symbol.cpp

   1 // The symbol table is a simple array of struct U.
   2
   3 #include "stdafx.h"
   4 #include "defs.h"
   5
   6 // put symbol at index n
   7
   8 void
   9 std_symbol(char *s, int n)
  10 {
  11         U *p;
  12         p = symtab + n;
  13         p->u.printname = s;
  14 }
  15
  16 // symbol lookup, create symbol if need be
  17
  18 U *
  19 usr_symbol(char *s)
  20 {
  21         int i;
  22         U *p;
  23         for (i = 0; i < NSYM; i++) {
  24                 if (symtab[i].u.printname == 0)
  25                         break;
  26                 if (strcmp(s, symtab[i].u.printname) == 0)
  27                         return symtab + i;
  28         }
  29         if (i == NSYM)
  30                 stop("symbol table overflow");
  31         p = symtab + i;
  32         p->u.printname = (char *)malloc(strlen(s)+1);
  33         strcpy(p->u.printname,s);
  34         return p;
  35 }
  36
  37 // get the symbol's printname
  38
  39 char *
  40 get_printname(U *p)
  41 {
  42         if (p->k != SYM)
  43                 stop("symbol error");
  44         return p->u.printname;
  45 }
  46
  47 // clears the arglist too
  48
  49 void
  50 set_binding(U *p, U *q)
  51 {
  52         if (p->k != SYM)
  53                 stop("symbol error");
  54         binding[p - symtab] = q;
  55         arglist[p - symtab] = symbol(NIL);
  56 }
  57
  58 U *
  59 get_binding(U *p)
  60 {
  61         if (p->k != SYM)
  62                 stop("symbol error");
  63         return binding[p - symtab];
  64 }
  65
  66 void
  67 set_binding_and_arglist(U *p, U *q, U *r)
  68 {
  69         if (p->k != SYM)
  70                 stop("symbol error");
  71         binding[p - symtab] = q;
  72         arglist[p - symtab] = r;
  73 }
  74
  75 U *
  76 get_arglist(U *p)
  77 {
  78         if (p->k != SYM)
  79                 stop("symbol error");
  80         return arglist[p - symtab];
  81 }
  82
  83 // get symbol's number from ptr
  84
  85 int
  86 symnum(U *p)
  87 {
  88         if (p->k != SYM)
  89                 stop("symbol error");
  90         return (int) (p - symtab);
  91 }
  92
  93 // push indexed symbol
  94
  95 void
  96 push_symbol(int k)
  97 {
  98         push(symtab + k);
  99 }
 100
 101 void
 102 clear_symbols(void)
 103 {
 104         int i;
 105         for (i = 0; i < NSYM; i++) {
 106                 binding[i] = symtab + i;
 107                 arglist[i] = symbol(NIL);
 108         }
 109 }