overloaded_function/detail/base.hpp

0001
0002 // Copyright (C) 2009-2012 Lorenzo Caminiti
0003 // Distributed under the Boost Software License, Version 1.0
0004 // (see accompanying file LICENSE_1_0.txt or a copy at
0005 // http://www.boost.org/LICENSE_1_0.txt)
0006 // Home at http://www.boost.org/libs/functional/overloaded_function
0007
0008 #if !BOOST_PP_IS_ITERATING
0009 #   ifndef BOOST_FUNCTIONAL_OVERLOADED_FUNCTION_DETAIL_BASE_HPP_
0010 #       define BOOST_FUNCTIONAL_OVERLOADED_FUNCTION_DETAIL_BASE_HPP_
0011
0012 #       include <boost/functional/overloaded_function/config.hpp>
0013 #       include <boost/function.hpp>
0014 #       include <boost/preprocessor/iteration/iterate.hpp>
0015 #       include <boost/preprocessor/repetition/enum.hpp>
0016 #       include <boost/preprocessor/cat.hpp>
0017 #       include <boost/preprocessor/comma_if.hpp>
0018
0019 #define BOOST_FUNCTIONAL_DETAIL_arg_type(z, n, unused) \
0020     BOOST_PP_CAT(A, n)
0021
0022 #define BOOST_FUNCTIONAL_DETAIL_arg_name(z, n, unused) \
0023     BOOST_PP_CAT(a, n)
0024
0025 #define BOOST_FUNCTIONAL_DETAIL_arg_tparam(z, n, unused) \
0026     typename BOOST_FUNCTIONAL_DETAIL_arg_type(z, n, unused)
0027
0028 #define BOOST_FUNCTIONAL_DETAIL_arg(z, n, unused) \
0029     BOOST_FUNCTIONAL_DETAIL_arg_type(z, n, unused) \
0030     BOOST_FUNCTIONAL_DETAIL_arg_name(z, n, unused)
0031
0032 #define BOOST_FUNCTIONAL_DETAIL_f \
0033     R (BOOST_PP_ENUM(BOOST_FUNCTIONAL_DETAIL_arity, \
0034             BOOST_FUNCTIONAL_DETAIL_arg_type, ~))
0035
0036 // Do not use namespace ::detail because overloaded_function is already a class.
0037 namespace boost { namespace overloaded_function_detail {
0038
0039 template<typename F>
0040 class base {}; // Empty template cannot be used directly (only its spec).
0041
0042 #       define BOOST_PP_ITERATION_PARAMS_1 \
0043                 (3, (0, BOOST_FUNCTIONAL_OVERLOADED_FUNCTION_CONFIG_ARITY_MAX, \
0044                 "boost/functional/overloaded_function/detail/base.hpp"))
0045 #       include BOOST_PP_ITERATE() // Iterate over funciton arity.
0046
0047 } } // namespace
0048
0049 #undef BOOST_FUNCTIONAL_DETAIL_arg_type
0050 #undef BOOST_FUNCTIONAL_DETAIL_arg_name
0051 #undef BOOST_FUNCTIONAL_DETAIL_arg_tparam
0052 #undef BOOST_FUNCTIONAL_DETAIL_arg
0053 #undef BOOST_FUNCTIONAL_DETAIL_f
0054
0055 #   endif // #include guard
0056
0057 #elif BOOST_PP_ITERATION_DEPTH() == 1
0058 #   define BOOST_FUNCTIONAL_DETAIL_arity BOOST_PP_FRAME_ITERATION(1)
0059
0060 template<
0061     typename R
0062     BOOST_PP_COMMA_IF(BOOST_FUNCTIONAL_DETAIL_arity)
0063     BOOST_PP_ENUM(BOOST_FUNCTIONAL_DETAIL_arity,
0064             BOOST_FUNCTIONAL_DETAIL_arg_tparam, ~)
0065 >
0066 class base< BOOST_FUNCTIONAL_DETAIL_f > {
0067 public:
0068     /* implicit */ inline base(
0069             // This requires specified type to be implicitly convertible to
0070             // a boost::function<> functor.
0071             boost::function< BOOST_FUNCTIONAL_DETAIL_f > const& f): f_(f)
0072     {}
0073
0074     inline R operator()(BOOST_PP_ENUM(BOOST_FUNCTIONAL_DETAIL_arity,
0075             BOOST_FUNCTIONAL_DETAIL_arg, ~)) const {
0076         return f_(BOOST_PP_ENUM(BOOST_FUNCTIONAL_DETAIL_arity,
0077                 BOOST_FUNCTIONAL_DETAIL_arg_name, ~));
0078     }
0079
0080 private:
0081     boost::function< BOOST_FUNCTIONAL_DETAIL_f > const f_;
0082 };
0083
0084 #   undef BOOST_FUNCTIONAL_DETAIL_arity
0085 #endif // iteration
0086