//---------------------------------------------------------------------------// // Copyright (c) 2013-2014 Kyle Lutz <kyle.r.lutz@gmail.com> // // 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 // // See http://boostorg.github.com/compute for more information. //---------------------------------------------------------------------------// #ifndef BOOST_COMPUTE_FUNCTIONAL_IDENTITY_HPP #define BOOST_COMPUTE_FUNCTIONAL_IDENTITY_HPP namespace boost { namespace compute { namespace detail { template<class T, class Arg> struct invoked_identity { typedef T result_type; invoked_identity(const Arg &arg) : m_arg(arg) { } Arg m_arg; }; } // end detail namespace /// Identity function which simply returns its input. /// /// For example, to directly copy values using the transform() algorithm: /// \code /// transform(input.begin(), input.end(), output.begin(), identity<int>(), queue); /// \endcode /// /// \see \ref as "as<T>", \ref convert "convert<T>" template<class T> class identity { public: /// Identity function result type. typedef T result_type; /// Creates a new identity function. identity() { } /// \internal_ template<class Arg> detail::invoked_identity<T, Arg> operator()(const Arg &arg) const { return detail::invoked_identity<T, Arg>(arg); } }; } // end compute namespace } // end boost namespace #endif // BOOST_COMPUTE_FUNCTIONAL_IDENTITY_HPP