[boost::range]chunkをsliceで分割してheaderをjoinしてみる

バイナリをchunkで分割し、そのサイズをヘッダーに付与してみた。
サイズは2byteで表現可能な64KBまで(256 x head[3] + head[2])

評価コード

# include <iostream>
# include <iterator> 
# include <fstream>
# include <sstream>
# include <boost/range/adaptor/sliced.hpp>
# include <boost/range/algorithm/copy.hpp>
# include <boost/range/join.hpp>

int main(){
  std::ifstream input( "1.jpg", std::ios::binary );
  std::vector<char> buffer((
    std::istreambuf_iterator<char>(input)), 
    (std::istreambuf_iterator<char>()));
  
  size_t chunkSize = 64 * 1024 -1; // 65535
  char head[4] = { 0x02, 0x01 };
  size_t end = 0;
  size_t byteSize = buffer.size();

  while(end < byteSize){
    size_t pos = end;
    end += chunkSize;
    if (end > byteSize)
      end = byteSize;
    
    int len = end - pos;
    head[2] = len;
    head[3] = int(len / 256);

    std::string str;
    boost::copy(
      boost::join(head, 
        buffer | boost::adaptors::sliced(pos,end)),
      std::back_inserter(str));
    
    // output test
    std::cout << "binary: ";
    std::stringstream ss;
    for (int x = 0; x < 10; x++)
      ss << std::hex << (int)(unsigned char)str[x];

    std::cout << ss.str();
    ss.str("");
    std::cout << " ... ";
    
    for (int x = str.size()-10; x < str.size(); x++)
      ss << std::hex << (int)(unsigned char)str[x];

    std::cout << ss.str() << std::endl;
    std::cout << "size: " << str.size() << std::endl;

    // std::ofstream ofs("out.bin", std::ios::binary);
    // ofs.write(&str[0], str.size());
  }
}

出力

binary: 21ffffffd8ffe0010 ... 1eae66bba547bd8836d8
size: 65539
binary: 21558d77b32e3232e1 ... 78d137b3c12e2bc1ffd9
size: 36185