/*-------------------------------------------------------------------------*/
svalue_t *
f_baseof (svalue_t *sp)
/* EFUN baseof()
*
* int baseof(struct b, struct s)
*
* Test if the type of struct <b> is a base of struct <s> (the values of
* <b> and <s> are irrelevant). Results are:
* 0: <b> is not a base of <s>, nor is <b> of equal type as <s> (though <s>
* might be a base of <b>).
* 1: <b> is a true base of <s>
* 2: <b> and <s> are the same struct type
*/
{
int rc;
/* Get the arguments from the stack */
rc = struct_baseof(sp[-1].u.strct->type, sp[0].u.strct->type);
/* Remove the arguments and push the result */
free_svalue(sp); sp--;
free_svalue(sp);
put_number(sp, rc);
return sp;
} /* f_baseof() */
/*-------------------------------------------------------------------------*/
static lpctype_t *
internal_get_common_type(lpctype_t *t1, lpctype_t* t2, bool find_one)
/* Determine the intersection of both types.
* Returns NULL if there is no common type.
* If one of both types is TYPE_UNKNOWN, then
* the result will by TYPE_UNKNOWN, too.
*
* If <find_one> is true, then it may finish even if only a part
* of the result type was found (used for has_common_type()).
*/
{
/* Hopefully the most common case. */
if (t1 && t1 == t2)
return ref_lpctype(t1);
/* We can't return NULL, as this is an error condition. */
if (t1 == NULL && t2 == NULL)
return lpctype_mixed;
else if (t1 == NULL)
return ref_lpctype(t2);
else if (t2 == NULL)
return ref_lpctype(t1);
if (t2->t_class == TCLASS_UNION && t1->t_class != TCLASS_UNION)
{
/* Switch them, so t2 is not a union unless t1 is one, too. */
lpctype_t *temp; temp = t1; t1 = t2; t2 = temp;
}
/* Some shortcuts, before we're diving into t1.*/
if (t2->t_class == TCLASS_PRIMARY)
{
switch (t2->t_primary)
{
case TYPE_UNKNOWN:
return ref_lpctype(t2);
case TYPE_ANY:
return ref_lpctype(t1);
default:
break;
}
}
switch (t1->t_class)
{
case TCLASS_PRIMARY:
switch (t1->t_primary)
{
case TYPE_UNKNOWN:
return ref_lpctype(t1);
case TYPE_ANY:
return ref_lpctype(t2);
default:
/* Primary types besides the above exceptions should
be identical (checked at the beginning of this function). */
return NULL;
}
case TCLASS_STRUCT:
if (t2->t_class != TCLASS_STRUCT)
return NULL;
else if (t1->t_struct == NULL)
return ref_lpctype(t2);
else if (t2->t_struct == NULL)
return ref_lpctype(t1);
/* This is somewhat counterintuitive, but the derived struct
is more specialized, so it is the result of the intersection. */
else if (struct_baseof(t1->t_struct, t2->t_struct))
return ref_lpctype(t2);
else if (struct_baseof(t2->t_struct, t1->t_struct))
return ref_lpctype(t1);
else
return NULL;
case TCLASS_ARRAY:
if (t2->t_class != TCLASS_ARRAY)
return NULL;
else
{
lpctype_t *common_element = get_common_type(t1->t_array.element, t2->t_array.element);
lpctype_t *result = get_array_type(common_element);
free_lpctype(common_element);
return result;
}
case TCLASS_UNION:
{
lpctype_t *result = NULL;
while (true)
{
lpctype_t *base = t1->t_class == TCLASS_UNION ? t1->t_union.member : t1;
lpctype_t *common_base = get_common_type(t2, base);
lpctype_t *oldresult = result;
if (find_one && common_base)
return common_base;
result = get_union_type(result, common_base);
free_lpctype(common_base);
free_lpctype(oldresult);
if (t1->t_class == TCLASS_UNION)
t1 = t1->t_union.head;
else
break;
}
return result;
}
default:
fatal("Unknown type class %d!\n", t1->t_class);
return NULL;
}
} /* internal_get_common_type() */
