// The subtype is an isect, the supertype could be anything.
static bool is_isect_subtype(ast_t* sub, ast_t* super)
{
if(ast_id(super) == TK_ISECTTYPE)
return is_isect_sub_isect(sub, super);
// One element of the intersection must be a subtype of super.
ast_t* child = ast_child(sub);
while(child != NULL)
{
if(is_subtype(child, super))
return true;
child = ast_sibling(child);
}
return false;
}
static bool is_isect_sub_x(ast_t* sub, ast_t* super, errorframe_t* errors)
{
switch(ast_id(super))
{
case TK_ISECTTYPE:
// (T1 & T2) <: (T3 & T4)
return is_isect_sub_isect(sub, super, errors);
case TK_NOMINAL:
{
ast_t* super_def = (ast_t*)ast_data(super);
// TODO: can satisfy the interface in aggregate
// (T1 & T2) <: I k
if(ast_id(super_def) == TK_INTERFACE)
{
// return is_isect_sub_interface(sub, super, errors);
}
break;
}
default: {}
}
// T1 <: T3 or T2 <: T3
// ---
// (T1 & T2) <: T3
for(ast_t* child = ast_child(sub);
child != NULL;
child = ast_sibling(child))
{
if(is_subtype(child, super, NULL))
return true;
}
if(errors != NULL)
{
ast_error_frame(errors, sub, "no element of %s is a subtype of %s",
ast_print_type(sub), ast_print_type(super));
}
return false;
}
