to visit */
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if (pt0 < pt0_end) {
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to_visit[0] = pt0;
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to_visit[1] = pt0_end;
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to_visit += 2;
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}
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#endif
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d0 = ArityOfFunctor(f);
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pt0 = ap2;
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pt0_end = ap2 + d0;
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}
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/* just continue the loop */
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}
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/* Do we still have compound terms to visit */
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if (to_visit > (CELL **)to_visit_base) {
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#ifdef RATIONAL_TREES
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to_visit -= 3;
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pt0 = to_visit[0];
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pt0_end = to_visit[1];
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*pt0 = (CELL)to_visit[2];
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#else
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to_visit -= 2;
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pt0 = to_visit[0];
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pt0_end = to_visit[1];
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#endif
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goto loop;
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}
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/* the term is ground */
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Yap_ReleasePreAllocCodeSpace((ADDR)to_visit);
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return FALSE;
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var_found:
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/* the term is non-ground */
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Yap_ReleasePreAllocCodeSpace((ADDR)to_visit);
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#ifdef RATIONAL_TREES
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while (to_visit > (CELL **)to_visit_base) {
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to_visit -= 3;
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pt0 = to_visit[0];
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pt0_end = to_visit[1];
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*pt0 = (CELL)to_visit[2];
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}
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#endif
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/* the system will take care of TR for me, no need to worry here! */
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return TRUE;
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aux_overflow:
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/* unwind stack */
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Yap_ReleasePreAllocCodeSpace((ADDR)to_visit);
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#ifdef RATIONAL_TREES
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while (to_visit > (CELL **)to_visit_base) {
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to_visit -= 3;
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pt0 = to_visit[0];
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*pt0 = (CELL)to_visit[2];
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}
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#endif
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return -1;
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}
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static int
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non_ground(Term t, Term *Var)
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{
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int out = -1;
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while (out < 0) {
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t = Deref(t);
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if (IsVarTerm(t)) {
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/* we found a variable */
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*Var = t;
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return TRUE;
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}
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if (IsPrimitiveTerm(t)) {
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return FALSE;
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} else if (IsPairTerm(t)) {
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out = non_ground_complex(RepPair(t)-1, RepPair(t)+1, Var);
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if (out >= 0)
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return out;
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} else {
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Functor f = FunctorOfTerm(t);
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if (IsExtensionFunctor(f)) {
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return FALSE;
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}
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out = non_ground_complex(RepAppl(t),
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RepAppl(t)+ArityOfFunctor(FunctorOfTerm(t)),
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Var);
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if (out >= 0)
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return out;
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}
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if (!Yap_ExpandPreAllocCodeSpace(0, NULL, TRUE)) {
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Yap_Error(OUT_OF_AUXSPACE_ERROR, ARG1, "overflow in ground");
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return FALSE;
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}
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}
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return FALSE;
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}
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#endif
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/* check whether the two terms unify and return what variables should
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be bound before the terms are exactly equal */
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static Int p_can_unify(void)
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{
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#ifdef COROUTINING
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Term r = TermNil;
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if (!can_unify(ARG1, ARG2, &r))
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return FALSE;
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return Yap_unify(ARG3, r);
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#else
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return FALSE;
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#endif
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}
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/* if the term is not ground return a variable in the term */
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static Int p_non_ground(void)
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{
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#ifdef COROUTINING
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Term r = TermNil;
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if (!non_ground(ARG1, &r))
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return(FALSE);
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return (Yap_unify(ARG2, r));
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#else
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return(FALSE);
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#endif
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}
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/* if the term is not ground return a variable in the term */
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static Int p_coroutining(void)
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{
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#ifdef COROUTINING
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return(TRUE);
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#else
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return(FALSE);
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#endif
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}
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#if COROUTINING
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static Term
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ListOfWokenGoals(void) {
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return Yap_ReadTimedVar(WokenGoals);
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}
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Term
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Yap_ListOfWokenGoals(void) {
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return ListOfWokenGoals();
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}
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#endif
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/* return a list of awoken goals */
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static Int p_awoken_goals(void)
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{
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#ifdef COROUTINING
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Term WGs = Yap_ReadTimedVar(WokenGoals);
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if (WGs == TermNil) {
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return(FALSE);
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}
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WGs = ListOfWokenGoals();
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Yap_UpdateTimedVar(WokenGoals, TermNil);
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return(Yap_unify(ARG1,WGs));
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#else
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return(FALSE);
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#endif
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}
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static Int
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p_yap_has_rational_trees(void)
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{
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#if RATIONAL_TREES
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return TRUE;
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#else
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return FALSE;
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#endif
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}
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static Int
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p_yap_has_coroutining(void)
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{
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#if COROUTINING
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return TRUE;
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#else
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return FALSE;
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#endif
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}
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void
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Yap_InitCoroutPreds(void)
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{
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#ifdef COROUTINING
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Atom at;
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PredEntry *pred;
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at = AtomWakeUpGoal;
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pred = RepPredProp(PredPropByFunc(Yap_MkFunctor(at, 2),0));
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WakeUpCode = pred;
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#endif
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Yap_InitAttVarPreds();
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Yap_InitCPred("$yap_has_rational_trees", 0, p_yap_has_rational_trees, SafePredFlag|HiddenPredFlag);
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Yap_InitCPred("$yap_has_coroutining", 0, p_yap_has_coroutining, SafePredFlag|HiddenPredFlag);
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Yap_InitCPred("$can_unify", 3, p_can_unify, SafePredFlag|HiddenPredFlag);
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Yap_InitCPred("$non_ground", 2, p_non_ground, SafePredFlag|HiddenPredFlag);
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Yap_InitCPred("$coroutining", 0, p_coroutining, SafePredFlag|HiddenPredFlag);
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Yap_InitCPred("$awoken_goals", 1, p_awoken_goals, SafePredFlag|HiddenPredFlag);
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}
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