64171744dc
## Summary Part of #13694 Narrow in or-patterns by taking the type union of the type constraints in each disjunct pattern. ## Test Plan Add new tests to narrow/match.md --------- Co-authored-by: Carl Meyer <carl@astral.sh>
3.0 KiB
3.0 KiB
Narrowing for match statements
Single match pattern
def _(flag: bool):
x = None if flag else 1
reveal_type(x) # revealed: None | Literal[1]
y = 0
match x:
case None:
y = x
reveal_type(y) # revealed: Literal[0] | None
Class patterns
def get_object() -> object:
return object()
class A: ...
class B: ...
x = get_object()
reveal_type(x) # revealed: object
match x:
case A():
reveal_type(x) # revealed: A
case B():
# TODO could be `B & ~A`
reveal_type(x) # revealed: B
reveal_type(x) # revealed: object
Class pattern with guard
def get_object() -> object:
return object()
class A:
def y() -> int:
return 1
class B: ...
x = get_object()
reveal_type(x) # revealed: object
match x:
case A() if reveal_type(x): # revealed: A
pass
case B() if reveal_type(x): # revealed: B
pass
reveal_type(x) # revealed: object
Value patterns
def get_object() -> object:
return object()
x = get_object()
reveal_type(x) # revealed: object
match x:
case "foo":
reveal_type(x) # revealed: Literal["foo"]
case 42:
reveal_type(x) # revealed: Literal[42]
case 6.0:
reveal_type(x) # revealed: float
case 1j:
reveal_type(x) # revealed: complex
case b"foo":
reveal_type(x) # revealed: Literal[b"foo"]
reveal_type(x) # revealed: object
Value patterns with guard
def get_object() -> object:
return object()
x = get_object()
reveal_type(x) # revealed: object
match x:
case "foo" if reveal_type(x): # revealed: Literal["foo"]
pass
case 42 if reveal_type(x): # revealed: Literal[42]
pass
case 6.0 if reveal_type(x): # revealed: float
pass
case 1j if reveal_type(x): # revealed: complex
pass
case b"foo" if reveal_type(x): # revealed: Literal[b"foo"]
pass
reveal_type(x) # revealed: object
Or patterns
def get_object() -> object:
return object()
x = get_object()
reveal_type(x) # revealed: object
match x:
case "foo" | 42 | None:
reveal_type(x) # revealed: Literal["foo", 42] | None
case "foo" | tuple():
reveal_type(x) # revealed: Literal["foo"] | tuple
case True | False:
reveal_type(x) # revealed: bool
case 3.14 | 2.718 | 1.414:
reveal_type(x) # revealed: float
reveal_type(x) # revealed: object
Or patterns with guard
def get_object() -> object:
return object()
x = get_object()
reveal_type(x) # revealed: object
match x:
case "foo" | 42 | None if reveal_type(x): # revealed: Literal["foo", 42] | None
pass
case "foo" | tuple() if reveal_type(x): # revealed: Literal["foo"] | tuple
pass
case True | False if reveal_type(x): # revealed: bool
pass
case 3.14 | 2.718 | 1.414 if reveal_type(x): # revealed: float
pass
reveal_type(x) # revealed: object