反序列化没有默认构造函数的类型的 STL 容器

Question

我最近学习了反序列化构造函数 (Deserializing constructor doesn't read data correctly) 的模式，以便对没有默认构造函数的类型使用序列化。现在我正在尝试序列化这些对象的 STL 容器，如下例所示：

#include <boost/archive/text_oarchive.hpp>
#include <boost/archive/text_iarchive.hpp>
#include <boost/serialization/split_member.hpp>
#include <boost/serialization/vector.hpp>

#include <fstream>

class Point
{
public:
    Point(double x) : mX(x) {}

    template<class TArchive>
    Point(TArchive& archive)
    {
        archive >> *this;
    }

    template<class TArchive>
    void serialize(TArchive& archive, const unsigned int version)
    {
        archive & mX;
    }

    double mX;
};

int main()
{
    std::vector<Point> pointVector;
    pointVector.push_back(Point(1));
    pointVector.push_back(Point(2));

    std::ofstream outputStream("test.txt");
    boost::archive::text_oarchive outputArchive(outputStream);

    outputArchive << pointVector;
    outputStream.close();

    std::vector<Point> readPointVector;
    std::ifstream inputStream("test.txt");
    boost::archive::text_iarchive inputArchive(inputStream);
    inputArchive >> readPointVector; // Compiler error - no matching function call to Point::Point()

    return 0;
}

这似乎很明显，这不应该起作用，但是我如何告诉存档它需要使用反序列化构造函数来构造它读取的对象，然后再将它们添加到容器中？

--------- 编辑 ----------

在唯一答案中实施建议后，此代码编译良好，但似乎没有正确反序列化。 readPointVector 的大小只有 1，但它的大小应该是 2（并且它包含的一个对象中的数据不正确）：

#include <boost/archive/text_oarchive.hpp>
#include <boost/archive/text_iarchive.hpp>
#include <boost/serialization/vector.hpp>

#include <fstream>

class Point
{
public:
    Point(double x) : mX(x) {}

    template<class TArchive>
    Point(TArchive& archive)
    {
        archive >> *this;
    }

    template<class TArchive>
    void serialize(TArchive& archive, const unsigned int version)
    {
        archive & mX;
    }

    double mX;
};

template <typename Archive>
Archive& operator >> (Archive& archive, std::vector<Point>& points)
{
    points.emplace_back(archive);
    return archive;
}

int main()
{
    std::vector<Point> pointVector;
    pointVector.push_back(Point(5.6));
    pointVector.push_back(Point(7.8));

    std::cout << pointVector.size() << std::endl; // outputs 2

    {
        std::ofstream outputStream("test.txt");
        boost::archive::text_oarchive outputArchive(outputStream);

        outputArchive << pointVector;
        outputStream.close();
    }

    std::vector<Point> readPointVector;
    std::ifstream inputStream("test.txt");
    boost::archive::text_iarchive inputArchive(inputStream);
    inputArchive >> readPointVector;

    std::cout << readPointVector.size() << std::endl; // outputs 1 (and readPointVector[0].mX is 2, but should be 7.8)

    return 0;
}

Answer 1

您可以专门研究点向量：

template <typename Archive>
Archive& operator >> (Archive& archive, std::vector<Point>& points)
{
    points.emplace_back(archive);
    return archive;
}