// Boost Lambda Library - is_instance_of.hpp ---------------------

// Copyright (C) 2001 Jaakko Järvi (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_IS_INSTANCE_OF

#define BOOST_LAMBDA_IS_INSTANCE_OF

#include "boost/config.hpp" // for BOOST_STATIC_CONSTANT

#include "boost/type_traits/conversion_traits.hpp" // for is_convertible

#include "boost/preprocessor/enum_shifted_params.hpp"

#include "boost/preprocessor/repeat_2nd.hpp"

// is_instance_of --------------------------------

// 

// is_instance_of_n<A, B>::value is true, if type A is 

// an instantiation of a template B, or A derives from an instantiation 

// of template B

//

// n is the number of template arguments for B

// 

// Example:

// is_instance_of_2<std::istream, basic_stream>::value == true

// The original implementation was somewhat different, with different versions

// for different compilers. However, there was still a problem

// with gcc.3.0.2 and 3.0.3 compilers, which didn't think regard

// is_instance_of_N<...>::value was a constant.

// John Maddock suggested the way around this problem by building 

// is_instance_of templates using boost::is_convertible.

// Now we only have one version of is_instance_of templates, which delagate

// all the nasty compiler tricks to is_convertible. 

#define BOOST_LAMBDA_CLASS(z, N,A) BOOST_PP_COMMA_IF(N) class

#define BOOST_LAMBDA_CLASS_ARG(z, N,A) BOOST_PP_COMMA_IF(N) class A##N 

#define BOOST_LAMBDA_ARG(z, N,A) BOOST_PP_COMMA_IF(N) A##N 

#define BOOST_LAMBDA_CLASS_LIST(n, NAME) BOOST_PP_REPEAT(n, BOOST_LAMBDA_CLASS, NAME)

#define BOOST_LAMBDA_CLASS_ARG_LIST(n, NAME) BOOST_PP_REPEAT(n, BOOST_LAMBDA_CLASS_ARG, NAME)

#define BOOST_LAMBDA_ARG_LIST(n, NAME) BOOST_PP_REPEAT(n, BOOST_LAMBDA_ARG, NAME)

namespace boost {

namespace lambda {

#define BOOST_LAMBDA_IS_INSTANCE_OF_TEMPLATE(INDEX)                         \

                                                                            \

namespace detail {                                                          \

                                                                            \

template <template<BOOST_LAMBDA_CLASS_LIST(INDEX,T)> class F>               \

struct BOOST_PP_CAT(conversion_tester_,INDEX) {                             \

  template<BOOST_LAMBDA_CLASS_ARG_LIST(INDEX,A)>                            \

  BOOST_PP_CAT(conversion_tester_,INDEX)                                    \

    (const F<BOOST_LAMBDA_ARG_LIST(INDEX,A)>&);                             \

};                                                                          \

                                                                            \

} /* end detail */                                                          \

                                                                            \

template <class From, template <BOOST_LAMBDA_CLASS_LIST(INDEX,T)> class To> \

struct BOOST_PP_CAT(is_instance_of_,INDEX)                                  \

{                                                                           \

 private:                                                                   \

   typedef ::boost::is_convertible<                                         \

     From,                                                                  \

     BOOST_PP_CAT(detail::conversion_tester_,INDEX)<To>                     \

   > helper_type;                                                           \

                                                                            \

public:                                                                     \

  BOOST_STATIC_CONSTANT(bool, value = helper_type::value);                  \

};

#define BOOST_LAMBDA_HELPER(z, N, A) BOOST_LAMBDA_IS_INSTANCE_OF_TEMPLATE( BOOST_PP_INC(N) )

// Generate the traits for 1-4 argument templates

BOOST_PP_REPEAT_2ND(4,BOOST_LAMBDA_HELPER,FOO)

#undef BOOST_LAMBDA_HELPER

#undef BOOST_LAMBDA_IS_INSTANCE_OF_TEMPLATE

#undef BOOST_LAMBDA_CLASS

#undef BOOST_LAMBDA_ARG

#undef BOOST_LAMBDA_CLASS_ARG

#undef BOOST_LAMBDA_CLASS_LIST

#undef BOOST_LAMBDA_ARG_LIST

#undef BOOST_LAMBDA_CLASS_ARG_LIST

} // lambda

} // boost

#endif