ceph/src/boost/libs/spirit/test/support/regression_multi_pass_functor.cpp

   1 //  Copyright (c) 2010 Larry Evans
   2 //
   3 //  Distributed under the Boost Software License, Version 1.0. (See accompanying
   4 //  file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   5
   6 //Purpose:
   7 //  Demonstrate error in non-classic multi_pass iterator compilation.
   8 //
   9
  10 #include <boost/spirit/home/qi.hpp>
  11 #include <boost/spirit/home/support.hpp>
  12 #include <boost/spirit/home/support/multi_pass.hpp>
  13 #include <boost/spirit/home/support/iterators/detail/functor_input_policy.hpp>
  14
  15 #include <fstream>
  16
  17 //[iterate_a2m:
  18 // copied from:
  19 //    http://www.boost.org/doc/libs/1_41_0/libs/spirit/doc/html/spirit/support/multi_pass.html
  20
  21 // define the function object
  22 template<typename CharT=char>
  23 class istreambuf_functor
  24 {
  25 public:
  26         typedef
  27       std::istreambuf_iterator<CharT>
  28     buf_iterator_type;
  29         typedef
  30       typename buf_iterator_type::int_type
  31     result_type;
  32         static
  33       result_type
  34     eof;
  35
  36     istreambuf_functor(void)
  37       : current_chr(eof)
  38     {}
  39
  40     istreambuf_functor(std::ifstream& input)
  41       : my_first(input)
  42       , current_chr(eof)
  43     {}
  44
  45     result_type operator()()
  46     {
  47         buf_iterator_type last;
  48         if (my_first == last)
  49         {
  50             return eof;
  51         }
  52         current_chr=*my_first;
  53         ++my_first;
  54         return current_chr;
  55     }
  56
  57 private:
  58     buf_iterator_type my_first;
  59     result_type current_chr;
  60 };
  61
  62 template<typename CharT>
  63   typename istreambuf_functor<CharT>::result_type
  64   istreambuf_functor<CharT>::
  65 eof
  66 ( istreambuf_functor<CharT>::buf_iterator_type::traits_type::eof()
  67 )
  68 ;
  69
  70 //]iterate_a2m:
  71
  72 typedef istreambuf_functor<char> base_iterator_type;
  73
  74 typedef
  75   boost::spirit::multi_pass
  76   < base_iterator_type
  77   , boost::spirit::iterator_policies::default_policy
  78     < boost::spirit::iterator_policies::first_owner
  79     , boost::spirit::iterator_policies::no_check
  80     , boost::spirit::iterator_policies::functor_input
  81     , boost::spirit::iterator_policies::split_std_deque
  82     >
  83   >
  84 chr_iterator_type;
  85
  86 // ======================================================================
  87 // Main
  88 int main()
  89 {
  90     std::ifstream in("multi_pass.txt");
  91
  92     unsigned num_toks=0;
  93     unsigned const max_toks=10;
  94
  95     base_iterator_type base_first(in);
  96     chr_iterator_type chr_first(base_first);
  97     chr_iterator_type chr_last;
  98     for
  99       (
 100       ; (chr_first != chr_last && ++num_toks < max_toks)
 101       ; ++chr_first
 102       )
 103     {
 104         std::cout<<":num_toks="<<num_toks<<":chr="<<*chr_first<<"\n";
 105     }
 106     return 0;
 107 }