.. _program_listing_file_eshet_unpack.hpp:

Program Listing for File unpack.hpp
===================================

|exhale_lsh| :ref:`Return to documentation for file <file_eshet_unpack.hpp>` (``eshet/unpack.hpp``)

.. |exhale_lsh| unicode:: U+021B0 .. UPWARDS ARROW WITH TIP LEFTWARDS

.. code-block:: cpp

   #pragma once
   #include "parse.hpp"
   #include <optional>
   #include <vector>
   
   namespace eshet {
   namespace detail {
   
   // accept a stream of data in arbitrary chunks, and produce complete messages
   class Unpacker {
     std::vector<uint8_t> buffer;
   
   public:
     void push(std::vector<uint8_t> buf) {
       for (uint8_t chr : buf)
         buffer.push_back(chr);
     }
   
     std::optional<std::vector<uint8_t>> read() {
       if (buffer.size() < 3)
         return std::nullopt;
   
       Parser p(buffer.data(), 3);
       uint8_t magic = p.read8();
       uint16_t length = p.read16();
       p.check_empty();
   
       if (magic != 0x47)
         throw ProtocolError();
   
       if (length > (buffer.size() - 3))
         return std::nullopt;
   
       std::vector<uint8_t> message(buffer.data() + 3, buffer.data() + 3 + length);
   
       for (size_t i = length + 3; i < buffer.size(); i++)
         buffer[i - (length + 3)] = buffer[i];
       buffer.resize(buffer.size() - (length + 3));
   
       return message;
     }
   };
   
   } // namespace detail
   } // namespace eshet