yap-6.3/C/attvar.c

/*************************************************************************
 *									 *
 *	 YAP Prolog 							 *
 *									 *
 *	Yap Prolog was developed at NCCUP - Universidade do Porto	 *
 *									 *
 * Copyright L.Damas, V.S.Costa and Universidade do Porto 1985-1997	 *
 *									 *
 **************************************************************************
 *									 *
 * File:		attvar.c						 *
 * Last rev:								 *
 * mods:									 *
 * comments:	YAP support for attributed vars				 *
 *									 *
 *************************************************************************/
#ifdef SCCS
static char SccsId[] = "%W% %G%";
#endif

#include "Yap.h"

#include "Yatom.h"
#include "YapHeap.h"
#include "heapgc.h"
#include "attvar.h"
#ifndef NULL
#define NULL (void *)0
#endif

/** @file attvars.c
    @{ */

/**
 * @defgroup AttributeVariables_Builtins Implementation of Attribute Declarations
    @ingroup AttributeVariables
*/

#ifdef COROUTINING

#define TermVoidAtt TermFoundVar

static CELL *AddToQueue(attvar_record *attv USES_REGS) {
  Term t[2];
  Term WGs, ng;

  t[0] = (CELL) & (attv->Done);
  t[1] = attv->Value;
  /* follow the chain */
  WGs = Yap_ReadTimedVar(LOCAL_WokenGoals);
  ng = Yap_MkApplTerm(FunctorAttGoal, 2, t);

  Yap_UpdateTimedVar(LOCAL_WokenGoals, MkPairTerm(ng, WGs));
  if ((Term)WGs == TermNil) {
    /* from now on, we have to start waking up goals */
    Yap_signal(YAP_WAKEUP_SIGNAL);
  }
  return (RepAppl(ng) + 2);
}

static void AddFailToQueue(USES_REGS1) {
  Term WGs;

  /* follow the chain */
  WGs = Yap_ReadTimedVar(LOCAL_WokenGoals);

  Yap_UpdateTimedVar(LOCAL_WokenGoals, MkPairTerm(MkAtomTerm(AtomFail), WGs));
  if ((Term)WGs == TermNil) {
    /* from now on, we have to start waking up goals */
    Yap_signal(YAP_WAKEUP_SIGNAL);
  }
}

static attvar_record *BuildNewAttVar(USES_REGS1) {
  attvar_record *newv;

  /* add a new attributed variable */
  newv = (attvar_record *)HR;
  HR = (CELL *)(newv + 1);
  newv->AttFunc = FunctorAttVar;
  RESET_VARIABLE(&(newv->Value));
  RESET_VARIABLE(&(newv->Done));
  RESET_VARIABLE(&(newv->Atts));
  return newv;
}

static int CopyAttVar(CELL *orig, struct cp_frame **to_visit_ptr,
                      CELL *res USES_REGS) {
  register attvar_record *attv = RepAttVar(orig);
  register attvar_record *newv;
  struct cp_frame *to_visit = *to_visit_ptr;
  CELL *vt;

  if (!(newv = BuildNewAttVar(PASS_REGS1)))
    return FALSE;
  vt = &(attv->Atts);
  to_visit->start_cp = vt - 1;
  to_visit->end_cp = vt;
  if (IsVarTerm(attv->Atts)) {
    Bind_Global_NonAtt(&newv->Atts, (CELL)HR);
    to_visit->to = HR;
    HR++;
  } else {
    to_visit->to = &(newv->Atts);
  }
  to_visit->oldv = vt[-1];
  to_visit->ground = FALSE;
  *to_visit_ptr = to_visit + 1;
  *res = (CELL) & (newv->Done);
  return TRUE;
}

static Term AttVarToTerm(CELL *orig) {
  attvar_record *attv = RepAttVar(orig);

  return attv->Atts;
}

static int IsEmptyWakeUp(Term atts) {
  Atom name = NameOfFunctor(FunctorOfTerm(atts));
  Atom *pt = EmptyWakeups;
  int i = 0;
  while (i < MaxEmptyWakeups) {
    if (pt[i++] == name)
      return TRUE;
  }
  return FALSE;
}

void Yap_MkEmptyWakeUp(Atom mod) {
  if (MaxEmptyWakeups == MAX_EMPTY_WAKEUPS)
    Yap_Error(SYSTEM_ERROR_INTERNAL, TermNil,
              "too many modules that do not wake up");
  EmptyWakeups[MaxEmptyWakeups++] = mod;
}

static int TermToAttVar(Term attvar, Term to USES_REGS) {
  attvar_record *attv = BuildNewAttVar(PASS_REGS1);
  if (!attv)
    return FALSE;
  Bind_Global_NonAtt(&attv->Atts, attvar);
  *VarOfTerm(to) = AbsAttVar(attv);
  return TRUE;
}

static void WakeAttVar(CELL *pt1, CELL reg2 USES_REGS) {

  /* if bound to someone else, follow until we find the last one */
  attvar_record *attv = RepAttVar(pt1);
  CELL *myH = HR;
  CELL *bind_ptr;

  if (IsVarTerm(Deref(attv->Atts))) {
    /* no attributes to wake */
    return;
  }
  if (IsVarTerm(reg2)) {
    if (pt1 == VarOfTerm(reg2))
      return;
    if (IsAttachedTerm(reg2)) {
      attvar_record *susp2 = RepAttVar(VarOfTerm(reg2));

      /* binding two suspended variables, be careful */
      if (susp2 >= attv) {
        if (!IsVarTerm(susp2->Value) || !IsUnboundVar(&susp2->Value)) {
          /* oops, our goal is on the queue to be woken */
          if (!Yap_unify(susp2->Value, (CELL)pt1)) {
            AddFailToQueue(PASS_REGS1);
          }
        }
        Bind_Global_NonAtt(&(susp2->Value), (CELL)pt1);
        AddToQueue(susp2 PASS_REGS);
        return;
      }
    } else {
      Bind_NonAtt(VarOfTerm(reg2), (CELL)pt1);
      return;
    }
  }
  if (IsEmptyWakeUp(attv->Atts)) {
    Bind_Global_NonAtt(&(attv->Value), reg2);
    Bind_Global_NonAtt(&(attv->Done), attv->Value);
    return;
  }
  if (!IsVarTerm(attv->Value) || !IsUnboundVar(&attv->Value)) {
    /* oops, our goal is on the queue to be woken */
    if (!Yap_unify(attv->Value, reg2)) {
      AddFailToQueue(PASS_REGS1);
    }
    return;
  }
  bind_ptr = AddToQueue(attv PASS_REGS);
  if (IsNonVarTerm(reg2)) {
    if (IsPairTerm(reg2) && RepPair(reg2) == myH)
      reg2 = AbsPair(HR);
    else if (IsApplTerm(reg2) && RepAppl(reg2) == myH)
      reg2 = AbsAppl(HR);
  }
  *bind_ptr = reg2;
  Bind_Global_NonAtt(&(attv->Value), reg2);
}

void Yap_WakeUp(CELL *pt0) {
  CACHE_REGS
    CELL d0 = *pt0;
  RESET_VARIABLE(pt0);
  WakeAttVar(pt0, d0 PASS_REGS);
}

static void mark_attvar(CELL *orig) { return; }

static Term BuildAttTerm(Functor mfun, UInt ar USES_REGS) {
  CELL *h0 = HR;
  UInt i;

  if (HR + (1024 + ar) > ASP) {
    LOCAL_Error_Size = ar * sizeof(CELL);
    return 0L;
  }
  HR[0] = (CELL)mfun;
  RESET_VARIABLE(HR + 1);
  HR += 2;
  for (i = 1; i < ar; i++) {
    *HR = TermVoidAtt;
    HR++;
  }
  return AbsAppl(h0);
}

static Term SearchAttsForModule(Term start, Functor mfun) {
  do {
    if (IsVarTerm(start) || FunctorOfTerm(start) == mfun)
      return start;
    start = ArgOfTerm(1, start);
  } while (TRUE);
}

static Term SearchAttsForModuleName(Term start, Atom mname) {
  do {
    if (IsVarTerm(start) || NameOfFunctor(FunctorOfTerm(start)) == mname)
      return start;
    start = ArgOfTerm(1, start);
  } while (TRUE);
}

static void AddNewModule(attvar_record *attv, Term t, int new,
                         int do_it USES_REGS) {
  CELL *newp = RepAppl(t) + 2;
  UInt i, ar = ArityOfFunctor((Functor)newp[-2]);

  for (i = 1; i < ar; i++) {
    Term n = Deref(*newp);
    if (n == TermFreeTerm) {
      *newp = TermVoidAtt;
    } else {
      if (n != TermVoidAtt)
        do_it = TRUE;
    }
    newp++;
  }
  if (!do_it)
    return;
  if (new) {
    attv->Atts = t;
  } else if (IsVarTerm(attv->Atts)) {
    MaBind(&(attv->Atts), t);
  } else {
    Term *wherep = &attv->Atts;

    do {
      if (IsVarTerm(*wherep)) {
        Bind_Global_NonAtt(wherep, t);
        return;
      } else {
        wherep = RepAppl(Deref(*wherep)) + 1;
      }
    } while (TRUE);
  }
}

static void ReplaceAtts(attvar_record *attv, Term oatt, Term att USES_REGS) {
  UInt ar = ArityOfFunctor(FunctorOfTerm(oatt)), i;
  CELL *oldp = RepAppl(oatt) + 1;
  CELL *newp;

  if (oldp > HB) {
    oldp++;
    newp = RepAppl(att) + 2;
    /* if deterministic */

    for (i = 1; i < ar; i++) {
      Term n = Deref(*newp);
      if (n != TermFreeTerm) {
        *oldp = n;
      }
      oldp++;
      newp++;
    }
    return;
  }
  newp = RepAppl(att) + 1;
  *newp++ = *oldp++;
  for (i = 1; i < ar; i++) {
    Term n = Deref(*newp);

    if (n == TermFreeTerm) {
      *newp = Deref(*oldp);
    }
    oldp++;
    newp++;
  }
  if (attv->Atts == oatt) {
    if (RepAppl(attv->Atts) >= HB)
      attv->Atts = att;
    else
      MaBind(&(attv->Atts), att);
  } else {
    Term *wherep = &attv->Atts;

    do {
      if (*wherep == oatt) {
        MaBind(wherep, att);
        return;
      } else {
        wherep = RepAppl(Deref(*wherep)) + 1;
      }
    } while (TRUE);
  }
}

static void DelAllAtts(attvar_record *attv USES_REGS) {
  MaBind(&(attv->Done), attv->Value);
}

static void DelAtts(attvar_record *attv, Term oatt USES_REGS) {
  Term t = ArgOfTerm(1, oatt);
  if (attv->Atts == oatt) {
    if (IsVarTerm(t)) {
      DelAllAtts(attv PASS_REGS);
      return;
    }
    if (RepAppl(attv->Atts) >= HB)
      attv->Atts = t;
    else
      MaBind(&(attv->Atts), t);
  } else {
    Term *wherep = &attv->Atts;

    do {
      if (*wherep == oatt) {
        MaBind(wherep, t);
        return;
      } else {
        wherep = RepAppl(Deref(*wherep)) + 1;
      }
    } while (TRUE);
  }
}

static void PutAtt(Int pos, Term atts, Term att USES_REGS) {
  if (IsVarTerm(att) && VarOfTerm(att) > HR && VarOfTerm(att) < LCL0) {
    /* globalise locals */
    Term tnew = MkVarTerm();
    Bind_NonAtt(VarOfTerm(att), tnew);
    att = tnew;
  }
  MaBind(RepAppl(atts) + pos, att);
}

static Int BindAttVar(attvar_record *attv USES_REGS) {
  if (IsVarTerm(attv->Done) && IsUnboundVar(&attv->Done)) {
    /* make sure we are not trying to bind a variable against itself */
    if (!IsVarTerm(attv->Value)) {
      Bind_Global_NonAtt(&(attv->Done), attv->Value);
    } else if (IsVarTerm(attv->Value)) {
      Term t = Deref(attv->Value);
      if (IsVarTerm(t)) {
        if (IsAttachedTerm(t)) {
          attvar_record *attv2 = RepAttVar(VarOfTerm(t));
          if (attv2 < attv) {
            Bind_Global_NonAtt(&(attv->Done), t);
          } else {
            Bind_Global_NonAtt(&(attv2->Done), AbsAttVar(attv));
          }
        } else {
          Yap_Error(SYSTEM_ERROR_INTERNAL, (CELL) & (attv->Done),
                    "attvar was bound when unset");
          return (FALSE);
        }
      } else {
        Bind_Global_NonAtt(&(attv->Done), t);
      }
    }
    return (TRUE);
  } else {
    Yap_Error(SYSTEM_ERROR_INTERNAL, (CELL) & (attv->Done),
              "attvar was bound when set");
    return (FALSE);
  }
}

static Int UnBindAttVar(attvar_record *attv) {
  RESET_VARIABLE(&(attv->Value));
  return (TRUE);
}

static Term GetAllAtts(attvar_record *attv) {
  /* check if we are already there */
  return attv->Atts;
}

static Int put_att(USES_REGS1) {
  /* receive a variable in ARG1 */
  Term inp = Deref(ARG1);
  /* if this is unbound, ok */
  if (IsVarTerm(inp)) {
    attvar_record *attv;
    Atom modname = AtomOfTerm(Deref(ARG2));
    UInt ar = IntegerOfTerm(Deref(ARG3));
    Functor mfun;
    Term tatts;
    int new = FALSE;

    if (IsAttachedTerm(inp)) {
      attv = RepAttVar(VarOfTerm(inp));
    } else {
      while (!(attv = BuildNewAttVar(PASS_REGS1))) {
        LOCAL_Error_Size = sizeof(attvar_record);
        if (!Yap_gcl(LOCAL_Error_Size, 5, ENV, gc_P(P, CP))) {
          Yap_Error(RESOURCE_ERROR_STACK, TermNil, LOCAL_ErrorMessage);
          return FALSE;
        }
      }
      new = TRUE;
    }
    mfun = Yap_MkFunctor(modname, ar);
    if (IsVarTerm(tatts = SearchAttsForModule(attv->Atts, mfun))) {
      while (!(tatts = BuildAttTerm(mfun, ar PASS_REGS))) {
        if (!Yap_gcl(LOCAL_Error_Size, 5, ENV, gc_P(P, CP))) {
          Yap_Error(RESOURCE_ERROR_STACK, TermNil, LOCAL_ErrorMessage);
          return FALSE;
        }
      }
      {
        CELL *ptr = VarOfTerm(Deref(ARG1));
        CELL d0 = AbsAttVar(attv);
        Bind_NonAtt(ptr, d0);
      }
      AddNewModule(attv, tatts, new, TRUE PASS_REGS);
    }
    PutAtt(IntegerOfTerm(Deref(ARG4)), tatts, Deref(ARG5) PASS_REGS);
    return TRUE;
  } else {
    Yap_Error(REPRESENTATION_ERROR_VARIABLE, inp,
              "first argument of put_attributes/2");
    return FALSE;
  }
}

static Int put_att_term(USES_REGS1) {
  /* receive a variable in ARG1 */
  Term inp = Deref(ARG1);
  /* if this is unbound, ok */
  if (IsVarTerm(inp)) {
    attvar_record *attv;

    if (IsAttachedTerm(inp)) {
      attv = RepAttVar(VarOfTerm(inp));
      MaBind(&(attv->Atts), Deref(ARG2));
    } else {
      while (!(attv = BuildNewAttVar(PASS_REGS1))) {
        LOCAL_Error_Size = sizeof(attvar_record);
        if (!Yap_gcl(LOCAL_Error_Size, 5, ENV, gc_P(P, CP))) {
          Yap_Error(RESOURCE_ERROR_STACK, TermNil, LOCAL_ErrorMessage);
          return FALSE;
        }
        inp = Deref(ARG1);
      }
      Bind_NonAtt(VarOfTerm(inp), AbsAttVar(attv));
      attv->Atts = Deref(ARG2);
    }
    return TRUE;
  } else {
    Yap_Error(REPRESENTATION_ERROR_VARIABLE, inp,
              "first argument of put_att_term/2");
    return (FALSE);
  }
}

static Int rm_att(USES_REGS1) {
  /* receive a variable in ARG1 */
  Term inp = Deref(ARG1);
  /* if this is unbound, ok */
  if (IsVarTerm(inp)) {
    attvar_record *attv;
    Atom modname = AtomOfTerm(Deref(ARG2));
    UInt ar = IntegerOfTerm(Deref(ARG3));
    Functor mfun;
    Term tatts;
    int new = FALSE;

    if (IsAttachedTerm(inp)) {
      attv = RepAttVar(VarOfTerm(inp));
    } else {
      while (!(attv = BuildNewAttVar(PASS_REGS1))) {
        LOCAL_Error_Size = sizeof(attvar_record);
        if (!Yap_gcl(LOCAL_Error_Size, 5, ENV, gc_P(P, CP))) {
          Yap_Error(RESOURCE_ERROR_STACK, TermNil, LOCAL_ErrorMessage);
          return FALSE;
        }
      }
      new = TRUE;
      Yap_unify(ARG1, AbsAttVar(attv));
    }
    mfun = Yap_MkFunctor(modname, ar);
    if (IsVarTerm(tatts = SearchAttsForModule(attv->Atts, mfun))) {
      while (!(tatts = BuildAttTerm(mfun, ar PASS_REGS))) {
        if (!Yap_gcl(LOCAL_Error_Size, 4, ENV, gc_P(P, CP))) {
          Yap_Error(RESOURCE_ERROR_STACK, TermNil, LOCAL_ErrorMessage);
          return FALSE;
        }
      }
      AddNewModule(attv, tatts, new, FALSE PASS_REGS);
    } else {
      PutAtt(IntegerOfTerm(Deref(ARG4)), tatts, TermVoidAtt PASS_REGS);
    }
    return TRUE;
  } else {
    Yap_Error(REPRESENTATION_ERROR_VARIABLE, inp, "first argument of rm_att/2");
    return (FALSE);
  }
}

static Int put_atts(USES_REGS1) {
  /* receive a variable in ARG1 */
  Term inp = Deref(ARG1);

  /* if this is unbound, ok */
  if (IsVarTerm(inp)) {
    attvar_record *attv;
    Term otatts;
    Term tatts = Deref(ARG2);
    Functor mfun = FunctorOfTerm(tatts);
    int new = FALSE;

    if (IsAttachedTerm(inp)) {
      attv = RepAttVar(VarOfTerm(inp));
    } else {
      while (!(attv = BuildNewAttVar(PASS_REGS1))) {
        LOCAL_Error_Size = sizeof(attvar_record);
        if (!Yap_gcl(LOCAL_Error_Size, 2, ENV, gc_P(P, CP))) {
          Yap_Error(RESOURCE_ERROR_STACK, TermNil, LOCAL_ErrorMessage);
          return FALSE;
        }
      }
      new = TRUE;
      Yap_unify(ARG1, AbsAttVar(attv));
    }
    /* we may have a stack shift meanwhile!! */
    tatts = Deref(ARG2);
    if (IsVarTerm(tatts)) {
      Yap_Error(INSTANTIATION_ERROR, tatts, "second argument of put_att/2");
      return FALSE;
    } else if (!IsApplTerm(tatts)) {
      Yap_Error(TYPE_ERROR_COMPOUND, tatts, "second argument of put_att/2");
      return FALSE;
    }
    if (IsVarTerm(otatts = SearchAttsForModule(attv->Atts, mfun))) {
      AddNewModule(attv, tatts, new, FALSE PASS_REGS);
    } else {
      ReplaceAtts(attv, otatts, tatts PASS_REGS);
    }
    return TRUE;
  } else {
    Yap_Error(REPRESENTATION_ERROR_VARIABLE, inp,
              "first argument of put_att/2");
    return FALSE;
  }
}

static Int del_atts(USES_REGS1) {
  /* receive a variable in ARG1 */
  Term inp = Deref(ARG1);
  Term otatts;

  /* if this is unbound, ok */
  if (IsVarTerm(inp)) {
    attvar_record *attv;
    Term tatts = Deref(ARG2);
    Functor mfun = FunctorOfTerm(tatts);

    if (IsAttachedTerm(inp)) {
      attv = RepAttVar(VarOfTerm(inp));
    } else {
      return TRUE;
    }
    if (IsVarTerm(otatts = SearchAttsForModule(attv->Atts, mfun))) {
      return TRUE;
    } else {
      DelAtts(attv, otatts PASS_REGS);
    }
    return TRUE;
  } else {
    return TRUE;
  }
}

static Int del_all_atts(USES_REGS1) {
  /* receive a variable in ARG1 */
  Term inp = Deref(ARG1);

  /* if this is unbound, ok */
  if (IsVarTerm(inp) && IsAttachedTerm(inp)) {
    attvar_record *attv;

    attv = RepAttVar(VarOfTerm(inp));
    DelAllAtts(attv PASS_REGS);
  }
  return TRUE;
}

static Int get_att(USES_REGS1) {
  /* receive a variable in ARG1 */
  Term inp = Deref(ARG1);
  /* if this is unbound, ok */
  if (IsVarTerm(inp)) {
    Atom modname = AtomOfTerm(Deref(ARG2));

    if (IsAttachedTerm(inp)) {
      attvar_record *attv;
      Term tout, tatts;

      attv = RepAttVar(VarOfTerm(inp));
      if (IsVarTerm(tatts = SearchAttsForModuleName(attv->Atts, modname)))
        return FALSE;
      tout = ArgOfTerm(IntegerOfTerm(Deref(ARG3)), tatts);
      if (tout == TermVoidAtt)
        return FALSE;
      return Yap_unify(tout, ARG4);
    } else {
      /* Yap_Error(INSTANTIATION_ERROR,inp,"get_att/2"); */
      return FALSE;
    }
  } else {
    Yap_Error(REPRESENTATION_ERROR_VARIABLE, inp,
              "first argument of get_att/2");
    return (FALSE);
  }
}

static Int free_att(USES_REGS1) {
  /* receive a variable in ARG1 */
  Term inp = Deref(ARG1);
  /* if this is unbound, ok */
  if (IsVarTerm(inp)) {
    Atom modname = AtomOfTerm(Deref(ARG2));

    if (IsAttachedTerm(inp)) {
      attvar_record *attv;
      Term tout, tatts;

      attv = RepAttVar(VarOfTerm(inp));
      if (IsVarTerm(tatts = SearchAttsForModuleName(attv->Atts, modname)))
        return TRUE;
      tout = ArgOfTerm(IntegerOfTerm(Deref(ARG3)), tatts);
      return (tout == TermVoidAtt);
    } else {
      /* Yap_Error(INSTANTIATION_ERROR,inp,"get_att/2"); */
      return TRUE;
    }
  } else {
    Yap_Error(REPRESENTATION_ERROR_VARIABLE, inp,
              "first argument of free_att/2");
    return (FALSE);
  }
}


static Int get_atts(USES_REGS1) {
  /* receive a variable in ARG1 */
  Term inp = Deref(ARG1);
  /* if this is unbound, ok */
  if (IsVarTerm(inp)) {
    if (IsAttachedTerm(inp)) {
      attvar_record *attv;
      Term tatts;
      Term access = Deref(ARG2);
      Functor mfun = FunctorOfTerm(access);
      UInt ar, i;
      CELL *old, *new;

      attv = RepAttVar(VarOfTerm(inp));
      if (IsVarTerm(tatts = SearchAttsForModule(attv->Atts, mfun)))
        return FALSE;

      ar = ArityOfFunctor(mfun);
      new = RepAppl(access) + 2;
      old = RepAppl(tatts) + 2;
      for (i = 1; i < ar; i++, new ++, old++) {
        if (*new != TermFreeTerm) {
          if (*old == TermVoidAtt && *new != TermVoidAtt)
            return FALSE;
          if (*new == TermVoidAtt &&*old != TermVoidAtt)
            return FALSE;
          if (!Yap_unify(*new, *old))
            return FALSE;
        }
      }
      return TRUE;
    } else {
      /* Yap_Error(INSTANTIATION_ERROR,inp,"get_att/2"); */
      return FALSE;
    }
  } else {
    return (FALSE);
  }
}

static Int has_atts(USES_REGS1) {
  /* receive a variable in ARG1 */
  Term inp = Deref(ARG1);
  /* if this is unbound, ok */
  if (IsVarTerm(inp)) {
    if (IsAttachedTerm(inp)) {
      attvar_record *attv;
      Term tatts;
      Term access = Deref(ARG2);
      Functor mfun = FunctorOfTerm(access);

      attv = RepAttVar(VarOfTerm(inp));
      return !IsVarTerm(tatts = SearchAttsForModule(attv->Atts, mfun));
    } else {
      /* Yap_Error(INSTANTIATION_ERROR,inp,"get_att/2"); */
      return FALSE;
    }
  } else {
    Yap_Error(REPRESENTATION_ERROR_VARIABLE, inp,
              "first argument of has_atts/2");
    return (FALSE);
  }
}

static Int bind_attvar(USES_REGS1) {
  /* receive a variable in ARG1 */
  Term inp = Deref(ARG1);
  /* if this is unbound, ok */
  if (IsVarTerm(inp)) {
    if (IsAttachedTerm(inp)) {
      attvar_record *attv = RepAttVar(VarOfTerm(inp));
      return (BindAttVar(attv PASS_REGS));
    }
    return (true);
  } else {
    Yap_Error(REPRESENTATION_ERROR_VARIABLE, inp,
              "first argument of bind_attvar/2");
    return (false);
  }
}

static Int unbind_attvar(USES_REGS1) {
  /* receive a variable in ARG1 */
  Term inp = Deref(ARG1);
  /* if this is unbound, ok */
  if (IsVarTerm(inp)) {
    if (IsAttachedTerm(inp)) {
      attvar_record *attv = RepAttVar(VarOfTerm(inp));
      return (UnBindAttVar(attv));
    }
    return (TRUE);
  } else {
    Yap_Error(REPRESENTATION_ERROR_VARIABLE, inp,
              "first argument of bind_attvar/2");
    return (FALSE);
  }
}

static Int get_all_atts(USES_REGS1) {
  /* receive a variable in ARG1 */
  Term inp = Deref(ARG1);
  /* if this is unbound, ok */
  if (IsVarTerm(inp)) {
    if (IsAttachedTerm(inp)) {
      attvar_record *attv = RepAttVar(VarOfTerm(inp));
      return Yap_unify(ARG2, GetAllAtts(attv));
    }
    return TRUE;
  } else {
    Yap_Error(REPRESENTATION_ERROR_VARIABLE, inp,
              "first argument of get_all_atts/2");
    return FALSE;
  }
}

static int ActiveAtt(Term tatt, UInt ar) {
  CELL *cp = RepAppl(tatt) + 1;
  UInt i;

  for (i = 1; i < ar; i++) {
    if (cp[i] != TermVoidAtt)
      return TRUE;
  }
  return FALSE;
}

static Int modules_with_atts(USES_REGS1) {
  /* receive a variable in ARG1 */
  Term inp = Deref(ARG1);
  /* if this is unbound, ok */
  if (IsVarTerm(inp)) {
    if (IsAttachedTerm(inp)) {
      attvar_record *attv = RepAttVar(VarOfTerm(inp));
      CELL *h0 = HR;
      Term tatt;

      if (IsVarTerm(tatt = attv->Atts))
        return Yap_unify(ARG2, TermNil);
      while (!IsVarTerm(tatt)) {
        Functor f = FunctorOfTerm(tatt);
        if (HR != h0)
          HR[-1] = AbsPair(HR);
        if (ActiveAtt(tatt, ArityOfFunctor(f))) {
          *HR = MkAtomTerm(NameOfFunctor(f));
          HR += 2;
        }
        tatt = ArgOfTerm(1, tatt);
      }
      if (h0 != HR) {
        HR[-1] = TermNil;
        return Yap_unify(ARG2, AbsPair(h0));
      }
    }
    return Yap_unify(ARG2, TermNil);
  } else {
    Yap_Error(REPRESENTATION_ERROR_VARIABLE, inp,
              "first argument of modules_with_attributes/2");
    return FALSE;
  }
}

static Int swi_all_atts(USES_REGS1) {
  /* receive a variable in ARG1 */
  Term inp = Deref(ARG1);
  Functor attf = FunctorAtt1;

  /* if this is unbound, ok */
  if (IsVarTerm(inp)) {
    if (IsAttachedTerm(inp)) {
      attvar_record *attv = RepAttVar(VarOfTerm(inp));
      CELL *h0 = HR;
      Term tatt;

      if (IsVarTerm(tatt = attv->Atts))
        return Yap_unify(ARG2, TermNil);
      while (!IsVarTerm(tatt)) {
        Functor f = FunctorOfTerm(tatt);
        UInt ar = ArityOfFunctor(f);

        if (HR != h0)
          HR[-1] = AbsAppl(HR);
        HR[0] = (CELL)attf;
        HR[1] = MkAtomTerm(NameOfFunctor(f));
        /* SWI */
        if (ar == 2)
          HR[2] = ArgOfTerm(2, tatt);
        else
          HR[2] = tatt;
        HR += 4;
        HR[-1] = AbsAppl(HR);
        tatt = ArgOfTerm(1, tatt);
      }
      if (h0 != HR) {
        HR[-1] = TermNil;
        return Yap_unify(ARG2, AbsAppl(h0));
      }
    }
    return Yap_unify(ARG2, TermNil);
  } else {
    Yap_Error(REPRESENTATION_ERROR_VARIABLE, inp,
              "first argument of get_all_swi_atts/2");
    return FALSE;
  }
}

static Term AllAttVars(USES_REGS1) {
  CELL *pt = H0;
  CELL *myH = HR;

  while (pt < myH) {
    switch (*pt) {
    case (CELL) FunctorAttVar:
      if (IsUnboundVar(pt + 1)) {
        if (ASP - myH < 1024) {
          LOCAL_Error_Size = (ASP - HR) * sizeof(CELL);
          return 0L;
        }
        if (myH != HR) {
          myH[-1] = AbsPair(myH);
        }
        myH[0] = AbsAttVar((attvar_record *)pt);
        myH += 2;
      }
      pt += (1 + ATT_RECORD_ARITY);
      break;
    case (CELL) FunctorDouble:
#if SIZEOF_DOUBLE == 2 * SIZEOF_INT_P
      pt += 4;
#else
      pt += 3;
#endif
      break;
    case (CELL) FunctorString:
      pt += 3 + pt[1];
      break;
    case (CELL) FunctorBigInt: {
      Int sz = 3 +
	(sizeof(MP_INT) +
	 (((MP_INT *)(pt + 2))->_mp_alloc * sizeof(mp_limb_t))) /
	sizeof(CELL);
      pt += sz;
    } break;
    case (CELL) FunctorLongInt:
      pt += 3;
      break;
    default:
      pt++;
    }
  }
  if (myH != HR) {
    Term out = AbsPair(HR);
    myH[-1] = TermNil;
    HR = myH;
    return out;
  } else {
    return TermNil;
  }
}

static Int all_attvars(USES_REGS1) {
  do {
    Term out;

    if (!(out = AllAttVars(PASS_REGS1))) {
      if (!Yap_gcl(LOCAL_Error_Size, 1, ENV, gc_P(P, CP))) {
        Yap_Error(RESOURCE_ERROR_STACK, TermNil, LOCAL_ErrorMessage);
        return FALSE;
      }
    } else {
      return Yap_unify(ARG1, out);
    }
  } while (TRUE);
}

/** @pred attvar( _-Var_)


    Succeed if  _Var_ is an attributed variable.



*/
static Int is_attvar(USES_REGS1) {
  Term t = Deref(ARG1);
  return (IsVarTerm(t) && IsAttVar(VarOfTerm(t)));
}

/* check if we are not redoing effort */
static Int attvar_bound(USES_REGS1) {
  Term t = Deref(ARG1);
  return IsVarTerm(t) && IsAttachedTerm(t) &&
    !IsUnboundVar(&(RepAttVar(VarOfTerm(t))->Done));
}

static Int void_term(USES_REGS1) { return Yap_unify(ARG1, TermVoidAtt); }

static Int free_term(USES_REGS1) { return Yap_unify(ARG1, TermFreeTerm); }

static Int fast_unify(USES_REGS1) {
  /*
    Case we want to unify two variables, but we do not
    think there is a point in waking them up
  */
  Term t1, t2;
  CELL *a, *b;
  if (!IsVarTerm(t1 = Deref(ARG1)))
    return FALSE;
  if (!IsVarTerm(t2 = Deref(ARG2)))
    return FALSE;
  a = VarOfTerm(t1);
  b = VarOfTerm(t2);
  if (a > b) {
    Bind_Global_NonAtt(a, t2);
  } else if ((a) < (b)) {
    Bind_Global_NonAtt(b, t1);
  }
  return TRUE;
}

#else

static Int all_attvars(USES_REGS1) { return FALSE; }

static Int is_attvar(USES_REGS1) { return FALSE; }

static Int attvar_bound(USES_REGS1) { return FALSE; }

#endif /* COROUTINING */

void Yap_InitAttVarPreds(void) {
  CACHE_REGS
    Term OldCurrentModule = CurrentModule;
  CurrentModule = ATTRIBUTES_MODULE;
#ifdef COROUTINING
  GLOBAL_attas[attvars_ext].bind_op = WakeAttVar;
  GLOBAL_attas[attvars_ext].copy_term_op = CopyAttVar;
  GLOBAL_attas[attvars_ext].to_term_op = AttVarToTerm;
  GLOBAL_attas[attvars_ext].term_to_op = TermToAttVar;
  GLOBAL_attas[attvars_ext].mark_op = mark_attvar;
  Yap_InitCPred("get_att", 4, get_att, SafePredFlag);
  Yap_InitCPred("get_module_atts", 2, get_atts, SafePredFlag);
  Yap_InitCPred("has_module_atts", 2, has_atts, SafePredFlag);
  Yap_InitCPred("get_all_atts", 2, get_all_atts, SafePredFlag);
  Yap_InitCPred("get_all_swi_atts", 2, swi_all_atts, SafePredFlag);
  Yap_InitCPred("free_att", 3, free_att, SafePredFlag);
  Yap_InitCPred("put_att", 5, put_att, 0);
  Yap_InitCPred("put_att_term", 2, put_att_term, 0);
  Yap_InitCPred("put_module_atts", 2, put_atts, 0);
  Yap_InitCPred("del_all_module_atts", 2, del_atts, 0);
  Yap_InitCPred("del_all_atts", 1, del_all_atts, 0);
  Yap_InitCPred("rm_att", 4, rm_att, 0);
  Yap_InitCPred("bind_attvar", 1, bind_attvar, SafePredFlag);
  Yap_InitCPred("unbind_attvar", 1, unbind_attvar, SafePredFlag);
  Yap_InitCPred("modules_with_attributes", 2, modules_with_atts,
                SafePredFlag);
  Yap_InitCPred("void_term", 1, void_term, SafePredFlag);
  Yap_InitCPred("free_term", 1, free_term, SafePredFlag);
  Yap_InitCPred("fast_unify_attributed", 2, fast_unify, 0);
#endif /* COROUTINING */
  Yap_InitCPred("all_attvars", 1, all_attvars, 0);
  CurrentModule = OldCurrentModule;
  Yap_InitCPred("attvar", 1, is_attvar, SafePredFlag | TestPredFlag);
  Yap_InitCPred("$att_bound", 1, attvar_bound, SafePredFlag | TestPredFlag);
}

/** @} */