Add boost::compat::invoke

include/boost/compat/detail/returns.hpp

@@ -0,0 +1,10 @@
+#ifndef BOOST_COMPAT_DETAIL_RETURNS_HPP_INCLUDED
+#define BOOST_COMPAT_DETAIL_RETURNS_HPP_INCLUDED
+
+// Copyright 2024 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#define BOOST_COMPAT_RETURNS(...) noexcept(noexcept(__VA_ARGS__)) -> decltype(__VA_ARGS__) { return __VA_ARGS__; }
+
+#endif // BOOST_COMPAT_DETAIL_RETURNS_HPP_INCLUDED

include/boost/compat/invoke.hpp

@@ -0,0 +1,26 @@
+#ifndef BOOST_COMPAT_INVOKE_HPP_INCLUDED
+#define BOOST_COMPAT_INVOKE_HPP_INCLUDED
+
+// Copyright 2024 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/compat/mem_fn.hpp>
+#include <boost/compat/detail/returns.hpp>
+#include <utility>
+
+namespace boost {
+namespace compat {
+
+template<class F, class... A>
+auto invoke( F&& f, A&&... a )
+BOOST_COMPAT_RETURNS( std::forward<F>(f)(std::forward<A>(a)...) )
+
+template<class M, class T, class... A>
+auto invoke( M T::* pm, A&&... a )
+BOOST_COMPAT_RETURNS( mem_fn(pm)(std::forward<A>(a)...) )
+
+} // namespace compat
+} // namespace boost
+
+#endif // BOOST_COMPAT_INVOKE_HPP_INCLUDED

include/boost/compat/mem_fn.hpp

@@ -0,0 +1,18 @@
+#ifndef BOOST_COMPAT_MEM_FN_HPP_INCLUDED
+#define BOOST_COMPAT_MEM_FN_HPP_INCLUDED
+
+// Copyright 2024 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <functional>
+
+namespace boost {
+namespace compat {
+
+using std::mem_fn;
+
+} // namespace compat
+} // namespace boost
+
+#endif // BOOST_COMPAT_MEM_FN_HPP_INCLUDED

test/Jamfile

@@ -25,5 +25,8 @@ project
 run quick.cpp ;
 
 run latch_test.cpp ;
+
 run shared_lock_test.cpp ;
 run shared_lock_test.cpp : : : <exception-handling>off : shared_lock_test_nx ;
+
+run invoke_fn_test.cpp ;

test/invoke_fn_test.cpp

@@ -0,0 +1,36 @@
+// Copyright 2024 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/compat/invoke.hpp>
+#include <boost/core/lightweight_test.hpp>
+
+int f0()
+{
+    return -1;
+}
+
+int f1( int x1 )
+{
+    return x1;
+}
+
+int f2( int x1, int x2 )
+{
+    return 10*x1+x2;
+}
+
+int f3( int x1, int x2, int x3 )
+{
+    return 100*x1 + 10*x2 + x3;
+}
+
+int main()
+{
+    BOOST_TEST_EQ( boost::compat::invoke( f0 ), -1 );
+    BOOST_TEST_EQ( boost::compat::invoke( f1, 1 ), 1 );
+    BOOST_TEST_EQ( boost::compat::invoke( f2, 1, 2 ), 12 );
+    BOOST_TEST_EQ( boost::compat::invoke( f3, 1, 2, 3 ), 123 );
+
+    return boost::report_errors();
+}