Repository: bitcoin/bitcoin
File: src/uint256.h (C/C++)

Code before:
    void Serialize(Stream& s) const
    {
        s << Span(m_data);
    }

    template<typename Stream>
    void Unserialize(Stream& s)
    {
        s.read(MakeWritableByteSpan(m_data));
    }
};

/** 160-bit opaque blob.
 * @note This type is called uint160 for historical reasons only. It is an opaque
 * blob of 160 bits and has no integer operations.
 */
class uint160 : public base_blob<160> {
public:
    constexpr uint160() = default;
    constexpr explicit uint160(Span<const unsigned char> vch) : base_blob<160>(vch) {}
};

/** 256-bit opaque blob.
 * @note This type is called uint256 for historical reasons only. It is an
 * opaque blob of 256 bits and has no integer operations. Use arith_uint256 if
 * those are required.
 */
class uint256 : public base_blob<256> {
public:
    constexpr uint256() = default;
    constexpr explicit uint256(uint8_t v) : base_blob<256>(v) {}
    constexpr explicit uint256(Span<const unsigned char> vch) : base_blob<256>(vch) {}
    static const uint256 ZERO;
    static const uint256 ONE;
};

/* uint256 from std::string_view, treated as little-endian.
 * This is not a uint256 constructor because of historical fears of uint256(0)
 * resolving to a NULL string and crashing.
 */
inline uint256 uint256S(std::string_view str)
{
    uint256 rv;
    rv.SetHex(str);
    return rv;
}

#endif // BITCOIN_UINT256_H


Review comment (suggestion):
after we get rid of the deprecation, these checks should ideally be done while iterating over the values to avoid multiple iterations (e.g. how Base58 parsing is done)

Code after:
    constexpr uint64_t GetUint64(int pos) const { return ReadLE64(m_data.data() + pos * 8); }

    template<typename Stream>
    void Serialize(Stream& s) const
    {
        s << Span(m_data);
    }

    template<typename Stream>
    void Unserialize(Stream& s)
    {
        s.read(MakeWritableByteSpan(m_data));
    }
};

namespace detail {
/**
 * Writes the hex string (treated as little-endian) into a new uintN_t object
 * and only returns a value iff all of the checks pass:
 *   - Input length is uintN_t::size()*2
 *   - All characters are hex
 */
template <class uintN_t>
std::optional<uintN_t> FromHex(std::string_view str)
{
    if (uintN_t::size() * 2 != str.size() || !IsHex(str)) return std::nullopt;
    uintN_t rv;
    rv.SetHexDeprecated(str);
    return rv;
}
} // namespace detail

/** 160-bit opaque blob.
 * @note This type is called uint160 for historical reasons only. It is an opaque
 * blob of 160 bits and has no integer operations.
 */
class uint160 : public base_blob<160> {
public:
    static std::optional<uint160> FromHex(std::string_view str) { return detail::FromHex<uint160>(str); }
    constexpr uint160() = default;
    constexpr explicit uint160(Span<const unsigned char> vch) : base_blob<160>(vch) {}
};

/** 256-bit opaque blob.
 * @note This type is called uint256 for historical reasons only. It is an
 * opaque blob of 256 bits and has no integer operations. Use arith_uint256 if
 * those are required.
 */
class uint256 : public base_blob<256> {
public:
    static std::optional<uint256> FromHex(std::string_view str) { return detail::FromHex<uint256>(str); }