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_BUFFERING_ITERATOR_INPUT_ITERATOR_POLICY_MAR_04_2010_1224AM)
8 #define BOOST_SPIRIT_BUFFERING_ITERATOR_INPUT_ITERATOR_POLICY_MAR_04_2010_1224AM
9 
10 #include <boost/spirit/home/support/iterators/multi_pass_fwd.hpp>
11 #include <boost/spirit/home/support/iterators/detail/multi_pass.hpp>
12 #include <boost/spirit/home/support/iterators/detail/input_iterator_policy.hpp>
13 #include <boost/detail/iterator.hpp> // for boost::detail::iterator_traits
14 #include <boost/assert.hpp>
15 
16 namespace boost { namespace spirit { namespace iterator_policies
17 {
18     ///////////////////////////////////////////////////////////////////////////
19     //  class input_iterator
20     //
21     //  Implementation of the InputPolicy used by multi_pass, this is different
22     //  from the input_iterator policy only as it is buffering the last input
23     //  character to allow returning it by reference. This is needed for
24     //  wrapping iterators not buffering the last item (such as the
25     //  std::istreambuf_iterator). Unfortunately there is no way to
26     //  automatically figure this out at compile time.
27     //
28     //  The buffering_input_iterator encapsulates an input iterator of type T
29     ///////////////////////////////////////////////////////////////////////////
30     struct buffering_input_iterator
31     {
32         ///////////////////////////////////////////////////////////////////////
33         template <typename T>
34         class unique // : public detail::default_input_policy
35         {
36         private:
37             typedef
38                 typename boost::detail::iterator_traits<T>::value_type
39             result_type;
40 
41         public:
42             typedef
43                 typename boost::detail::iterator_traits<T>::difference_type
44             difference_type;
45             typedef
46                 typename boost::detail::iterator_traits<T>::difference_type
47             distance_type;
48             typedef
49                 typename boost::detail::iterator_traits<T>::pointer
50             pointer;
51             typedef result_type& reference;
52             typedef result_type value_type;
53 
54         protected:
unique()55             unique() {}
unique(T x)56             explicit unique(T x) {}
57 
swap(unique &)58             void swap(unique&) {}
59 
60         public:
61             template <typename MultiPass>
destroy(MultiPass &)62             static void destroy(MultiPass&) {}
63 
64             template <typename MultiPass>
get_input(MultiPass & mp)65             static typename MultiPass::reference get_input(MultiPass& mp)
66             {
67                 return mp.shared()->get_input();
68             }
69 
70             template <typename MultiPass>
advance_input(MultiPass & mp)71             static void advance_input(MultiPass& mp)
72             {
73                 BOOST_ASSERT(0 != mp.shared());
74                 mp.shared()->advance_input();
75             }
76 
77             // test, whether we reached the end of the underlying stream
78             template <typename MultiPass>
input_at_eof(MultiPass const & mp)79             static bool input_at_eof(MultiPass const& mp)
80             {
81                 static T const end_iter;
82                 return mp.shared()->input_ == end_iter;
83             }
84 
85             template <typename MultiPass>
input_is_valid(MultiPass const & mp,value_type const & t)86             static bool input_is_valid(MultiPass const& mp, value_type const& t)
87             {
88                 return mp.shared()->input_is_valid_;
89             }
90 
91             // no unique data elements
92         };
93 
94         ///////////////////////////////////////////////////////////////////////
95         template <typename T>
96         struct shared
97         {
98             typedef
99                 typename boost::detail::iterator_traits<T>::value_type
100             result_type;
101 
sharedboost::spirit::iterator_policies::buffering_input_iterator::shared102             explicit shared(T const& input)
103               : input_(input), curtok_(0), input_is_valid_(false) {}
104 
advance_inputboost::spirit::iterator_policies::buffering_input_iterator::shared105             void advance_input()
106             {
107                 ++input_;
108                 input_is_valid_ = false;
109             }
110 
get_inputboost::spirit::iterator_policies::buffering_input_iterator::shared111             result_type& get_input()
112             {
113                 if (!input_is_valid_) {
114                     curtok_ = *input_;
115                     input_is_valid_ = true;
116                 }
117                 return curtok_;
118             }
119 
120             T input_;
121             result_type curtok_;
122             bool input_is_valid_;
123         };
124     };
125 
126 }}}
127 
128 #endif
129