src/symtab.c

   1 /* Symbol table manager for Bison,
   2    Copyright 1984, 1989, 2000 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 "xalloc.h"
  24 #include "symtab.h"
  25 #include "gram.h"
  26
  27
  28 bucket *firstsymbol;
  29 static bucket *lastsymbol;
  30 static bucket **symtab;
  31
  32 static int
  33 hash (const char *key)
  34 {
  35   const char *cp;
  36   int k;
  37
  38   cp = key;
  39   k = 0;
  40   while (*cp)
  41     k = ((k << 1) ^ (*cp++)) & 0x3fff;
  42
  43   return k % TABSIZE;
  44 }
  45
  46 /*--------------------------------------------------------------.
  47 | Create a new symbol, named TAG, which hash value is HASHVAL.  |
  48 `--------------------------------------------------------------*/
  49
  50 static bucket *
  51 bucket_new (const char *tag, int hashval)
  52 {
  53   bucket *res = XMALLOC (bucket, 1);
  54
  55   res->link = symtab[hashval];
  56   res->next = NULL;
  57   res->tag = xstrdup (tag);
  58   res->type_name = NULL;
  59   res->value = 0;
  60   res->prec = 0;
  61   res->assoc = right_assoc;
  62   res->user_token_number = 0;
  63   res->alias = NULL;
  64   res->class = unknown_sym;
  65
  66   nsyms++;
  67
  68   return res;
  69 }
  70
  71
  72 void
  73 tabinit (void)
  74 {
  75   symtab = XCALLOC (bucket *, TABSIZE);
  76
  77   firstsymbol = NULL;
  78   lastsymbol = NULL;
  79 }
  80
  81
  82 /*----------------------------------------------------------------.
  83 | Find the symbol named KEY, and return it.  If it does not exist |
  84 | yet, create it.                                                 |
  85 `----------------------------------------------------------------*/
  86
  87 bucket *
  88 getsym (const char *key)
  89 {
  90   int hashval;
  91   bucket *bp;
  92   int found;
  93
  94   hashval = hash (key);
  95   bp = symtab[hashval];
  96
  97   found = 0;
  98   while (bp != NULL && found == 0)
  99     {
 100       if (strcmp (key, bp->tag) == 0)
 101         found = 1;
 102       else
 103         bp = bp->link;
 104     }
 105
 106   if (found == 0)
 107     {
 108       bp = bucket_new (key, hashval);
 109
 110       if (firstsymbol == NULL)
 111         {
 112           firstsymbol = bp;
 113           lastsymbol = bp;
 114         }
 115       else
 116         {
 117           lastsymbol->next = bp;
 118           lastsymbol = bp;
 119         }
 120
 121       symtab[hashval] = bp;
 122     }
 123
 124   return bp;
 125 }
 126
 127
 128 void
 129 free_symtab (void)
 130 {
 131   int i;
 132   bucket *bp, *bptmp;           /* JF don't use ptr after free */
 133
 134   for (i = 0; i < TABSIZE; i++)
 135     {
 136       bp = symtab[i];
 137       while (bp)
 138         {
 139           bptmp = bp->link;
 140 #if 0
 141           /* This causes crashes because one string can appear more
 142              than once.  */
 143           if (bp->type_name)
 144             XFREE (bp->type_name);
 145 #endif
 146           XFREE (bp);
 147           bp = bptmp;
 148         }
 149     }
 150   XFREE (symtab);
 151 }