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   /* Hack, until we have a Bison parser. */
  53   extern int lineno;
  54
  55   bucket *res = XMALLOC (bucket, 1);
  56
  57   res->link = symtab[hashval];
  58   res->next = NULL;
  59   res->tag = xstrdup (tag);
  60   res->type_name = NULL;
  61   res->value = 0;
  62   res->prec = 0;
  63   res->assoc = right_assoc;
  64   res->user_token_number = SUNDEF;
  65   res->alias = NULL;
  66   res->class = unknown_sym;
  67   res->line = lineno;
  68
  69   nsyms++;
  70
  71   return res;
  72 }
  73
  74
  75 void
  76 tabinit (void)
  77 {
  78   symtab = XCALLOC (bucket *, TABSIZE);
  79
  80   firstsymbol = NULL;
  81   lastsymbol = NULL;
  82 }
  83
  84
  85 /*----------------------------------------------------------------.
  86 | Find the symbol named KEY, and return it.  If it does not exist |
  87 | yet, create it.                                                 |
  88 `----------------------------------------------------------------*/
  89
  90 bucket *
  91 getsym (const char *key)
  92 {
  93   int hashval;
  94   bucket *bp;
  95   int found;
  96
  97   hashval = hash (key);
  98   bp = symtab[hashval];
  99
 100   found = 0;
 101   while (bp != NULL && found == 0)
 102     {
 103       if (strcmp (key, bp->tag) == 0)
 104         found = 1;
 105       else
 106         bp = bp->link;
 107     }
 108
 109   if (found == 0)
 110     {
 111       bp = bucket_new (key, hashval);
 112
 113       if (firstsymbol == NULL)
 114         {
 115           firstsymbol = bp;
 116           lastsymbol = bp;
 117         }
 118       else
 119         {
 120           lastsymbol->next = bp;
 121           lastsymbol = bp;
 122         }
 123
 124       symtab[hashval] = bp;
 125     }
 126
 127   return bp;
 128 }
 129
 130
 131 void
 132 free_symtab (void)
 133 {
 134   int i;
 135   bucket *bp, *bptmp;           /* JF don't use ptr after free */
 136
 137   for (i = 0; i < TABSIZE; i++)
 138     {
 139       bp = symtab[i];
 140       while (bp)
 141         {
 142           bptmp = bp->link;
 143 #if 0
 144           /* This causes crashes because one string can appear more
 145              than once.  */
 146           if (bp->type_name)
 147             XFREE (bp->type_name);
 148 #endif
 149           XFREE (bp->tag);
 150           XFREE (bp);
 151           bp = bptmp;
 152         }
 153     }
 154   XFREE (symtab);
 155 }