The underlying CPU-specific instructions for operating on UTF-16 strings
behave differently for null inputs. Add an explicit check for this state
for consistency.
Currently, invoking StringBuilder::to_string will re-allocate the string
data to construct the String. This is wasteful both in terms of memory
and speed.
The goal here is to simply hand the string buffer over to String, and
let String take ownership of that buffer. To do this, StringBuilder must
have the same memory layout as Detail::StringData. This layout is just
the members of the StringData class followed by the string itself.
So when a StringBuilder is created, we reserve sizeof(StringData) bytes
at the front of the buffer. StringData can then construct itself into
the buffer with placement new.
Things to note:
* StringData must now be aware of the actual capacity of its buffer, as
that can be larger than the string size.
* We must take care not to pass ownership of inlined string buffers, as
these live on the stack.
Utf16View currently assumes host endianness. Add support for specifying
either big or little endianness (which we mostly just pipe through to
simdutf). This will allow using simdutf facilities with LibTextCodec.
The one behavior difference is that we will now actually fail on invalid
code units with Utf16View::to_utf8(AllowInvalidCodeUnits::No). It was
arguably a bug that this wasn't already the case.
currently crashes with an assertion failure in `String::repeated` if
malloc can't serve a `count * input_size` sized request, so add
`String::repeated_with_error` to propagate the error.
The idea is to eventually get rid of protected state in StringBase. To
do this, we first need to remove all references to m_data and
m_short_string from String.
This starts separating memory management of string data and string
utilities like `String::formatted`. This would also allow to reuse the
same storage in `DeprecatedString` in the future.
UTF8Decoder was already converting invalid data into replacement
characters while converting, so we know for sure we have valid UTF-8
by the time conversion is finished.
This patch adds a new StringBuilder::to_string_without_validation()
and uses it to make UTF8Decoder avoid half the work it was doing.
Instead of using a StringBuilder, add a String::repeated(String, N)
overload that takes advantage of knowing it's already all UTF-8.
This makes the following microbenchmark go 4x faster:
"foo".repeat(100_000_000)
And for single character strings, we can even go 10x faster:
"x".repeat(100_000_000)
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')
In cases where we know a string literal will fit in the short string
storage, we can do so at compile time without needing to handle error
propagation. If the provided string literal is too long, a compilation
error will be emitted due to the failed VERIFY statement being a non-
constant expression.
This implements a FlyString that will de-duplicate String instances. The
FlyString will store the raw encoded data of the String instance: If the
String is a short string, FlyString holds the String::ShortString bytes;
otherwise FlyString holds a pointer to the Detail::StringData.
FlyString itself does not know about String's storage or how to refcount
its Detail::StringData. It defers to String to implement these details.
