47 lines
1.1 KiB
C++
47 lines
1.1 KiB
C++
/*=============================================================================
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Copyright (c) 2001-2003 Joel de Guzman
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Distributed under the Boost Software License, Version 1.0. (See accompanying
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file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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==============================================================================*/
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#include <vector>
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#include <algorithm>
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#include <iostream>
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#include <boost/phoenix/core.hpp>
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#include <boost/phoenix/function.hpp>
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struct factorial_impl
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{
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template <typename Sig>
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struct result;
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template <typename This, typename Arg>
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struct result<This(Arg)>
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: result<This(Arg const &)>
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{};
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template <typename This, typename Arg>
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struct result<This(Arg &)>
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{
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typedef Arg type;
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};
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template <typename Arg>
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Arg operator()(Arg n) const
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{
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return (n <= 0) ? 1 : n * this->operator()(n-1);
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}
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};
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int
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main()
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{
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using boost::phoenix::arg_names::arg1;
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boost::phoenix::function<factorial_impl> factorial;
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int i = 4;
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std::cout << factorial(i)() << std::endl;
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std::cout << factorial(arg1)(i) << std::endl;
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return 0;
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}
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