Class VectorWriter

src/streams.h:34–78

Minimal stream for overwriting and/or appending to an existing byte vector * * The referenced vector will grow as necessary */

 * The referenced vector will grow as necessary
 */
class VectorWriter
{
public:
/*
 * @param[in]  vchDataIn  Referenced byte vector to overwrite/append
 * @param[in]  nPosIn Starting position. Vector index where writes should start. The vector will initially
 *                    grow as necessary to max(nPosIn, vec.size()). So to append, use vec.size().
*/
    VectorWriter(std::vector<unsigned char>& vchDataIn, size_t nPosIn) : vchData{vchDataIn}, nPos{nPosIn}
    {
        if(nPos > vchData.size())
            vchData.resize(nPos);
    }
/*
 * (other params same as above)
 * @param[in]  args  A list of items to serialize starting at nPosIn.
*/
    template <typename... Args>
    VectorWriter(std::vector<unsigned char>& vchDataIn, size_t nPosIn, Args&&... args) : VectorWriter{vchDataIn, nPosIn}
    {
        ::SerializeMany(*this, std::forward<Args>(args)...);
    }
    void write(std::span<const std::byte> src)
    {
        assert(nPos <= vchData.size());
        size_t nOverwrite = std::min(src.size(), vchData.size() - nPos);
        if (nOverwrite) {
            memcpy(vchData.data() + nPos, src.data(), nOverwrite);
        }
        if (nOverwrite < src.size()) {
            vchData.insert(vchData.end(), UCharCast(src.data()) + nOverwrite, UCharCast(src.data() + src.size()));
        }
        nPos += src.size();
    }
    template <typename T>
    VectorWriter& operator<<(const T& obj)
    {
        ::Serialize(*this, obj);
        return (*this);
    }

private:
    std::vector<unsigned char>& vchData;
    size_t nPos;
};

/** Minimal stream for reading from an existing byte array by std::span.
 */