"""Miscellaneous type operations and helpers for use during type checking. NOTE: These must not be accessed from mypy.nodes or mypy.types to avoid import cycles. These must not be called from the semantic analysis main pass since these may assume that MROs are ready. """ from __future__ import annotations import itertools from typing import Any, Iterable, List, Sequence, Type as TypingType, TypeVar, cast from mypy.copytype import copy_type from mypy.expandtype import expand_type, expand_type_by_instance from mypy.maptype import map_instance_to_supertype from mypy.nodes import ( ARG_POS, ARG_STAR, ARG_STAR2, SYMBOL_FUNCBASE_TYPES, Decorator, Expression, FuncBase, FuncDef, FuncItem, OverloadedFuncDef, StrExpr, TypeInfo, Var, ) from mypy.state import state from mypy.types import ( ENUM_REMOVED_PROPS, AnyType, CallableType, FormalArgument, FunctionLike, Instance, LiteralType, NoneType, Overloaded, Parameters, ParamSpecType, ProperType, TupleType, Type, TypeAliasType, TypeOfAny, TypeQuery, TypeType, TypeVarLikeType, TypeVarTupleType, TypeVarType, UninhabitedType, UnionType, UnpackType, flatten_nested_unions, get_proper_type, get_proper_types, ) from mypy.typevars import fill_typevars def is_recursive_pair(s: Type, t: Type) -> bool: """Is this a pair of recursive types? There may be more cases, and we may be forced to use e.g. has_recursive_types() here, but this function is called in very hot code, so we try to keep it simple and return True only in cases we know may have problems. """ if isinstance(s, TypeAliasType) and s.is_recursive: return ( isinstance(get_proper_type(t), Instance) or isinstance(t, TypeAliasType) and t.is_recursive ) if isinstance(t, TypeAliasType) and t.is_recursive: return ( isinstance(get_proper_type(s), Instance) or isinstance(s, TypeAliasType) and s.is_recursive ) return False def tuple_fallback(typ: TupleType) -> Instance: """Return fallback type for a tuple.""" from mypy.join import join_type_list info = typ.partial_fallback.type if info.fullname != "builtins.tuple": return typ.partial_fallback items = [] for item in typ.items: if isinstance(item, UnpackType): unpacked_type = get_proper_type(item.type) if isinstance(unpacked_type, TypeVarTupleType): items.append(unpacked_type.upper_bound) elif isinstance(unpacked_type, TupleType): # TODO: might make sense to do recursion here to support nested unpacks # of tuple constants items.extend(unpacked_type.items) else: raise NotImplementedError else: items.append(item) return Instance(info, [join_type_list(items)]) def type_object_type_from_function( signature: FunctionLike, info: TypeInfo, def_info: TypeInfo, fallback: Instance, is_new: bool ) -> FunctionLike: # We first need to record all non-trivial (explicit) self types in __init__, # since they will not be available after we bind them. Note, we use explicit # self-types only in the defining class, similar to __new__ (but not exactly the same, # see comment in class_callable below). This is mostly useful for annotating library # classes such as subprocess.Popen. default_self = fill_typevars(info) if not is_new and not info.is_newtype: orig_self_types = [ ( it.arg_types[0] if it.arg_types and it.arg_types[0] != default_self and it.arg_kinds[0] == ARG_POS else None ) for it in signature.items ] else: orig_self_types = [None] * len(signature.items) # The __init__ method might come from a generic superclass 'def_info' # with type variables that do not map identically to the type variables of # the class 'info' being constructed. For example: # # class A(Generic[T]): # def __init__(self, x: T) -> None: ... # class B(A[List[T]]): # ... # # We need to map B's __init__ to the type (List[T]) -> None. signature = bind_self(signature, original_type=default_self, is_classmethod=is_new) signature = cast(FunctionLike, map_type_from_supertype(signature, info, def_info)) special_sig: str | None = None if def_info.fullname == "builtins.dict": # Special signature! special_sig = "dict" if isinstance(signature, CallableType): return class_callable(signature, info, fallback, special_sig, is_new, orig_self_types[0]) else: # Overloaded __init__/__new__. assert isinstance(signature, Overloaded) items: list[CallableType] = [] for item, orig_self in zip(signature.items, orig_self_types): items.append(class_callable(item, info, fallback, special_sig, is_new, orig_self)) return Overloaded(items) def class_callable( init_type: CallableType, info: TypeInfo, type_type: Instance, special_sig: str | None, is_new: bool, orig_self_type: Type | None = None, ) -> CallableType: """Create a type object type based on the signature of __init__.""" variables: list[TypeVarLikeType] = [] variables.extend(info.defn.type_vars) variables.extend(init_type.variables) from mypy.subtypes import is_subtype init_ret_type = get_proper_type(init_type.ret_type) orig_self_type = get_proper_type(orig_self_type) default_ret_type = fill_typevars(info) explicit_type = init_ret_type if is_new else orig_self_type if ( isinstance(explicit_type, (Instance, TupleType)) # We have to skip protocols, because it can be a subtype of a return type # by accident. Like `Hashable` is a subtype of `object`. See #11799 and isinstance(default_ret_type, Instance) and not default_ret_type.type.is_protocol # Only use the declared return type from __new__ or declared self in __init__ # if it is actually returning a subtype of what we would return otherwise. and is_subtype(explicit_type, default_ret_type, ignore_type_params=True) ): ret_type: Type = explicit_type else: ret_type = default_ret_type callable_type = init_type.copy_modified( ret_type=ret_type, fallback=type_type, name=None, variables=variables, special_sig=special_sig, ) c = callable_type.with_name(info.name) return c def map_type_from_supertype(typ: Type, sub_info: TypeInfo, super_info: TypeInfo) -> Type: """Map type variables in a type defined in a supertype context to be valid in the subtype context. Assume that the result is unique; if more than one type is possible, return one of the alternatives. For example, assume class D(Generic[S]): ... class C(D[E[T]], Generic[T]): ... Now S in the context of D would be mapped to E[T] in the context of C. """ # Create the type of self in subtype, of form t[a1, ...]. inst_type = fill_typevars(sub_info) if isinstance(inst_type, TupleType): inst_type = tuple_fallback(inst_type) # Map the type of self to supertype. This gets us a description of the # supertype type variables in terms of subtype variables, i.e. t[t1, ...] # so that any type variables in tN are to be interpreted in subtype # context. inst_type = map_instance_to_supertype(inst_type, super_info) # Finally expand the type variables in type with those in the previously # constructed type. Note that both type and inst_type may have type # variables, but in type they are interpreted in supertype context while # in inst_type they are interpreted in subtype context. This works even if # the names of type variables in supertype and subtype overlap. return expand_type_by_instance(typ, inst_type) def supported_self_type(typ: ProperType) -> bool: """Is this a supported kind of explicit self-types? Currently, this means a X or Type[X], where X is an instance or a type variable with an instance upper bound. """ if isinstance(typ, TypeType): return supported_self_type(typ.item) return isinstance(typ, TypeVarType) or ( isinstance(typ, Instance) and typ != fill_typevars(typ.type) ) F = TypeVar("F", bound=FunctionLike) def bind_self(method: F, original_type: Type | None = None, is_classmethod: bool = False) -> F: """Return a copy of `method`, with the type of its first parameter (usually self or cls) bound to original_type. If the type of `self` is a generic type (T, or Type[T] for classmethods), instantiate every occurrence of type with original_type in the rest of the signature and in the return type. original_type is the type of E in the expression E.copy(). It is None in compatibility checks. In this case we treat it as the erasure of the declared type of self. This way we can express "the type of self". For example: T = TypeVar('T', bound='A') class A: def copy(self: T) -> T: ... class B(A): pass b = B().copy() # type: B """ if isinstance(method, Overloaded): return cast( F, Overloaded([bind_self(c, original_type, is_classmethod) for c in method.items]) ) assert isinstance(method, CallableType) func = method if not func.arg_types: # Invalid method, return something. return cast(F, func) if func.arg_kinds[0] == ARG_STAR: # The signature is of the form 'def foo(*args, ...)'. # In this case we shouldn't drop the first arg, # since func will be absorbed by the *args. # TODO: infer bounds on the type of *args? return cast(F, func) self_param_type = get_proper_type(func.arg_types[0]) variables: Sequence[TypeVarLikeType] = [] if func.variables and supported_self_type(self_param_type): from mypy.infer import infer_type_arguments if original_type is None: # TODO: type check method override (see #7861). original_type = erase_to_bound(self_param_type) original_type = get_proper_type(original_type) all_ids = func.type_var_ids() typeargs = infer_type_arguments(all_ids, self_param_type, original_type, is_supertype=True) if ( is_classmethod # TODO: why do we need the extra guards here? and any(isinstance(get_proper_type(t), UninhabitedType) for t in typeargs) and isinstance(original_type, (Instance, TypeVarType, TupleType)) ): # In case we call a classmethod through an instance x, fallback to type(x) typeargs = infer_type_arguments( all_ids, self_param_type, TypeType(original_type), is_supertype=True ) ids = [tid for tid in all_ids if any(tid == t.id for t in get_type_vars(self_param_type))] # Technically, some constrains might be unsolvable, make them . to_apply = [t if t is not None else UninhabitedType() for t in typeargs] def expand(target: Type) -> Type: return expand_type(target, {id: to_apply[all_ids.index(id)] for id in ids}) arg_types = [expand(x) for x in func.arg_types[1:]] ret_type = expand(func.ret_type) variables = [v for v in func.variables if v.id not in ids] else: arg_types = func.arg_types[1:] ret_type = func.ret_type variables = func.variables original_type = get_proper_type(original_type) if isinstance(original_type, CallableType) and original_type.is_type_obj(): original_type = TypeType.make_normalized(original_type.ret_type) res = func.copy_modified( arg_types=arg_types, arg_kinds=func.arg_kinds[1:], arg_names=func.arg_names[1:], variables=variables, ret_type=ret_type, bound_args=[original_type], ) return cast(F, res) def erase_to_bound(t: Type) -> Type: # TODO: use value restrictions to produce a union? t = get_proper_type(t) if isinstance(t, TypeVarType): return t.upper_bound if isinstance(t, TypeType): if isinstance(t.item, TypeVarType): return TypeType.make_normalized(t.item.upper_bound) return t def callable_corresponding_argument( typ: CallableType | Parameters, model: FormalArgument ) -> FormalArgument | None: """Return the argument a function that corresponds to `model`""" by_name = typ.argument_by_name(model.name) by_pos = typ.argument_by_position(model.pos) if by_name is None and by_pos is None: return None if by_name is not None and by_pos is not None: if by_name == by_pos: return by_name # If we're dealing with an optional pos-only and an optional # name-only arg, merge them. This is the case for all functions # taking both *args and **args, or a pair of functions like so: # def right(a: int = ...) -> None: ... # def left(__a: int = ..., *, a: int = ...) -> None: ... from mypy.subtypes import is_equivalent if ( not (by_name.required or by_pos.required) and by_pos.name is None and by_name.pos is None and is_equivalent(by_name.typ, by_pos.typ) ): return FormalArgument(by_name.name, by_pos.pos, by_name.typ, False) return by_name if by_name is not None else by_pos def simple_literal_value_key(t: ProperType) -> tuple[str, ...] | None: """Return a hashable description of simple literal type. Return None if not a simple literal type. The return value can be used to simplify away duplicate types in unions by comparing keys for equality. For now enum, string or Instance with string last_known_value are supported. """ if isinstance(t, LiteralType): if t.fallback.type.is_enum or t.fallback.type.fullname == "builtins.str": assert isinstance(t.value, str) return "literal", t.value, t.fallback.type.fullname if isinstance(t, Instance): if t.last_known_value is not None and isinstance(t.last_known_value.value, str): return "instance", t.last_known_value.value, t.type.fullname return None def simple_literal_type(t: ProperType | None) -> Instance | None: """Extract the underlying fallback Instance type for a simple Literal""" if isinstance(t, Instance) and t.last_known_value is not None: t = t.last_known_value if isinstance(t, LiteralType): return t.fallback return None def is_simple_literal(t: ProperType) -> bool: """Fast way to check if simple_literal_value_key() would return a non-None value.""" if isinstance(t, LiteralType): return t.fallback.type.is_enum or t.fallback.type.fullname == "builtins.str" if isinstance(t, Instance): return t.last_known_value is not None and isinstance(t.last_known_value.value, str) return False def make_simplified_union( items: Sequence[Type], line: int = -1, column: int = -1, *, keep_erased: bool = False, contract_literals: bool = True, ) -> ProperType: """Build union type with redundant union items removed. If only a single item remains, this may return a non-union type. Examples: * [int, str] -> Union[int, str] * [int, object] -> object * [int, int] -> int * [int, Any] -> Union[int, Any] (Any types are not simplified away!) * [Any, Any] -> Any Note: This must NOT be used during semantic analysis, since TypeInfos may not be fully initialized. The keep_erased flag is used for type inference against union types containing type variables. If set to True, keep all ErasedType items. The contract_literals flag indicates whether we need to contract literal types back into a sum type. Set it to False when called by try_expanding_sum_type_ to_union(). """ # Step 1: expand all nested unions items = flatten_nested_unions(items) # Step 2: remove redundant unions simplified_set: Sequence[Type] = _remove_redundant_union_items(items, keep_erased) # Step 3: If more than one literal exists in the union, try to simplify if ( contract_literals and sum(isinstance(get_proper_type(item), LiteralType) for item in simplified_set) > 1 ): simplified_set = try_contracting_literals_in_union(simplified_set) return get_proper_type(UnionType.make_union(simplified_set, line, column)) def _remove_redundant_union_items(items: list[Type], keep_erased: bool) -> list[Type]: from mypy.subtypes import is_proper_subtype removed: set[int] = set() seen: set[tuple[str, ...]] = set() # NB: having a separate fast path for Union of Literal and slow path for other things # would arguably be cleaner, however it breaks down when simplifying the Union of two # different enum types as try_expanding_sum_type_to_union works recursively and will # trigger intermediate simplifications that would render the fast path useless for i, item in enumerate(items): proper_item = get_proper_type(item) if i in removed: continue # Avoid slow nested for loop for Union of Literal of strings/enums (issue #9169) k = simple_literal_value_key(proper_item) if k is not None: if k in seen: removed.add(i) continue # NB: one would naively expect that it would be safe to skip the slow path # always for literals. One would be sorely mistaken. Indeed, some simplifications # such as that of None/Optional when strict optional is false, do require that we # proceed with the slow path. Thankfully, all literals will have the same subtype # relationship to non-literal types, so we only need to do that walk for the first # literal, which keeps the fast path fast even in the presence of a mixture of # literals and other types. safe_skip = len(seen) > 0 seen.add(k) if safe_skip: continue # Keep track of the truthiness info for deleted subtypes which can be relevant cbt = cbf = False for j, tj in enumerate(items): proper_tj = get_proper_type(tj) if ( i == j # avoid further checks if this item was already marked redundant. or j in removed # if the current item is a simple literal then this simplification loop can # safely skip all other simple literals as two literals will only ever be # subtypes of each other if they are equal, which is already handled above. # However, if the current item is not a literal, it might plausibly be a # supertype of other literals in the union, so we must check them again. # This is an important optimization as is_proper_subtype is pretty expensive. or (k is not None and is_simple_literal(proper_tj)) ): continue # actual redundancy checks (XXX?) if is_redundant_literal_instance(proper_item, proper_tj) and is_proper_subtype( tj, item, keep_erased_types=keep_erased ): # We found a redundant item in the union. removed.add(j) cbt = cbt or tj.can_be_true cbf = cbf or tj.can_be_false # if deleted subtypes had more general truthiness, use that if not item.can_be_true and cbt: items[i] = true_or_false(item) elif not item.can_be_false and cbf: items[i] = true_or_false(item) return [items[i] for i in range(len(items)) if i not in removed] def _get_type_special_method_bool_ret_type(t: Type) -> Type | None: t = get_proper_type(t) if isinstance(t, Instance): bool_method = t.type.get("__bool__") if bool_method: callee = get_proper_type(bool_method.type) if isinstance(callee, CallableType): return callee.ret_type return None def true_only(t: Type) -> ProperType: """ Restricted version of t with only True-ish values """ t = get_proper_type(t) if not t.can_be_true: # All values of t are False-ish, so there are no true values in it return UninhabitedType(line=t.line, column=t.column) elif not t.can_be_false: # All values of t are already True-ish, so true_only is idempotent in this case return t elif isinstance(t, UnionType): # The true version of a union type is the union of the true versions of its components new_items = [true_only(item) for item in t.items] can_be_true_items = [item for item in new_items if item.can_be_true] return make_simplified_union(can_be_true_items, line=t.line, column=t.column) else: ret_type = _get_type_special_method_bool_ret_type(t) if ret_type and ret_type.can_be_false and not ret_type.can_be_true: new_t = copy_type(t) new_t.can_be_true = False return new_t new_t = copy_type(t) new_t.can_be_false = False return new_t def false_only(t: Type) -> ProperType: """ Restricted version of t with only False-ish values """ t = get_proper_type(t) if not t.can_be_false: if state.strict_optional: # All values of t are True-ish, so there are no false values in it return UninhabitedType(line=t.line) else: # When strict optional checking is disabled, everything can be # False-ish since anything can be None return NoneType(line=t.line) elif not t.can_be_true: # All values of t are already False-ish, so false_only is idempotent in this case return t elif isinstance(t, UnionType): # The false version of a union type is the union of the false versions of its components new_items = [false_only(item) for item in t.items] can_be_false_items = [item for item in new_items if item.can_be_false] return make_simplified_union(can_be_false_items, line=t.line, column=t.column) else: ret_type = _get_type_special_method_bool_ret_type(t) if ret_type and ret_type.can_be_true and not ret_type.can_be_false: new_t = copy_type(t) new_t.can_be_false = False return new_t new_t = copy_type(t) new_t.can_be_true = False return new_t def true_or_false(t: Type) -> ProperType: """ Unrestricted version of t with both True-ish and False-ish values """ t = get_proper_type(t) if isinstance(t, UnionType): new_items = [true_or_false(item) for item in t.items] return make_simplified_union(new_items, line=t.line, column=t.column) new_t = copy_type(t) new_t.can_be_true = new_t.can_be_true_default() new_t.can_be_false = new_t.can_be_false_default() return new_t def erase_def_to_union_or_bound(tdef: TypeVarLikeType) -> Type: # TODO(PEP612): fix for ParamSpecType if isinstance(tdef, ParamSpecType): return AnyType(TypeOfAny.from_error) assert isinstance(tdef, TypeVarType) if tdef.values: return make_simplified_union(tdef.values) else: return tdef.upper_bound def erase_to_union_or_bound(typ: TypeVarType) -> ProperType: if typ.values: return make_simplified_union(typ.values) else: return get_proper_type(typ.upper_bound) def function_type(func: FuncBase, fallback: Instance) -> FunctionLike: if func.type: assert isinstance(func.type, FunctionLike) return func.type else: # Implicit type signature with dynamic types. if isinstance(func, FuncItem): return callable_type(func, fallback) else: # Broken overloads can have self.type set to None. # TODO: should we instead always set the type in semantic analyzer? assert isinstance(func, OverloadedFuncDef) any_type = AnyType(TypeOfAny.from_error) dummy = CallableType( [any_type, any_type], [ARG_STAR, ARG_STAR2], [None, None], any_type, fallback, line=func.line, is_ellipsis_args=True, ) # Return an Overloaded, because some callers may expect that # an OverloadedFuncDef has an Overloaded type. return Overloaded([dummy]) def callable_type( fdef: FuncItem, fallback: Instance, ret_type: Type | None = None ) -> CallableType: # TODO: somewhat unfortunate duplication with prepare_method_signature in semanal if fdef.info and not fdef.is_static and fdef.arg_names: self_type: Type = fill_typevars(fdef.info) if fdef.is_class or fdef.name == "__new__": self_type = TypeType.make_normalized(self_type) args = [self_type] + [AnyType(TypeOfAny.unannotated)] * (len(fdef.arg_names) - 1) else: args = [AnyType(TypeOfAny.unannotated)] * len(fdef.arg_names) return CallableType( args, fdef.arg_kinds, fdef.arg_names, ret_type or AnyType(TypeOfAny.unannotated), fallback, name=fdef.name, line=fdef.line, column=fdef.column, implicit=True, # We need this for better error messages, like missing `self` note: definition=fdef if isinstance(fdef, FuncDef) else None, ) def try_getting_str_literals(expr: Expression, typ: Type) -> list[str] | None: """If the given expression or type corresponds to a string literal or a union of string literals, returns a list of the underlying strings. Otherwise, returns None. Specifically, this function is guaranteed to return a list with one or more strings if one of the following is true: 1. 'expr' is a StrExpr 2. 'typ' is a LiteralType containing a string 3. 'typ' is a UnionType containing only LiteralType of strings """ if isinstance(expr, StrExpr): return [expr.value] # TODO: See if we can eliminate this function and call the below one directly return try_getting_str_literals_from_type(typ) def try_getting_str_literals_from_type(typ: Type) -> list[str] | None: """If the given expression or type corresponds to a string Literal or a union of string Literals, returns a list of the underlying strings. Otherwise, returns None. For example, if we had the type 'Literal["foo", "bar"]' as input, this function would return a list of strings ["foo", "bar"]. """ return try_getting_literals_from_type(typ, str, "builtins.str") def try_getting_int_literals_from_type(typ: Type) -> list[int] | None: """If the given expression or type corresponds to an int Literal or a union of int Literals, returns a list of the underlying ints. Otherwise, returns None. For example, if we had the type 'Literal[1, 2, 3]' as input, this function would return a list of ints [1, 2, 3]. """ return try_getting_literals_from_type(typ, int, "builtins.int") T = TypeVar("T") def try_getting_literals_from_type( typ: Type, target_literal_type: TypingType[T], target_fullname: str ) -> list[T] | None: """If the given expression or type corresponds to a Literal or union of Literals where the underlying values correspond to the given target type, returns a list of those underlying values. Otherwise, returns None. """ typ = get_proper_type(typ) if isinstance(typ, Instance) and typ.last_known_value is not None: possible_literals: list[Type] = [typ.last_known_value] elif isinstance(typ, UnionType): possible_literals = list(typ.items) else: possible_literals = [typ] literals: list[T] = [] for lit in get_proper_types(possible_literals): if isinstance(lit, LiteralType) and lit.fallback.type.fullname == target_fullname: val = lit.value if isinstance(val, target_literal_type): literals.append(val) else: return None else: return None return literals def is_literal_type_like(t: Type | None) -> bool: """Returns 'true' if the given type context is potentially either a LiteralType, a Union of LiteralType, or something similar. """ t = get_proper_type(t) if t is None: return False elif isinstance(t, LiteralType): return True elif isinstance(t, UnionType): return any(is_literal_type_like(item) for item in t.items) elif isinstance(t, TypeVarType): return is_literal_type_like(t.upper_bound) or any( is_literal_type_like(item) for item in t.values ) else: return False def is_singleton_type(typ: Type) -> bool: """Returns 'true' if this type is a "singleton type" -- if there exists exactly only one runtime value associated with this type. That is, given two values 'a' and 'b' that have the same type 't', 'is_singleton_type(t)' returns True if and only if the expression 'a is b' is always true. Currently, this returns True when given NoneTypes, enum LiteralTypes, enum types with a single value and ... (Ellipses). Note that other kinds of LiteralTypes cannot count as singleton types. For example, suppose we do 'a = 100000 + 1' and 'b = 100001'. It is not guaranteed that 'a is b' will always be true -- some implementations of Python will end up constructing two distinct instances of 100001. """ typ = get_proper_type(typ) return typ.is_singleton_type() def try_expanding_sum_type_to_union(typ: Type, target_fullname: str) -> ProperType: """Attempts to recursively expand any enum Instances with the given target_fullname into a Union of all of its component LiteralTypes. For example, if we have: class Color(Enum): RED = 1 BLUE = 2 YELLOW = 3 class Status(Enum): SUCCESS = 1 FAILURE = 2 UNKNOWN = 3 ...and if we call `try_expanding_enum_to_union(Union[Color, Status], 'module.Color')`, this function will return Literal[Color.RED, Color.BLUE, Color.YELLOW, Status]. """ typ = get_proper_type(typ) if isinstance(typ, UnionType): items = [ try_expanding_sum_type_to_union(item, target_fullname) for item in typ.relevant_items() ] return make_simplified_union(items, contract_literals=False) elif isinstance(typ, Instance) and typ.type.fullname == target_fullname: if typ.type.is_enum: new_items = [] for name, symbol in typ.type.names.items(): if not isinstance(symbol.node, Var): continue # Skip these since Enum will remove it if name in ENUM_REMOVED_PROPS: continue new_items.append(LiteralType(name, typ)) return make_simplified_union(new_items, contract_literals=False) elif typ.type.fullname == "builtins.bool": return make_simplified_union( [LiteralType(True, typ), LiteralType(False, typ)], contract_literals=False ) return typ def try_contracting_literals_in_union(types: Sequence[Type]) -> list[ProperType]: """Contracts any literal types back into a sum type if possible. Will replace the first instance of the literal with the sum type and remove all others. If we call `try_contracting_union(Literal[Color.RED, Color.BLUE, Color.YELLOW])`, this function will return Color. We also treat `Literal[True, False]` as `bool`. """ proper_types = [get_proper_type(typ) for typ in types] sum_types: dict[str, tuple[set[Any], list[int]]] = {} marked_for_deletion = set() for idx, typ in enumerate(proper_types): if isinstance(typ, LiteralType): fullname = typ.fallback.type.fullname if typ.fallback.type.is_enum or isinstance(typ.value, bool): if fullname not in sum_types: sum_types[fullname] = ( set(typ.fallback.get_enum_values()) if typ.fallback.type.is_enum else {True, False}, [], ) literals, indexes = sum_types[fullname] literals.discard(typ.value) indexes.append(idx) if not literals: first, *rest = indexes proper_types[first] = typ.fallback marked_for_deletion |= set(rest) return list( itertools.compress( proper_types, [(i not in marked_for_deletion) for i in range(len(proper_types))] ) ) def coerce_to_literal(typ: Type) -> Type: """Recursively converts any Instances that have a last_known_value or are instances of enum types with a single value into the corresponding LiteralType. """ original_type = typ typ = get_proper_type(typ) if isinstance(typ, UnionType): new_items = [coerce_to_literal(item) for item in typ.items] return UnionType.make_union(new_items) elif isinstance(typ, Instance): if typ.last_known_value: return typ.last_known_value elif typ.type.is_enum: enum_values = typ.get_enum_values() if len(enum_values) == 1: return LiteralType(value=enum_values[0], fallback=typ) return original_type def get_type_vars(tp: Type) -> list[TypeVarType]: return tp.accept(TypeVarExtractor()) class TypeVarExtractor(TypeQuery[List[TypeVarType]]): def __init__(self) -> None: super().__init__(self._merge) def _merge(self, iter: Iterable[list[TypeVarType]]) -> list[TypeVarType]: out = [] for item in iter: out.extend(item) return out def visit_type_var(self, t: TypeVarType) -> list[TypeVarType]: return [t] def custom_special_method(typ: Type, name: str, check_all: bool = False) -> bool: """Does this type have a custom special method such as __format__() or __eq__()? If check_all is True ensure all items of a union have a custom method, not just some. """ typ = get_proper_type(typ) if isinstance(typ, Instance): method = typ.type.get(name) if method and isinstance(method.node, (SYMBOL_FUNCBASE_TYPES, Decorator, Var)): if method.node.info: return not method.node.info.fullname.startswith("builtins.") return False if isinstance(typ, UnionType): if check_all: return all(custom_special_method(t, name, check_all) for t in typ.items) return any(custom_special_method(t, name) for t in typ.items) if isinstance(typ, TupleType): return custom_special_method(tuple_fallback(typ), name, check_all) if isinstance(typ, CallableType) and typ.is_type_obj(): # Look up __method__ on the metaclass for class objects. return custom_special_method(typ.fallback, name, check_all) if isinstance(typ, AnyType): # Avoid false positives in uncertain cases. return True # TODO: support other types (see ExpressionChecker.has_member())? return False def is_redundant_literal_instance(general: ProperType, specific: ProperType) -> bool: if not isinstance(general, Instance) or general.last_known_value is None: return True if isinstance(specific, Instance) and specific.last_known_value == general.last_known_value: return True if isinstance(specific, UninhabitedType): return True return False def separate_union_literals(t: UnionType) -> tuple[Sequence[LiteralType], Sequence[Type]]: """Separate literals from other members in a union type.""" literal_items = [] union_items = [] for item in t.items: proper = get_proper_type(item) if isinstance(proper, LiteralType): literal_items.append(proper) else: union_items.append(item) return literal_items, union_items