This will change behaviour for moved-from `Optional<T>`s, since they
will now no longer clear their value if `T` is trivial. However, a
moved-from value should be considered to be in an unspecified state.
Use `Optional<T>::clear` or `Optional<T>::release_value` instead.
C++ will jovially select the implicit conversion operator, even if it's
complete bogus, such as for unknown-size types or non-destructible
types. Therefore, all such conversions (which incur a copy) must
(unfortunately) be explicit so that non-copyable types continue to work.
NOTE: We make an exception for trivially copyable types, since they
are, well, trivially copyable.
Co-authored-by: kleines Filmröllchen <filmroellchen@serenityos.org>
This makes them trivially copyable/movable, silencing
> "parameter is copied for each invocation"
warnings on `Optional<T&>`, which are unnecessairy,
since `Optional<T&>` is just a trivially copyable pointer.
This creates a slight change in behaviour when moving out of an
`Optional<T&>`, since the moved-from optional no longer gets cleared.
Moved-from values should be considered to be in an undefined state,
and if clearing a moved-from `Optional<T&>` is desired, you should be
using `Optional<T&>::release_value()` instead.
There was an existing check to ensure that `U` was an lvalue reference,
but when this check fails, overload resolution will just move right on
to the copy asignment operator, which will cause the temporary to be
assigned anyway.
Disallowing `Optional<T&>`s to be created from temporaries entirely
would be undesired, since existing code has valid reasons for creating
`Optional<T&>`s from temporaries, such as for function call arguments.
This fix explicitly deletes the `Optional::operator=(U&&)` operator,
so overload resolution stops.
This commit un-deprecates DeprecatedString, and repurposes it as a byte
string.
As the null state has already been removed, there are no other
particularly hairy blockers in repurposing this type as a byte string
(what it _really_ is).
This commit is auto-generated:
$ xs=$(ack -l \bDeprecatedString\b\|deprecated_string AK Userland \
Meta Ports Ladybird Tests Kernel)
$ perl -pie 's/\bDeprecatedString\b/ByteString/g;
s/deprecated_string/byte_string/g' $xs
$ clang-format --style=file -i \
$(git diff --name-only | grep \.cpp\|\.h)
$ gn format $(git ls-files '*.gn' '*.gni')
We have a new, improved string type coming up in AK (OOM aware, no null
state), and while it's going to use UTF-8, the name UTF8String is a
mouthful - so let's free up the String name by renaming the existing
class.
Making the old one have an annoying name will hopefully also help with
quick adoption :^)
Each of these strings would previously rely on StringView's char const*
constructor overload, which would call __builtin_strlen on the string.
Since we now have operator ""sv, we can replace these with much simpler
versions. This opens the door to being able to remove
StringView(char const*).
No functional changes.
This implements Optional<T&> as a T*, whose presence has been missing
since the early days of Optional.
As a lot of find_foo() APIs return an Optional<T> which imposes a
pointless copy on the underlying value, and can sometimes be very
misleading, with this change, those APIs can return Optional<T&>.
This avoids a value copy when calling value() or value_or() on a
temporary Optional. This is very common when using the HashMap::get()
API like this:
auto value = hash_map.get(key).value_or(fallback_value);
This patch introduces a new operator== to compare an Optional to its
contained type directly. If the Optional does not contain a value, the
comparison will always return false.
This also adds a test case for the new behavior as well as comparison
between Optional objects themselves.
