Esempio n. 1
0
int
isvectordef (const char *type, relation rel)
{
  definition *def;

  for (;;)
    {
      switch (rel)
	{
	case REL_VECTOR:
	  return !streq (type, "string");
	case REL_ARRAY:
	  return 0;
	case REL_POINTER:
	  return 0;
	case REL_ALIAS:
	  def = findval (defined, type, typedefed);
	  if (def == NULL)
	    {
	      return 0;
	    }
	  type = def->def.ty.old_type;
	  rel = def->def.ty.rel;
	}
    }
}
/*
 * You might think that to add a new binding to an
 * environment, we would always have to insert a new
 * binding at the beginning of the lists. But we can get
 * away with an optimization. If x in dom rho, instead
 * of extending rho by making rho{x |->v}, we can
 * overwrite the old binding of x. This optimization is
 * safe only because no program written in Impcore can
 * tell the difference. We can prove this by examining
 * the rules of the operational semantics, which show
 * that in any context where rho{x |->v} appears, there
 * is no way to get to the old rho(x). (See Exercise 
 * [->].) [*]
 * <env.c>=
 */
void bindval(Name name, Value val, Valenv env) {
    Value *vp = findval(name, env);
    if (vp != NULL)
        *vp = val;              /* safe optimization */
    else {
        env->nl = mkNL(name, env->nl);
        env->vl = mkVL(val,  env->vl);
    }
}
Esempio n. 3
0
static const char *
fixit (const char *type, const char *orig)
{
  definition *def;

  def = findval (defined, type, findit);
  if (def == NULL || def->def_kind != DEF_TYPEDEF)
    {
      return orig;
    }
  switch (def->def.ty.rel)
    {
    case REL_VECTOR:
      if (streq (def->def.ty.old_type, "opaque"))
	return ("char");
      else
	return (def->def.ty.old_type);
    case REL_ALIAS:
      return (fixit (def->def.ty.old_type, orig));
    default:
      return orig;
    }
}
Esempio n. 4
0
void BST<elemtype>::find(elemtype valu){
	findval(root,valu);
}
/*
 * We fetch a value through the pointer returned by
 * [[findval]], if any.
 * <env.c>=
 */
Value fetchval(Name name, Valenv env) {
    Value *vp = findval(name, env);
    assert(vp != NULL);
    return *vp;
}
/*
 * A name is bound if the find function found it.
 * <env.c>=
 */
int isvalbound(Name name, Valenv env) {
    return findval(name, env) != NULL;
}