support/utility/lambda_visitor.hpp

0001 /*=============================================================================
0002     Copyright (c) 2014 Joel de Guzman
0003
0004     Distributed under the Boost Software License, Version 1.0. (See accompanying
0005     file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
0006 ==============================================================================*/
0007 #if !defined(BOOST_SPIRIT_X3_LAMBDA_VISITOR_MAY_19_2014_1116AM)
0008 #define BOOST_SPIRIT_X3_LAMBDA_VISITOR_MAY_19_2014_1116AM
0009
0010 namespace boost { namespace spirit { namespace x3
0011 {
0012     template <typename RT, typename... Lambdas>
0013     struct lambda_visitor;
0014
0015     template <typename RT, typename F, typename... Lambdas>
0016     struct lambda_visitor<RT, F, Lambdas...> : F, lambda_visitor<RT, Lambdas...>
0017     {
0018         typedef lambda_visitor<RT , Lambdas...> base_type;
0019         using F::operator();
0020         using base_type::operator();
0021         lambda_visitor(F f, Lambdas... lambdas)
0022           : F(f), base_type(lambdas...)
0023         {}
0024     };
0025
0026     template <typename RT, typename F>
0027     struct lambda_visitor<RT, F> : F
0028     {
0029         typedef RT result_type;
0030         using F::operator();
0031         lambda_visitor(F f)
0032           : F(f)
0033         {}
0034     };
0035
0036     template <typename RT>
0037     struct lambda_visitor<RT>
0038     {
0039         typedef RT result_type;
0040     };
0041
0042     template <typename RT, typename... Lambdas>
0043     lambda_visitor<RT, Lambdas...> make_lambda_visitor(Lambdas... lambdas)
0044     {
0045         return { lambdas... };
0046     }
0047 }}}
0048
0049 #endif