constexpr div (#691)

doc/sf/ccmath.qbk

@@ -64,6 +64,12 @@ All of the following functions require C++17 or greater.
         template <typename Integer>
         inline constexpr double ldexp(Integer arg, int exp);
 
+        template <typename Integer>
+        struct div_t {Integer quot; Integer rem;};
+
+        template <typename Integer>
+        inline constexpr div_t<Integer> div(Integer x, Integer y);
+
     } // Namespaces
 
 [endsect] [/section:ccmath Constexpr CMath]

include/boost/math/ccmath/ccmath.hpp

@@ -4,8 +4,8 @@
 //  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
 //
 
-#ifndef BOOST_MATH_CCMATH
-#define BOOST_MATH_CCMATH
+#ifndef BOOST_MATH_CCMATH_HPP
+#define BOOST_MATH_CCMATH_HPP
 
 #include <boost/math/ccmath/sqrt.hpp>
 #include <boost/math/ccmath/isinf.hpp>
@@ -16,5 +16,6 @@
 #include <boost/math/ccmath/isnormal.hpp>
 #include <boost/math/ccmath/fpclassify.hpp>
 #include <boost/math/ccmath/frexp.hpp>
+#include <boost/math/ccmath/div.hpp>
 
-#endif // BOOST_MATH_CCMATH
+#endif // BOOST_MATH_CCMATH_HPP

include/boost/math/ccmath/div.hpp

@@ -0,0 +1,84 @@
+//  (C) Copyright Matt Borland 2021.
+//  Use, modification and distribution are subject to the
+//  Boost Software License, Version 1.0. (See accompanying file
+//  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_MATH_CCMATH_DIV_HPP
+#define BOOST_MATH_CCMATH_DIV_HPP
+
+#include <cmath>
+#include <cstdlib>
+#include <cinttypes>
+#include <cstdint>
+#include <type_traits>
+
+namespace boost::math::ccmath {
+
+namespace detail {
+
+template <typename ReturnType, typename Z>
+inline constexpr ReturnType div_impl(const Z x, const Z y) noexcept
+{
+    // std::div_t/ldiv_t/lldiv_t/imaxdiv_t can be defined as either { Z quot; Z rem; }; or { Z rem; Z quot; };
+    // so don't use braced initialziation to guarantee compatibility
+    ReturnType ans {0, 0};
+
+    ans.quot = x / y;
+    ans.rem = x % y;
+
+    return ans;
+}
+
+} // Namespace detail
+
+// Used for types other than built-ins (e.g. boost multiprecision)
+template <typename Z>
+struct div_t
+{
+    Z quot;
+    Z rem;
+};
+
+template <typename Z>
+inline constexpr auto div(Z x, Z y) noexcept
+{
+    if constexpr (std::is_same_v<Z, int>)
+    {
+        return detail::div_impl<std::div_t>(x, y);
+    }
+    else if constexpr (std::is_same_v<Z, long>)
+    {
+        return detail::div_impl<std::ldiv_t>(x, y);
+    }
+    else if constexpr (std::is_same_v<Z, long long>)
+    {
+        return detail::div_impl<std::lldiv_t>(x, y);
+    }
+    else if constexpr (std::is_same_v<Z, std::intmax_t>)
+    {
+        return detail::div_impl<std::imaxdiv_t>(x, y);
+    }
+    else
+    {
+        return detail::div_impl<boost::math::ccmath::div_t<Z>>(x, y);
+    }
+}
+
+inline constexpr std::ldiv_t ldiv(long x, long y) noexcept
+{
+    return detail::div_impl<std::ldiv_t>(x, y);
+}
+
+inline constexpr std::lldiv_t lldiv(long long x, long long y) noexcept
+{
+    return detail::div_impl<std::lldiv_t>(x, y);
+}
+
+inline constexpr std::imaxdiv_t imaxdiv(std::intmax_t x, std::intmax_t y) noexcept
+{
+    return detail::div_impl<std::imaxdiv_t>(x, y);
+}
+
+} // Namespaces
+
+#endif // BOOST_MATH_CCMATH_DIV_HPP

test/Jamfile.v2

@@ -130,6 +130,7 @@ test-suite special_fun :
    [ run ccmath_fpclassify_test.cpp ../../test/build//boost_unit_test_framework : : : [ requires cxx17_if_constexpr ] ]
    [ run ccmath_frexp_test.cpp ../../test/build//boost_unit_test_framework : : : [ requires cxx17_if_constexpr ] ]
    [ run ccmath_ldexp_test.cpp ../../test/build//boost_unit_test_framework : : : [ requires cxx17_if_constexpr ] ]
+   [ run ccmath_div_test.cpp ../../test/build//boost_unit_test_framework : : : [ requires cxx17_if_constexpr ] ]
    [ run log1p_expm1_test.cpp test_instances//test_instances pch_light ../../test/build//boost_unit_test_framework  ]
    [ run powm1_sqrtp1m1_test.cpp test_instances//test_instances pch_light ../../test/build//boost_unit_test_framework  ]
    [ run special_functions_test.cpp ../../test/build//boost_unit_test_framework  ]

test/ccmath_div_test.cpp

@@ -0,0 +1,47 @@
+//  (C) Copyright Matt Borland 2021.
+//  Use, modification and distribution are subject to the
+//  Boost Software License, Version 1.0. (See accompanying file
+//  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+
+#include <cstdint>
+#include <cinttypes>
+#include <boost/math/ccmath/div.hpp>
+#include <boost/math/tools/is_constant_evaluated.hpp>
+#include <boost/multiprecision/cpp_int.hpp>
+
+template <typename Z>
+constexpr void test()
+{
+    constexpr auto test_val1 = boost::math::ccmath::div(Z(1), Z(1));
+    static_assert(test_val1.quot == Z(1));
+    static_assert(test_val1.rem == Z(0));
+
+    constexpr auto test_val2 = boost::math::ccmath::div(Z(1'000'000), Z(3));
+    static_assert(test_val2.quot == Z(333'333));
+    static_assert(test_val2.rem == Z(1));
+}
+
+#if !defined(BOOST_MATH_NO_CONSTEXPR_DETECTION) && !defined(BOOST_MATH_USING_BUILTIN_CONSTANT_P)
+int main()
+{
+    test<int>();
+    test<long>();
+    test<long long>();
+    test<std::intmax_t>();
+
+    test<std::int32_t>();
+    test<std::int64_t>();
+    test<std::uint32_t>();
+
+    test<boost::multiprecision::int128_t>();
+    test<boost::multiprecision::int256_t>();
+    test<boost::multiprecision::int512_t>();
+
+    return 0;
+}
+#else
+int main()
+{
+    return 0;
+}
+#endif

test/compile_test/ccmath_div_incl_test.cpp

@@ -0,0 +1,14 @@
+//  (C) Copyright Matt Borland 2021.
+//  Use, modification and distribution are subject to the
+//  Boost Software License, Version 1.0. (See accompanying file
+//  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+
+#include <boost/math/ccmath/div.hpp>
+#include "test_compile_result.hpp"
+
+void compile_and_link_test()
+{
+   check_result<std::div_t>(boost::math::ccmath::div(1, 1));
+   check_result<std::ldiv_t>(boost::math::ccmath::div(1l, 1l));
+   check_result<std::lldiv_t>(boost::math::ccmath::div(1ll, 1ll));
+}