// Boost Lambda Library lambda_functor_base.hpp ----------------------------- // // Copyright (C) 1999, 2000 Jaakko Jarvi (jaakko.jarvi@cs.utu.fi) // // 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) // // For more information, see www.boost.org // ------------------------------------------------------------ #ifndef BOOST_LAMBDA_LAMBDA_FUNCTOR_BASE_HPP #define BOOST_LAMBDA_LAMBDA_FUNCTOR_BASE_HPP #include "boost/type_traits/add_reference.hpp" #include "boost/type_traits/add_const.hpp" #include "boost/type_traits/remove_const.hpp" #include "boost/lambda/detail/lambda_fwd.hpp" #include "boost/lambda/detail/lambda_traits.hpp" namespace boost { namespace lambda { #if BOOST_WORKAROUND(BOOST_MSVC, >= 1400) #pragma warning(push) #pragma warning(disable:4512) //assignment operator could not be generated #endif // for return type deductions we wrap bound argument to this class, // which fulfils the base class contract for lambda_functors template class identity { T elem; public: typedef T element_t; // take all parameters as const references. Note that non-const references // stay as they are. typedef typename boost::add_reference< typename boost::add_const::type >::type par_t; explicit identity(par_t t) : elem(t) {} template struct sig { typedef typename boost::remove_const::type type; }; template RET call(CALL_FORMAL_ARGS) const { CALL_USE_ARGS; return elem; } }; #if BOOST_WORKAROUND(BOOST_MSVC, >= 1400) #pragma warning(pop) #endif template inline lambda_functor > var(T& t) { return identity(t); } // for lambda functors, var is an identity operator. It was forbidden // at some point, but we might want to var something that can be a // non-lambda functor or a lambda functor. template lambda_functor var(const lambda_functor& t) { return t; } template struct var_type { typedef lambda_functor > type; }; template inline lambda_functor::type> > constant(const T& t) { return identity::type>(t); } template lambda_functor constant(const lambda_functor& t) { return t; } template struct constant_type { typedef lambda_functor< identity::type> > type; }; template inline lambda_functor > constant_ref(const T& t) { return identity(t); } template lambda_functor constant_ref(const lambda_functor& t) { return t; } template struct constant_ref_type { typedef lambda_functor > type; }; // as_lambda_functor turns any types to lambda functors // non-lambda_functors will be bound argument types template struct as_lambda_functor { typedef typename detail::remove_reference_and_cv::type plain_T; typedef typename detail::IF::value, plain_T, lambda_functor< identity::type> > >::RET type; }; // turns arbitrary objects into lambda functors template inline lambda_functor::type> > to_lambda_functor(const T& t) { return identity::type>(t); } template inline lambda_functor to_lambda_functor(const lambda_functor& t) { return t; } namespace detail { // In a call constify_rvals::go(x) // x should be of type T. If T is a non-reference type, do // returns x as const reference. // Otherwise the type doesn't change. // The purpose of this class is to avoid // 'cannot bind temporaries to non-const references' errors. template struct constify_rvals { template static inline const U& go(const U& u) { return u; } }; template struct constify_rvals { template static inline U& go(U& u) { return u; } }; // check whether one of the elements of a tuple (cons list) is of type // null_type. Needed, because the compiler goes ahead and instantiates // sig template for nullary case even if the nullary operator() is not // called template struct is_null_type { BOOST_STATIC_CONSTANT(bool, value = false); }; template <> struct is_null_type { BOOST_STATIC_CONSTANT(bool, value = true); }; template struct has_null_type { BOOST_STATIC_CONSTANT(bool, value = (is_null_type::value || has_null_type::value)); }; template<> struct has_null_type { BOOST_STATIC_CONSTANT(bool, value = false); }; // helpers ------------------- template class deduce_argument_types_ { typedef typename as_lambda_functor::type lf_t; typedef typename lf_t::inherited::template sig::type el_t; public: typedef boost::tuples::cons< el_t, typename deduce_argument_types_::type > type; }; template class deduce_argument_types_ { public: typedef null_type type; }; // // note that tuples cannot have plain function types as elements. // // Hence, all other types will be non-const, except references to // // functions. // template struct remove_reference_except_from_functions { // typedef typename boost::remove_reference::type t; // typedef typename detail::IF::value, T, t>::RET type; // }; template class deduce_non_ref_argument_types_ { typedef typename as_lambda_functor::type lf_t; typedef typename lf_t::inherited::template sig::type el_t; public: typedef boost::tuples::cons< // typename detail::remove_reference_except_from_functions::type, typename boost::remove_reference::type, typename deduce_non_ref_argument_types_::type > type; }; template class deduce_non_ref_argument_types_ { public: typedef null_type type; }; // ------------- // take stored Args and Open Args, and return a const list with // deduced elements (real return types) template class deduce_argument_types { typedef typename deduce_argument_types_::type t1; public: typedef typename detail::IF< has_null_type::value, null_type, t1 >::RET type; }; // take stored Args and Open Args, and return a const list with // deduced elements (references are stripped from the element types) template class deduce_non_ref_argument_types { typedef typename deduce_non_ref_argument_types_::type t1; public: typedef typename detail::IF< has_null_type::value, null_type, t1 >::RET type; }; template struct nth_return_type_sig { typedef typename as_lambda_functor< typename boost::tuples::element::type // typename tuple_element_as_reference::type >::type lf_type; typedef typename lf_type::inherited::template sig::type type; }; template struct element_or_null { typedef typename boost::tuples::element::type type; }; template struct element_or_null { typedef null_type type; }; } // end detail // -- lambda_functor base --------------------- // the explicit_return_type_action case ----------------------------------- template class lambda_functor_base, Args> { public: Args args; typedef RET result_type; explicit lambda_functor_base(const Args& a) : args(a) {} template struct sig { typedef RET type; }; template RET call(CALL_FORMAL_ARGS) const { return detail::constify_rvals::go( detail::r_select::go(boost::tuples::get<0>(args), CALL_ACTUAL_ARGS)); } }; // the protect_action case ----------------------------------- template class lambda_functor_base { public: Args args; public: explicit lambda_functor_base(const Args& a) : args(a) {} template RET call(CALL_FORMAL_ARGS) const { CALL_USE_ARGS; return boost::tuples::get<0>(args); } template struct sig { // typedef typename detail::tuple_element_as_reference<0, SigArgs>::type type; typedef typename boost::tuples::element<0, Args>::type type; }; }; // Do nothing -------------------------------------------------------- class do_nothing_action {}; template class lambda_functor_base { // Args args; public: // explicit lambda_functor_base(const Args& a) {} lambda_functor_base() {} template RET call(CALL_FORMAL_ARGS) const { return CALL_USE_ARGS; } template struct sig { typedef void type; }; }; // These specializations provide a shorter notation to define actions. // These lambda_functor_base instances take care of the recursive evaluation // of the arguments and pass the evaluated arguments to the apply function // of an action class. To make action X work with these classes, one must // instantiate the lambda_functor_base as: // lambda_functor_base, Args> // Where ARITY is the arity of the apply function in X // The return type is queried as: // return_type_N::type // for which there must be a specialization. // Function actions, casts, throws,... all go via these classes. template class lambda_functor_base, Args> { public: // Args args; not needed explicit lambda_functor_base(const Args& /*a*/) {} template struct sig { typedef typename return_type_N::type type; }; template RET call(CALL_FORMAL_ARGS) const { CALL_USE_ARGS; return Act::template apply(); } }; #if defined BOOST_LAMBDA_LAMBDA_FUNCTOR_BASE_FIRST_PART #error "Multiple defines of BOOST_LAMBDA_LAMBDA_FUNCTOR_BASE_FIRST_PART" #endif #define BOOST_LAMBDA_LAMBDA_FUNCTOR_BASE_FIRST_PART(ARITY) \ template \ class lambda_functor_base, Args> \ { \ public: \ Args args; \ \ explicit lambda_functor_base(const Args& a) : args(a) {} \ \ template struct sig { \ typedef typename \ detail::deduce_argument_types::type rets_t; \ public: \ typedef typename \ return_type_N_prot::type type; \ }; \ \ \ template \ RET call(CALL_FORMAL_ARGS) const { \ using boost::tuples::get; \ using detail::constify_rvals; \ using detail::r_select; \ using detail::element_or_null; \ using detail::deduce_argument_types; BOOST_LAMBDA_LAMBDA_FUNCTOR_BASE_FIRST_PART(1) typedef typename deduce_argument_types >::type rets_t; typedef typename element_or_null<0, rets_t>::type rt0; return Act::template apply( constify_rvals::go(r_select::go(get<0>(args), CALL_ACTUAL_ARGS)) ); } }; BOOST_LAMBDA_LAMBDA_FUNCTOR_BASE_FIRST_PART(2) typedef typename deduce_argument_types >::type rets_t; typedef typename element_or_null<0, rets_t>::type rt0; typedef typename element_or_null<1, rets_t>::type rt1; return Act::template apply( constify_rvals::go(r_select::go(get<0>(args), CALL_ACTUAL_ARGS)), constify_rvals::go(r_select::go(get<1>(args), CALL_ACTUAL_ARGS)) ); } }; BOOST_LAMBDA_LAMBDA_FUNCTOR_BASE_FIRST_PART(3) typedef typename deduce_argument_types >::type rets_t; typedef typename element_or_null<0, rets_t>::type rt0; typedef typename element_or_null<1, rets_t>::type rt1; typedef typename element_or_null<2, rets_t>::type rt2; return Act::template apply( constify_rvals::go(r_select::go(get<0>(args), CALL_ACTUAL_ARGS)), constify_rvals::go(r_select::go(get<1>(args), CALL_ACTUAL_ARGS)), constify_rvals::go(r_select::go(get<2>(args), CALL_ACTUAL_ARGS)) ); } }; BOOST_LAMBDA_LAMBDA_FUNCTOR_BASE_FIRST_PART(4) typedef typename deduce_argument_types >::type rets_t; typedef typename element_or_null<0, rets_t>::type rt0; typedef typename element_or_null<1, rets_t>::type rt1; typedef typename element_or_null<2, rets_t>::type rt2; typedef typename element_or_null<3, rets_t>::type rt3; return Act::template apply( constify_rvals::go(r_select::go(get<0>(args), CALL_ACTUAL_ARGS)), constify_rvals::go(r_select::go(get<1>(args), CALL_ACTUAL_ARGS)), constify_rvals::go(r_select::go(get<2>(args), CALL_ACTUAL_ARGS)), constify_rvals::go(r_select::go(get<3>(args), CALL_ACTUAL_ARGS)) ); } }; BOOST_LAMBDA_LAMBDA_FUNCTOR_BASE_FIRST_PART(5) typedef typename deduce_argument_types >::type rets_t; typedef typename element_or_null<0, rets_t>::type rt0; typedef typename element_or_null<1, rets_t>::type rt1; typedef typename element_or_null<2, rets_t>::type rt2; typedef typename element_or_null<3, rets_t>::type rt3; typedef typename element_or_null<4, rets_t>::type rt4; return Act::template apply( constify_rvals::go(r_select::go(get<0>(args), CALL_ACTUAL_ARGS)), constify_rvals::go(r_select::go(get<1>(args), CALL_ACTUAL_ARGS)), constify_rvals::go(r_select::go(get<2>(args), CALL_ACTUAL_ARGS)), constify_rvals::go(r_select::go(get<3>(args), CALL_ACTUAL_ARGS)), constify_rvals::go(r_select::go(get<4>(args), CALL_ACTUAL_ARGS)) ); } }; BOOST_LAMBDA_LAMBDA_FUNCTOR_BASE_FIRST_PART(6) typedef typename deduce_argument_types >::type rets_t; typedef typename element_or_null<0, rets_t>::type rt0; typedef typename element_or_null<1, rets_t>::type rt1; typedef typename element_or_null<2, rets_t>::type rt2; typedef typename element_or_null<3, rets_t>::type rt3; typedef typename element_or_null<4, rets_t>::type rt4; typedef typename element_or_null<5, rets_t>::type rt5; return Act::template apply( constify_rvals::go(r_select::go(get<0>(args), CALL_ACTUAL_ARGS)), constify_rvals::go(r_select::go(get<1>(args), CALL_ACTUAL_ARGS)), constify_rvals::go(r_select::go(get<2>(args), CALL_ACTUAL_ARGS)), constify_rvals::go(r_select::go(get<3>(args), CALL_ACTUAL_ARGS)), constify_rvals::go(r_select::go(get<4>(args), CALL_ACTUAL_ARGS)), constify_rvals::go(r_select::go(get<5>(args), CALL_ACTUAL_ARGS)) ); } }; BOOST_LAMBDA_LAMBDA_FUNCTOR_BASE_FIRST_PART(7) typedef typename deduce_argument_types >::type rets_t; typedef typename element_or_null<0, rets_t>::type rt0; typedef typename element_or_null<1, rets_t>::type rt1; typedef typename element_or_null<2, rets_t>::type rt2; typedef typename element_or_null<3, rets_t>::type rt3; typedef typename element_or_null<4, rets_t>::type rt4; typedef typename element_or_null<5, rets_t>::type rt5; typedef typename element_or_null<6, rets_t>::type rt6; return Act::template apply( constify_rvals::go(r_select::go(get<0>(args), CALL_ACTUAL_ARGS)), constify_rvals::go(r_select::go(get<1>(args), CALL_ACTUAL_ARGS)), constify_rvals::go(r_select::go(get<2>(args), CALL_ACTUAL_ARGS)), constify_rvals::go(r_select::go(get<3>(args), CALL_ACTUAL_ARGS)), constify_rvals::go(r_select::go(get<4>(args), CALL_ACTUAL_ARGS)), constify_rvals::go(r_select::go(get<5>(args), CALL_ACTUAL_ARGS)), constify_rvals::go(r_select::go(get<6>(args), CALL_ACTUAL_ARGS)) ); } }; BOOST_LAMBDA_LAMBDA_FUNCTOR_BASE_FIRST_PART(8) typedef typename deduce_argument_types >::type rets_t; typedef typename element_or_null<0, rets_t>::type rt0; typedef typename element_or_null<1, rets_t>::type rt1; typedef typename element_or_null<2, rets_t>::type rt2; typedef typename element_or_null<3, rets_t>::type rt3; typedef typename element_or_null<4, rets_t>::type rt4; typedef typename element_or_null<5, rets_t>::type rt5; typedef typename element_or_null<6, rets_t>::type rt6; typedef typename element_or_null<7, rets_t>::type rt7; return Act::template apply( constify_rvals::go(r_select::go(get<0>(args), CALL_ACTUAL_ARGS)), constify_rvals::go(r_select::go(get<1>(args), CALL_ACTUAL_ARGS)), constify_rvals::go(r_select::go(get<2>(args), CALL_ACTUAL_ARGS)), constify_rvals::go(r_select::go(get<3>(args), CALL_ACTUAL_ARGS)), constify_rvals::go(r_select::go(get<4>(args), CALL_ACTUAL_ARGS)), constify_rvals::go(r_select::go(get<5>(args), CALL_ACTUAL_ARGS)), constify_rvals::go(r_select::go(get<6>(args), CALL_ACTUAL_ARGS)), constify_rvals::go(r_select::go(get<7>(args), CALL_ACTUAL_ARGS)) ); } }; BOOST_LAMBDA_LAMBDA_FUNCTOR_BASE_FIRST_PART(9) typedef typename deduce_argument_types >::type rets_t; typedef typename element_or_null<0, rets_t>::type rt0; typedef typename element_or_null<1, rets_t>::type rt1; typedef typename element_or_null<2, rets_t>::type rt2; typedef typename element_or_null<3, rets_t>::type rt3; typedef typename element_or_null<4, rets_t>::type rt4; typedef typename element_or_null<5, rets_t>::type rt5; typedef typename element_or_null<6, rets_t>::type rt6; typedef typename element_or_null<7, rets_t>::type rt7; typedef typename element_or_null<8, rets_t>::type rt8; return Act::template apply( constify_rvals::go(r_select::go(get<0>(args), CALL_ACTUAL_ARGS)), constify_rvals::go(r_select::go(get<1>(args), CALL_ACTUAL_ARGS)), constify_rvals::go(r_select::go(get<2>(args), CALL_ACTUAL_ARGS)), constify_rvals::go(r_select::go(get<3>(args), CALL_ACTUAL_ARGS)), constify_rvals::go(r_select::go(get<4>(args), CALL_ACTUAL_ARGS)), constify_rvals::go(r_select::go(get<5>(args), CALL_ACTUAL_ARGS)), constify_rvals::go(r_select::go(get<6>(args), CALL_ACTUAL_ARGS)), constify_rvals::go(r_select::go(get<7>(args), CALL_ACTUAL_ARGS)), constify_rvals::go(r_select::go(get<8>(args), CALL_ACTUAL_ARGS)) ); } }; BOOST_LAMBDA_LAMBDA_FUNCTOR_BASE_FIRST_PART(10) typedef typename deduce_argument_types >::type rets_t; typedef typename element_or_null<0, rets_t>::type rt0; typedef typename element_or_null<1, rets_t>::type rt1; typedef typename element_or_null<2, rets_t>::type rt2; typedef typename element_or_null<3, rets_t>::type rt3; typedef typename element_or_null<4, rets_t>::type rt4; typedef typename element_or_null<5, rets_t>::type rt5; typedef typename element_or_null<6, rets_t>::type rt6; typedef typename element_or_null<7, rets_t>::type rt7; typedef typename element_or_null<8, rets_t>::type rt8; typedef typename element_or_null<9, rets_t>::type rt9; return Act::template apply( constify_rvals::go(r_select::go(get<0>(args), CALL_ACTUAL_ARGS)), constify_rvals::go(r_select::go(get<1>(args), CALL_ACTUAL_ARGS)), constify_rvals::go(r_select::go(get<2>(args), CALL_ACTUAL_ARGS)), constify_rvals::go(r_select::go(get<3>(args), CALL_ACTUAL_ARGS)), constify_rvals::go(r_select::go(get<4>(args), CALL_ACTUAL_ARGS)), constify_rvals::go(r_select::go(get<5>(args), CALL_ACTUAL_ARGS)), constify_rvals::go(r_select::go(get<6>(args), CALL_ACTUAL_ARGS)), constify_rvals::go(r_select::go(get<7>(args), CALL_ACTUAL_ARGS)), constify_rvals::go(r_select::go(get<8>(args), CALL_ACTUAL_ARGS)), constify_rvals::go(r_select::go(get<9>(args), CALL_ACTUAL_ARGS)) ); } }; #undef BOOST_LAMBDA_LAMBDA_FUNCTOR_BASE_FIRST_PART } // namespace lambda } // namespace boost #endif