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Optimize to_string #1615

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Yexuan Xiao (YexuanXiao) wants to merge 8 commits into
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Optimize to_string #1615

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d9c702c
Optimize `to_string`
YexuanXiao Aug 3, 2026
a81cb51
Replace tab with space
YexuanXiao Aug 3, 2026
daa9e9f
Improve buffer size verification
YexuanXiao Aug 3, 2026
d790563
Fix WINRT_VERIFY_ check for bytes_written
YexuanXiao Aug 3, 2026
4120584
Update base_string.h
YexuanXiao Aug 7, 2026
fa9d953
Update base_string.h
YexuanXiao Aug 7, 2026
f7e67bf
Update base_string.h
YexuanXiao Aug 20, 2026
33fbb32
Merge branch 'master' into patch-7
YexuanXiao Aug 20, 2026
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18 changes: 10 additions & 8 deletions strings/base_string.h
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Original file line number Diff line number Diff line change
Expand Up @@ -674,14 +674,7 @@ WINRT_EXPORT namespace winrt
template <typename T, std::enable_if_t<std::is_same_v<T, bool>, int> = 0>
hstring to_hstring(T const value)
{
if (value)
{
return hstring{ L"true" };
}
else
{
return hstring{ L"false" };
}
return hstring{ value ? L"true" : L"false" };
}

inline hstring to_hstring(guid const& value)
Expand Down Expand Up @@ -719,8 +712,17 @@ WINRT_EXPORT namespace winrt
return{};
}

#if defined(__cpp_lib_string_resize_and_overwrite) && __cpp_lib_string_resize_and_overwrite >= 202110L
std::string result;
result.resize_and_overwrite(size, [&](char* buffer, std::size_t) -> std::size_t

@DefaultRyan Ryan Shepherd (DefaultRyan) Aug 19, 2026

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Nit: Feels slightly dirty to capture size instead of using the lambda's param. Perhaps this is simplified if we are selective about our lambda captures and capture only &value.

{
WINRT_VERIFY_(size, WINRT_IMPL_WideCharToMultiByte(65001 /*CP_UTF8*/, 0, value.data(), static_cast<std::int32_t>(value.size()), buffer, size, nullptr, nullptr));
return size;
});
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#else
std::string result(size, '?');
WINRT_VERIFY_(size, WINRT_IMPL_WideCharToMultiByte(65001 /*CP_UTF8*/, 0, value.data(), static_cast<std::int32_t>(value.size()), result.data(), size, nullptr, nullptr));
#endif
return result;
}
}