def typed_dict_setdefault_callback(ctx: MethodContext) -> Type:
"""Type check TypedDict.setdefault and infer a precise return type."""
if (isinstance(ctx.type, TypedDictType) and len(ctx.arg_types) == 2
and len(ctx.arg_types[0]) == 1 and len(ctx.arg_types[1]) == 1):
keys = try_getting_str_literals(ctx.args[0][0], ctx.arg_types[0][0])
if keys is None:
ctx.api.fail(message_registry.TYPEDDICT_KEY_MUST_BE_STRING_LITERAL,
ctx.context)
return AnyType(TypeOfAny.from_error)
default_type = ctx.arg_types[1][0]
value_types = []
for key in keys:
value_type = ctx.type.items.get(key)
if value_type is None:
ctx.api.msg.typeddict_key_not_found(ctx.type, key, ctx.context)
return AnyType(TypeOfAny.from_error)
# The signature_callback above can't always infer the right signature
# (e.g. when the expression is a variable that happens to be a Literal str)
# so we need to handle the check ourselves here and make sure the provided
# default can be assigned to all key-value pairs we're updating.
if not is_subtype(default_type, value_type):
ctx.api.msg.typeddict_setdefault_arguments_inconsistent(
default_type, value_type, ctx.context)
return AnyType(TypeOfAny.from_error)
value_types.append(value_type)
return make_simplified_union(value_types)
return ctx.default_return_type
def typed_dict_get_callback(ctx: MethodContext) -> Type:
"""Infer a precise return type for TypedDict.get with literal first argument."""
if (isinstance(ctx.type, TypedDictType) and len(ctx.arg_types) >= 1
and len(ctx.arg_types[0]) == 1):
keys = try_getting_str_literals(ctx.args[0][0], ctx.arg_types[0][0])
if keys is None:
return ctx.default_return_type
output_types = [] # type: List[Type]
for key in keys:
value_type = get_proper_type(ctx.type.items.get(key))
if value_type is None:
ctx.api.msg.typeddict_key_not_found(ctx.type, key, ctx.context)
return AnyType(TypeOfAny.from_error)
if len(ctx.arg_types) == 1:
output_types.append(value_type)
elif (len(ctx.arg_types) == 2 and len(ctx.arg_types[1]) == 1
and len(ctx.args[1]) == 1):
default_arg = ctx.args[1][0]
if (isinstance(default_arg, DictExpr)
and len(default_arg.items) == 0
and isinstance(value_type, TypedDictType)):
# Special case '{}' as the default for a typed dict type.
output_types.append(
value_type.copy_modified(required_keys=set()))
else:
output_types.append(value_type)
output_types.append(ctx.arg_types[1][0])
if len(ctx.arg_types) == 1:
output_types.append(NoneType())
return make_simplified_union(output_types)
return ctx.default_return_type
def typed_dict_pop_callback(ctx: MethodContext) -> Type:
"""Type check and infer a precise return type for TypedDict.pop."""
if (isinstance(ctx.type, TypedDictType) and len(ctx.arg_types) >= 1
and len(ctx.arg_types[0]) == 1):
keys = try_getting_str_literals(ctx.args[0][0], ctx.arg_types[0][0])
if keys is None:
ctx.api.fail(message_registry.TYPEDDICT_KEY_MUST_BE_STRING_LITERAL,
ctx.context)
return AnyType(TypeOfAny.from_error)
value_types = []
for key in keys:
if key in ctx.type.required_keys:
ctx.api.msg.typeddict_key_cannot_be_deleted(
ctx.type, key, ctx.context)
value_type = ctx.type.items.get(key)
if value_type:
value_types.append(value_type)
else:
ctx.api.msg.typeddict_key_not_found(ctx.type, key, ctx.context)
return AnyType(TypeOfAny.from_error)
if len(ctx.args[1]) == 0:
return make_simplified_union(value_types)
elif (len(ctx.arg_types) == 2 and len(ctx.arg_types[1]) == 1
and len(ctx.args[1]) == 1):
return make_simplified_union([*value_types, ctx.arg_types[1][0]])
return ctx.default_return_type
def typed_dict_delitem_callback(ctx: MethodContext) -> Type:
"""Type check TypedDict.__delitem__."""
if (isinstance(ctx.type, TypedDictType)
and len(ctx.arg_types) == 1
and len(ctx.arg_types[0]) == 1):
keys = try_getting_str_literals(ctx.args[0][0], ctx.arg_types[0][0])
if keys is None:
ctx.api.fail(message_registry.TYPEDDICT_KEY_MUST_BE_STRING_LITERAL, ctx.context)
return AnyType(TypeOfAny.from_error)
for key in keys:
if key in ctx.type.required_keys:
ctx.api.msg.typeddict_key_cannot_be_deleted(ctx.type, key, ctx.context)
elif key not in ctx.type.items:
ctx.api.msg.typeddict_key_not_found(ctx.type, key, ctx.context)
return ctx.default_return_type