commands/byacc/symtab.c

   1 #include "defs.h"
   2
   3
   4 /* TABLE_SIZE is the number of entries in the symbol table. */
   5 /* TABLE_SIZE must be a power of two.                       */
   6
   7 #define TABLE_SIZE 1024
   8
   9
  10 bucket **symbol_table;
  11 bucket *first_symbol;
  12 bucket *last_symbol;
  13
  14
  15 int
  16 hash(name)
  17 char *name;
  18 {
  19     register char *s;
  20     register int c, k;
  21
  22     assert(name && *name);
  23     s = name;
  24     k = *s;
  25     while (c = *++s)
  26         k = (31*k + c) & (TABLE_SIZE - 1);
  27
  28     return (k);
  29 }
  30
  31
  32 bucket *
  33 make_bucket(name)
  34 char *name;
  35 {
  36     register bucket *bp;
  37
  38     assert(name);
  39     bp = (bucket *) MALLOC(sizeof(bucket));
  40     if (bp == 0) no_space();
  41     bp->link = 0;
  42     bp->next = 0;
  43     bp->name = MALLOC(strlen(name) + 1);
  44     if (bp->name == 0) no_space();
  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
  52     if (bp->name == 0) no_space();
  53     strcpy(bp->name, name);
  54
  55     return (bp);
  56 }
  57
  58
  59 bucket *
  60 lookup(name)
  61 char *name;
  62 {
  63     register bucket *bp, **bpp;
  64
  65     bpp = symbol_table + hash(name);
  66     bp = *bpp;
  67
  68     while (bp)
  69     {
  70         if (strcmp(name, bp->name) == 0) return (bp);
  71         bpp = &bp->link;
  72         bp = *bpp;
  73     }
  74
  75     *bpp = bp = make_bucket(name);
  76     last_symbol->next = bp;
  77     last_symbol = bp;
  78
  79     return (bp);
  80 }
  81
  82
  83 create_symbol_table()
  84 {
  85     register int i;
  86     register bucket *bp;
  87
  88     symbol_table = (bucket **) MALLOC(TABLE_SIZE*sizeof(bucket *));
  89     if (symbol_table == 0) no_space();
  90     for (i = 0; i < TABLE_SIZE; i++)
  91         symbol_table[i] = 0;
  92
  93     bp = make_bucket("error");
  94     bp->index = 1;
  95     bp->class = TERM;
  96
  97     first_symbol = bp;
  98     last_symbol = bp;
  99     symbol_table[hash("error")] = bp;
 100 }
 101
 102
 103 free_symbol_table()
 104 {
 105     FREE(symbol_table);
 106     symbol_table = 0;
 107 }
 108
 109
 110 free_symbols()
 111 {
 112     register bucket *p, *q;
 113
 114     for (p = first_symbol; p; p = q)
 115     {
 116         q = p->next;
 117         FREE(p);
 118     }
 119 }