Add tuple_for_each.

include/boost/tuple_for_each.hpp

@@ -0,0 +1,33 @@
+#ifndef BOOST_TUPLE_FOR_EACH_HPP_INCLUDED
+#define BOOST_TUPLE_FOR_EACH_HPP_INCLUDED
+
+#include <boost/integer_sequence.hpp>
+#include <boost/config.hpp>
+#include <tuple>
+#include <utility>
+#include <type_traits>
+#include <cstddef>
+
+namespace boost
+{
+
+namespace detail
+{
+
+template<class Tp, std::size_t... J, class F> BOOST_CONSTEXPR F tuple_for_each_impl( Tp && tp, boost::integer_sequence<std::size_t, J...>, F && f )
+{
+    using A = int[sizeof...(J)];
+    return (void)A{ (f(std::get<J>(std::forward<Tp>(tp))), 0)... }, std::forward<F>(f);
+}
+
+} // namespace detail
+
+template<class Tp, class F> BOOST_CONSTEXPR F tuple_for_each( Tp && tp, F && f )
+{
+    using seq = boost::make_index_sequence<std::tuple_size<typename std::remove_reference<Tp>::type>::value>;
+    return detail::tuple_for_each_impl( std::forward<Tp>(tp), seq(), std::forward<F>(f) );
+}
+
+} // namespace boost
+
+#endif // #ifndef BOOST_TUPLE_FOR_EACH_HPP_INCLUDED

test/Jamfile.v2

@@ -52,3 +52,7 @@ run mp_eval_if.cpp : : : $(REQ) ;
 
 # integer_sequence
 run integer_sequence.cpp : : : $(REQ) ;
+
+# tuple_for_each
+run tuple_for_each.cpp : : : $(REQ) ;
+run tuple_for_each_cx.cpp : : : $(REQ) ;

test/tuple_for_each.cpp

@@ -0,0 +1,90 @@
+
+//  Copyright 2015 Peter Dimov.
+//
+// Distributed under 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/tuple_for_each.hpp>
+#include <boost/core/lightweight_test.hpp>
+#include <tuple>
+#include <memory>
+#include <utility>
+#include <array>
+
+int main()
+{
+    {
+        std::tuple<int, short, char> tp{ 1, 2, 3 };
+
+        {
+            int s = 0;
+
+            boost::tuple_for_each( tp, [&]( int x ){ s = s * 10 + x; } );
+
+            BOOST_TEST_EQ( s, 123 );
+        }
+
+        {
+            int s = 0;
+
+            boost::tuple_for_each( std::move(tp), [&]( int x ){ s = s * 10 + x; } );
+
+            BOOST_TEST_EQ( s, 123 );
+        }
+    }
+
+    {
+        std::tuple<std::unique_ptr<int>, std::unique_ptr<int>, std::unique_ptr<int>> tp{ std::unique_ptr<int>(new int(1)), std::unique_ptr<int>(new int(2)), std::unique_ptr<int>(new int(3)) };
+
+        int s = 0;
+
+        boost::tuple_for_each( std::move(tp), [&]( std::unique_ptr<int> p ){ s = s * 10 + *p; } );
+
+        BOOST_TEST_EQ( s, 123 );
+    }
+
+    {
+        std::pair<int, short> tp{ 1, 2 };
+
+        {
+            int s = 0;
+
+            boost::tuple_for_each( tp, [&]( int x ){ s = s * 10 + x; } );
+
+            BOOST_TEST_EQ( s, 12 );
+        }
+
+        {
+            int s = 0;
+
+            boost::tuple_for_each( std::move(tp), [&]( int x ){ s = s * 10 + x; } );
+
+            BOOST_TEST_EQ( s, 12 );
+        }
+    }
+
+    {
+        std::array<int, 3> tp{{ 1, 2, 3 }};
+
+        {
+            int s = 0;
+
+            boost::tuple_for_each( tp, [&]( int x ){ s = s * 10 + x; } );
+
+            BOOST_TEST_EQ( s, 123 );
+        }
+
+        {
+            int s = 0;
+
+            boost::tuple_for_each( std::move(tp), [&]( int x ){ s = s * 10 + x; } );
+
+            BOOST_TEST_EQ( s, 123 );
+        }
+    }
+
+    return boost::report_errors();
+}

test/tuple_for_each_cx.cpp

@@ -0,0 +1,37 @@
+
+//  Copyright 2015 Peter Dimov.
+//
+// Distributed under 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/tuple_for_each.hpp>
+#include <boost/config.hpp>
+
+#if defined( BOOST_NO_CXX11_CONSTEXPR )
+
+int main() {}
+
+#else
+
+#include <tuple>
+#include <type_traits>
+
+struct assert_is_integral
+{
+    template<class T> constexpr bool operator()( T ) const
+    {
+        static_assert( std::is_integral<T>::value, "T must be an integral type" );
+        return true;
+    }
+};
+
+int main()
+{
+    constexpr std::tuple<int, short, char> tp{ 1, 2, 3 };
+    constexpr auto r = boost::tuple_for_each( tp, assert_is_integral() );
+    (void)r;
+}
+
+#endif