168ade72f8
in in {fmt} before v10, it provides the specialization of `fmt::formatter<..>`
for `std::string_view` as well as the specialization of `fmt::formatter<..>`
for `fmt::string_view` which is an implementation builtin in {fmt} for
compatibility of pre-C++17. and this type is used even if the code is
compiled with C++ stadandard greater or equal to C++17. also, before v10,
the `fmt::formatter<std::string_view>::format()` is defined so it accepts
`std::string_view`. after v10, `fmt::formatter<std::string_view>` still
exists, but it is now defined using `format_as()` machinery, so it's
`format()` method does not actually accept `std::string_view`, it
accepts `fmt::string_view`, as the former can be converted to
`fmt::string_view`.
this is why we can inherit from `fmt::formatter<std::string_view>` and
use `formatter<std::string_view>::format(foo, ctx);` to implement the
`format()` method with {fmt} v9, but we cannot do this with {fmt} v10,
and we would have following compilation failure:
```
FAILED: service/CMakeFiles/service.dir/RelWithDebInfo/topology_state_machine.cc.o
/home/kefu/.local/bin/clang++ -DFMT_DEPRECATED_OSTREAM -DFMT_SHARED -DSCYLLA_BUILD_MODE=release -DSEASTAR_API_LEVEL=7 -DSEASTAR_LOGGER_COMPILE_TIME_FMT -DSEASTAR_LOGGER_TYPE_STDOUT -DSEASTAR_SCHEDULING_GROUPS_COUNT=16 -DSEASTAR_SSTRING -DXXH_PRIVATE_API -DCMAKE_INTDIR=\"RelWithDebInfo\" -I/home/kefu/dev/scylladb -I/home/kefu/dev/scylladb/build/gen -I/home/kefu/dev/scylladb/seastar/include -I/home/kefu/dev/scylladb/build/seastar/gen/include -I/home/kefu/dev/scylladb/build/seastar/gen/src -ffunction-sections -fdata-sections -O3 -g -gz -std=gnu++20 -fvisibility=hidden -Wall -Werror -Wextra -Wno-error=deprecated-declarations -Wimplicit-fallthrough -Wno-c++11-narrowing -Wno-deprecated-copy -Wno-mismatched-tags -Wno-missing-field-initializers -Wno-overloaded-virtual -Wno-unsupported-friend -Wno-enum-constexpr-conversion -Wno-unused-parameter -ffile-prefix-map=/home/kefu/dev/scylladb=. -march=westmere -mllvm -inline-threshold=2500 -fno-slp-vectorize -U_FORTIFY_SOURCE -Werror=unused-result -MD -MT service/CMakeFiles/service.dir/RelWithDebInfo/topology_state_machine.cc.o -MF service/CMakeFiles/service.dir/RelWithDebInfo/topology_state_machine.cc.o.d -o service/CMakeFiles/service.dir/RelWithDebInfo/topology_state_machine.cc.o -c /home/kefu/dev/scylladb/service/topology_state_machine.cc
/home/kefu/dev/scylladb/service/topology_state_machine.cc:254:41: error: no matching member function for call to 'format'
254 | return formatter<std::string_view>::format(it->second, ctx);
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~
/usr/include/fmt/core.h:2759:22: note: candidate function template not viable: no known conversion from 'seastar::basic_sstring<char, unsigned int, 15>' to 'const fmt::basic_string_view<char>' for 1st argument
2759 | FMT_CONSTEXPR auto format(const T& val, FormatContext& ctx) const
| ^ ~~~~~~~~~~~~
```
because the inherited `format()` method actually comes from
`fmt::formatter<fmt::string_view>`. to reduce the confusion, in this
change, we just inherit from `fmt::format<string_view>`, where
`string_view` is actually `fmt::string_view`. this follows
the document at
https://fmt.dev/latest/api.html#formatting-user-defined-types,
and since there is less indirection under the hood -- we do not
use the specialization created by `FMT_FORMAT_AS` which inherit
from `formatter<fmt::string_view>`, hopefully this can improve
the compilation speed a little bit. also, this change addresses
the build failure with {fmt} v10.
Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>
Closes scylladb/scylladb#18299
56 lines
1.5 KiB
C++
56 lines
1.5 KiB
C++
/*
|
|
* Copyright (C) 2015-present ScyllaDB
|
|
*/
|
|
|
|
/*
|
|
* SPDX-License-Identifier: AGPL-3.0-or-later
|
|
*/
|
|
|
|
#pragma once
|
|
|
|
#include "multiprecision_int.hh"
|
|
#include <boost/multiprecision/cpp_int.hpp>
|
|
#include <compare>
|
|
#include <concepts>
|
|
|
|
#include "bytes.hh"
|
|
|
|
uint64_t from_varint_to_integer(const utils::multiprecision_int& varint);
|
|
|
|
class big_decimal {
|
|
private:
|
|
int32_t _scale;
|
|
boost::multiprecision::cpp_int _unscaled_value;
|
|
public:
|
|
enum class rounding_mode {
|
|
HALF_EVEN,
|
|
};
|
|
|
|
explicit big_decimal(sstring_view text);
|
|
big_decimal();
|
|
big_decimal(int32_t scale, boost::multiprecision::cpp_int unscaled_value);
|
|
big_decimal(std::integral auto v) : big_decimal(0, v) {}
|
|
|
|
int32_t scale() const { return _scale; }
|
|
const boost::multiprecision::cpp_int& unscaled_value() const { return _unscaled_value; }
|
|
boost::multiprecision::cpp_rational as_rational() const;
|
|
|
|
sstring to_string() const;
|
|
|
|
std::strong_ordering operator<=>(const big_decimal& other) const;
|
|
|
|
big_decimal& operator+=(const big_decimal& other);
|
|
big_decimal& operator-=(const big_decimal& other);
|
|
big_decimal operator+(const big_decimal& other) const;
|
|
big_decimal operator-(const big_decimal& other) const;
|
|
big_decimal div(const ::uint64_t y, const rounding_mode mode) const;
|
|
};
|
|
|
|
template <>
|
|
struct fmt::formatter<big_decimal> : fmt::formatter<string_view> {
|
|
template <typename FormatContext>
|
|
auto format(const big_decimal& v, FormatContext& ctx) const {
|
|
return fmt::format_to(ctx.out(), "{}", v.to_string());
|
|
}
|
|
};
|