def instantiated_generic_structural_type_is_sub_type_of_other_instantiated_generic_structural_type_if_it_has_matching_attributes(self):
iterator = types.generic_structural_type("iterator", [types.covariant("T")], lambda T: [
types.attr("__iter__", types.func([], iterator(T))),
types.attr("__next__", types.func([], T)),
])
iterable = types.generic_structural_type("iterable", [types.covariant("T")], lambda T: [
types.attr("__iter__", types.func([], iterator(T))),
])
assert types.is_sub_type(
iterable(types.int_type),
iterator(types.int_type),
)
def type_is_instance_of_generic_type_when_type_is_direct_instantiation(self):
generic_type = types.generic_structural_type("box", ["T"], lambda T: [
types.attr("value", T)
])
class_type = types.class_type("boxed_int", [types.attr("value", "int")])
assert generic_type.is_instantiated_type(generic_type(types.int_type))
assert not generic_type.is_instantiated_type(class_type)
def recursive_instantiated_generic_structural_type_is_sub_type_of_same_instantiated_generic_structural_type_if_it_has_matching_attributes(self):
recursive = types.generic_structural_type("recursive", [types.covariant("T")], lambda T: [
types.attr("__iter__", types.func([], recursive(T))),
])
assert types.is_sub_type(
recursive(types.int_type),
recursive(types.int_type),
)
def invariant_type_parameter_can_be_unified_when_part_of_recursive_structural_type(self):
invariant_type_param = types.invariant("T")
recursive = types.generic_structural_type("recursive", [types.covariant("T")], lambda T: [
types.attr("__iter__", types.func([], recursive(T))),
])
assert types.is_sub_type(
recursive(invariant_type_param),
recursive(types.int_type),
unify=[invariant_type_param]
)
def instantiating_type_replaces_type_in_attributes(self):
generic_type = types.generic_structural_type("box", ["T"], lambda T: [
types.attr("value", T)
])
assert_equal(int_type, generic_type(int_type).attrs.type_of("value"))
