ceph/src/boost/libs/spirit/include/boost/spirit/home/qi/stream/detail/iterator_source.hpp

   1 /*=============================================================================
   2     Copyright (c) 2001-2011 Hartmut Kaiser
   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 #if !defined(BOOST_SPIRIT_ITERATOR_ISTREAM_MAY_05_2007_0110PM)
   8 #define BOOST_SPIRIT_ITERATOR_ISTREAM_MAY_05_2007_0110PM
   9
  10 #if defined(_MSC_VER)
  11 #pragma once
  12 #endif
  13
  14 #include <boost/iostreams/stream.hpp>
  15 #include <boost/detail/iterator.hpp>
  16
  17 ///////////////////////////////////////////////////////////////////////////////
  18 namespace boost { namespace spirit { namespace qi { namespace detail
  19 {
  20     ///////////////////////////////////////////////////////////////////////////
  21     template <typename Iterator>
  22     struct iterator_source
  23     {
  24         typedef typename
  25             boost::detail::iterator_traits<Iterator>::value_type
  26         char_type;
  27         typedef boost::iostreams::seekable_device_tag category;
  28
  29         iterator_source (Iterator const& first_, Iterator const& last_)
  30           : first(first_), last(last_), pos(0)
  31         {}
  32
  33         // Read up to n characters from the input sequence into the buffer s,
  34         // returning the number of characters read, or -1 to indicate
  35         // end-of-sequence.
  36         std::streamsize read (char_type* s, std::streamsize n)
  37         {
  38             if (first == last)
  39                 return -1;
  40
  41             std::streamsize bytes_read = 0;
  42             while (n--) {
  43                 *s = *first;
  44                 ++s; ++bytes_read;
  45                 if (++first == last)
  46                     break;
  47             }
  48
  49             pos += bytes_read;
  50             return bytes_read;
  51         }
  52
  53         // Write is implemented only to satisfy the requirements of a
  54         // boost::iostreams::seekable_device. We need to have see support to
  55         // be able to figure out how many characters have been actually
  56         // consumed by the stream.
  57         std::streamsize write(const char_type*, std::streamsize)
  58         {
  59             BOOST_ASSERT(false);    // not supported
  60             return -1;
  61         }
  62
  63         std::streampos seek(boost::iostreams::stream_offset, std::ios_base::seekdir way)
  64         {
  65             BOOST_ASSERT(way == std::ios_base::cur);    // only support queries
  66             return pos;                              // return current position
  67         }
  68
  69         Iterator first;
  70         Iterator const& last;
  71         std::streamsize pos;
  72
  73     private:
  74         // silence MSVC warning C4512: assignment operator could not be generated
  75         iterator_source& operator= (iterator_source const&);
  76     };
  77
  78 }}}}
  79
  80 #endif