object_with_copy.hpp

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//=======================================================================
// Copyright (c) 2013 Piotr Wygocki
//
// 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)
//=======================================================================
#ifndef PAAL_OBJECT_WITH_COPY_HPP
#define PAAL_OBJECT_WITH_COPY_HPP

namespace paal {
namespace data_structures {

template <typename T> class object_with_copy {
  public:
    typedef T ObjectType;

    object_with_copy(T t) : m_obj(std::move(t)), m_copy(m_obj) {}

    // if you use *. in decltype instead of -> you get
    // "sorry, unimplemented: mangling dotstar_expr" :)
    template <typename F, typename... Args>
    typename std::result_of<F(T*, Args...)>::type
        invoke(F f, Args... args) {
        (m_copy.*(f))(args...);
        return (m_obj.*(f))(args...);
    }

    template <typename F, typename... Args>
    typename std::result_of<F(T*, Args...)>::type
    invoke_on_copy(F f, Args... args) const {
        return (m_copy.*(f))(args...);
    }

    const T *operator->() const { return &m_obj; }

    T &get_obj() { return m_obj; }

    const T &get_obj() const { return m_obj; }

  private:
    T m_obj;
    mutable T m_copy;
};

} // data_structures
} // paal

#endif // PAAL_OBJECT_WITH_COPY_HPP