stream_parser.h

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#pragma once
 
#include "bcnp/packet.h"
 
#include <array>
#include <cstddef>
#include <cstdint>
#include <functional>
#include <utility>
 
namespace bcnp {
 
class StreamParser {
public:
    using PacketCallback = std::function<void(const PacketView&)>;
    struct ErrorInfo {
        PacketError code{PacketError::None};
        std::size_t offset{0};
        uint64_t consecutiveErrors{0};
    };
    using ErrorCallback = std::function<void(const ErrorInfo&)>;
    
    using WireSizeLookup = std::function<std::size_t(MessageTypeId)>;
 
    StreamParser(PacketCallback onPacket, ErrorCallback onError = {}, std::size_t bufferSize = 4096);
 
    void Push(const uint8_t* data, std::size_t length);
 
    void Reset(bool resetErrorState = true);
    
    void SetWireSizeLookup(WireSizeLookup lookup) { m_wireSizeLookup = std::move(lookup); }
 
    static constexpr std::size_t kMaxParseIterationsPerPush = 1024;
 
private:
    void EmitPacket(const PacketView& packet);
    void EmitError(PacketError error, std::size_t offset);
 
    void WriteToBuffer(const uint8_t* data, std::size_t length);
    void CopyOut(std::size_t offset, std::size_t length, uint8_t* dest) const;
    void Discard(std::size_t count);
    void ParseBuffer(std::size_t& iterationBudget);
    std::size_t FindNextHeaderCandidate() const;
    std::size_t LookupWireSize(MessageTypeId typeId) const;
 
    PacketCallback m_onPacket;
    ErrorCallback m_onError;
    WireSizeLookup m_wireSizeLookup;
    std::vector<uint8_t> m_buffer;
    std::vector<uint8_t> m_decodeScratch;
    std::size_t m_head{0};
    std::size_t m_size{0};
    std::size_t m_streamOffset{0};
    uint64_t m_consecutiveErrors{0};
};
 
} // namespace bcnp