yap-6.3/C/errors.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:		errors.c *
 * Last Rev:								 *
 * Mods: *
 * Comments:	Yap'S error handlers					 *
 *									 *
 *************************************************************************/

#include "absmi.h"
#include "yapio.h"
#if HAVE_STDARG_H
#include <stdarg.h>
#endif
#include <stdlib.h>
#if HAVE_UNISTD_H
#include <unistd.h>
#endif
#if HAVE_STRING_H
#include <string.h>
#endif
#if HAVE_EXECINFO_H
#include <execinfo.h>
#endif
#include "Foreign.h"

#if DEBUG
void Yap_PrintPredName(PredEntry *ap) {
  CACHE_REGS
  Term tmod = ap->ModuleOfPred;
  if (!tmod)
    tmod = TermProlog;
#if THREADS
  Yap_DebugPlWrite(MkIntegerTerm(worker_id));
  Yap_DebugPutc(stderr, ' ');
#endif
  Yap_DebugPutc(stderr, '>');
  Yap_DebugPutc(stderr, '\t');
  Yap_DebugPlWrite(tmod);
  Yap_DebugPutc(stderr, ':');
  if (ap->ModuleOfPred == IDB_MODULE) {
    Term t = Deref(ARG1);
    if (IsAtomTerm(t)) {
      Yap_DebugPlWrite(t);
    } else if (IsIntegerTerm(t)) {
      Yap_DebugPlWrite(t);
    } else {
      Functor f = FunctorOfTerm(t);
      Atom At = NameOfFunctor(f);
      Yap_DebugPlWrite(MkAtomTerm(At));
      Yap_DebugPutc(stderr, '/');
      Yap_DebugPlWrite(MkIntegerTerm(ArityOfFunctor(f)));
    }
  } else {
    if (ap->ArityOfPE == 0) {
      Atom At = (Atom)ap->FunctorOfPred;
      Yap_DebugPlWrite(MkAtomTerm(At));
    } else {
      Functor f = ap->FunctorOfPred;
      Atom At = NameOfFunctor(f);
      Yap_DebugPlWrite(MkAtomTerm(At));
      Yap_DebugPutc(stderr, '/');
      Yap_DebugPlWrite(MkIntegerTerm(ArityOfFunctor(f)));
    }
  }
  char s[1024];
  if (ap->PredFlags & StandardPredFlag)
    fprintf(stderr, "S");
  if (ap->PredFlags & CPredFlag)
    fprintf(stderr, "C");
  if (ap->PredFlags & UserCPredFlag)
    fprintf(stderr, "U");
  if (ap->PredFlags & SyncPredFlag)
    fprintf(stderr, "Y");
  if (ap->PredFlags & LogUpdatePredFlag)
    fprintf(stderr, "Y");
  if (ap->PredFlags & HiddenPredFlag)
    fprintf(stderr, "H");
  sprintf(s, "   %llx\n", ap->PredFlags);
  Yap_DebugPuts(stderr, s);
}
#endif

bool Yap_Warning(const char *s, ...) {
  CACHE_REGS
  va_list ap;
  PredEntry *pred;
  bool rc;
  Term ts[2];
  const char *format;
  char tmpbuf[MAXPATHLEN];

  if (LOCAL_within_print_message) {
    /* error within error */
    fprintf(stderr, "%% WARNING WITHIN WARNING\n");
    Yap_RestartYap(1);
  }
  LOCAL_DoingUndefp = true;
  LOCAL_within_print_message = true;
  pred = RepPredProp(PredPropByFunc(FunctorPrintMessage,
                                    PROLOG_MODULE)); // PROCEDURE_print_message2
  va_start(ap, s);
  format = va_arg(ap, char *);
  if (format != NULL) {
#if HAVE_VSNPRINTF
    vsnprintf(tmpbuf, MAXPATHLEN - 1, format, ap);
#else
    (void)vsprintf(tmpbuf, format, ap);
#endif
  } else
    return false;
  va_end(ap);
  if (pred->OpcodeOfPred == UNDEF_OPCODE||
      pred->OpcodeOfPred == FAIL_OPCODE) {
    fprintf(stderr, "warning message: %s\n", tmpbuf);
    LOCAL_DoingUndefp = false;
    LOCAL_within_print_message = false;
    return false;
  }

  ts[1] = MkAtomTerm(AtomWarning);
  ts[0] = MkAtomTerm(Yap_LookupAtom(tmpbuf));
  rc = Yap_execute_pred(pred, ts, true PASS_REGS);
  return rc;
}

bool Yap_PrintWarning(Term twarning) {
  CACHE_REGS
  PredEntry *pred = RepPredProp(PredPropByFunc(
      FunctorPrintMessage, PROLOG_MODULE)); // PROCEDURE_print_message2;
  Term cmod = ( CurrentModule == PROLOG_MODULE ? TermProlog : CurrentModule );
  bool rc;
  Term ts[2];

  if (LOCAL_within_print_message) {
    /* error within error */
    fprintf(stderr, "%% WARNING WITHIN WARNING\n");
    Yap_RestartYap(1);
  }
  LOCAL_DoingUndefp = true;
  LOCAL_within_print_message = true;
  if (pred->OpcodeOfPred == UNDEF_OPCODE ||
      pred->OpcodeOfPred == FAIL_OPCODE 
  ) {
     fprintf(stderr, "warning message:\n");
     Yap_DebugPlWrite(twarning);
     fprintf(stderr, "\n");
    LOCAL_DoingUndefp = false;
    LOCAL_within_print_message = false;
    CurrentModule = cmod;
    return false;
  }
  ts[1] = twarning;
  ts[0] = MkAtomTerm(AtomWarning);
  HB = B->cp_h = HR;
  B->cp_tr = TR; 
  rc = Yap_execute_pred(pred, ts, true PASS_REGS);
  LOCAL_within_print_message = false;
  LOCAL_DoingUndefp = false;
  return rc;
}

bool Yap_HandleError__(const char *file, const char *function, int lineno, const char *s, ...) {
  CACHE_REGS
  yap_error_number err = LOCAL_Error_TYPE;
  const char *serr;

  LOCAL_Error_TYPE = YAP_NO_ERROR;
  if (LOCAL_ErrorMessage) {
    serr = LOCAL_ErrorMessage;
  } else {
    serr = s;
  }
  switch (err) {
  case RESOURCE_ERROR_STACK:
    if (!Yap_gc(2, ENV, gc_P(P, CP))) {
      Yap_Error__(file, function, lineno, RESOURCE_ERROR_STACK, ARG1, serr);
      return false;
    }
    return true;
  case RESOURCE_ERROR_AUXILIARY_STACK:
    if (LOCAL_MAX_SIZE < (char *)AuxSp - AuxBase) {
      LOCAL_MAX_SIZE += 1024;
    }
    if (!Yap_ExpandPreAllocCodeSpace(0, NULL, TRUE)) {
      /* crash in flames */
      Yap_Error__(file, function, lineno, RESOURCE_ERROR_AUXILIARY_STACK, ARG1, serr);
      return false;
    }
    return true;
  case RESOURCE_ERROR_HEAP:
    if (!Yap_growheap(FALSE, 0, NULL)) {
      Yap_Error__(file, function, lineno, RESOURCE_ERROR_HEAP, ARG2, serr);
      return false;
    }
  default:
    Yap_Error__(file, function, lineno, err, LOCAL_Error_Term, serr);
    return false;
  }
}

int Yap_SWIHandleError(const char *s, ...) {
  CACHE_REGS
  yap_error_number err = LOCAL_Error_TYPE;
  char *serr;

  LOCAL_Error_TYPE = YAP_NO_ERROR;
  if (LOCAL_ErrorMessage) {
    serr = LOCAL_ErrorMessage;
  } else {
    serr = (char *)s;
  }
  switch (err) {
  case RESOURCE_ERROR_STACK:
    if (!Yap_gc(2, ENV, gc_P(P, CP))) {
      Yap_Error(RESOURCE_ERROR_STACK, TermNil, serr);
      return (FALSE);
    }
    return TRUE;
  case RESOURCE_ERROR_AUXILIARY_STACK:
    if (LOCAL_MAX_SIZE < (char *)AuxSp - AuxBase) {
      LOCAL_MAX_SIZE += 1024;
    }
    if (!Yap_ExpandPreAllocCodeSpace(0, NULL, TRUE)) {
      /* crash in flames */
      Yap_Error(RESOURCE_ERROR_AUXILIARY_STACK, ARG1, serr);
      return FALSE;
    }
    return TRUE;
  case RESOURCE_ERROR_HEAP:
    if (!Yap_growheap(FALSE, 0, NULL)) {
      Yap_Error(RESOURCE_ERROR_HEAP, ARG2, serr);
      return FALSE;
    }
  default:
    Yap_Error(err, LOCAL_Error_Term, serr);
    return (FALSE);
  }
}

void Yap_RestartYap(int flag) {
  CACHE_REGS
#if PUSH_REGS
  restore_absmi_regs(&Yap_standard_regs);
#endif
  siglongjmp(LOCAL_RestartEnv, 1);
}

static void error_exit_yap(int value) {
  CACHE_REGS
  if (!(LOCAL_PrologMode & BootMode)) {

#if DEBUG
#endif
  }
  fprintf(stderr, "\n   Exiting ....\n");
  Yap_exit(value);
}

/* This needs to be a static because I can't trust the stack (WIN32), and
 I can't trust the Yap stacks  (error) */
#define YAP_BUF_SIZE 512

static char tmpbuf[YAP_BUF_SIZE];

// error classes: based on OSI errors.
//
//     - The extra argument says whether there different instances
//
//     - Events are treated within the same pipeline as errors.
//

#undef BEGIN_ERROR_CLASSES
#undef ECLASS
#undef END_ERROR_CLASSES
#undef BEGIN_ERRORS
#undef E0
#undef E
#undef E2
#undef END_ERRORS

#define BEGIN_ERROR_CLASSES()                                                  \
  static Term mkerrorct(yap_error_class_number c, Term *ts) {                  \
    switch (c) {

#define ECLASS(CL, A, B)                                                       \
  case CL:                                                                     \
    if (A == 0)                                                                \
      return MkAtomTerm(Yap_LookupAtom(A));                                    \
    else {                                                                     \
      return Yap_MkApplTerm(Yap_MkFunctor(Yap_LookupAtom(A), B), B, ts);       \
    }

#define END_ERROR_CLASSES()                                                    \
  }                                                                            \
  }

#define BEGIN_ERRORS()                                                         \
  static Term mkerrort(yap_error_number e, Term *ts) {                         \
    switch (e) {

#define E0(A, B)                                                               \
  case A:                                                                      \
    return mkerrorct(B, ts);

#define E(A, B, C)                                                             \
  case A:                                                                      \
  ts -= 1;                                                                   \
  ts[0] = MkAtomTerm(Yap_LookupAtom(C));                                     \
  return mkerrorct(B, ts);

#define E2(A, B, C, D)                                                         \
case A:                                                                      \
  ts -= 2;                                                                   \
  ts[0] = MkAtomTerm(Yap_LookupAtom(C));                                     \
  ts[1] = MkAtomTerm(Yap_LookupAtom(D));                                     \
  return mkerrorct(B, ts);

#define END_ERRORS()                                                           \
}                                                                            \
}

#include "YapErrors.h"

/**
* @brief Yap_Error
 *   This function handles errors in the C code. Check errors.yap for the
 *corresponding Prolog code.
 *
 * @param file      C source
 * @param function  C function
 * @param lineno    C exact line
 * @param type      the error ID (in YAP this is a single integer)
 * @param where     the culprit
 * @return usually FAILCODE
 *
 * In a good day, the error handler's job is to generate a throw. This includes:
 *   - constructing an ISO style error term;
 *   - constructing a list with all available info on the bug
 *   - generating the throw
 *   - forcing backtracking in order to restart.
 *
 * In a bad day, it has to deal with OOM, abort, and errors within errorts.
 *
 * The list includes the following options:
 *   + c=c(file, line, function): where the bug was detected;
 *
 *   + e=p(mod, name, arity, cl, file, lin): where the code was entered;
 *
 *   + p=p(mod, name, arity, cl, file, line): the prolog procedure that caused
 *the bug,
 *and optionally,
 *
 *   + g=g(Goal):   the goal that created this mess
 *
 *   + i=i(Comment): an user-written comment on this bug.
 */
yamop *Yap_Error__(const char *file, const char *function, int lineno,
                   yap_error_number type, Term where, ...) {
  CACHE_REGS
  va_list ap;
  CELL nt[3];
  Functor fun;
  bool serious;
  Term tf, error_t, comment, culprit = TermNil;
  char *format;
  char s[MAXPATHLEN];

  /* disallow recursive error handling */
  if (LOCAL_PrologMode & InErrorMode) {
    fprintf(stderr, "%% ERROR WITHIN ERROR %d: %s\n", LOCAL_CurrentError,
            tmpbuf);
    Yap_RestartYap(1);
  }
  LOCAL_PrologMode |= InErrorMode;
  LOCAL_Error_TYPE = YAP_NO_ERROR;
  Yap_ClearExs();
  if (where == 0L) {
    where = TermNil;
  }
  // first, obtain current location
  sprintf(LOCAL_FileNameBuf, "%s:%d in C-function %s ", file, lineno, function);
  tf = MkAtomTerm(Yap_LookupAtom(LOCAL_FileNameBuf));
#if DEBUG_STRICT
  if (Yap_heap_regs && !(LOCAL_PrologMode & BootMode))
    fprintf(stderr, "***** Processing Error %d (%lx,%x) %s***\n", type,
            (unsigned long int)LOCAL_Signals, LOCAL_PrologMode, format);
  else
    fprintf(stderr, "***** Processing Error %d (%x) %s***\n", type,
            LOCAL_PrologMode, format);
#endif
  if (type == INTERRUPT_EVENT) {
    fprintf(stderr, "%% YAP exiting: cannot handle signal %d\n",
            (int)IntOfTerm(where));
    LOCAL_PrologMode &= ~InErrorMode;
    Yap_exit(1);
  }
  if (LOCAL_within_print_message) {
    /* error within error */
    fprintf(stderr, "%% ERROR WITHIN WARNING %d: %s\n", LOCAL_CurrentError,
            tmpbuf);
    LOCAL_PrologMode &= ~InErrorMode;
    Yap_exit(1);
  }
  va_start(ap, where);
  format = va_arg(ap, char *);
  if (format != NULL) {
#if HAVE_VSNPRINTF
    (void)vsnprintf(s, MAXPATHLEN - 1, format, ap);
#else
    (void)vsprintf(s, format, ap);
#endif
    // fprintf(stderr, "warning: ");
    comment = MkAtomTerm(Yap_LookupAtom(s));
  } else if (LOCAL_ErrorSay && LOCAL_ErrorSay[0]) {
    comment = MkAtomTerm(Yap_LookupAtom(LOCAL_ErrorSay));
  } else {
    comment = TermNil;
  }
  va_end(ap);
  if (P == (yamop *)(FAILCODE)) {
    LOCAL_PrologMode &= ~InErrorMode;
    return P;
  }
  /* PURE_ABORT may not have set where correctly, BootMode may not have the data
   * terms ready */
  if (type == ABORT_EVENT || LOCAL_PrologMode & BootMode) {
    where = TermNil;
    LOCAL_PrologMode &= ~AbortMode;
    LOCAL_CurrentError = type;
    LOCAL_PrologMode |= InErrorMode;
    /* make sure failure will be seen at next port */
    // no need to lock & unlock
    if (LOCAL_PrologMode & AsyncIntMode)
      Yap_signal(YAP_FAIL_SIGNAL);
    P = FAILCODE;
  } else {
    if (IsVarTerm(where)) {
      /* we must be careful someone gave us a copy to a local variable */
      Term t = MkVarTerm();
      Yap_unify(t, where);
      where = Deref(where);
    }
    /* Exit Abort Mode, if we were there */
    LOCAL_PrologMode &= ~AbortMode;
    LOCAL_CurrentError = type;
    LOCAL_PrologMode |= InErrorMode;
    if (!(where = Yap_CopyTerm(where))) {
      where = TermNil;
    }
  }

  if (LOCAL_PrologMode & BootMode) {
    /* crash in flames! */
    fprintf(stderr, "%s:%d:0 YAP Fatal Error %d in function %s:\n  %s exiting....\n", file, lineno, type, function, s);
    error_exit_yap(1);
  }
#ifdef DEBUG
  // DumpActiveGoals( USES_REGS1 );
#endif /* DEBUG */
  if (!IsVarTerm(where) &&
      IsApplTerm(where) &&
      FunctorOfTerm(where) == FunctorError) {
    error_t = where;
    Yap_JumpToEnv(error_t);
    P = (yamop *)FAILCODE;
    LOCAL_PrologMode &= ~InErrorMode;
    return P;
  }
  switch (type) {
    case SYSTEM_ERROR_INTERNAL: {
      fprintf(stderr, "%% Internal YAP Error: %s exiting....\n", tmpbuf);
     serious = TRUE;
     if (LOCAL_PrologMode & BootMode) {
      fprintf(stderr, "%% YAP crashed while booting %s\n", tmpbuf);
    } else {
      Yap_detect_bug_location(P, FIND_PRED_FROM_ANYWHERE, YAP_BUF_SIZE);
      if (tmpbuf[0]) {
      fprintf(stderr, "%% Bug found while executing %s\n", tmpbuf);
        }
#if HAVE_BACKTRACE
      void *callstack[256];
      int i;
      int frames = backtrace(callstack, 256);
      char** strs = backtrace_symbols(callstack, frames);
      fprintf(stderr, "Execution stack:\n");
      for (i = 0; i < frames; ++i) {
      fprintf(stderr, "       %s\n", strs[i]);

      }
      free(strs);
#endif
    }
    error_exit_yap(1);
  }
  case SYSTEM_ERROR_FATAL: {
    fprintf(stderr, "%% Fatal YAP Error: %s exiting....\n", tmpbuf);
    error_exit_yap(1);
  }
  case INTERRUPT_EVENT: {
    error_exit_yap(1);
  }
  case ABORT_EVENT:
    nt[0] = MkAtomTerm(AtomDAbort);
    fun = FunctorDollarVar;
    serious = TRUE;
    break;
  case CALL_COUNTER_UNDERFLOW_EVENT:
    /* Do a long jump */
    LOCAL_ReductionsCounterOn = FALSE;
    LOCAL_PredEntriesCounterOn = FALSE;
    LOCAL_RetriesCounterOn = FALSE;
    Yap_JumpToEnv(MkAtomTerm(AtomCallCounter));
    P = (yamop *)FAILCODE;
    LOCAL_PrologMode &= ~InErrorMode;
    return (P);
  case PRED_ENTRY_COUNTER_UNDERFLOW_EVENT:
    /* Do a long jump */
    LOCAL_ReductionsCounterOn = FALSE;
    LOCAL_PredEntriesCounterOn = FALSE;
    LOCAL_RetriesCounterOn = FALSE;
    Yap_JumpToEnv(MkAtomTerm(AtomCallAndRetryCounter));
    P = (yamop *)FAILCODE;
    LOCAL_PrologMode &= ~InErrorMode;
    return (P);
  case RETRY_COUNTER_UNDERFLOW_EVENT:
    /* Do a long jump */
    LOCAL_ReductionsCounterOn = FALSE;
    LOCAL_PredEntriesCounterOn = FALSE;
    LOCAL_RetriesCounterOn = FALSE;
    Yap_JumpToEnv(MkAtomTerm(AtomRetryCounter));
    P = (yamop *)FAILCODE;
    LOCAL_PrologMode &= ~InErrorMode;
    return (P);
  default: {
    Term ts[3];
    ts[2] = where;
    nt[0] = mkerrort(type, ts + 2);
  }



    }
  if (type != ABORT_EVENT) {
    Term location;

    /* This is used by some complex procedures to detect there was an error */
    if (IsAtomTerm(nt[0])) {
      strncpy(LOCAL_ErrorSay, (char *) RepAtom(AtomOfTerm(nt[0]))->StrOfAE,
              MAX_ERROR_MSG_SIZE);
      LOCAL_ErrorMessage = LOCAL_ErrorSay;
    } else {
      strncpy(LOCAL_ErrorSay,
              (char *) RepAtom(NameOfFunctor(FunctorOfTerm(nt[0])))->StrOfAE,
              MAX_ERROR_MSG_SIZE);
      LOCAL_ErrorMessage = LOCAL_ErrorSay;
    }
    nt[1] = TermNil;
    switch (type) {
      case RESOURCE_ERROR_HEAP:
      case RESOURCE_ERROR_STACK:
      case RESOURCE_ERROR_TRAIL:
        comment = MkAtomTerm(Yap_LookupAtom(tmpbuf));
      default: 
           if (comment != TermNil)
              nt[1] = MkPairTerm(MkPairTerm(MkAtomTerm(Yap_LookupAtom("i")), comment),
                                 nt[1]);
            if (file && function) {
              Term ts[3], t3;
              ts[0] = MkAtomTerm(Yap_LookupAtom(file));
              ts[1] = MkIntegerTerm(lineno);
              ts[2] = MkAtomTerm(Yap_LookupAtom(function));
              t3 = Yap_MkApplTerm(Yap_MkFunctor(Yap_LookupAtom("c"), 3), 3, ts);
              nt[1] =
                      MkPairTerm(MkPairTerm(MkAtomTerm(Yap_LookupAtom("c")), t3), nt[1]);
            }
            if ((location = Yap_pc_location(P, B, ENV)) != TermNil) {
              nt[1] = MkPairTerm(MkPairTerm(MkAtomTerm(Yap_LookupAtom("p")), location),
                                 nt[1]);
            }
            if ((location = Yap_env_location(CP, B, ENV, 0)) != TermNil) {
              nt[1] = MkPairTerm(MkPairTerm(MkAtomTerm(Yap_LookupAtom("e")), location),
                                 nt[1]);
            }
    }
  }
    /* disable active signals at this point */
    LOCAL_Signals = 0;
    CalculateStackGap(PASS_REGS1);
    LOCAL_PrologMode &= ~InErrorMode;
    /* we might be in the middle of a critical region */
    if (LOCAL_InterruptsDisabled) {
      LOCAL_InterruptsDisabled = 0;
      LOCAL_UncaughtThrow = TRUE;
      Yap_RestartYap(1);
    }
#if DEBUG
//    DumpActiveGoals( PASS_REGS1 );
#endif
    /* wait if we we are in user code,
     it's up to her to decide */
    fun = FunctorError;
    if (LOCAL_PrologMode & UserCCallMode) {
      error_t = Yap_MkApplTerm(fun, 2, nt);
      if (!(EX = Yap_StoreTermInDB(error_t, 2))) {
        /* fat chance */
        Yap_RestartYap(1);
      }
    } else {
      if (type == ABORT_EVENT) {
        error_t = MkAtomTerm(AtomDAbort);
      } else {
        error_t = Yap_MkApplTerm(fun, 2, nt);
      }
      Yap_JumpToEnv(error_t);
      P = (yamop *)FAILCODE;
    }

    LOCAL_PrologMode &= ~InErrorMode;
    return P;
  }

static Int
is_boolean( USES_REGS1 )
{
  Term t = Deref(ARG1);
  //Term Context = Deref(ARG2)Yap_Error(INSTANTIATION_ERROR, t, NULL);;
  if (IsVarTerm(t)) {
    Yap_Error(INSTANTIATION_ERROR, t, NULL);
    return false;
  }
  return t == TermTrue || t == TermFalse;
}

static Int
is_atom( USES_REGS1 )
{
  Term t = Deref(ARG1);
  //Term Context = Deref(ARG2)Yap_Error(INSTANTIATION_ERROR, t, NULL);;
  if (IsVarTerm(t)) {
    Yap_Error(INSTANTIATION_ERROR, t, NULL);
    return false;
  }
  return IsAtomTerm( t );
}



static Int
is_callable( USES_REGS1 )
{
  Term G = Deref(ARG1);
  //Term Context = Deref(ARG2);
  while (true) {
    if (IsVarTerm(G)) {
      Yap_Error(INSTANTIATION_ERROR, G, NULL);
      return false;
    }
    if (IsApplTerm(G)) {
      Functor f = FunctorOfTerm(G);
      if (IsExtensionFunctor(f)) {
        Yap_Error(TYPE_ERROR_CALLABLE, G, NULL);
      }
      if (f == FunctorModule) {
        Term tm = ArgOfTerm( 1, G);
        if (IsVarTerm(tm)) {
          Yap_Error(INSTANTIATION_ERROR, G, NULL);
          return false;
        }
        if (!IsAtomTerm(tm)) {
          Yap_Error(TYPE_ERROR_CALLABLE, G, NULL);
          return false;
        }
        G = ArgOfTerm( 2, G );
      } else {
        return true;
      }
    } else if (IsPairTerm(G) || IsAtomTerm(G)) {
      return true;
    } else {
      Yap_Error(TYPE_ERROR_CALLABLE, G, NULL);
      return false;
    }
  }
  return false;
}

static Int
is_predicate_indicator( USES_REGS1 )
{
  Term G = Deref(ARG1);
  //Term Context = Deref(ARG2);
  Term mod = CurrentModule;

  G = Yap_YapStripModule(G, &mod);
  if (IsVarTerm(G)) {
    Yap_Error(INSTANTIATION_ERROR, G, NULL);
    return false;
  }
  if (!IsVarTerm(mod) && !IsAtomTerm(mod)) {
    Yap_Error(TYPE_ERROR_ATOM, G, NULL);
    return false;
  }
  if (IsApplTerm(G)) {
    Functor f = FunctorOfTerm(G);
    if (IsExtensionFunctor(f)) {
      Yap_Error(TYPE_ERROR_PREDICATE_INDICATOR, G, NULL);
    }
    if (f == FunctorSlash || f == FunctorDoubleSlash) {
      return true;
    }
  }
  Yap_Error(TYPE_ERROR_PREDICATE_INDICATOR, G, NULL);
  return false;
}


void
Yap_InitErrorPreds( void )
{
  CACHE_REGS
  Term cm = CurrentModule;
  CurrentModule = ERROR_MODULE;
  Yap_InitCPred("is_boolean", 2, is_boolean, TestPredFlag);
  Yap_InitCPred("is_callable", 2, is_callable, TestPredFlag);
  Yap_InitCPred("is_atom", 2, is_atom, TestPredFlag);
  Yap_InitCPred("is_predicate_indicator", 2, is_predicate_indicator, TestPredFlag);
  CurrentModule = cm;
}