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hsearch.c

/***********************************************************************
*                                                                      *
*               This software is part of the ast package               *
*                  Copyright (c) 1985-2005 AT&T Corp.                  *
*                      and is licensed under the                       *
*                  Common Public License, Version 1.0                  *
*                            by AT&T Corp.                             *
*                                                                      *
*                A copy of the License is available at                 *
*            http://www.opensource.org/licenses/cpl1.0.txt             *
*         (with md5 checksum 059e8cd6165cb4c31e351f2b69388fd9)         *
*                                                                      *
*              Information and Software Systems Research               *
*                            AT&T Research                             *
*                           Florham Park NJ                            *
*                                                                      *
*                 Glenn Fowler <gsf@research.att.com>                  *
*                  David Korn <dgk@research.att.com>                   *
*                   Phong Vo <kpv@research.att.com>                    *
*                                                                      *
***********************************************************************/
/*
 * hsearch() for systems that have <search.h> but no hsearch()
 * why would such a system provide the interface but not the
 * implementation? that's what happens when one slimes their
 * way through standards compliance
 *
 * NOTE: please excuse the crude feature test
 */

#if !_UWIN

void _STUB_hsearch(){}

#else

#if _PACKAGE_ast
#include    <ast.h>
#endif

#define hcreate         ______hcreate
#define hdestroy  ______hdestroy
#define hsearch         ______hsearch

#include    <search.h>

#undef      hcreate
#undef      hdestroy
#undef      hsearch

#include    "dthdr.h"

#if defined(__EXPORT__)
#define extern    __EXPORT__
#endif

/*    POSIX hsearch library based on libdt
**    Written by Kiem-Phong Vo (AT&T Research, 07/19/95)
*/

/* type of objects in hash table */
typedef struct _hash_s
{     Dtlink_t    link;
      ENTRY       item;
} Hash_t;

/* object delete function */
#if __STD_C
static void hashfree(Dt_t* dt, Void_t* obj, Dtdisc_t* disc)
#else
static void hashfree(dt, obj, disc)
Dt_t*       dt;
Void_t*           obj;
Dtdisc_t*   disc;
#endif
{
      free(((Hash_t*)obj)->item.key);
      free(obj);
}

static Dt_t*      Hashtab;    /* object dictionary    */
static Dtdisc_t   Hashdisc =  /* discipline           */
{     sizeof(Dtlink_t), -1,
      0,
      NIL(Dtmake_f), hashfree,
      NIL(Dtcompar_f),  /* always use strcmp    */
      NIL(Dthash_f),
      NIL(Dtmemory_f),
      NIL(Dtevent_f)
};

extern
#if __STD_C
int hcreate(size_t nel)
#else
int hcreate(nel)
size_t      nel;
#endif
{
      if(Hashtab) /* already opened */
            return 0;

      if(!(Hashtab = dtopen(&Hashdisc,Dtset)) )
            return 0;

      return 1;
}

extern void hdestroy()
{     if(Hashtab)
            dtclose(Hashtab);
      Hashtab = NIL(Dt_t*);
}

extern
#if __STD_C
ENTRY* hsearch(ENTRY item, ACTION action)
#else
ENTRY* hsearch(item, action)
ENTRY item;
ACTION      action;
#endif
{
      reg Hash_t* o;

      if(!Hashtab)
            return NIL(ENTRY*);

      if(!(o = (Hash_t*)dtmatch(Hashtab,item.key)) && action == ENTER &&
         (o = (Hash_t*)malloc(sizeof(Hash_t)) ) )
      {     o->item = item;
            o = (Hash_t*)dtinsert(Hashtab,o);
      }

      return o ? &(o->item) : NIL(ENTRY*);
}

#endif

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