Some embedded platforms do not wish to support the C library functionality
for handling wchar_t because they have no use for it. It makes sense for
libc++ to work properly on those platforms, so this commit adds a carve-out
of functionality for wchar_t.
Unfortunately, unlike some other carve-outs (e.g. random device), this
patch touches several parts of the library. However, despite the wide
impact of this patch, I still think it is important to support this
configuration since it makes it much simpler to port libc++ to some
embedded platforms.
Differential Revision: https://reviews.llvm.org/D111265
This implements the initial version of the `std::formatter` class and its specializations. It also implements the following formatting functions:
- `format`
- `vformat`
- `format_to`
- `vformat_to`
- `format_to_n`
- `formatted_size`
All functions have a `char` and `wchar_t` version. Parsing the format-spec and
using the parsed format-spec hasn't been implemented. The code isn't optimized,
neither for speed, nor for size.
The goal is to have the rudimentary basics working, which can be used as a
basis to improve upon. The formatters used in this commit are simple stubs that
will be replaced by real formatters in later commits.
The formatters that are slated to be replaced in this patch series don't have
an availability macro to avoid merge conflicts.
Note the formatter for `bool` uses `0` and `1` instead of "false" and
"true". This will be fixed when the stub is replaced with a real
formatter.
Implements parts of:
- P0645 Text Formatting
Completes:
- LWG3539 format_to must not copy models of output_iterator<const charT&>
Reviewed By: ldionne, #libc, vitaut
Differential Revision: https://reviews.llvm.org/D96664
This implements the struct `__format_arg_store` and its dependencies:
* the class basic_format_arg,
* the class basic_format_args,
* the class basic_format_context,
* the function make_format_args,
* the function wmake_format_args,
* the function visit_format_arg,
* several Standard required typedefs.
The following parts will be implemented in a later patch:
* the child class `basic_format_arg::handle`,
* the function `basic_format_arg::basic_format_arg(const T* p)`.
The following extension has been implemented:
* the class basic_format_arg supports `__[u]int128_t` on platform where libc++ supports 128 bit integrals.
Implements parts of:
* P0645 Text Formatting
Completes:
* LWG3371 visit_format_arg and make_format_args are not hidden friends
* LWG3542 basic_format_arg mishandles basic_string_view with custom traits
Note https://mordante.github.io/blog/2021/06/05/format.html gives a bit more information about the goals and non-goals of this initial patch series.
Reviewed By: #libc, ldionne, vitaut
Differential Revision: https://reviews.llvm.org/D103357
Louis Dionne