blame: source/code/Libs/include/cereal/details/polymorphic_impl.hpp

/*! \file polymorphic_impl.hpp

    \brief Internal polymorphism support

    \ingroup Internal */

/*

  Copyright (c) 2014, Randolph Voorhies, Shane Grant

  All rights reserved.

  Redistribution and use in source and binary forms, with or without

  modification, are permitted provided that the following conditions are met:

      * Redistributions of source code must retain the above copyright

        notice, this list of conditions and the following disclaimer.

      * Redistributions in binary form must reproduce the above copyright

        notice, this list of conditions and the following disclaimer in the

        documentation and/or other materials provided with the distribution.

      * Neither the name of cereal nor the

        names of its contributors may be used to endorse or promote products

        derived from this software without specific prior written permission.

  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND

  ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED

  WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE

  DISCLAIMED. IN NO EVENT SHALL RANDOLPH VOORHIES OR SHANE GRANT BE LIABLE FOR ANY

  DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES

  (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;

  LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND

  ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS

  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

*/

/* This code is heavily inspired by the boost serialization implementation by the following authors

   (C) Copyright 2002 Robert Ramey - http://www.rrsd.com .

   Use, modification and distribution is subject to the Boost Software

   License, Version 1.0. (See http://www.boost.org/LICENSE_1_0.txt)

    See http://www.boost.org for updates, documentation, and revision history.

   (C) Copyright 2006 David Abrahams - http://www.boost.org.

   See /boost/serialization/export.hpp and /boost/archive/detail/register_archive.hpp for their

   implementation.

*/

#ifndef CEREAL_DETAILS_POLYMORPHIC_IMPL_HPP_

#define CEREAL_DETAILS_POLYMORPHIC_IMPL_HPP_

#include <cereal/details/static_object.hpp>

#include <cereal/types/memory.hpp>

#include <cereal/types/string.hpp>

#include <functional>

#include <typeindex>

#include <map>

//! Binds a polymorhic type to all registered archives

/*! This binds a polymorphic type to all compatible registered archives that

    have been registered with CEREAL_REGISTER_ARCHIVE.  This must be called

    after all archives are registered (usually after the archives themselves

    have been included). */

#define CEREAL_BIND_TO_ARCHIVES(T)                   \

    namespace cereal {                               \

    namespace detail {                               \

    template<>                                       \

    struct init_binding<T> {                         \

        static bind_to_archives<T> const & b;        \

        static void unused() { (void)b; }            \

    };                                               \

    bind_to_archives<T> const & init_binding<T>::b = \

        ::cereal::detail::StaticObject<              \

            bind_to_archives<T>                      \

        >::getInstance().bind();                     \

    }} /* end namespaces */

namespace cereal

{

  namespace detail

  {

    //! Binds a compile time type with a user defined string

    template <class T>

    struct binding_name {};

    //! A structure holding a map from type_indices to output serializer functions

    /*! A static object of this map should be created for each registered archive

        type, containing entries for every registered type that describe how to

        properly cast the type to its real type in polymorphic scenarios for

        shared_ptr, weak_ptr, and unique_ptr. */

    template <class Archive>

    struct OutputBindingMap

    {

      //! A serializer function

      /*! Serializer functions return nothing and take an archive as

          their first parameter (will be cast properly inside the function,

          and a pointer to actual data (contents of smart_ptr's get() function)

          as their second parameter */

      typedef std::function<void(void*, void const *)> Serializer;

      //! Struct containing the serializer functions for all pointer types

      struct Serializers

      {

        Serializer shared_ptr, //!< Serializer function for shared/weak pointers

                   unique_ptr; //!< Serializer function for unique pointers

      };

      //! A map of serializers for pointers of all registered types

      std::map<std::type_index, Serializers> map;

    };

    //! An empty noop deleter

    template<class T> struct EmptyDeleter { void operator()(T *) const {} };

    //! A structure holding a map from type name strings to input serializer functions

    /*! A static object of this map should be created for each registered archive

        type, containing entries for every registered type that describe how to

        properly cast the type to its real type in polymorphic scenarios for

        shared_ptr, weak_ptr, and unique_ptr. */

    template <class Archive>

    struct InputBindingMap

    {

      //! Shared ptr serializer function

      /*! Serializer functions return nothing and take an archive as

          their first parameter (will be cast properly inside the function,

          and a shared_ptr (or unique_ptr for the unique case) of any base

          type.  Internally it will properly be loaded and cast to the

          correct type. */

      typedef std::function<void(void*, std::shared_ptr<void> & )> SharedSerializer;

      //! Unique ptr serializer function

      typedef std::function<void(void*, std::unique_ptr<void, EmptyDeleter<void>> & )> UniqueSerializer;

      //! Struct containing the serializer functions for all pointer types

      struct Serializers

      {

        SharedSerializer shared_ptr; //!< Serializer function for shared/weak pointers

        UniqueSerializer unique_ptr; //!< Serializer function for unique pointers

      };

      //! A map of serializers for pointers of all registered types

      std::map<std::string, Serializers> map;

    };

    // forward decls for archives from cereal.hpp

    class InputArchiveBase;

    class OutputArchiveBase;

    //! Creates a binding (map entry) between an input archive type and a polymorphic type

    /*! Bindings are made when types are registered, assuming that at least one

        archive has already been registered.  When this struct is created,

        it will insert (at run time) an entry into a map that properly handles

        casting for serializing polymorphic objects */

    template <class Archive, class T> struct InputBindingCreator

    {

      //! Initialize the binding

      InputBindingCreator()

      {

        auto & map = StaticObject<InputBindingMap<Archive>>::getInstance().map;

        auto key = std::string(binding_name<T>::name());

        auto lb = map.lower_bound(key);

        if (lb != map.end() && lb->first == key)

          return;

        typename InputBindingMap<Archive>::Serializers serializers;

        serializers.shared_ptr =

          [](void * arptr, std::shared_ptr<void> & dptr)

          {

            Archive & ar = *static_cast<Archive*>(arptr);

            std::shared_ptr<T> ptr;

            ar( CEREAL_NVP_("ptr_wrapper", ::cereal::memory_detail::make_ptr_wrapper(ptr)) );

            dptr = ptr;

          };

        serializers.unique_ptr =

          [](void * arptr, std::unique_ptr<void, EmptyDeleter<void>> & dptr)

          {

            Archive & ar = *static_cast<Archive*>(arptr);

            std::unique_ptr<T> ptr;

            ar( CEREAL_NVP_("ptr_wrapper", ::cereal::memory_detail::make_ptr_wrapper(ptr)) );

            dptr.reset(ptr.release());

          };

        map.insert( lb, { std::move(key), std::move(serializers) } );

      }

    };

    //! Creates a binding (map entry) between an output archive type and a polymorphic type

    /*! Bindings are made when types are registered, assuming that at least one

        archive has already been registered.  When this struct is created,

        it will insert (at run time) an entry into a map that properly handles

        casting for serializing polymorphic objects */

    template <class Archive, class T> struct OutputBindingCreator

    {

      //! Writes appropriate metadata to the archive for this polymorphic type

      static void writeMetadata(Archive & ar)

      {

        // Register the polymorphic type name with the archive, and get the id

        char const * name = binding_name<T>::name();

        std::uint32_t id = ar.registerPolymorphicType(name);

        // Serialize the id

        ar( CEREAL_NVP_("polymorphic_id", id) );

        // If the msb of the id is 1, then the type name is new, and we should serialize it

        if( id & detail::msb_32bit )

        {

          std::string namestring(name);

          ar( CEREAL_NVP_("polymorphic_name", namestring) );

        }

      }

      //! Holds a properly typed shared_ptr to the polymorphic type

      class PolymorphicSharedPointerWrapper

      {

        public:

          /*! Wrap a raw polymorphic pointer in a shared_ptr to its true type

              The wrapped pointer will not be responsible for ownership of the held pointer

              so it will not attempt to destroy it; instead the refcount of the wrapped

              pointer will be tied to a fake 'ownership pointer' that will do nothing

              when it ultimately goes out of scope.

              The main reason for doing this, other than not to destroy the true object

              with our wrapper pointer, is to avoid meddling with the internal reference

              count in a polymorphic type that inherits from std::enable_shared_from_this.

              @param dptr A void pointer to the contents of the shared_ptr to serialize */

          PolymorphicSharedPointerWrapper( void const * dptr ) : refCount()

          {

            #ifdef _LIBCPP_VERSION

            // libc++ needs this hacky workaround, see http://llvm.org/bugs/show_bug.cgi?id=18843

            wrappedPtr = std::shared_ptr<T const>(

                std::const_pointer_cast<T const>(

                  std::shared_ptr<T>( refCount, static_cast<T *>(const_cast<void *>(dptr) ))));

            #else // NOT _LIBCPP_VERSION

            wrappedPtr = std::shared_ptr<T const>( refCount, static_cast<T const *>(dptr) );

            #endif // _LIBCPP_VERSION

          }

          //! Get the wrapped shared_ptr */

          inline std::shared_ptr<T const> const & operator()() const { return wrappedPtr; }

        private:

          std::shared_ptr<void> refCount;      //!< The ownership pointer

          std::shared_ptr<T const> wrappedPtr; //!< The wrapped pointer

      };

      //! Does the actual work of saving a polymorphic shared_ptr

      /*! This function will properly create a shared_ptr from the void * that is passed in

          before passing it to the archive for serialization.

          In addition, this will also preserve the state of any internal enable_shared_from_this mechanisms

          @param ar The archive to serialize to

          @param dptr Pointer to the actual data held by the shared_ptr */

      static inline void savePolymorphicSharedPtr( Archive & ar, void const * dptr, std::true_type /* has_shared_from_this */ )

      {

        ::cereal::memory_detail::EnableSharedStateHelper<T> state( static_cast<T *>(const_cast<void *>(dptr)) );

        PolymorphicSharedPointerWrapper psptr( dptr );

        ar( CEREAL_NVP_("ptr_wrapper", memory_detail::make_ptr_wrapper( psptr() ) ) );

      }

      //! Does the actual work of saving a polymorphic shared_ptr

      /*! This function will properly create a shared_ptr from the void * that is passed in

          before passing it to the archive for serialization.

          This version is for types that do not inherit from std::enable_shared_from_this.

          @param ar The archive to serialize to

          @param dptr Pointer to the actual data held by the shared_ptr */

      static inline void savePolymorphicSharedPtr( Archive & ar, void const * dptr, std::false_type /* has_shared_from_this */ )

      {

        PolymorphicSharedPointerWrapper psptr( dptr );

        ar( CEREAL_NVP_("ptr_wrapper", memory_detail::make_ptr_wrapper( psptr() ) ) );

      }

      //! Initialize the binding

      OutputBindingCreator()

      {

        auto & map = StaticObject<OutputBindingMap<Archive>>::getInstance().map;

        auto key = std::type_index(typeid(T));

        auto lb = map.lower_bound(key);

        if (lb != map.end() && lb->first == key)

          return;

        typename OutputBindingMap<Archive>::Serializers serializers;

        serializers.shared_ptr =

          [&](void * arptr, void const * dptr)

          {

            Archive & ar = *static_cast<Archive*>(arptr);

            writeMetadata(ar);

            #ifdef _MSC_VER

            savePolymorphicSharedPtr( ar, dptr, ::cereal::traits::has_shared_from_this<T>::type() ); // MSVC doesn't like typename here

            #else // not _MSC_VER

            savePolymorphicSharedPtr( ar, dptr, typename ::cereal::traits::has_shared_from_this<T>::type() );

            #endif // _MSC_VER

          };

        serializers.unique_ptr =

          [&](void * arptr, void const * dptr)

          {

            Archive & ar = *static_cast<Archive*>(arptr);

            writeMetadata(ar);

            std::unique_ptr<T const, EmptyDeleter<T const>> const ptr(static_cast<T const *>(dptr));

            ar( CEREAL_NVP_("ptr_wrapper", memory_detail::make_ptr_wrapper(ptr)) );

          };

        map.insert( { std::move(key), std::move(serializers) } );

      }

    };

    //! Used to help out argument dependent lookup for finding potential overloads

    //! of instantiate_polymorphic_binding

    struct adl_tag {};

    //! Tag for init_binding, bind_to_archives and instantiate_polymorphic_binding. Due to the use of anonymous

    //! namespace it becomes a different type in each translation unit.

    namespace { struct polymorphic_binding_tag {}; }

    //! Causes the static object bindings between an archive type and a serializable type T

    template <class Archive, class T>

    struct create_bindings

    {

      static const InputBindingCreator<Archive, T> &

      load(std::true_type)

      {

        return cereal::detail::StaticObject<InputBindingCreator<Archive, T>>::getInstance();

      }

      static const OutputBindingCreator<Archive, T> &

      save(std::true_type)

      {

        return cereal::detail::StaticObject<OutputBindingCreator<Archive, T>>::getInstance();

      }

      inline static void load(std::false_type) {}

      inline static void save(std::false_type) {}

    };

    //! When specialized, causes the compiler to instantiate its parameter

    template <void(*)()>

    struct instantiate_function {};

    /*! This struct is used as the return type of instantiate_polymorphic_binding

        for specific Archive types.  When the compiler looks for overloads of

        instantiate_polymorphic_binding, it will be forced to instantiate this

        struct during overload resolution, even though it will not be part of a valid

        overload */

    template <class Archive, class T>

    struct polymorphic_serialization_support

    {

      #if defined(_MSC_VER) && !defined(__INTEL_COMPILER)

      //! Creates the appropriate bindings depending on whether the archive supports

      //! saving or loading

      virtual CEREAL_DLL_EXPORT void instantiate() CEREAL_USED;

      #else // NOT _MSC_VER

      //! Creates the appropriate bindings depending on whether the archive supports

      //! saving or loading

      static CEREAL_DLL_EXPORT void instantiate() CEREAL_USED;

      //! This typedef causes the compiler to instantiate this static function

      typedef instantiate_function<instantiate> unused;

      #endif // _MSC_VER

    };

    // instantiate implementation

    template <class Archive, class T>

    CEREAL_DLL_EXPORT void polymorphic_serialization_support<Archive,T>::instantiate()

    {

      create_bindings<Archive,T>::save( std::integral_constant<bool,

                                          std::is_base_of<detail::OutputArchiveBase, Archive>::value &&

                                          traits::is_output_serializable<T, Archive>::value>{} );

      create_bindings<Archive,T>::load( std::integral_constant<bool,

                                          std::is_base_of<detail::InputArchiveBase, Archive>::value &&

                                          traits::is_input_serializable<T, Archive>::value>{} );

    }

    //! Begins the binding process of a type to all registered archives

    /*! Archives need to be registered prior to this struct being instantiated via

        the CEREAL_REGISTER_ARCHIVE macro.  Overload resolution will then force

        several static objects to be made that allow us to bind together all

        registered archive types with the parameter type T. */

    template <class T, class Tag = polymorphic_binding_tag>

    struct bind_to_archives

    {

      //! Binding for non abstract types

      void bind(std::false_type) const

	    {

		    instantiate_polymorphic_binding((T*) 0, 0, Tag{}, adl_tag{});

      }

      //! Binding for abstract types

      void bind(std::true_type) const

      { }

      //! Binds the type T to all registered archives

      /*! If T is abstract, we will not serialize it and thus

          do not need to make a binding */

      bind_to_archives const & bind() const

      {

        static_assert( std::is_polymorphic<T>::value,

                       "Attempting to register non polymorphic type" );

        bind( std::is_abstract<T>() );

        return *this;

      }

    };

    //! Used to hide the static object used to bind T to registered archives

    template <class T, class Tag = polymorphic_binding_tag>

    struct init_binding;

    //! Base case overload for instantiation

    /*! This will end up always being the best overload due to the second

        parameter always being passed as an int.  All other overloads will

        accept pointers to archive types and have lower precedence than int.

        Since the compiler needs to check all possible overloads, the

        other overloads created via CEREAL_REGISTER_ARCHIVE, which will have

        lower precedence due to requring a conversion from int to (Archive*),

        will cause their return types to be instantiated through the static object

        mechanisms even though they are never called.

        See the documentation for the other functions to try and understand this */

    template <class T, typename BindingTag>

    void instantiate_polymorphic_binding( T*, int, BindingTag, adl_tag ) {}

  } // namespace detail

} // namespace cereal

#endif // CEREAL_DETAILS_POLYMORPHIC_IMPL_HPP_