src/symtab.c

   1 /* Symbol table manager for Bison,
   2    Copyright (C) 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 void
  48 tabinit (void)
  49 {
  50   symtab = XCALLOC (bucket *, TABSIZE);
  51
  52   firstsymbol = NULL;
  53   lastsymbol = NULL;
  54 }
  55
  56
  57 bucket *
  58 getsym (const char *key)
  59 {
  60   int hashval;
  61   bucket *bp;
  62   int found;
  63
  64   hashval = hash (key);
  65   bp = symtab[hashval];
  66
  67   found = 0;
  68   while (bp != NULL && found == 0)
  69     {
  70       if (strcmp (key, bp->tag) == 0)
  71         found = 1;
  72       else
  73         bp = bp->link;
  74     }
  75
  76   if (found == 0)
  77     {
  78       nsyms++;
  79
  80       bp = XCALLOC (bucket, 1);
  81       bp->link = symtab[hashval];
  82       bp->next = NULL;
  83       bp->tag = xstrdup (key);
  84       bp->class = unknown_sym;
  85
  86       if (firstsymbol == NULL)
  87         {
  88           firstsymbol = bp;
  89           lastsymbol = bp;
  90         }
  91       else
  92         {
  93           lastsymbol->next = bp;
  94           lastsymbol = bp;
  95         }
  96
  97       symtab[hashval] = bp;
  98     }
  99
 100   return bp;
 101 }
 102
 103
 104 void
 105 free_symtab (void)
 106 {
 107   int i;
 108   bucket *bp, *bptmp;           /* JF don't use ptr after free */
 109
 110   for (i = 0; i < TABSIZE; i++)
 111     {
 112       bp = symtab[i];
 113       while (bp)
 114         {
 115           bptmp = bp->link;
 116 #if 0
 117           /* This causes crashes because one string can appear more
 118              than once.  */
 119           if (bp->type_name)
 120             XFREE (bp->type_name);
 121 #endif
 122           XFREE (bp);
 123           bp = bptmp;
 124         }
 125     }
 126   XFREE (symtab);
 127 }