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Avoid specializing std::formatter for std::tm (not a great idea after all)

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Charless Milette
2021-11-15 15:27:34 -05:00
parent f6901606f5
commit 2d77ef92b0
5 changed files with 73 additions and 95 deletions
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59
include/spdlog/sinks/daily_file_sink.h
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@@ -5,9 +5,9 @@
#include <spdlog/common.h>
#include <spdlog/details/file_helper.h>
#include <spdlog/details/fmt_helper.h>
#include <spdlog/details/null_mutex.h>
#include <spdlog/fmt/fmt.h>
#include <spdlog/fmt/chrono.h>
#include <spdlog/sinks/base_sink.h>
#include <spdlog/details/os.h>
#include <spdlog/details/circular_q.h>
@@ -48,14 +48,57 @@ struct daily_filename_format_calculator
{
static filename_t calc_filename(const filename_t &filename, const tm &now_tm)
{
// generate fmt datetime format string, e.g. {:%Y-%m-%d}.
filename_t fmt_filename = fmt_lib::format(SPDLOG_FILENAME_T("{{:{}}}"), filename);
#if defined(SPDLOG_USE_STD_FORMAT)
return std::vformat(fmt_filename, std::make_format_args(now_tm));
#elif defined(_MSC_VER) && defined(SPDLOG_WCHAR_FILENAMES) // for some reason msvc doesn't allow fmt::runtime(..) with wchar here
return fmt::format(fmt_filename, now_tm);
// adapted from fmtlib
#ifdef SPDLOG_USE_STD_FORMAT
filename_t tm_format;
tm_format.append(filename);
// By appending an extra space we can distinguish an empty result that
// indicates insufficient buffer size from a guaranteed non-empty result
// https://github.com/fmtlib/fmt/issues/2238
tm_format.push_back(' ');
const size_t MIN_SIZE = 10;
filename_t buf;
buf.resize(MIN_SIZE);
for (;;)
{
size_t count = details::fmt_helper::strftime(buf.data(), buf.size(), tm_format.c_str(), &now_tm);
if (count != 0)
{
// Remove the extra space.
buf.resize(count - 1);
break;
}
buf.resize(buf.size() * 2);
}
return buf;
#else
return fmt::format(SPDLOG_FMT_RUNTIME(fmt_filename), now_tm);
fmt::basic_memory_buffer<Char> tm_format;
tm_format.append(specs.begin(), specs.end());
// By appending an extra space we can distinguish an empty result that
// indicates insufficient buffer size from a guaranteed non-empty result
// https://github.com/fmtlib/fmt/issues/2238
tm_format.push_back(' ');
tm_format.push_back('\0');
fmt::basic_memory_buffer<Char> buf;
size_t start = buf.size();
for (;;)
{
size_t size = buf.capacity() - start;
size_t count = details::fmt_helper:::strftime(&buf[start], size, &tm_format[0], &tm);
if (count != 0)
{
// Remove the extra space.
buf.resize(start + count - 1);
break;
}
const size_t MIN_GROWTH = 10;
buf.reserve(buf.capacity() + (size > MIN_GROWTH ? size : MIN_GROWTH));
}
return fmt::to_string(buf);
#endif
}
};