regina/extlib.c

   1 #ifndef lint
   2 static char *RCSid = "$Id$";
   3 #endif
   4
   5 /*
   6  *  The Regina Rexx Interpreter
   7  *  Copyright (C) 1993-1994  Anders Christensen <anders@pvv.unit.no>
   8  *
   9  *  This library is free software; you can redistribute it and/or
  10  *  modify it under the terms of the GNU Library General Public
  11  *  License as published by the Free Software Foundation; either
  12  *  version 2 of the License, or (at your option) any later version.
  13  *
  14  *  This library is distributed in the hope that it will be useful,
  15  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  17  *  Library General Public License for more details.
  18  *
  19  *  You should have received a copy of the GNU Library General Public
  20  *  License along with this library; if not, write to the Free
  21  *  Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  22  */
  23
  24 #include "rexx.h"
  25
  26 struct extlib_funcbox {
  27    struct extlib_funcbox *next, *prev ;
  28    streng *name ;
  29    int type ;
  30    int hash1 ;
  31 };
  32
  33 #define EXTFUNCS_COUNT (sizeof(((tsd_t *)0)->extfuncs) /   \
  34                         sizeof(((tsd_t *)0)->extfuncs[0]))
  35
  36 static struct extlib_funcbox *findfunc( const tsd_t *TSD, const streng *name, int *hash,
  37                                         int *hashbox )
  38 {
  39    struct extlib_funcbox *fptr=NULL ;
  40    int lhashbox, lhash ;
  41
  42    *hash = lhash = hashvalue( name->value, name->len ) ;
  43    *hashbox = lhashbox = lhash % EXTFUNCS_COUNT ;
  44    for (fptr=TSD->extfuncs[lhashbox]; fptr; fptr=fptr->prev)
  45       if (fptr->hash1 == lhash)
  46          if (!Str_cmp(name, fptr->name))
  47             return fptr ;
  48
  49    return NULL ;
  50 }
  51
  52 int delfunc( tsd_t *TSD, const streng *name )
  53 {
  54    struct extlib_funcbox *old=NULL ;
  55    int hash, hashbox ;
  56
  57    old = findfunc( TSD, name, &hash, &hashbox ) ;
  58    if (!old)
  59       return 1 ;
  60
  61    Free_stringTSD( old->name ) ;
  62    if (old==TSD->extfuncs[hashbox])
  63       TSD->extfuncs[hashbox] = old->prev ;
  64    else
  65       old->next->prev = old->prev ;
  66
  67    if (old->prev)
  68       old->prev->next = old->next ;
  69
  70    FreeTSD( old ) ;
  71    return 0 ;
  72 }
  73
  74 /* addfunc returns 1 on success, 0 if already defined, -1 if memory is short.
  75  * The argument name is used for further operation on success only.
  76  */
  77 int addfunc( tsd_t *TSD, streng *name, int type )
  78 {
  79    struct extlib_funcbox *new=NULL ;
  80    int hashbox, hash ;
  81
  82    if (findfunc( TSD, name, &hash, &hashbox ))
  83       return 0 ;
  84
  85    new = MallocTSD( sizeof(struct extlib_funcbox )) ;
  86    if (!new)
  87       return -1 ;
  88
  89    new->name = name ;
  90    new->type = type ;
  91    new->next = NULL ;
  92    new->hash1 = hash ;
  93    new->prev = TSD->extfuncs[hashbox] ;
  94    if (TSD->extfuncs[hashbox])
  95       TSD->extfuncs[hashbox]->next = new ;
  96    TSD->extfuncs[hashbox] = new ;
  97
  98    return 1 ;
  99 }
 100
 101 int external_func( const tsd_t *TSD, const streng *name )
 102 {
 103    struct extlib_funcbox *ptr=NULL ;
 104    int hash, hashbox ;
 105
 106    ptr = findfunc( TSD, name, &hash, &hashbox ) ;
 107    if (ptr)
 108       return 1 ;
 109    else
 110       return 0 ;
 111 }
 112