ceph/src/boost/boost/spirit/home/support/iterators/detail/lex_input_policy.hpp

   1 //  Copyright (c) 2001 Daniel C. Nuffer
   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_LEX_INPUT_POLICY_MAR_16_2007_1205PM)
   8 #define BOOST_SPIRIT_ITERATOR_LEX_INPUT_POLICY_MAR_16_2007_1205PM
   9
  10 #include <boost/spirit/home/support/iterators/multi_pass_fwd.hpp>
  11 #include <boost/spirit/home/support/iterators/detail/multi_pass.hpp>
  12
  13 namespace boost { namespace spirit { namespace iterator_policies
  14 {
  15     ///////////////////////////////////////////////////////////////////////////////
  16     //  class lex_input
  17     //  Implementation of the InputPolicy used by multi_pass
  18     //
  19     //  The lex_input class gets tokens (integers) from yylex()
  20     ///////////////////////////////////////////////////////////////////////////
  21     struct lex_input
  22     {
  23         typedef int value_type;
  24
  25         ///////////////////////////////////////////////////////////////////////
  26         template <typename T>
  27         class unique : public detail::default_input_policy
  28         {
  29         public:
  30             typedef std::ptrdiff_t difference_type;
  31             typedef std::ptrdiff_t distance_type;
  32             typedef int* pointer;
  33             typedef int& reference;
  34
  35         protected:
  36             unique() {}
  37             explicit unique(T) {}
  38
  39         public:
  40             template <typename MultiPass>
  41             static typename MultiPass::reference get_input(MultiPass& mp)
  42             {
  43                 value_type& curtok = mp.shared()->curtok;
  44                 if (-1 == curtok)
  45                 {
  46                     extern int yylex();
  47                     curtok = yylex();
  48                 }
  49                 return curtok;
  50             }
  51
  52             template <typename MultiPass>
  53             static void advance_input(MultiPass& mp)
  54             {
  55                 extern int yylex();
  56                 mp.shared()->curtok = yylex();
  57             }
  58
  59             // test, whether we reached the end of the underlying stream
  60             template <typename MultiPass>
  61             static bool input_at_eof(MultiPass const& mp)
  62             {
  63                 return mp.shared()->curtok == 0;
  64             }
  65
  66             template <typename MultiPass>
  67             static bool input_is_valid(MultiPass const&, value_type const& t)
  68             {
  69                 return -1 != t;
  70             }
  71         };
  72
  73         ///////////////////////////////////////////////////////////////////////
  74         template <typename T>
  75         struct shared
  76         {
  77             explicit shared(T) : curtok(-1) {}
  78
  79             value_type curtok;
  80         };
  81     };
  82
  83 }}}
  84
  85 #endif
  86