/*****************************************************************************/
/**
 * \file portable_iarchive.hpp
 * \brief Provides an archive to read from portable binary files.
 * \author christian.pfligersdorffer@eos.info
 * \version 4.2
 *
 * This archive (pair) brings the advantanges of binary streams to the cross
 * platform boost::serialization user. While being almost as fast as the native
 * binary archive it allows its files to be exchanged between cpu architectures
 * using different byte order (endianness). Speaking of speed: in serializing
 * numbers the (portable) binary approach is approximately ten times faster than
 * the ascii implementation (that is inherently portable)!
 *
 * Based on the portable archive example by Robert Ramey this implementation
 * uses Beman Dawes endian library and fp_utilities from Johan Rade, both being
 * in boost since 1.36. Prior to that you need to add them both (header only)
 * to your boost directory before you're able to use the archives provided.
 * Our archives have been tested successfully for boost versions 1.33 to 1.46!
 *
 * \note Correct behaviour has so far been confirmed using PowerPC-32, x86-32
 *       and x86-64 platforms featuring different byte order. So there is a good
 *       chance it will instantly work for your specific setup. If you encounter
 *       problems or have suggestions please contact the author.
 *
 * \note Version 4.2 maintains compatibility with the latest boost 1.46 and adds
 *       serialization of special floating point values inf and NaN as proposed
 *       by Francois Mauger.
 *
 * \note Version 4.1 makes the archives work together with boost 1.40 and 1.41.
 *       Thanks to Francois Mauger for his suggestions.
 *
 * \note Version 4 removes one level of the inheritance hierachy and directly
 *       builds upon binary primitive and basic binary archive, thereby fixing
 *       the last open issue regarding array serialization. Thanks to Robert
 *       Ramey for the hint.
 *
 * \note A few fixes introduced in version 3.1 let the archives pass all of the
 *       serialization tests. Thanks to Sergey Morozov for running the tests.
 *       Wouter Bijlsma pointed out where to find the fp_utilities and endian
 *       libraries headers inside the boost distribution. I would never have
 *       found them so thank him it works out of the box since boost 1.36.
 *
 * \note With Version 3.0 the archives have been made portable across different
 *       boost versions. For that purpose a header is added to the data that
 *       supplies the underlying serialization library version. Backwards
 *       compatibility is maintained by assuming library version boost 1.33 if
 *       the iarchive is created using the no_header flag. Whether a header is
 *       present or not can be guessed by peeking into the stream: the header's
 *       first byte is the magic number 127 coinciding with 'e' | 'o' | 's' :-)
 *
 * \note Version 2.1 removes several compiler warnings and enhances floating
 *       point diagnostics to inform the user if some preconditions are violated
 *               on his platform. We do not strive for the universally portable solution
 *       in binary floating point serialization as desired by some boost users.
 *       Instead we support only the most widely used IEEE 754 format and try to
 *       detect when requirements are not met and hence our approach must fail.
 *       Contributions we made by Johan Rade and Ákos Maróy.
 *
 * \note Version 2.0 fixes a serious bug that effectively transformed most
 *       of negative integral values into positive values! For example the two
 *       numbers -12 and 234 were stored in the same 8-bit pattern and later
 *       always restored to 234. This was fixed in this version in a way that
 *       does not change the interpretation of existing archives that did work
 *       because there were no negative numbers. The other way round archives
 *       created by version 2.0 and containing negative numbers will raise an
 *       integer type size exception when reading it with version 1.0. Thanks
 *       to Markus Frohnmaier for testing the archives and finding the bug.
 *
 * \copyright The boost software license applies.
 */
/*****************************************************************************/

#pragma once

#include <istream>

// basic headers
#include <boost/version.hpp>
#include <boost/utility/enable_if.hpp>
#include <boost/archive/basic_binary_iprimitive.hpp>
#include <boost/archive/basic_binary_iarchive.hpp>

#if BOOST_VERSION >= 103500
#include <boost/archive/shared_ptr_helper.hpp>
#endif

// funny polymorphics
#if BOOST_VERSION < 103500
#include <boost/archive/detail/polymorphic_iarchive_impl.hpp>
#define POLYMORPHIC(T) boost::archive::detail::polymorphic_iarchive_impl<T>

#elif BOOST_VERSION < 103600
#include <boost/archive/detail/polymorphic_iarchive_dispatch.hpp>
#define POLYMORPHIC(T) boost::archive::detail::polymorphic_iarchive_dispatch<T>

#else
#include <boost/archive/detail/polymorphic_iarchive_route.hpp>
#define POLYMORPHIC(T) boost::archive::detail::polymorphic_iarchive_route<T>
#endif

// endian and fpclassify
#if BOOST_VERSION < 103600
#include <boost/integer/endian.hpp>
#include <boost/math/fpclassify.hpp>
#elif BOOST_VERSION < 104800
#include <boost/spirit/home/support/detail/integer/endian.hpp>
#include <boost/spirit/home/support/detail/math/fpclassify.hpp>
#else
#include <boost/spirit/home/support/detail/endian.hpp>
#include <boost/spirit/home/support/detail/math/fpclassify.hpp>
#endif

// namespace alias
#if BOOST_VERSION < 103800
    namespace fp = boost::math;
#else
namespace fp = boost::spirit::math;
#endif

// generic type traits for numeric types
#include <boost/type_traits/is_integral.hpp>
#include <boost/type_traits/is_unsigned.hpp>
#include <boost/type_traits/is_arithmetic.hpp>
#include <boost/type_traits/is_floating_point.hpp>

#include "portable_archive_exception.hpp"

// hint from Johan Rade: on VMS there is still support for
// the VAX floating point format and this macro detects it
#if defined(__vms) && defined(__DECCXX) && !__IEEE_FLOAT
#error "VAX floating point format is not supported!"
#endif

namespace eos {

    // forward declaration
    class portable_iarchive;

    typedef boost::archive::basic_binary_iprimitive<
        portable_iarchive
#if BOOST_VERSION < 103400
                    , std::istream
#else
                    , std::istream::char_type
                    , std::istream::traits_type
#endif
                    > portable_iprimitive;

    /**
     * \brief Portable binary input archive using little endian format.
     *
     * This archive addresses integer size, endianness and floating point types so
     * that data can be transferred across different systems. There may still be
     * constraints as to what systems are compatible and the user will have to take
     * care that e.g. a very large int being saved on a 64 bit machine will result
     * in a portable_archive_exception if loaded into an int on a 32 bit system.
     * A possible workaround to this would be to use fixed types like
     * boost::uint64_t in your serialization structures.
     *
     * \note The class is based on the portable binary example by Robert Ramey and
     *           uses Beman Dawes endian library plus fp_utilities by Johan Rade.
     */
    class portable_iarchive : public portable_iprimitive

    // the example derives from common_oarchive but that lacks the
    // load_override functions so we chose to stay one level higher
                            , public boost::archive::basic_binary_iarchive<portable_iarchive>

#if BOOST_VERSION >= 103500
                              // mix-in helper class for serializing shared_ptr
                            , public boost::archive::detail::shared_ptr_helper
#endif
    {
        // only needed for Robert's hack in basic_binary_iarchive::init
        friend class boost::archive::basic_binary_iarchive<portable_iarchive>;

        // workaround for gcc: use a dummy struct
        // as additional argument type for overloading
        template <int> struct dummy { dummy(int) {}};

        // loads directly from stream
        signed char load_signed_char()
            {
                signed char c;
                portable_iprimitive::load(c);
                return c;
            }

        // archive initialization
        void init(unsigned flags)
            {
                using namespace boost::archive;
                archive_version_type input_library_version(3);

                // it is vital to have version information!
                // if we don't have any we assume boost 1.33
                if (flags & no_header)
                    set_library_version(input_library_version);

                // extract and check the magic eos byte
                else if (load_signed_char() != magic_byte)
                    throw archive_exception(archive_exception::invalid_signature);

                else
                {
                    // extract version information
                    operator>>(input_library_version);

                    // throw if file version is newer than we are
                    if (input_library_version > archive_version)
                        throw archive_exception(archive_exception::unsupported_version);

                    // else set the library version accordingly
                    else set_library_version(input_library_version);
                }
            }

    public:
        //! Load string types.
        template <class C, class T, class A>
        void load(std::basic_string<C, T, A>& s)
            {
                // implementation only valid for narrow string
                BOOST_STATIC_ASSERT(sizeof(C) == sizeof(char));
                portable_iprimitive::load(s);
            }

        //! Special case loading bool type, preserving compatibility
        //! to integer types - this is somewhat redundant but simply
        //! treating bool as integer type generates lots of warnings
        void load(bool& b)
            {
                switch (signed char c = load_signed_char())
                {
                case 0: b = false; break;
                case 1: b = load_signed_char(); break;
                default: throw portable_archive_exception(c);
                }
            }

        /**
         * \brief Load integer types.
         *
         * First we load the size information ie. the number of bytes that
         * hold the actual data. Then we retrieve the data and transform it
         * to the original value by using load_little_endian.
         */
        template <typename T>
        typename boost::enable_if<boost::is_integral<T> >::type
        load(T & t, dummy<2> = 0)
            {
                // get the number of bytes in the stream
                if (signed char size = load_signed_char())
                {
                    // check for negative value in unsigned type
                    if (size < 0 && boost::is_unsigned<T>::value)
                        throw portable_archive_exception();

                    // check that our type T is large enough
                    else if ((unsigned) abs(size) > sizeof(T))
                        throw portable_archive_exception(size);

                    // reconstruct the value
                    T temp = size < 0 ? -1 : 0;
                    load_binary(&temp, abs(size));

                    // load the value from little endian - is is then converted
                    // to the target type T and fits it because size <= sizeof(T)
#if BOOST_VERSION < 104800
                    t = boost::detail::load_little_endian<T, sizeof(T)>(&temp);
#else
                    t = boost::spirit::detail::load_little_endian<T, sizeof(T)>(&temp);
#endif
                }

                else t = 0; // zero optimization
            }

        /**
         * \brief Load floating point types.
         *
         * We simply rely on fp_traits to set the bit pattern from the (unsigned)
         * integral type that was stored in the stream. Francois Mauger provided
         * standardized behaviour for special values like inf and NaN, that need to
         * be serialized in his application.
         *
         * \note by Johan Rade (author of the floating point utilities library):
         * Be warned that the math::detail::fp_traits<T>::type::get_bits() function
         * is *not* guaranteed to give you all bits of the floating point number. It
         * will give you all bits if and only if there is an integer type that has
         * the same size as the floating point you are copying from. It will not
         * give you all bits for double if there is no uint64_t. It will not give
         * you all bits for long double if sizeof(long double) > 8 or there is no
         * uint64_t.
         *
         * The member fp_traits<T>::type::coverage will tell you whether all bits
         * are copied. This is a typedef for either math::detail::all_bits or
         * math::detail::not_all_bits.
         *
         * If the function does not copy all bits, then it will copy the most
         * significant bits. So if you serialize and deserialize the way you
         * describe, and fp_traits<T>::type::coverage is math::detail::not_all_bits,
         * then your floating point numbers will be truncated. This will introduce
         * small rounding off errors.
         */
        template <typename T>
        typename boost::enable_if<boost::is_floating_point<T> >::type
        load(T & t, dummy<3> = 0)
            {
                typedef typename fp::detail::fp_traits<T>::type traits;

                // if you end here there are three possibilities:
                // 1. you're serializing a long double which is not portable
                // 2. you're serializing a double but have no 64 bit integer
                // 3. your machine is using an unknown floating point format
                // after reading the note above you still might decide to
                // deactivate this static assert and try if it works out.
                typename traits::bits bits;
                BOOST_STATIC_ASSERT(sizeof(bits) == sizeof(T));
                BOOST_STATIC_ASSERT(std::numeric_limits<T>::is_iec559);

                load(bits);
                traits::set_bits(t, bits);

                // if the no_infnan flag is set we must throw here
                if (get_flags() & no_infnan && !fp::isfinite(t))
                    throw portable_archive_exception(t);

                // if you end here your floating point type does not support
                // denormalized numbers. this might be the case even though
                // your type conforms to IEC 559 (and thus to IEEE 754)
                if (std::numeric_limits<T>::has_denorm == std::denorm_absent
                    && fp::fpclassify(t) == (int) FP_SUBNORMAL) // GCC4
                    throw portable_archive_exception(t);
            }

        /**
         * \brief Constructor on a stream using ios::binary mode!
         *
         * We cannot call basic_binary_iprimitive::init which tries to detect
         * if the binary archive stems from a different platform by examining
         * type sizes.
         *
         * We could have called basic_binary_iarchive::init which would create
         * the boost::serialization standard archive header containing also the
         * library version. Due to efficiency we stick with our own.
         */
        portable_iarchive(std::istream& is, unsigned flags = 0)
#if BOOST_VERSION < 103400
            : portable_iprimitive(is, flags & boost::archive::no_codecvt)
#else
              : portable_iprimitive(*is.rdbuf(), flags & boost::archive::no_codecvt)
#endif
            , boost::archive::basic_binary_iarchive<portable_iarchive>(flags)
            {
                init(flags);
            }

#if BOOST_VERSION >= 103400
        portable_iarchive(std::streambuf& sb, unsigned flags = 0)
            : portable_iprimitive(sb, flags & boost::archive::no_codecvt)
            , boost::archive::basic_binary_iarchive<portable_iarchive>(flags)
            {
                init(flags);
            }
#endif

#if BOOST_VERSION >= 104400
        // in boost 1.44 version_type was splitted into library_version_type and
        // item_version_type, plus a whole bunch of additional strong typedefs
        void load(boost::archive::library_version_type& version)
            {
                load((boost::uint_least16_t&)(version));
            }

        void load(boost::archive::class_id_type& class_id)
            {
                load((boost::uint_least16_t&)(class_id));
            }

        void load(boost::serialization::item_version_type& version)
            {
                load((boost::uint_least32_t&)(version));
            }

        void load(boost::serialization::collection_size_type& version)
            {
                load((boost::uint_least32_t&)(version));
            }

        void load(boost::archive::object_id_type& object_id)
            {
                load((boost::uint_least32_t&)(object_id));
            }

        void load(boost::archive::version_type& version)
            {
                load((boost::uint_least32_t&)(version));
            }
#endif
    };

    // polymorphic portable binary iarchive typdef
    typedef POLYMORPHIC(portable_iarchive) polymorphic_portable_iarchive;
#undef POLYMORPHIC

} // namespace eos

// this is required by export which registers all of your
// classes with all the inbuilt archives plus our archive.
#if BOOST_VERSION < 103500
#define BOOST_ARCHIVE_CUSTOM_IARCHIVE_TYPES eos::portable_iarchive
#else
BOOST_SERIALIZATION_REGISTER_ARCHIVE(eos::portable_iarchive)
BOOST_SERIALIZATION_REGISTER_ARCHIVE(eos::polymorphic_portable_iarchive)
#endif

// if you include this header multiple times and your compiler is picky
// about multiple template instantiations (eg. gcc is) then you need to
// define NO_EXPLICIT_TEMPLATE_INSTANTIATION before every include but one
// or you move the instantiation section into an implementation file
#ifndef NO_EXPLICIT_TEMPLATE_INSTANTIATION

#include <boost/archive/impl/basic_binary_iarchive.ipp>
#include <boost/archive/impl/basic_binary_iprimitive.ipp>

#if BOOST_VERSION < 104000
#include <boost/archive/impl/archive_pointer_iserializer.ipp>
#elif !defined BOOST_ARCHIVE_SERIALIZER_INCLUDED
#include <boost/archive/impl/archive_serializer_map.ipp>
#define BOOST_ARCHIVE_SERIALIZER_INCLUDED
#endif

namespace boost { namespace archive {

        // explicitly instantiate for this type of binary stream
        template class basic_binary_iarchive<eos::portable_iarchive>;

        template class basic_binary_iprimitive<
            eos::portable_iarchive
#if BOOST_VERSION < 103400
            , std::istream
#else
            , std::istream::char_type
            , std::istream::traits_type
#endif
            >;

#if BOOST_VERSION < 104000
        template class detail::archive_pointer_iserializer<eos::portable_iarchive>;
#else
        template class detail::archive_serializer_map<eos::portable_iarchive>;
        //template class detail::archive_serializer_map<eos::polymorphic_portable_iarchive>;
#endif

    } } // namespace boost::archive

#endif
