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## Summary Minor follow-up to #13917 — thanks @AlexWaygood for the post-merge review. - Add SliceLiteralType::as_tuple - Use .expect() instead of SAFETY comment - Match on ::try_from result - Add TODO comment regarding raising a diagnostic for `"foo"["bar":"baz"]`
3.1 KiB
3.1 KiB
String subscripts
Indexing
s = "abcde"
reveal_type(s[0]) # revealed: Literal["a"]
reveal_type(s[1]) # revealed: Literal["b"]
reveal_type(s[-1]) # revealed: Literal["e"]
reveal_type(s[-2]) # revealed: Literal["d"]
reveal_type(s[False]) # revealed: Literal["a"]
reveal_type(s[True]) # revealed: Literal["b"]
a = s[8] # error: [index-out-of-bounds] "Index 8 is out of bounds for string `Literal["abcde"]` with length 5"
reveal_type(a) # revealed: Unknown
b = s[-8] # error: [index-out-of-bounds] "Index -8 is out of bounds for string `Literal["abcde"]` with length 5"
reveal_type(b) # revealed: Unknown
def int_instance() -> int: ...
a = "abcde"[int_instance()]
# TODO: Support overloads... Should be `str`
reveal_type(a) # revealed: @Todo
Slices
s = "abcde"
reveal_type(s[0:0]) # revealed: Literal[""]
reveal_type(s[0:1]) # revealed: Literal["a"]
reveal_type(s[0:2]) # revealed: Literal["ab"]
reveal_type(s[0:5]) # revealed: Literal["abcde"]
reveal_type(s[0:6]) # revealed: Literal["abcde"]
reveal_type(s[1:3]) # revealed: Literal["bc"]
reveal_type(s[-3:5]) # revealed: Literal["cde"]
reveal_type(s[-4:-2]) # revealed: Literal["bc"]
reveal_type(s[-10:10]) # revealed: Literal["abcde"]
reveal_type(s[0:]) # revealed: Literal["abcde"]
reveal_type(s[2:]) # revealed: Literal["cde"]
reveal_type(s[5:]) # revealed: Literal[""]
reveal_type(s[:2]) # revealed: Literal["ab"]
reveal_type(s[:0]) # revealed: Literal[""]
reveal_type(s[:2]) # revealed: Literal["ab"]
reveal_type(s[:10]) # revealed: Literal["abcde"]
reveal_type(s[:]) # revealed: Literal["abcde"]
reveal_type(s[::-1]) # revealed: Literal["edcba"]
reveal_type(s[::2]) # revealed: Literal["ace"]
reveal_type(s[-2:-5:-1]) # revealed: Literal["dcb"]
reveal_type(s[::-2]) # revealed: Literal["eca"]
reveal_type(s[-1::-3]) # revealed: Literal["eb"]
reveal_type(s[None:2:None]) # revealed: Literal["ab"]
reveal_type(s[1:None:1]) # revealed: Literal["bcde"]
reveal_type(s[None:None:None]) # revealed: Literal["abcde"]
start = 1
stop = None
step = 2
reveal_type(s[start:stop:step]) # revealed: Literal["bd"]
reveal_type(s[False:True]) # revealed: Literal["a"]
reveal_type(s[True:3]) # revealed: Literal["bc"]
s[0:4:0] # error: [zero-stepsize-in-slice]
s[:4:0] # error: [zero-stepsize-in-slice]
s[0::0] # error: [zero-stepsize-in-slice]
s[::0] # error: [zero-stepsize-in-slice]
def int_instance() -> int: ...
substring1 = s[int_instance() : int_instance()]
# TODO: Support overloads... Should be `LiteralString`
reveal_type(substring1) # revealed: @Todo
def str_instance() -> str: ...
substring2 = str_instance()[0:5]
# TODO: Support overloads... Should be `str`
reveal_type(substring2) # revealed: @Todo
Unsupported slice types
# TODO: It would be great if we raised an error here. This can be done once
# we have support for overloads and generics, and once typeshed has a more
# precise annotation for `str.__getitem__`, that makes use of the generic
# `slice[..]` type. We could then infer `slice[str, str]` here and see that
# it doesn't match the signature of `str.__getitem__`.
"foo"["bar":"baz"]