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saturate_cast #200
Description
With C++26, there is std::saturate_cast https://en.cppreference.com/w/cpp/numeric/saturate_cast.html
Can you provide this as well?
I'm not sure if boost::core is the right library.
My implementation requires boost::is_integer (boostorg/type_traits#186), but they didn't understand what I meant and therefore rejected/closed it.
// Distributed under the Boost Software License Version 1.0 https://www.boost.org/LICENSE_1_0.txt
// Copyright Gero Peterhoff
#ifndef BOOST_CORE_SATURATE_CAST_HPP
#define BOOST_CORE_SATURATE_CAST_HPP
#include <boost/type_traits/is_integer.hpp>
#include <limits>
namespace boost
{
namespace core
{
template <typename To, typename From>
inline BOOST_CXX14_CONSTEXPR typename std::enable_if<boost::is_integer<To>::value && boost::is_integer<From>::value, To>::type saturate_cast(const From& from) noexcept
{
using limits = std::numeric_limits<To>;
BOOST_IF_CONSTEXPR (std::is_same<To, From>::value)
{
return from;
}
else BOOST_IF_CONSTEXPR (std::is_signed<To>::value && std::is_unsigned<From>::value)
{
using type = typename std::make_unsigned<To>::type;
return
(from > type(limits::max())) ? limits::max() :
To(from);
}
else BOOST_IF_CONSTEXPR (std::is_unsigned<To>::value && std::is_signed<From>::value)
{
using type = typename std::make_unsigned<From>::type;
return
(from < 0) ? To{} :
(type(from) > limits::max()) ? limits::max() :
To(from);
}
else BOOST_IF_CONSTEXPR (std::is_signed<To>::value && std::is_signed<From>::value)
{
return
(from < limits::min()) ? limits::min() :
(from > limits::max()) ? limits::max() :
To(from);
}
else
{
return
(from > limits::max()) ? limits::max() :
To(from);
}
}
} // core
} // boost
#endif // BOOST_CORE_SATURATE_CAST_HPP
thx
Gero
Activity
pdimov commentedon Aug 23, 2025
We tend to put these into Boost.Compat nowadays.
gpeterhoff commentedon Aug 23, 2025
Are there any guidelines/documents that could be followed?
There are, for example,
core
compat
compatibility
...
Which one is correct?
There are also some similar implementations, e.g. boost::core::detail::string_view and boost::utility::string_view.
Can you please consolidate this?
I can't see through this thicket anymore.
In addition, some libraries are “stand alone,” meaning they implement everything themselves instead of using available libraries. This is not only cumbersome but also prone to errors.
Years ago, there was a paper (I think it was even written by you, but I can't find it right now) that said that only C++ code from the last 10 years should be supported, and everything older than that should be discarded. Then boost could go from being a conservative library back to a progressive one.
pdimov commentedon Aug 23, 2025
Compat is correct. We used Core before Compat was added. Core is also still C++03, which needlessly complicates implementations.
Lastique commentedon Aug 23, 2025
This is not accurate. Each component in Core has its own C++ version requirement. New additions need not be compatible with C++03.