boost/parameter/aux_/preprocessor/impl/function_cast.hpp
// Copyright Daniel Wallin 2006. // Copyright Cromwell D. Enage 2017. // 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) #ifndef BOOST_PARAMETER_AUX_PREPROCESSOR_IMPL_FUNCTION_CAST_HPP #define BOOST_PARAMETER_AUX_PREPROCESSOR_IMPL_FUNCTION_CAST_HPP #include <boost/parameter/config.hpp> #if defined(BOOST_PARAMETER_HAS_PERFECT_FORWARDING) namespace boost { namespace parameter { namespace aux { // Handles possible implicit casts. Used by preprocessor.hpp // to normalize user input. // // cast<void*>::execute() is identity // cast<void*(X)>::execute() is identity // cast<void(X)>::execute() casts to X // // preprocessor.hpp uses this like this: // // #define X(value, predicate) // cast<void predicate>::execute(value) // // X(something, *) // X(something, *(predicate)) // X(something, (int)) template <typename VoidExpr, typename Args> struct cast; }}} // namespace boost::parameter::aux #include <boost/parameter/aux_/use_default_tag.hpp> namespace boost { namespace parameter { namespace aux { template <typename T, typename B> inline ::boost::parameter::aux::use_default_tag forward(::boost::parameter::aux::use_default_tag) { return ::boost::parameter::aux::use_default_tag(); } }}} // namespace boost::parameter::aux #include <boost/mpl/bool.hpp> #include <boost/mpl/if.hpp> #if defined(BOOST_PARAMETER_CAN_USE_MP11) #include <boost/mp11/integral.hpp> #include <boost/mp11/utility.hpp> #endif namespace boost { namespace parameter { namespace aux { template <typename Args> struct cast<void*,Args> { template <typename T, typename B> struct apply { typedef typename ::boost::mpl ::if_<B,T,::boost::mpl::true_>::type type; }; #if defined(BOOST_PARAMETER_CAN_USE_MP11) template <typename T, typename B> using fn = ::boost::mp11::mp_if<B,T,::boost::mp11::mp_true>; #endif }; }}} // namespace boost::parameter::aux #include <boost/parameter/aux_/void.hpp> namespace boost { namespace parameter { namespace aux { template <typename Predicate, typename Args> struct cast<void*(Predicate),Args> : ::boost::parameter::aux::cast<void*,Args> { }; }}} // namespace boost::parameter::aux #include <boost/mpl/placeholders.hpp> namespace boost { namespace parameter { namespace aux { // This is a hack used in cast<> to turn the user supplied type, // which may or may not be a placeholder expression, into one, // so that it will be properly evaluated by mpl::apply. template <typename T, typename Dummy = ::boost::mpl::_1> struct as_placeholder_expr { typedef T type; }; }}} // namespace boost::parameter::aux #if defined(BOOST_PARAMETER_CAN_USE_MP11) #include <boost/mp11/list.hpp> namespace boost { namespace parameter { namespace aux { template <typename Target, typename Source, typename Args> struct apply_target_fn { using type = ::boost::mp11 ::mp_apply_q<Target,::boost::mp11::mp_list<Source,Args> >; }; }}} // namespace boost::parameter::aux #endif #include <boost/mpl/apply.hpp> #if defined(BOOST_PARAMETER_CAN_USE_MP11) #include <boost/parameter/aux_/has_nested_template_fn.hpp> #include <type_traits> #else #include <boost/type_traits/is_same.hpp> #include <boost/type_traits/remove_const.hpp> #include <boost/type_traits/remove_reference.hpp> #endif namespace boost { namespace parameter { namespace aux { template <typename Target, typename Source, typename Args> #if defined(BOOST_PARAMETER_CAN_USE_MP11) using is_target_same_as_source = ::std::is_same< typename ::std::remove_const< typename ::std::remove_reference< typename ::boost::mp11::mp_if< ::boost::parameter::aux::has_nested_template_fn<Target> , ::boost::parameter::aux ::apply_target_fn<Target,Source,Args> , ::boost::mpl::apply2< ::boost::parameter::aux::as_placeholder_expr<Target> , Source , Args > >::type >::type >::type , typename ::std::remove_const<Source>::type >; #else // !defined(BOOST_PARAMETER_CAN_USE_MP11) struct is_target_same_as_source : ::boost::mpl::if_< ::boost::is_same< typename ::boost::remove_const< typename ::boost::remove_reference< typename ::boost::mpl::apply2< ::boost::parameter::aux ::as_placeholder_expr<Target> , Source , Args >::type >::type >::type , typename ::boost::remove_const<Source>::type > , ::boost::mpl::true_ , ::boost::mpl::false_ >::type { }; #endif // BOOST_PARAMETER_CAN_USE_MP11 }}} // namespace boost::parameter::aux #if !defined(BOOST_PARAMETER_CAN_USE_MP11) #include <boost/type_traits/add_const.hpp> #include <boost/type_traits/is_const.hpp> #endif namespace boost { namespace parameter { namespace aux { // Covers the case where is_convertible<Source,Target> but not // is_same<Source,Target>. Use cases are covered // by test/normalize_argument_types.cpp template <typename Source, typename Target> class cast_convert { typedef ::boost::parameter::aux::cast_convert<Source,Target> _self; public: #if defined(BOOST_PARAMETER_CAN_USE_MP11) using type = typename ::boost::mp11::mp_if< ::std::is_const<Source> , ::std::add_const<Target> , ::std::remove_const<Target> >::type; #else typedef typename boost::mpl::eval_if< ::boost::is_const<Source> , ::boost::add_const<Target> , ::boost::remove_const<Target> >::type type; #endif private: inline static typename _self::type #if defined(BOOST_PARAMETER_CAN_USE_MP11) _copy(typename ::std::remove_const<Target>::type value) #else _copy(typename ::boost::remove_const<Target>::type value) #endif { return value; } public: inline static typename _self::type evaluate(Source&& source) { return _self::_copy(source); } }; template <typename Target, typename Source, typename Args> #if defined(BOOST_PARAMETER_CAN_USE_MP11) using cast_impl = ::std::remove_reference< typename ::boost::mp11::mp_if< ::boost::parameter::aux::has_nested_template_fn<Target> , ::boost::parameter::aux ::is_target_same_as_source<Target,Source,Args> , ::boost::mpl::apply2< ::boost::parameter::aux::as_placeholder_expr<Target> , Source , Args > >::type >; #else struct cast_impl : ::boost::remove_reference< typename ::boost::mpl::apply2< ::boost::parameter::aux::as_placeholder_expr<Target> , Source , Args >::type > { }; #endif // BOOST_PARAMETER_CAN_USE_MP11 }}} // namespace boost::parameter::aux #include <boost/mpl/eval_if.hpp> #include <boost/mpl/identity.hpp> namespace boost { namespace parameter { namespace aux { template <typename Target, typename Args> struct cast<void(Target),Args> { template <typename T, typename B> struct apply { typedef typename ::boost::mpl::eval_if< B , ::boost::mpl::eval_if< ::boost::parameter::aux ::is_target_same_as_source<Target,T,Args> , ::boost::mpl::identity<T> , ::boost::parameter::aux::cast_impl<Target,T,Args> > , ::boost::parameter::aux ::is_target_same_as_source<Target,T,Args> >::type type; }; #if defined(BOOST_PARAMETER_CAN_USE_MP11) template <typename T, typename B> using fn = typename ::boost::mp11::mp_if< B , ::boost::mp11::mp_if< ::boost::parameter::aux ::is_target_same_as_source<Target,T,Args> , ::boost::mp11::mp_identity<T> , ::boost::parameter::aux::cast_impl<Target,T,Args> > , ::boost::parameter::aux ::is_target_same_as_source<Target,T,Args> >::type; #endif }; }}} // namespace boost::parameter::aux #include <boost/parameter/value_type.hpp> #if !defined(BOOST_PARAMETER_CAN_USE_MP11) #include <boost/mpl/apply_wrap.hpp> #endif // Expands to the target type of the argument as indicated by the predicate. #if defined(BOOST_PARAMETER_CAN_USE_MP11) #define BOOST_PARAMETER_FUNCTION_CAST_T(tag, predicate, args) \ ::boost::mp11::mp_apply_q< \ ::boost::parameter::aux::cast<void predicate, args> \ , ::boost::mp11::mp_list< \ typename ::boost::parameter::value_type< \ args \ , tag \ , ::boost::parameter::aux::use_default_tag \ >::type \ , ::boost::mp11::mp_true \ > \ > /**/ #else // !defined(BOOST_PARAMETER_CAN_USE_MP11) #define BOOST_PARAMETER_FUNCTION_CAST_T(tag, predicate, args) \ typename ::boost::mpl::apply_wrap2< \ ::boost::parameter::aux::cast<void predicate, args> \ , typename ::boost::parameter::value_type< \ args \ , tag \ , ::boost::parameter::aux::use_default_tag \ >::type \ , ::boost::mpl::true_ \ >::type /**/ #endif // BOOST_PARAMETER_CAN_USE_MP11 // Expands to boost::mpl::true_ if and only if the argument's source and // target types are the same. #if defined(BOOST_PARAMETER_CAN_USE_MP11) #define BOOST_PARAMETER_FUNCTION_CAST_B(tag, predicate, args) \ ::boost::mp11::mp_apply_q< \ ::boost::parameter::aux::cast<void predicate, args> \ , ::boost::mp11::mp_list< \ typename ::boost::parameter::value_type< \ args \ , tag \ , ::boost::parameter::aux::use_default_tag \ >::type \ , ::boost::mp11::mp_false \ > \ > /**/ #else // !defined(BOOST_PARAMETER_CAN_USE_MP11) #define BOOST_PARAMETER_FUNCTION_CAST_B(tag, predicate, args) \ typename ::boost::mpl::apply_wrap2< \ ::boost::parameter::aux::cast<void predicate, args> \ , typename ::boost::parameter::value_type< \ args \ , tag \ , ::boost::parameter::aux::use_default_tag \ >::type \ , ::boost::mpl::false_ \ >::type /**/ #endif // BOOST_PARAMETER_CAN_USE_MP11 #include <boost/core/enable_if.hpp> #include <utility> namespace boost { namespace parameter { namespace aux { // If the source and target types are not the same, // then perform an implicit conversion. template <typename Target, typename B, typename Source> inline typename ::boost::lazy_disable_if< B , ::boost::parameter::aux::cast_convert<Source,Target> >::type forward(Source&& source) { return ::boost::parameter::aux::cast_convert<Source,Target> ::evaluate(::std::forward<Source>(source)); } // If the source and target types are the same, // then simply forward the argument. // However, treat rvalue references to scalars as const lvalue references. template <typename T, typename B> inline typename ::boost::enable_if<B,T const&>::type forward(T const& t) { return t; } template <typename T, typename B> inline typename ::boost::enable_if< #if defined(BOOST_PARAMETER_CAN_USE_MP11) ::boost::mp11::mp_if< B , ::boost::mp11::mp_if< ::std::is_const<T> , ::boost::mp11::mp_false , ::boost::mp11::mp_true > , ::boost::mp11::mp_false > #else typename ::boost::mpl::eval_if< B , ::boost::mpl::if_< ::boost::is_const<T> , ::boost::mpl::false_ , ::boost::mpl::true_ > , ::boost::mpl::false_ >::type #endif // BOOST_PARAMETER_CAN_USE_MP11 , T& >::type forward(T& t) { return t; } }}} // namespace boost::parameter::aux #include <boost/type_traits/is_scalar.hpp> namespace boost { namespace parameter { namespace aux { template <typename T, typename B> inline typename ::boost::enable_if< #if defined(BOOST_PARAMETER_CAN_USE_MP11) ::boost::mp11::mp_if< B , ::boost::mp11::mp_if< ::std::is_scalar<T> , ::boost::mp11::mp_false , ::boost::mp11::mp_true > , ::boost::mp11::mp_false > #else typename ::boost::mpl::eval_if< B , ::boost::mpl::if_< ::boost::is_scalar<T> , ::boost::mpl::false_ , ::boost::mpl::true_ > , ::boost::mpl::false_ >::type #endif // BOOST_PARAMETER_CAN_USE_MP11 , T const&& >::type forward(T const&& t) { return static_cast<T const&&>(t); } template <typename T, typename B> inline typename ::boost::enable_if< #if defined(BOOST_PARAMETER_CAN_USE_MP11) ::boost::mp11::mp_if< B , ::boost::mp11::mp_if< ::std::is_scalar<T> , ::boost::mp11::mp_false , ::boost::mp11::mp_true > , ::boost::mp11::mp_false > #else typename ::boost::mpl::eval_if< B , ::boost::mpl::if_< ::boost::is_scalar<T> , ::boost::mpl::false_ , ::boost::mpl::true_ > , ::boost::mpl::false_ >::type #endif // BOOST_PARAMETER_CAN_USE_MP11 , T&& >::type forward(T&& t) { return ::std::forward<T>(t); } }}} // namespace boost::parameter::aux #elif BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x564)) #define BOOST_PARAMETER_FUNCTION_CAST_T(value_t, predicate, args) value_t #define BOOST_PARAMETER_FUNCTION_CAST_B(value, predicate, args) value #else // no perfect forwarding support and no Borland workarounds needed namespace boost { namespace parameter { namespace aux { // Handles possible implicit casts. Used by preprocessor.hpp // to normalize user input. // // cast<void*>::execute() is identity // cast<void*(X)>::execute() is identity // cast<void(X)>::execute() casts to X // // preprocessor.hpp uses this like this: // // #define X(value, predicate) // cast<void predicate>::execute(value) // // X(something, *) // X(something, *(predicate)) // X(something, (int)) template <typename VoidExpr, typename Args> struct cast; }}} // namespace boost::parameter::aux #include <boost/parameter/aux_/use_default_tag.hpp> #include <boost/mpl/bool.hpp> #include <boost/mpl/if.hpp> namespace boost { namespace parameter { namespace aux { template <typename Args> struct cast<void*,Args> { template <typename T> struct apply { typedef T& type; }; inline static ::boost::parameter::aux::use_default_tag execute(::boost::parameter::aux::use_default_tag) { return ::boost::parameter::aux::use_default_tag(); } template <typename U> inline static U& execute(U& value) { return value; } }; }}} // namespace boost::parameter::aux #include <boost/parameter/aux_/void.hpp> namespace boost { namespace parameter { namespace aux { template <typename Predicate, typename Args> #if BOOST_WORKAROUND(__SUNPRO_CC, BOOST_TESTED_AT(0x580)) struct cast< ::boost::parameter::aux::voidstar(Predicate),Args> #else struct cast<void*(Predicate),Args> #endif : ::boost::parameter::aux::cast<void*,Args> { }; }}} // namespace boost::parameter::aux #include <boost/mpl/placeholders.hpp> namespace boost { namespace parameter { namespace aux { // This is a hack used in cast<> to turn the user supplied type, // which may or may not be a placeholder expression, into one, // so that it will be properly evaluated by mpl::apply. template <typename T, typename Dummy = ::boost::mpl::_1> struct as_placeholder_expr { typedef T type; }; }}} // namespace boost::parameter::aux #include <boost/mpl/apply.hpp> #include <boost/type_traits/is_same.hpp> #include <boost/type_traits/remove_const.hpp> #include <boost/type_traits/remove_reference.hpp> namespace boost { namespace parameter { namespace aux { template <typename Target, typename Source, typename Args> struct is_target_same_as_source : ::boost::mpl::if_< ::boost::is_same< typename ::boost::remove_const< typename ::boost::remove_reference< typename ::boost::mpl::apply2< ::boost::parameter::aux ::as_placeholder_expr<Target> , Source , Args >::type >::type >::type , typename ::boost::remove_const<Source>::type > , ::boost::mpl::true_ , ::boost::mpl::false_ >::type { }; template < typename Target , typename Source , typename Args , typename Enable = ::boost::parameter::aux ::is_target_same_as_source<Target,Source,Args> > struct cast_impl { typedef Source& type; inline static Source& evaluate(Source& value) { return value; } }; }}} // namespace boost::parameter::aux #include <boost/type_traits/add_const.hpp> #include <boost/type_traits/add_lvalue_reference.hpp> namespace boost { namespace parameter { namespace aux { // Covers the case where is_convertible<Source,Target> but not // is_same<Source,Target>. Use cases are covered // by test/normalize_argument_types.cpp template <typename Source, typename Target> class cast_convert { typedef ::boost::parameter::aux::cast_convert<Source,Target> _self; public: typedef typename ::boost::add_lvalue_reference< typename ::boost::add_const<Target>::type >::type type; private: template <typename U> inline static typename _self::type _mod_const(U const& u) { return u; } inline static Target _copy(Target value) { return value; } public: inline static typename _self::type evaluate(Source& source) { return _self::_mod_const(_self::_copy(source)); } }; template <typename Target, typename Source, typename Args> struct cast_impl<Target,Source,Args,::boost::mpl::false_> : ::boost::parameter::aux::cast_convert< Source, typename ::boost::mpl::apply2< ::boost::parameter::aux::as_placeholder_expr<Target> , Source , Args >::type > { }; }}} // namespace boost::parameter::aux #include <boost/mpl/eval_if.hpp> namespace boost { namespace parameter { namespace aux { template <typename Target, typename Args> struct cast<void(Target),Args> { template <typename T> struct apply { typedef typename ::boost::mpl::eval_if< ::boost::parameter::aux ::is_target_same_as_source<Target,T,Args> , ::boost::add_lvalue_reference<T> , ::boost::parameter::aux::cast_impl< Target , T , Args , ::boost::mpl::false_ > >::type type; }; inline static ::boost::parameter::aux::use_default_tag execute(::boost::parameter::aux::use_default_tag) { return ::boost::parameter::aux::use_default_tag(); } template <typename U> inline static typename ::boost::parameter::aux ::cast_impl<Target,U const,Args>::type execute(U const& value) { return ::boost::parameter::aux ::cast_impl<Target,U const,Args>::evaluate(value); } template <typename U> inline static typename ::boost::parameter::aux ::cast_impl<Target,U,Args>::type execute(U& value) { return ::boost::parameter::aux ::cast_impl<Target,U,Args>::evaluate(value); } }; }}} // namespace boost::parameter::aux #include <boost/mpl/apply_wrap.hpp> #include <boost/parameter/value_type.hpp> // Expands to the reference-qualified target type of the argument // as indicated by the predicate. #define BOOST_PARAMETER_FUNCTION_CAST_T(tag, predicate, args) \ typename ::boost::mpl::apply_wrap1< \ ::boost::parameter::aux::cast<void predicate, args> \ , typename ::boost::parameter::value_type< \ args \ , tag \ , ::boost::parameter::aux::use_default_tag \ >::type \ >::type /**/ // Expands to the converted or passed-through value // as indicated by the predicate. #define BOOST_PARAMETER_FUNCTION_CAST_B(value, predicate, args) \ ::boost::parameter::aux::cast<void predicate, args>::execute(value) /**/ #endif // perfect forwarding support, or Borland workarounds needed #endif // include guard