API muesli monostate_codec

muesli/monostate_codec

Defined in header <muesli/monostate_codec>

monostate_codec

inline constexpr constant_codec<std::monostate> monostate_codec{};

Codec for std::monostate (empty variant state).

Encodes and decodes std::monostate, the empty state type used in std::variant. Useful as a placeholder codec when representing absence of data, particularly in optional or nullable contexts where no actual value needs to be encoded.

Example

// Used internally by optional_codec to represent absent values
auto opt_codec = muesli::int32_codec.optional();
std::optional<int32_t> absent = std::nullopt;
auto encoded = opt_codec.encode(absent);  // Uses monostate_codec for the empty variant

Related

• constant_codec
• optional_codec
• nullable_codec

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