A format string like "{}" is quite common. In this case avoid parsing
the format-spec when it's not present. Before the parsing was always
called, therefore some refactoring is done to make sure the formatters
work properly when their parse member isn't called.
From the wording it's not entirely clear whether this optimization is
allowed
[tab:formatter]
```
and the range [pc.begin(), pc.end()) from the last call to f.parse(pc).
```
Implies there's always a call to `f.parse` even when the format-spec
isn't present. Therefore this optimization isn't done for handle
classes; it's unclear whether that would break user defined formatters.
The improvements give a small reduciton is code size:
719408 12472 488 732368 b2cd0 before
718824 12472 488 731784 b2a88 after
The performance benefits when not using a format-spec are:
```
Comparing ./formatter_int.libcxx.out-baseline to ./formatter_int.libcxx.out
Benchmark Time CPU Time Old Time New CPU Old CPU New
----------------------------------------------------------------------------------------------------------------------------------------------------
BM_Basic<uint32_t> -0.0688 -0.0687 67 62 67 62
BM_Basic<int32_t> -0.1105 -0.1107 73 65 73 65
BM_Basic<uint64_t> -0.1053 -0.1049 95 85 95 85
BM_Basic<int64_t> -0.0889 -0.0888 93 85 93 85
BM_BasicLow<__uint128_t> -0.0655 -0.0655 96 90 96 90
BM_BasicLow<__int128_t> -0.0693 -0.0694 97 90 97 90
BM_Basic<__uint128_t> -0.0359 -0.0359 256 247 256 247
BM_Basic<__int128_t> -0.0414 -0.0414 239 229 239 229
```
For the cases where a format-spec is used the results remain similar,
some are faster some are slower, differing per run.
Reviewed By: ldionne, #libc
Differential Revision: https://reviews.llvm.org/D129426
This changes the implementation of the formatter. Instead of inheriting
from a specialized parser all formatters will use the same generic
parser. This reduces the binary size.
The new parser contains some additional fields only used in the chrono
formatting. Since this doesn't change the size of the parser the fields
are in the generic parser. The parser is designed to fit in 128-bit,
making it cheap to pass by value.
The new format function is a const member function. This isn't required
by the Standard yet, but it will be after LWG-3636 is accepted.
Additionally P2286 adds a formattable concept which requires the member
function to be const qualified in C++23. This paper is likely to be
accepted in the 2022 July plenary.
This is based on D125606. That commit did the groundwork and did similar
changes for the string formatters.
Depends on D125606
Reviewed By: #libc, ldionne
Differential Revision: https://reviews.llvm.org/D128139
All supported compilers that support C++20 now support concepts. So, remove
`_LIB_LIBCPP_HAS_NO_CONCEPTS` in favor of `_LIBCPP_STD_VER > 17`. Similarly in
the tests, remove `// UNSUPPORTED: libcpp-no-concepts`.
Differential Revision: https://reviews.llvm.org/D121528
This commit reverts 5aaefa51 (and also partly 7f285f48e7 and b6d75682f9,
which were related to the original commit). As landed, 5aaefa51 had
unintended consequences on some downstream bots and didn't have proper
coverage upstream due to a few subtle things. Implementing this is
something we should do in libc++, however we'll first need to address
a few issues listed in https://reviews.llvm.org/D106124#3349710.
Differential Revision: https://reviews.llvm.org/D120683
libc++ has started splicing standard library headers into much more
fine-grained content for maintainability. It's very likely that outdated
and naive tooling (some of which is outside of LLVM's scope) will
suggest users include things such as <__ranges/access.h> instead of
<ranges>, and Hyrum's law suggests that users will eventually begin to
rely on this without the help of tooling. As such, this commit
intends to protect users from themselves, by making it a hard error for
anyone outside of the standard library to include libc++ detail headers.
Differential Revision: https://reviews.llvm.org/D106124
This is the first step towards disentangling the debug mode and assertions
in libc++. This patch doesn't make any functional change: it simply moves
_LIBCPP_ASSERT-related stuff to its own file so as to make it clear that
libc++ assertions and the debug mode are different things. Future patches
will make it possible to enable assertions without enabling the debug
mode.
Differential Revision: https://reviews.llvm.org/D119769
This properly implements the formatter for floating-point types.
Completes:
- P1652R1 Printf corner cases in std::format
- LWG 3250 std::format: # (alternate form) for NaN and inf
- LWG 3243 std::format and negative zeroes
Implements parts of:
- P0645 Text Formatting
Reviewed By: #libc, ldionne, vitaut
Differential Revision: https://reviews.llvm.org/D114001
The NFC part of D116809. We still want to enforce this in CI,
but the mechanism for that is still to-be-determined.
Differential Revision: https://reviews.llvm.org/D116809
Implements the formatter for all fundamental integer types
(except `char`, `wchar_t`, and `bool`).
[format.formatter.spec]/2.3
For each charT, for each cv-unqualified arithmetic type ArithmeticT other
than char, wchar_t, char8_t, char16_t, or char32_t, a specialization
```
template<> struct formatter<ArithmeticT, charT>;
```
This removes the stub implemented in D96664.
As an extension it adds partial support for 128-bit integer types.
Implements parts of:
- P0645 Text Formatting
- P1652 Printf corner cases in std::format
Completes:
- LWG-3248 #b, #B, #o, #x, and #X presentation types misformat negative numbers
Reviewed By: #libc, ldionne, vitaut
Differential Revision: https://reviews.llvm.org/D103433
Mark de Wever