您可以使用 boost 序列化进行序列化:
template <typename Ar> void serialize(Ar& ar, A& a, unsigned) {
ar & a.Value & a.SomeChar;
}
template <typename Ar> void serialize(Ar& ar, B& b, unsigned) {
ar & b.data & b.SomeFloat;
}
使用这些,你将already使用 C 数组和 std::vector 方法都具有开箱即用的正确行为。
如果您想继续使用固定大小的可简单复制类型²,您可以使用 Boost Container 之类的东西static_vector
:它将跟踪当前大小,但数据是在结构内部静态分配的。
三重演示
这是一个三重演示程序,具有三种实现,具体取决于IMPL
多变的。
正如您所看到的,大部分代码保持不变。然而,为了“最佳比较”,我确保所有容器在序列化之前都处于一半容量(50/25)。
主程序也反序列化。
Live On Coliru http://coliru.stacked-crooked.com/a/4c7d57a4a6d56d64
#include <boost/iostreams/device/back_inserter.hpp>
#include <boost/iostreams/device/array.hpp>
#include <boost/iostreams/stream.hpp>
#include <boost/archive/binary_oarchive.hpp>
#include <boost/archive/binary_iarchive.hpp>
#include <boost/serialization/access.hpp>
#include <boost/serialization/is_bitwise_serializable.hpp>
#include <boost/serialization/binary_object.hpp>
#include <iostream>
#if (IMPL==0) // C arrays
struct A {
int Value[100];
char SomeChar = 'a';
};
struct B {
A data[50];
float SomeFloat = 0.1f;
};
template <typename Ar> void serialize(Ar& ar, A& a, unsigned) {
ar & a.Value & a.SomeChar;
}
template <typename Ar> void serialize(Ar& ar, B& b, unsigned) {
ar & b.data & b.SomeFloat;
}
#elif (IMPL==1) // std::vector
#include <boost/serialization/vector.hpp>
struct A {
std::vector<int> Value;
char SomeChar = 'a';
};
struct B {
std::vector<A> data;
float SomeFloat = 0.1f;
};
template <typename Ar> void serialize(Ar& ar, A& a, unsigned) {
ar & a.Value & a.SomeChar;
}
template <typename Ar> void serialize(Ar& ar, B& b, unsigned) {
ar & b.data & b.SomeFloat;
}
#elif (IMPL==2) // static_vector
#include <boost/serialization/vector.hpp>
#include <boost/container/static_vector.hpp>
struct A {
boost::container::static_vector<int, 100> Value;
char SomeChar = 'a';
};
struct B {
boost::container::static_vector<A, 50> data;
float SomeFloat = 0.1f;
};
template <typename Ar> void serialize(Ar& ar, A& a, unsigned) {
ar & boost::serialization::make_array(a.Value.data(), a.Value.size()) & a.SomeChar;
}
template <typename Ar> void serialize(Ar& ar, B& b, unsigned) {
ar & boost::serialization::make_array(b.data.data(), b.data.size()) & b.SomeFloat;
}
#endif
namespace bio = boost::iostreams;
static constexpr auto flags = boost::archive::archive_flags::no_header;
using BinaryData = std::vector</*unsigned*/ char>;
int main() {
char const* impls[] = {"C style arrays", "std::vector", "static_vector"};
std::cout << "Using " << impls[IMPL] << " implementation: ";
BinaryData serialized_data;
{
B object = {};
#if IMPL>0
{
// makes sure all containers half-full
A element;
element.Value.resize(50);
object.data.assign(25, element);
}
#endif
bio::stream<bio::back_insert_device<BinaryData>> os { serialized_data };
boost::archive::binary_oarchive oa(os, flags);
oa << object;
}
std::cout << "Size: " << serialized_data.size() << "\n";
{
bio::array_source as { serialized_data.data(), serialized_data.size() };
bio::stream<bio::array_source> os { as };
boost::archive::binary_iarchive ia(os, flags);
B object;
ia >> object;
}
}
Printing
Using C style arrays implementation: Size: 20472
Using std::vector implementation: Size: 5256
Using static_vector implementation: Size: 5039
最后的想法
也可以看看:
- 提高序列化按位序列化能力 https://stackoverflow.com/questions/28121545/boost-serialization-bitwise-serializability
- https://www.boost.org/doc/libs/1_72_0/libs/serialization/doc/wrappers.html#binaryobjects https://www.boost.org/doc/libs/1_72_0/libs/serialization/doc/wrappers.html#binaryobjects
1(但请记住可移植性,因为您可能已经了解 POD 方法,请参阅C++ Boost::serialization:如何在一个程序中归档对象并在另一个程序中恢复它? https://stackoverflow.com/questions/27073936/c-boostserialization-how-do-i-archive-an-object-in-one-program-and-restore/27075717#27075717)
² 不是 POD,就像 NSMI 一样,您的类型不是 POD