ceph/src/Beast/include/beast/http/detail/chunk_encode.hpp

   1 //
   2 // Copyright (c) 2013-2017 Vinnie Falco (vinnie dot falco at gmail dot com)
   3 //
   4 // Distributed under the Boost Software License, Version 1.0. (See accompanying
   5 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   6 //
   7
   8 #ifndef BEAST_HTTP_DETAIL_CHUNK_ENCODE_HPP
   9 #define BEAST_HTTP_DETAIL_CHUNK_ENCODE_HPP
  10
  11 #include <boost/asio/buffer.hpp>
  12 #include <algorithm>
  13 #include <array>
  14 #include <cstddef>
  15
  16 namespace beast {
  17 namespace http {
  18 namespace detail {
  19
  20 class chunk_encode_delim
  21 {
  22     boost::asio::const_buffer cb_;
  23
  24     // Storage for the longest hex string we might need, plus delimiters.
  25     std::array<char, 2 * sizeof(std::size_t) + 2> buf_;
  26
  27     template<class = void>
  28     void
  29     copy(chunk_encode_delim const& other);
  30
  31     template<class = void>
  32     void
  33     setup(std::size_t n);
  34
  35     template<class OutIter>
  36     static
  37     OutIter
  38     to_hex(OutIter last, std::size_t n)
  39     {
  40         if(n == 0)
  41         {
  42             *--last = '0';
  43             return last;
  44         }
  45         while(n)
  46         {
  47             *--last = "0123456789abcdef"[n&0xf];
  48             n>>=4;
  49         }
  50         return last;
  51     }
  52
  53 public:
  54     using value_type = boost::asio::const_buffer;
  55
  56     using const_iterator = value_type const*;
  57
  58     chunk_encode_delim(chunk_encode_delim const& other)
  59     {
  60         copy(other);
  61     }
  62
  63     explicit
  64     chunk_encode_delim(std::size_t n)
  65     {
  66         setup(n);
  67     }
  68
  69     const_iterator
  70     begin() const
  71     {
  72         return &cb_;
  73     }
  74
  75     const_iterator
  76     end() const
  77     {
  78         return begin() + 1;
  79     }
  80 };
  81
  82 template<class>
  83 void
  84 chunk_encode_delim::
  85 copy(chunk_encode_delim const& other)
  86 {
  87     auto const n =
  88         boost::asio::buffer_size(other.cb_);
  89     buf_ = other.buf_;
  90     cb_ = boost::asio::const_buffer(
  91         &buf_[buf_.size() - n], n);
  92 }
  93
  94 template<class>
  95 void
  96 chunk_encode_delim::
  97 setup(std::size_t n)
  98 {
  99     buf_[buf_.size() - 2] = '\r';
 100     buf_[buf_.size() - 1] = '\n';
 101     auto it = to_hex(buf_.end() - 2, n);
 102     cb_ = boost::asio::const_buffer{&*it,
 103         static_cast<std::size_t>(
 104             std::distance(it, buf_.end()))};
 105 }
 106
 107 } // detail
 108 } // http
 109 } // beast
 110
 111 #endif