allocator_traits.hpp

/*****************************************************************************
 * \file
 * \brief This header contains the trait type \c allocator_traits that
 *        determines or infers default values for the Allocator concept
 *****************************************************************************/

/*
  The MIT License (MIT)

  Copyright (c) 2018 Matthew Rodusek

  Permission is hereby granted, free of charge, to any person obtaining a copy
  of this software and associated documentation files (the "Software"), to deal
  in the Software without restriction, including without limitation the rights
  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  copies of the Software, and to permit persons to whom the Software is
  furnished to do so, subject to the following conditions:

  The above copyright notice and this permission notice shall be included in
  all copies or substantial portions of the Software.

  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  SOFTWARE.
*/
#ifndef BIT_MEMORY_TRAITS_ALLOCATOR_TRAITS_HPP
#define BIT_MEMORY_TRAITS_ALLOCATOR_TRAITS_HPP

#if defined(_MSC_VER) && (_MSC_VER >= 1200)
# pragma once
#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)

#include "../utilities/allocator_info.hpp"        // allocator_info
#include "../utilities/errors.hpp"                // get_out_of_memory_handler
#include "../utilities/macros.hpp"                // BIT_MEMORY_UNUSED
#include "../utilities/owner.hpp"                 // owner
#include "../utilities/pointer_utilities.hpp"     // to_raw_pointer
#include "../utilities/uninitialized_storage.hpp" // destroy_at, etc

#include "../concepts/Allocator.hpp" // is_allocator, allocator_has_allocate,

#include <type_traits> // std::true_type, std::false_type, etc
#include <cstddef>     // std::size_t, std::ptrdiff_t
#include <limits>      // std::numeric_limits
#include <memory>      // std::addressof. std::pointer_traits
#include <typeinfo>    // std::type_info
#include <utility>     // std::move, std::forward

namespace bit {
  namespace memory {
    namespace detail {

      template<typename Allocator, typename T, typename=void>
      struct allocator_pointer_rebind
      {
        using type = typename std::pointer_traits<allocator_pointer_t<Allocator>>::template rebind<T>;
      };

      template<typename Allocator, typename T>
      struct allocator_pointer_rebind<Allocator,T,void_t<typename Allocator::template pointer_rebind<T>>>
      {
        using type = typename Allocator::template pointer_rebind<T>;
      };

    } // namespace detail

    template<typename Allocator>
    class allocator_traits
    {
      static_assert( is_allocator<Allocator>::value,
                     "Allocator must be an Allocator" );

      template<typename T>
      struct negation : std::integral_constant<bool,!T::value>{};

      //-----------------------------------------------------------------------
      // Public Members
      //-----------------------------------------------------------------------
    public:

      // aliases
      using pointer         = allocator_pointer_t<Allocator>;
      using const_pointer   = allocator_const_pointer_t<Allocator>;
      using size_type       = allocator_size_type_t<Allocator>;
      using difference_type = allocator_difference_type_t<Allocator>;

      template<typename T>
      using pointer_rebind = typename detail::allocator_pointer_rebind<Allocator,T>::type;

      // properties
      using default_alignment          = allocator_default_alignment<Allocator>;
      using max_alignment              = allocator_max_alignment<Allocator>;
      using can_truncate_deallocations = allocator_can_truncate_deallocations<Allocator>;
      using knows_ownership            = allocator_knows_ownership<Allocator>;
      using uses_pretty_pointers       = negation<std::is_same<void*,pointer_rebind<void>>>;

    private:

      template<typename Pointer>
      static constexpr bool is_typed_pointer = std::is_same<typename std::pointer_traits<Pointer>::template rebind<void>,
                                                            pointer>::value;

      //-----------------------------------------------------------------------
      // Allocation
      //-----------------------------------------------------------------------
    public:

      static pointer try_allocate( Allocator& alloc,
                                   size_type size,
                                   size_type align ) noexcept;
      static pointer try_allocate( Allocator& alloc,
                                   const_pointer hint,
                                   size_type size,
                                   size_type align ) noexcept;

      //-----------------------------------------------------------------------

      static pointer allocate( Allocator& alloc,
                               size_type size,
                               size_type align );
      static pointer allocate( Allocator& alloc,
                               const_pointer hint,
                               size_type size,
                               size_type align );

      static bool expand( Allocator& alloc,
                          pointer p,
                          size_type new_size );

      //-----------------------------------------------------------------------
      // Deallocation
      //-----------------------------------------------------------------------
    public:

      static void deallocate( Allocator& alloc, pointer p, size_type size );

      template<typename U = Allocator, typename = std::enable_if<can_truncate_deallocations::value>>
      static void deallocate_all( Allocator& alloc );

      //-----------------------------------------------------------------------
      // Constructions
      //-----------------------------------------------------------------------
    public:

      // Unfortunately, MSVC is unable to compile 'pointer_rebind<T>' as a
      // return type, with the definition written out-of-line -- so the following
      // is expanded in place.
      //
      // gcc/clang accept 'pointer_rebind<T>' with its expansion:
      // typename bit::memory::allocator_traits<Allocator>::template pointer_rebind<T>
      // MSVC does not, but curiously will accept the ever-verbose expansion
      // of what 'pointer_rebind<T>' aliases.

      template<typename T, typename...Args>
      static void construct( Allocator& alloc, void* p, Args&&...args );

      template<typename T, typename...Args>
      static typename detail::allocator_pointer_rebind<Allocator,T>::type
        make( Allocator& alloc, Args&&...args );

      //-----------------------------------------------------------------------

      template<typename T>
      static typename std::pointer_traits<pointer>::template rebind<T>
        make_array( Allocator& alloc, size_type n );
      template<typename T>
      static typename std::pointer_traits<pointer>::template rebind<T>
        make_array( Allocator& alloc, size_type n, const T& copy );

      //-----------------------------------------------------------------------
      // Destruction
      //-----------------------------------------------------------------------
    public:

      template<typename T>
      static void destroy( Allocator& alloc, T* p );

      template<typename Pointer,
               typename=std::enable_if_t<is_typed_pointer<Pointer>>>
      static void dispose( Allocator& alloc, const Pointer& p );

      template<typename Pointer,
               typename=std::enable_if_t<is_typed_pointer<Pointer>>>
      static void dispose_array( Allocator& alloc, const Pointer& p, size_type n );

      //-----------------------------------------------------------------------
      // Observers
      //-----------------------------------------------------------------------
    public:

      size_type recommended_allocation_size( const Allocator& alloc,
                                             size_type requested );

      //-----------------------------------------------------------------------

      static bool owns( const Allocator& alloc, const_pointer p ) noexcept;

      static allocator_info info( const Allocator& alloc ) noexcept;

      //-----------------------------------------------------------------------
      // Conversion
      //-----------------------------------------------------------------------
    public:

      template<typename T>
      static typename std::pointer_traits<pointer>::template rebind<T>
        pointer_to( Allocator& alloc, T& x ) noexcept;

      template<typename Pointer,
               typename=std::enable_if_t<is_typed_pointer<Pointer>>>
      static typename std::pointer_traits<Pointer>::element_type*
        to_raw_pointer( Allocator& alloc,
                        const Pointer& p ) noexcept;

      //-----------------------------------------------------------------------
      // Capacity
      //-----------------------------------------------------------------------
    public:

      static bool is_unbounded( const Allocator& alloc ) noexcept;

      //-----------------------------------------------------------------------

      static size_type max_size( const Allocator& alloc ) noexcept;

      static size_type min_size( const Allocator& alloc ) noexcept;
    };
  } // namespace memory
} // namespace bit

#include "detail/allocator_traits.inl"

#endif /* BIT_MEMORY_TRAITS_ALLOCATOR_TRAITS_HPP */