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110 lines
2.8 KiB
110 lines
2.8 KiB
// -- Boost Lambda Library ------------------------------------------------- |
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// Copyright (C) 1999, 2000 Jaakko Jarvi (jaakko.jarvi@cs.utu.fi) |
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// |
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// Distributed under the Boost Software License, Version 1.0. (See |
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// accompanying file LICENSE_1_0.txt or copy at |
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// http://www.boost.org/LICENSE_1_0.txt) |
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// |
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// For more information, see www.boost.org |
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// -------------------------------------------------- |
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#ifndef BOOST_LAMBDA_ARITY_CODE_HPP |
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#define BOOST_LAMBDA_ARITY_CODE_HPP |
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#include "boost/type_traits/cv_traits.hpp" |
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#include "boost/type_traits/transform_traits.hpp" |
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namespace boost { |
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namespace lambda { |
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// These constants state, whether a lambda_functor instantiation results from |
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// an expression which contains no placeholders (NONE), |
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// only free1 placeholders (FIRST), |
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// free2 placeholders and maybe free1 placeholders (SECOND), |
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// free3 and maybe free1 and free2 placeholders (THIRD), |
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// freeE placeholders and maybe free1 and free2 (EXCEPTION). |
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// RETHROW means, that a rethrow expression is used somewhere in the lambda_functor. |
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enum { NONE = 0x00, // Notice we are using bits as flags here. |
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FIRST = 0x01, |
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SECOND = 0x02, |
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THIRD = 0x04, |
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EXCEPTION = 0x08, |
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RETHROW = 0x10}; |
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template<class T> |
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struct get_tuple_arity; |
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namespace detail { |
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template <class T> struct get_arity_; |
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} // end detail; |
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template <class T> struct get_arity { |
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BOOST_STATIC_CONSTANT(int, value = detail::get_arity_<typename boost::remove_cv<typename boost::remove_reference<T>::type>::type>::value); |
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}; |
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namespace detail { |
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template<class T> |
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struct get_arity_ { |
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BOOST_STATIC_CONSTANT(int, value = 0); |
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}; |
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template<class T> |
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struct get_arity_<lambda_functor<T> > { |
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BOOST_STATIC_CONSTANT(int, value = get_arity<T>::value); |
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}; |
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template<class Action, class Args> |
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struct get_arity_<lambda_functor_base<Action, Args> > { |
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BOOST_STATIC_CONSTANT(int, value = get_tuple_arity<Args>::value); |
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}; |
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template<int I> |
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struct get_arity_<placeholder<I> > { |
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BOOST_STATIC_CONSTANT(int, value = I); |
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}; |
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} // detail |
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template<class T> |
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struct get_tuple_arity { |
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BOOST_STATIC_CONSTANT(int, value = get_arity<typename T::head_type>::value | get_tuple_arity<typename T::tail_type>::value); |
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}; |
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template<> |
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struct get_tuple_arity<null_type> { |
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BOOST_STATIC_CONSTANT(int, value = 0); |
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}; |
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// Does T have placeholder<I> as it's subexpression? |
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template<class T, int I> |
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struct has_placeholder { |
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BOOST_STATIC_CONSTANT(bool, value = (get_arity<T>::value & I) != 0); |
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}; |
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template<int I, int J> |
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struct includes_placeholder { |
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BOOST_STATIC_CONSTANT(bool, value = (J & I) != 0); |
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}; |
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template<int I, int J> |
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struct lacks_placeholder { |
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BOOST_STATIC_CONSTANT(bool, value = ((J & I) == 0)); |
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}; |
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} // namespace lambda |
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} // namespace boost |
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#endif
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