// -- Boost Lambda Library ------------------------------------------------- | |
// 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_ARITY_CODE_HPP | |
#define BOOST_LAMBDA_ARITY_CODE_HPP | |
#include "boost/type_traits/cv_traits.hpp" | |
#include "boost/type_traits/transform_traits.hpp" | |
namespace boost { | |
namespace lambda { | |
// These constants state, whether a lambda_functor instantiation results from | |
// an expression which contains no placeholders (NONE), | |
// only free1 placeholders (FIRST), | |
// free2 placeholders and maybe free1 placeholders (SECOND), | |
// free3 and maybe free1 and free2 placeholders (THIRD), | |
// freeE placeholders and maybe free1 and free2 (EXCEPTION). | |
// RETHROW means, that a rethrow expression is used somewhere in the lambda_functor. | |
enum { NONE = 0x00, // Notice we are using bits as flags here. | |
FIRST = 0x01, | |
SECOND = 0x02, | |
THIRD = 0x04, | |
EXCEPTION = 0x08, | |
RETHROW = 0x10}; | |
template<class T> | |
struct get_tuple_arity; | |
namespace detail { | |
template <class T> struct get_arity_; | |
} // end detail; | |
template <class T> struct get_arity { | |
BOOST_STATIC_CONSTANT(int, value = detail::get_arity_<typename boost::remove_cv<typename boost::remove_reference<T>::type>::type>::value); | |
}; | |
namespace detail { | |
template<class T> | |
struct get_arity_ { | |
BOOST_STATIC_CONSTANT(int, value = 0); | |
}; | |
template<class T> | |
struct get_arity_<lambda_functor<T> > { | |
BOOST_STATIC_CONSTANT(int, value = get_arity<T>::value); | |
}; | |
template<class Action, class Args> | |
struct get_arity_<lambda_functor_base<Action, Args> > { | |
BOOST_STATIC_CONSTANT(int, value = get_tuple_arity<Args>::value); | |
}; | |
template<int I> | |
struct get_arity_<placeholder<I> > { | |
BOOST_STATIC_CONSTANT(int, value = I); | |
}; | |
} // detail | |
template<class T> | |
struct get_tuple_arity { | |
BOOST_STATIC_CONSTANT(int, value = get_arity<typename T::head_type>::value | get_tuple_arity<typename T::tail_type>::value); | |
}; | |
template<> | |
struct get_tuple_arity<null_type> { | |
BOOST_STATIC_CONSTANT(int, value = 0); | |
}; | |
// Does T have placeholder<I> as it's subexpression? | |
template<class T, int I> | |
struct has_placeholder { | |
BOOST_STATIC_CONSTANT(bool, value = (get_arity<T>::value & I) != 0); | |
}; | |
template<int I, int J> | |
struct includes_placeholder { | |
BOOST_STATIC_CONSTANT(bool, value = (J & I) != 0); | |
}; | |
template<int I, int J> | |
struct lacks_placeholder { | |
BOOST_STATIC_CONSTANT(bool, value = ((J & I) == 0)); | |
}; | |
} // namespace lambda | |
} // namespace boost | |
#endif |