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3rdparty/boost_1_81_0/boost/move/traits.hpp 2.49 KB
598bfd3f   Hu Chunming   提交_GLIBCXX_USE_CX...
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  //////////////////////////////////////////////////////////////////////////////
  //
  // (C) Copyright Ion Gaztanaga 2009-2012.
  // 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://www.boost.org/libs/move for documentation.
  //
  //////////////////////////////////////////////////////////////////////////////
  
  //! \file
  
  #ifndef BOOST_MOVE_TRAITS_HPP
  #define BOOST_MOVE_TRAITS_HPP
  
  #ifndef BOOST_CONFIG_HPP
  #  include <boost/config.hpp>
  #endif
  #
  #if defined(BOOST_HAS_PRAGMA_ONCE)
  #  pragma once
  #endif
  
  #include <boost/move/detail/config_begin.hpp>
  
  #ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
  #include <boost/move/core.hpp>
  #endif
  #include <boost/move/detail/meta_utils.hpp>
  #include <boost/move/detail/type_traits.hpp>
  
  namespace boost {
  
  //! If this trait yields to true
  //! (<i>has_trivial_destructor_after_move &lt;T&gt;::value == true</i>)
  //! means that if T is used as argument of a move construction/assignment,
  //! there is no need to call T's destructor.
  //! This optimization tipically is used to improve containers' performance.
  //!
  //! By default this trait is true if the type has trivial destructor,
  //! every class should specialize this trait if it wants to improve performance
  //! when inserted in containers.
  template <class T>
  struct has_trivial_destructor_after_move
     : ::boost::move_detail::is_trivially_destructible<T>
  {};
  
  //! By default this traits returns
  //! <pre>boost::is_nothrow_move_constructible<T>::value && boost::is_nothrow_move_assignable<T>::value </pre>.
  //! Classes with non-throwing move constructor
  //! and assignment can specialize this trait to obtain some performance improvements.
  template <class T>
  struct has_nothrow_move
  {
     static const bool value = boost::move_detail::is_nothrow_move_constructible<T>::value &&
                               boost::move_detail::is_nothrow_move_assignable<T>::value;
  };
  
  namespace move_detail {
  
  template <class T>
  struct is_nothrow_move_constructible_or_uncopyable
  {
     //The standard requires is_nothrow_move_constructible for move_if_noexcept
     //but a user (usually in C++03) might specialize has_nothrow_move which includes it
     static const bool value = is_nothrow_move_constructible<T>::value ||
                               has_nothrow_move<T>::value ||
                              !is_copy_constructible<T>::value;
  };
  
  }  //move_detail {
  }  //namespace boost {
  
  #include <boost/move/detail/config_end.hpp>
  
  #endif //#ifndef BOOST_MOVE_TRAITS_HPP