Crunch::SerdesPolicy Concept Reference

Concept defining a Serialization/Deserialization policy. More...

#include <crunch_serdes.hpp>

Concept definition

template<typename Policy, typename Message>
concept Crunch::SerdesPolicy = 
    messages::CrunchMessage<Message> &&
    requires(const Message& msg, std::span<std::byte> output,
             std::span<const std::byte> input) {
        {
            std::bool_constant<(Policy::template Size<Message>(), true)>()
        } -> std::same_as<std::true_type>;
        { Policy::template Size<Message>() } -> std::same_as<std::size_t>;
 
        { Policy::Serialize(msg, output) } -> std::same_as<std::size_t>;
        {
            Policy::Deserialize(input, const_cast<Message&>(msg))
        } -> std::same_as<std::optional<Error>>;
        {
            std::bool_constant<(Policy::GetFormat(), true)>()
        } -> std::same_as<std::true_type>;
        { Policy::GetFormat() } -> std::same_as<Format>;
    }

Detailed Description

Concept defining a Serialization/Deserialization policy.

A SerdesPolicy knows how to serialize a specific Message type. It must provide:

• Size<Message>(): Returns the maximum serialized size. Must be constexpr.
• GetFormat(): Returns the format of the message. Must be constexpr.
• Serialize(msg, output): Serializes the message into the output span. Must be constexpr.
• Deserialize(input, msg): Deserializes the input span into the message object. Must be constexpr.

Note

The Deserialize and Serialize functions must be constexpr. However, this requirement is not enforced by the concept because the arguments provided in the requires-expression are not constant expressions, preventing verification via std::bool_constant.

Serialize passes the entire buffer - including the already-parsed header - to the policy. The policy generally should just skip the header bytes when serializing. I wasn't sure if there may be a good reason in the future to give the policy more context on the header and wanted to hedge my bets.