79 lines
2.4 KiB
C++
79 lines
2.4 KiB
C++
//-----------------------------------------------------------------------------
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// ___ __ _ _
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// / _ \__ _ _ __ ___ ___ / /(_)_ __ | | __
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// / /_)/ _` | '__/ __|/ _ \/ / | | '_ \| |/ /
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// / ___/ (_| | | \__ \ __/ /__| | | | | <
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// \/ \__,_|_| |___/\___\____/_|_| |_|_|\_\ .
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//
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//-----------------------------------------------------------------------------
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// Author: Kurt Sassenrath
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// Module: Message
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//
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// Message types.
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//
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// Copyright (c) 2023 Kurt Sassenrath.
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//
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// License TBD.
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//-----------------------------------------------------------------------------
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#ifndef message_0c61530748b9f966
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#define message_0c61530748b9f966
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#include <span>
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#include <cstdint>
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#include <tl/expected.hpp>
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namespace parselink {
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namespace message {
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enum class error {
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bad_magic, // Did not get the message magic expected
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too_large, // The message size was too large.
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unknown_type, // The message type is not known
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};
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// Parselink messages are encoded with MessagePack and take the form of:
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// | magic | size | content |
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// - [magic] is the string "prs", in "fixstr" format.
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// - [size] is the size of the message, not including this header.
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// - [content] is [size] bytes of MessagePack data, including the
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// specific type of message presented.
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// This class is responsible for consuming buffer data and yielding a message
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// instance when complete. Will throw an error if data is incorrect.
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//
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class builder {
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public:
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// For now, builders don't manage any buffers themselves. Later, that
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// may change.
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builder() = default;
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// Reset the builder to its initial state. This means any partially-decoded
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// message data will be lost.
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void reset() noexcept;
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// How many bytes are needed to perform a meaningful amount of work.
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std::size_t bytes_needed() noexcept;
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// Process data from a buffer, building messages. Returns the number of
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// bytes read from the buffer for the caller's bookkeeping. May yield a
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// message in addition.
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std::size_t process(std::span<std::byte const> buffer) noexcept;
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private:
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enum class state {
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magic,
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size,
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payload
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};
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state state_{state::magic};
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std::size_t payload_size_{};
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std::size_t payload_remaining_{};
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};
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} // namespace message
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} // namespace parselink
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#endif // message_0c61530748b9f966
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