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//////////////////////////////////////////////////////////////////////////////
//
// (C) Copyright Ion Gaztanaga 2015-2015. 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/container for documentation.
//
//////////////////////////////////////////////////////////////////////////////

#ifndef BOOST_CONTAINER_PMR_POLYMORPHIC_ALLOCATOR_HPP
#define BOOST_CONTAINER_PMR_POLYMORPHIC_ALLOCATOR_HPP

#if defined (_MSC_VER)
#  pragma once 
#endif

#include <boost/config.hpp>
#include <boost/move/detail/type_traits.hpp>
#include <boost/move/utility_core.hpp>
#include <boost/container/detail/dispatch_uses_allocator.hpp>
#include <boost/container/new_allocator.hpp>
#include <boost/container/pmr/memory_resource.hpp>
#include <boost/container/pmr/global_resource.hpp>

#include <cstddef>

namespace boost {
namespace container {
namespace pmr {

//! A specialization of class template `polymorphic_allocator` conforms to the Allocator requirements.
//! Constructed with different memory resources, different instances of the same specialization of
//! `polymorphic_allocator` can exhibit entirely different allocation behavior. This runtime
//! polymorphism allows objects that use polymorphic_allocator to behave as if they used different
//! allocator types at run time even though they use the same static allocator type.
template <class T>
class polymorphic_allocator
{
   public:
   typedef T value_type;

   //! <b>Effects</b>: Sets m_resource to
   //! `get_default_resource()`.
   polymorphic_allocator() BOOST_NOEXCEPT
      : m_resource(::boost::container::pmr::get_default_resource())
   {}

   //! <b>Requires</b>: r is non-null.
   //!
   //! <b>Effects</b>: Sets m_resource to r.
   //!
   //! <b>Throws</b>: Nothing
   //!
   //! <b>Notes</b>: This constructor provides an implicit conversion from memory_resource*.
   //!   Non-standard extension: if r is null m_resource is set to get_default_resource().
   polymorphic_allocator(memory_resource* r)
      : m_resource(r ? r : ::boost::container::pmr::get_default_resource())
   {}

   //! <b>Effects</b>: Sets m_resource to
   //!   other.resource().
   polymorphic_allocator(const polymorphic_allocator& other)
      : m_resource(other.m_resource)
   {}

   //! <b>Effects</b>: Sets m_resource to
   //!   other.resource().
   template <class U>
   polymorphic_allocator(const polymorphic_allocator<U>& other) BOOST_NOEXCEPT
      : m_resource(other.resource())
   {}

   //! <b>Effects</b>: Sets m_resource to
   //!   other.resource().
   polymorphic_allocator& operator=(const polymorphic_allocator& other)
   {  m_resource = other.m_resource;   return *this;  }

   //! <b>Returns</b>: Equivalent to
   //!   `static_cast<T*>(m_resource->allocate(n * sizeof(T), alignof(T)))`.
   T* allocate(size_t n)
   {  return static_cast<T*>(m_resource->allocate(n*sizeof(T), ::boost::move_detail::alignment_of<T>::value));  }

   //! <b>Requires</b>: p was allocated from a memory resource, x, equal to *m_resource,