pl-flag.c

/*  Part of SWI-Prolog

    Author:        Jan Wielemaker
    E-mail:        J.Wielemaker@vu.nl
    WWW:           http://www.swi-prolog.org
    Copyright (c)  1985-2017, University of Amsterdam
                              VU University Amsterdam
    All rights reserved.

    Redistribution and use in source and binary forms, with or without
    modification, are permitted provided that the following conditions
    are met:

    1. Redistributions of source code must retain the above copyright
       notice, this list of conditions and the following disclaimer.

    2. Redistributions in binary form must reproduce the above copyright
       notice, this list of conditions and the following disclaimer in
       the documentation and/or other materials provided with the
       distribution.

    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
    "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
    LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
    FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
    COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
    INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
    BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
    LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
    CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
    LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
    ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
    POSSIBILITY OF SUCH DAMAGE.
*/

#include "pl-flag.h"
#include "pl-rec.h"

typedef enum flag_type
{ FLG_ATOM,
  FLG_INTEGER,
  FLG_FLOAT
} flag_type;

typedef struct flag
{ word	key;				/* key to the flag */
  int	type;				/* type (atom, int, float */
  union
  { atom_t  a;				/* atom */
    int64_t i;				/* integer */
    double  f;				/* float */
  } value;				/* value of the flag */
} *Flag;

static void	freeFlagValue(Flag f);

#define flagTable (GD->flags.table)

#undef LD
#define LD LOCAL_LD

static void
freeFlagSymbol(void *name, void *value)
{ Flag f = value;

  freeFlagValue(f);
  freeHeap(f, sizeof(*f));
}


void
initFlags(void)
{ flagTable = newHTable(FLAGHASHSIZE);
  flagTable->free_symbol = freeFlagSymbol;
}


void
cleanupFlags(void)
{ Table t;

  if ( (t=flagTable) )
  { flagTable = NULL;
    destroyHTable(t);
  }
}


static Flag
lookupFlag(word key)
{ GET_LD
  Flag f, of;

  if ( (f = lookupHTable(flagTable, (void *)key)) )
    return f;

  f = (Flag) allocHeapOrHalt(sizeof(struct flag));
  f->key = key;
  if ( isAtom(key) )
    PL_register_atom(key);
  f->type = FLG_INTEGER;
  f->value.i = 0;
  if ( (of=addHTable(flagTable, (void *)key, f)) != f )
  { freeHeap(f, sizeof(*f));
    f = of;
  }

  return f;
}


static void
freeFlagValue(Flag f)
{ if ( f->type == FLG_ATOM )
    PL_unregister_atom(f->value.a);
}


static
PRED_IMPL("get_flag", 2, get_flag, 0)
{ PRED_LD
  Flag f;
  word key;
  int rc;

  term_t name  = A1;
  term_t value = A2;

  if ( !getKeyEx(name, &key) )
    return FALSE;

  f = lookupFlag(key);
  PL_LOCK(L_FLAG);
  switch(f->type)
  { case FLG_ATOM:
      rc = PL_unify_atom(value, f->value.a);
      break;
    case FLG_INTEGER:
      rc = PL_unify_int64(value, f->value.i);
      break;
    case FLG_FLOAT:
      rc = PL_unify_float(value, f->value.f);
      break;
    default:
      rc = FALSE;
      assert(0);
  }
  PL_UNLOCK(L_FLAG);

  return rc;
}


static
PRED_IMPL("set_flag", 2, set_flag, 0)
{ PRED_LD
  Flag f;
  word key;
  atom_t a;
  number n;

  term_t name  = A1;
  term_t value = A2;

  if ( !getKeyEx(name, &key) )
    return FALSE;
  f = lookupFlag(key);

  if ( PL_get_atom(value, &a) )
  { PL_LOCK(L_FLAG);
    freeFlagValue(f);
    f->type = FLG_ATOM;
    f->value.a = a;
    PL_register_atom(a);
    PL_UNLOCK(L_FLAG);
    return TRUE;
  } else if ( PL_get_number(value, &n) )
  { switch(n.type)
    { case V_INTEGER:
      { PL_LOCK(L_FLAG);
	freeFlagValue(f);
	f->type = FLG_INTEGER;
	f->value.i = n.value.i;
	PL_UNLOCK(L_FLAG);
	return TRUE;
      }
#ifdef O_GMP
      case V_MPZ:
	return PL_error(NULL, 0, NULL, ERR_REPRESENTATION, ATOM_int64_t);
      case V_MPQ:
	goto type_error;
#endif
      case V_FLOAT:
      { PL_LOCK(L_FLAG);
	freeFlagValue(f);
	f->type = FLG_FLOAT;
        f->value.f = n.value.f;
	PL_UNLOCK(L_FLAG);
	return TRUE;
      }
      default:
	goto type_error;
    }
  } else
  {
  type_error:
    return PL_error("flag", 3, NULL, ERR_TYPE, ATOM_flag_value, value);
  }
}


word
pl_current_flag(term_t k, control_t h)
{ GET_LD
  Flag f;
  TableEnum e;

  switch( ForeignControl(h) )
  { case FRG_FIRST_CALL:
    { word key;

      if ( PL_is_variable(k) )
      {	e = newTableEnum(flagTable);
	break;
      }
      if ( getKeyEx(k, &key) &&
	   lookupHTable(flagTable, (void *)key) )
	succeed;
      fail;
    }
    case FRG_REDO:
      e = ForeignContextPtr(h);
      break;
    case FRG_CUTTED:
      e = ForeignContextPtr(h);
      freeTableEnum(e);
    default:
      succeed;
  }

  while( advanceTableEnum(e, NULL, (void**)&f) )
  { if ( !unifyKey(k, f->key) )
      continue;

    ForeignRedoPtr(e);
  }

  freeTableEnum(e);
  fail;
}


		 /*******************************
		 *      PUBLISH PREDICATES	*
		 *******************************/

BeginPredDefs(flag)
  PRED_DEF("get_flag", 2, get_flag, 0)
  PRED_DEF("set_flag", 2, set_flag, 0)
EndPredDefs