ceph/src/Beast/include/beast/core/prepare_buffer.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_PREPARE_BUFFER_HPP
   9 #define BEAST_PREPARE_BUFFER_HPP
  10
  11 #include <beast/config.hpp>
  12 #include <boost/asio/buffer.hpp>
  13 #include <algorithm>
  14
  15 namespace beast {
  16
  17 /** Return a shortened buffer.
  18
  19     The returned buffer points to the same memory as the
  20     passed buffer, but with a size that is equal to or less
  21     than the size of the original buffer.
  22
  23     @param n The size of the returned buffer.
  24
  25     @param buffer The buffer to shorten. Ownership of the
  26     underlying memory is not transferred.
  27
  28     @return A new buffer that points to the first `n` bytes
  29     of the original buffer.
  30 */
  31 inline
  32 boost::asio::const_buffer
  33 prepare_buffer(std::size_t n,
  34     boost::asio::const_buffer buffer)
  35 {
  36     using boost::asio::buffer_cast;
  37     using boost::asio::buffer_size;
  38     return { buffer_cast<void const*>(buffer),
  39         (std::min)(n, buffer_size(buffer)) };
  40 }
  41
  42 /** Return a shortened buffer.
  43
  44     The returned buffer points to the same memory as the
  45     passed buffer, but with a size that is equal to or less
  46     than the size of the original buffer.
  47
  48     @param n The size of the returned buffer.
  49
  50     @param buffer The buffer to shorten. Ownership of the
  51     underlying memory is not transferred.
  52
  53     @return A new buffer that points to the first `n` bytes
  54     of the original buffer.
  55 */
  56 inline
  57 boost::asio::mutable_buffer
  58 prepare_buffer(std::size_t n,
  59     boost::asio::mutable_buffer buffer)
  60 {
  61     using boost::asio::buffer_cast;
  62     using boost::asio::buffer_size;
  63     return { buffer_cast<void*>(buffer),
  64         (std::min)(n, buffer_size(buffer)) };
  65 }
  66
  67 } // beast
  68
  69 #endif