423 lines
16 KiB
C++
423 lines
16 KiB
C++
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/*! \file helpers.hpp
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\brief Internal helper functionality
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\ingroup Internal */
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/*
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Copyright (c) 2014, Randolph Voorhies, Shane Grant
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All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions are met:
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* Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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* Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in the
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documentation and/or other materials provided with the distribution.
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* Neither the name of cereal nor the
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names of its contributors may be used to endorse or promote products
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derived from this software without specific prior written permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
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ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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DISCLAIMED. IN NO EVENT SHALL RANDOLPH VOORHIES OR SHANE GRANT BE LIABLE FOR ANY
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DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef CEREAL_DETAILS_HELPERS_HPP_
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#define CEREAL_DETAILS_HELPERS_HPP_
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#include <type_traits>
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#include <cstdint>
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#include <utility>
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#include <memory>
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#include <unordered_map>
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#include <stdexcept>
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#include "cereal/macros.hpp"
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#include "cereal/details/static_object.hpp"
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namespace cereal
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{
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// ######################################################################
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//! An exception class thrown when things go wrong at runtime
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/*! @ingroup Utility */
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struct Exception : public std::runtime_error
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{
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explicit Exception( const std::string & what_ ) : std::runtime_error(what_) {}
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explicit Exception( const char * what_ ) : std::runtime_error(what_) {}
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};
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// ######################################################################
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//! The size type used by cereal
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/*! To ensure compatability between 32, 64, etc bit machines, we need to use
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a fixed size type instead of size_t, which may vary from machine to
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machine.
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The default value for CEREAL_SIZE_TYPE is specified in cereal/macros.hpp */
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using size_type = CEREAL_SIZE_TYPE;
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// forward decls
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class BinaryOutputArchive;
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class BinaryInputArchive;
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// ######################################################################
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namespace detail
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{
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struct NameValuePairCore {}; //!< Traits struct for NVPs
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struct DeferredDataCore {}; //!< Traits struct for DeferredData
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}
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// ######################################################################
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//! For holding name value pairs
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/*! This pairs a name (some string) with some value such that an archive
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can potentially take advantage of the pairing.
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In serialization functions, NameValuePairs are usually created like so:
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@code{.cpp}
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struct MyStruct
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{
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int a, b, c, d, e;
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template<class Archive>
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void serialize(Archive & archive)
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{
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archive( CEREAL_NVP(a),
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CEREAL_NVP(b),
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CEREAL_NVP(c),
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CEREAL_NVP(d),
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CEREAL_NVP(e) );
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}
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};
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@endcode
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Alternatively, you can give you data members custom names like so:
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@code{.cpp}
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struct MyStruct
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{
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int a, b, my_embarrassing_variable_name, d, e;
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template<class Archive>
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void serialize(Archive & archive)
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{
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archive( CEREAL_NVP(a),
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CEREAL_NVP(b),
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cereal::make_nvp("var", my_embarrassing_variable_name) );
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CEREAL_NVP(d),
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CEREAL_NVP(e) );
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}
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};
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@endcode
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There is a slight amount of overhead to creating NameValuePairs, so there
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is a third method which will elide the names when they are not used by
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the Archive:
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@code{.cpp}
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struct MyStruct
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{
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int a, b;
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template<class Archive>
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void serialize(Archive & archive)
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{
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archive( cereal::make_nvp<Archive>(a),
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cereal::make_nvp<Archive>(b) );
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}
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};
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@endcode
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This third method is generally only used when providing generic type
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support. Users writing their own serialize functions will normally
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explicitly control whether they want to use NVPs or not.
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@internal */
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template <class T>
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class NameValuePair : detail::NameValuePairCore
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{
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private:
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// If we get passed an array, keep the type as is, otherwise store
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// a reference if we were passed an l value reference, else copy the value
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using Type = typename std::conditional<std::is_array<typename std::remove_reference<T>::type>::value,
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typename std::remove_cv<T>::type,
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typename std::conditional<std::is_lvalue_reference<T>::value,
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T,
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typename std::decay<T>::type>::type>::type;
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// prevent nested nvps
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static_assert( !std::is_base_of<detail::NameValuePairCore, T>::value,
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"Cannot pair a name to a NameValuePair" );
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NameValuePair & operator=( NameValuePair const & ) = delete;
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public:
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//! Constructs a new NameValuePair
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/*! @param n The name of the pair
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@param v The value to pair. Ideally this should be an l-value reference so that
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the value can be both loaded and saved to. If you pass an r-value reference,
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the NameValuePair will store a copy of it instead of a reference. Thus you should
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only pass r-values in cases where this makes sense, such as the result of some
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size() call.
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@internal */
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NameValuePair( char const * n, T && v ) : name(n), value(std::forward<T>(v)) {}
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char const * name;
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Type value;
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};
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//! A specialization of make_nvp<> that simply forwards the value for binary archives
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/*! @relates NameValuePair
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@internal */
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template<class Archive, class T> inline
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typename
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std::enable_if<std::is_same<Archive, ::cereal::BinaryInputArchive>::value ||
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std::is_same<Archive, ::cereal::BinaryOutputArchive>::value,
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T && >::type
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make_nvp( const char *, T && value )
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{
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return std::forward<T>(value);
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}
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//! A specialization of make_nvp<> that actually creates an nvp for non-binary archives
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/*! @relates NameValuePair
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@internal */
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template<class Archive, class T> inline
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typename
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std::enable_if<!std::is_same<Archive, ::cereal::BinaryInputArchive>::value &&
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!std::is_same<Archive, ::cereal::BinaryOutputArchive>::value,
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NameValuePair<T> >::type
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make_nvp( const char * name, T && value)
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{
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return {name, std::forward<T>(value)};
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}
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//! Convenience for creating a templated NVP
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/*! For use in internal generic typing functions which have an
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Archive type declared
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@internal */
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#define CEREAL_NVP_(name, value) ::cereal::make_nvp<Archive>(name, value)
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// ######################################################################
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//! A wrapper around data that can be serialized in a binary fashion
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/*! This class is used to demarcate data that can safely be serialized
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as a binary chunk of data. Individual archives can then choose how
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best represent this during serialization.
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@internal */
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template <class T>
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struct BinaryData
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{
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//! Internally store the pointer as a void *, keeping const if created with
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//! a const pointer
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using PT = typename std::conditional<std::is_const<typename std::remove_pointer<typename std::remove_reference<T>::type>::type>::value,
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const void *,
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void *>::type;
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BinaryData( T && d, uint64_t s ) : data(std::forward<T>(d)), size(s) {}
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PT data; //!< pointer to beginning of data
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uint64_t size; //!< size in bytes
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};
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// ######################################################################
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//! A wrapper around data that should be serialized after all non-deferred data
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/*! This class is used to demarcate data that can only be safely serialized after
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any data not wrapped in this class.
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@internal */
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template <class T>
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class DeferredData : detail::DeferredDataCore
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{
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private:
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// If we get passed an array, keep the type as is, otherwise store
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// a reference if we were passed an l value reference, else copy the value
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using Type = typename std::conditional<std::is_array<typename std::remove_reference<T>::type>::value,
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typename std::remove_cv<T>::type,
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typename std::conditional<std::is_lvalue_reference<T>::value,
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T,
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typename std::decay<T>::type>::type>::type;
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// prevent nested nvps
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static_assert( !std::is_base_of<detail::DeferredDataCore, T>::value,
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"Cannot defer DeferredData" );
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DeferredData & operator=( DeferredData const & ) = delete;
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public:
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//! Constructs a new NameValuePair
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/*! @param v The value to defer. Ideally this should be an l-value reference so that
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the value can be both loaded and saved to. If you pass an r-value reference,
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the DeferredData will store a copy of it instead of a reference. Thus you should
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only pass r-values in cases where this makes sense, such as the result of some
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size() call.
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@internal */
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DeferredData( T && v ) : value(std::forward<T>(v)) {}
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Type value;
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};
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// ######################################################################
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namespace detail
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{
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// base classes for type checking
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/* The rtti virtual function only exists to enable an archive to
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be used in a polymorphic fashion, if necessary. See the
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archive adapters for an example of this */
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class OutputArchiveBase
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{
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public:
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OutputArchiveBase() = default;
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OutputArchiveBase( OutputArchiveBase && ) CEREAL_NOEXCEPT {}
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OutputArchiveBase & operator=( OutputArchiveBase && ) CEREAL_NOEXCEPT { return *this; }
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virtual ~OutputArchiveBase() CEREAL_NOEXCEPT = default;
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private:
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virtual void rtti() {}
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};
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class InputArchiveBase
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{
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public:
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InputArchiveBase() = default;
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InputArchiveBase( InputArchiveBase && ) CEREAL_NOEXCEPT {}
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InputArchiveBase & operator=( InputArchiveBase && ) CEREAL_NOEXCEPT { return *this; }
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virtual ~InputArchiveBase() CEREAL_NOEXCEPT = default;
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private:
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virtual void rtti() {}
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};
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// forward decls for polymorphic support
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template <class Archive, class T> struct polymorphic_serialization_support;
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struct adl_tag;
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// used during saving pointers
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static const uint32_t msb_32bit = 0x80000000;
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static const int32_t msb2_32bit = 0x40000000;
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}
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// ######################################################################
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//! A wrapper around size metadata
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/*! This class provides a way for archives to have more flexibility over how
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they choose to serialize size metadata for containers. For some archive
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types, the size may be implicitly encoded in the output (e.g. JSON) and
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not need an explicit entry. Specializing serialize or load/save for
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your archive and SizeTags allows you to choose what happens.
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@internal */
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template <class T>
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class SizeTag
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{
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private:
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// Store a reference if passed an lvalue reference, otherwise
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// make a copy of the data
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using Type = typename std::conditional<std::is_lvalue_reference<T>::value,
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T,
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typename std::decay<T>::type>::type;
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SizeTag & operator=( SizeTag const & ) = delete;
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public:
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SizeTag( T && sz ) : size(std::forward<T>(sz)) {}
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Type size;
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};
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// ######################################################################
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//! A wrapper around a key and value for serializing data into maps.
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/*! This class just provides a grouping of keys and values into a struct for
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human readable archives. For example, XML archives will use this wrapper
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to write maps like so:
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@code{.xml}
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<mymap>
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<item0>
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<key>MyFirstKey</key>
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<value>MyFirstValue</value>
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</item0>
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<item1>
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<key>MySecondKey</key>
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<value>MySecondValue</value>
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</item1>
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</mymap>
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@endcode
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\sa make_map_item
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@internal */
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template <class Key, class Value>
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struct MapItem
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{
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using KeyType = typename std::conditional<
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std::is_lvalue_reference<Key>::value,
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Key,
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typename std::decay<Key>::type>::type;
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using ValueType = typename std::conditional<
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std::is_lvalue_reference<Value>::value,
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Value,
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typename std::decay<Value>::type>::type;
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//! Construct a MapItem from a key and a value
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/*! @internal */
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MapItem( Key && key_, Value && value_ ) : key(std::forward<Key>(key_)), value(std::forward<Value>(value_)) {}
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MapItem & operator=( MapItem const & ) = delete;
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KeyType key;
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ValueType value;
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//! Serialize the MapItem with the NVPs "key" and "value"
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template <class Archive> inline
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void CEREAL_SERIALIZE_FUNCTION_NAME(Archive & archive)
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{
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archive( make_nvp<Archive>("key", key),
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make_nvp<Archive>("value", value) );
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}
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};
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//! Create a MapItem so that human readable archives will group keys and values together
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/*! @internal
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@relates MapItem */
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template <class KeyType, class ValueType> inline
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MapItem<KeyType, ValueType> make_map_item(KeyType && key, ValueType && value)
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{
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return {std::forward<KeyType>(key), std::forward<ValueType>(value)};
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}
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namespace detail
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{
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//! Tag for Version, which due to its anonymous namespace, becomes a different
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//! type in each translation unit
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/*! This allows CEREAL_CLASS_VERSION to be safely called in a header file */
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namespace{ struct version_binding_tag {}; }
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// ######################################################################
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//! Version information class
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/*! This is the base case for classes that have not been explicitly
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registered */
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template <class T, class BindingTag = version_binding_tag> struct Version
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{
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static const std::uint32_t version = 0;
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// we don't need to explicitly register these types since they
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// always get a version number of 0
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};
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//! Holds all registered version information
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struct Versions
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{
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std::unordered_map<std::size_t, std::uint32_t> mapping;
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std::uint32_t find( std::size_t hash, std::uint32_t version )
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{
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const auto result = mapping.emplace( hash, version );
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return result.first->second;
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}
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}; // struct Versions
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} // namespace detail
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} // namespace cereal
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#endif // CEREAL_DETAILS_HELPERS_HPP_
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