src/symtab.c

   1 /* Symbol table manager for Bison,
   2    Copyright 1984, 1989, 2000, 2001 Free Software Foundation, Inc.
   3
   4    This file is part of Bison, the GNU Compiler Compiler.
   5
   6    Bison is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 2, or (at your option)
   9    any later version.
  10
  11    Bison is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with Bison; see the file COPYING.  If not, write to
  18    the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  19    Boston, MA 02111-1307, USA.  */
  20
  21
  22 #include "system.h"
  23 #include "symtab.h"
  24 #include "gram.h"
  25
  26
  27 bucket *firstsymbol;
  28 static bucket *lastsymbol;
  29 static bucket **symtab;
  30
  31 static int
  32 hash (const char *key)
  33 {
  34   const char *cp;
  35   int k;
  36
  37   cp = key;
  38   k = 0;
  39   while (*cp)
  40     k = ((k << 1) ^ (*cp++)) & 0x3fff;
  41
  42   return k % TABSIZE;
  43 }
  44
  45 /*--------------------------------------------------------------.
  46 | Create a new symbol, named TAG, which hash value is HASHVAL.  |
  47 `--------------------------------------------------------------*/
  48
  49 static bucket *
  50 bucket_new (const char *tag, int hashval)
  51 {
  52   bucket *res = XMALLOC (bucket, 1);
  53
  54   res->link = symtab[hashval];
  55   res->next = NULL;
  56   res->tag = xstrdup (tag);
  57   res->type_name = NULL;
  58   res->value = 0;
  59   res->prec = 0;
  60   res->assoc = right_assoc;
  61   res->user_token_number = SUNDEF;
  62   res->alias = NULL;
  63   res->class = unknown_sym;
  64
  65   nsyms++;
  66
  67   return res;
  68 }
  69
  70
  71 void
  72 tabinit (void)
  73 {
  74   symtab = XCALLOC (bucket *, TABSIZE);
  75
  76   firstsymbol = NULL;
  77   lastsymbol = NULL;
  78 }
  79
  80
  81 /*----------------------------------------------------------------.
  82 | Find the symbol named KEY, and return it.  If it does not exist |
  83 | yet, create it.                                                 |
  84 `----------------------------------------------------------------*/
  85
  86 bucket *
  87 getsym (const char *key)
  88 {
  89   int hashval;
  90   bucket *bp;
  91   int found;
  92
  93   hashval = hash (key);
  94   bp = symtab[hashval];
  95
  96   found = 0;
  97   while (bp != NULL && found == 0)
  98     {
  99       if (strcmp (key, bp->tag) == 0)
 100         found = 1;
 101       else
 102         bp = bp->link;
 103     }
 104
 105   if (found == 0)
 106     {
 107       bp = bucket_new (key, hashval);
 108
 109       if (firstsymbol == NULL)
 110         {
 111           firstsymbol = bp;
 112           lastsymbol = bp;
 113         }
 114       else
 115         {
 116           lastsymbol->next = bp;
 117           lastsymbol = bp;
 118         }
 119
 120       symtab[hashval] = bp;
 121     }
 122
 123   return bp;
 124 }
 125
 126
 127 void
 128 free_symtab (void)
 129 {
 130   int i;
 131   bucket *bp, *bptmp;           /* JF don't use ptr after free */
 132
 133   for (i = 0; i < TABSIZE; i++)
 134     {
 135       bp = symtab[i];
 136       while (bp)
 137         {
 138           bptmp = bp->link;
 139 #if 0
 140           /* This causes crashes because one string can appear more
 141              than once.  */
 142           if (bp->type_name)
 143             XFREE (bp->type_name);
 144 #endif
 145           XFREE (bp->tag);
 146           XFREE (bp);
 147           bp = bptmp;
 148         }
 149     }
 150   XFREE (symtab);
 151 }