Formatting code is extracted to _M_format_to function, that produced output
to specified iterator. This function is now invoked either with __fc.out()
directly (if width is not specified) or _Padding_sink::out().
This avoid formatting to temporary string if no padding is requested,
and minimize allocations otherwise. For more details see commit message of
r16-142-g01e5ef3e8b91288f5d387a27708f9f8979a50edf.
This should not increase number of instantiations, as implementation only
produce basis_format_context with _Sink_iter as iterator, which is also
_Padding_sink iterator.
libstdc++-v3/ChangeLog:
* include/bits/chrono_io.h (__formatter_chrono::_M_format_to):
Extracted from _M_format.
(__formatter_chrono::_M_format): Use _Padding_sink and delegate
to _M_format_to.
---
I have checked that there are no other calls to out() in this file,
so _M_format_to uses only __out, and not iterator from __fc.
Testing on x86_64-linux. OK for trunk?
libstdc++-v3/include/bits/chrono_io.h | 55 ++++++++++-----------------
1 file changed, 20 insertions(+), 35 deletions(-)
diff --git a/libstdc++-v3/include/bits/chrono_io.h
b/libstdc++-v3/include/bits/chrono_io.h
index 620227a9f35..ace8b9f2629 100644
--- a/libstdc++-v3/include/bits/chrono_io.h
+++ b/libstdc++-v3/include/bits/chrono_io.h
@@ -503,9 +503,7 @@ namespace __format
_M_format(const _Tp& __t, _FormatContext& __fc,
bool __is_neg = false) const
{
- auto __first = _M_spec._M_chrono_specs.begin();
- const auto __last = _M_spec._M_chrono_specs.end();
- if (__first == __last)
+ if (_M_spec._M_chrono_specs.empty())
return _M_format_to_ostream(__t, __fc, __is_neg);
#if defined _GLIBCXX_USE_NL_LANGINFO_L && __CHAR_BIT__ == 8
@@ -525,29 +523,29 @@ namespace __format
__fc._M_loc = __with_encoding_conversion(__loc);
}
#endif
-
- _Sink_iter<_CharT> __out;
- __format::_Str_sink<_CharT> __sink;
- bool __write_direct = false;
- if constexpr (is_same_v<typename _FormatContext::iterator,
- _Sink_iter<_CharT>>)
- {
- if (_M_spec._M_width_kind == __format::_WP_none)
- {
- __out = __fc.out();
- __write_direct = true;
- }
- else
- __out = __sink.out();
- }
- else
- __out = __sink.out();
-
// formatter<duration> passes the correct value of __is_neg
// for durations but for hh_mm_ss we decide it here.
if constexpr (__is_specialization_of<_Tp, chrono::hh_mm_ss>)
__is_neg = __t.is_negative();
+ const size_t __padwidth = _M_spec._M_get_width(__fc);
+ if (__padwidth == 0)
+ return _M_format_to(__t, __fc.out(), __fc, __is_neg);
+
+ using _Out = typename _FormatContext::iterator;
+ _Padding_sink<_Out, _CharT> __sink(__fc.out(), __padwidth);
+ _M_format_to(__t, __sink.out(), __fc, __is_neg);
+ return __sink._M_finish(_M_spec._M_align, _M_spec._M_fill);
+ }
+
+ template<typename _Tp, typename _Out, typename _FormatContext>
+ _Out
+ _M_format_to(const _Tp& __t, _Out __out, _FormatContext& __fc,
+ bool __is_neg) const
+ {
+ auto __first = _M_spec._M_chrono_specs.begin();
+ const auto __last = _M_spec._M_chrono_specs.end();
+
auto __print_sign = [&__is_neg, &__out] {
if constexpr (chrono::__is_duration_v<_Tp>
|| __is_specialization_of<_Tp, chrono::hh_mm_ss>)
@@ -699,20 +697,7 @@ namespace __format
}
}
while (__first != __last);
-
- if constexpr (is_same_v<typename _FormatContext::iterator,
- _Sink_iter<_CharT>>)
- if (__write_direct)
- return __out;
-
- auto __str = __sink.view();
- size_t __width;
- if constexpr (__unicode::__literal_encoding_is_unicode<_CharT>())
- __width = __unicode::__field_width(__str);
- else
- __width = __str.size();
- return __format::__write_padded_as_spec(__str, __width,
- __fc, _M_spec);
+ return std::move(__out);
}
_ChronoSpec<_CharT> _M_spec;
--
2.49.0
