build/byacc/symtab.c

   1 /* $Id: symtab.c,v 1.9 2010/11/24 15:12:29 tom Exp $ */
   2
   3 #include "defs.h"
   4
   5 /* TABLE_SIZE is the number of entries in the symbol table. */
   6 /* TABLE_SIZE must be a power of two.                       */
   7
   8 #define TABLE_SIZE 1024
   9
  10 static bucket **symbol_table = 0;
  11 bucket *first_symbol;
  12 bucket *last_symbol;
  13
  14 static int
  15 hash(const char *name)
  16 {
  17     const char *s;
  18     int c, k;
  19
  20     assert(name && *name);
  21     s = name;
  22     k = *s;
  23     while ((c = *++s) != 0)
  24         k = (31 * k + c) & (TABLE_SIZE - 1);
  25
  26     return (k);
  27 }
  28
  29 bucket *
  30 make_bucket(const char *name)
  31 {
  32     bucket *bp;
  33
  34     assert(name != 0);
  35
  36     bp = (bucket *)MALLOC(sizeof(bucket));
  37     NO_SPACE(bp);
  38
  39     bp->link = 0;
  40     bp->next = 0;
  41
  42     bp->name = MALLOC(strlen(name) + 1);
  43     NO_SPACE(bp->name);
  44
  45     bp->tag = 0;
  46     bp->value = UNDEFINED;
  47     bp->index = 0;
  48     bp->prec = 0;
  49     bp->class = UNKNOWN;
  50     bp->assoc = TOKEN;
  51     strcpy(bp->name, name);
  52
  53     return (bp);
  54 }
  55
  56 bucket *
  57 lookup(const char *name)
  58 {
  59     bucket *bp, **bpp;
  60
  61     bpp = symbol_table + hash(name);
  62     bp = *bpp;
  63
  64     while (bp)
  65     {
  66         if (strcmp(name, bp->name) == 0)
  67             return (bp);
  68         bpp = &bp->link;
  69         bp = *bpp;
  70     }
  71
  72     *bpp = bp = make_bucket(name);
  73     last_symbol->next = bp;
  74     last_symbol = bp;
  75
  76     return (bp);
  77 }
  78
  79 void
  80 create_symbol_table(void)
  81 {
  82     int i;
  83     bucket *bp;
  84
  85     symbol_table = (bucket **)MALLOC(TABLE_SIZE * sizeof(bucket *));
  86     NO_SPACE(symbol_table);
  87
  88     for (i = 0; i < TABLE_SIZE; i++)
  89         symbol_table[i] = 0;
  90
  91     bp = make_bucket("error");
  92     bp->index = 1;
  93     bp->class = TERM;
  94
  95     first_symbol = bp;
  96     last_symbol = bp;
  97     symbol_table[hash("error")] = bp;
  98 }
  99
 100 void
 101 free_symbol_table(void)
 102 {
 103     FREE(symbol_table);
 104     symbol_table = 0;
 105 }
 106
 107 void
 108 free_symbols(void)
 109 {
 110     bucket *p, *q;
 111
 112     for (p = first_symbol; p; p = q)
 113     {
 114         q = p->next;
 115         FREE(p);
 116     }
 117 }