1 // (C) Copyright 2008 CodeRage, LLC (turkanis at coderage dot com)
2 // (C) Copyright 2003-2007 Jonathan Turkanis
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 // See http://www.boost.org/libs/iostreams for documentation.
7 
8 #ifndef BOOST_IOSTREAMS_DETAIL_RANGE_ADAPTER_HPP_INCLUDED
9 #define BOOST_IOSTREAMS_DETAIL_RANGE_ADAPTER_HPP_INCLUDED
10 
11 #if defined(_MSC_VER)
12 # pragma once
13 #endif
14 
15 #include <algorithm>                             // min.
16 #include <boost/assert.hpp>
17 #include <cstddef>                               // ptrdiff_t.
18 #include <iosfwd>                                // streamsize, streamoff.
19 #include <boost/detail/iterator.hpp>             // boost::iterator_traits.
20 #include <boost/iostreams/categories.hpp>
21 #include <boost/iostreams/detail/error.hpp>
22 #include <boost/iostreams/positioning.hpp>
23 #include <boost/mpl/if.hpp>
24 #include <boost/throw_exception.hpp>
25 #include <boost/type_traits/is_convertible.hpp>
26 #include <boost/utility/enable_if.hpp>
27 
28 // Must come last.
29 #include <boost/iostreams/detail/config/disable_warnings.hpp>  // MSVC.
30 
31 namespace boost { namespace iostreams { namespace detail {
32 
33 // Used for simulated tag dispatch.
34 template<typename Traversal> struct range_adapter_impl;
35 
36 //
37 // Template name: range_adapter
38 // Description: Device based on an instance of boost::iterator_range.
39 // Template parameters:
40 //     Mode - A mode tag.
41 //     Range - An instance of iterator_range.
42 //
43 template<typename Mode, typename Range>
44 class range_adapter {
45 private:
46     typedef typename Range::iterator                  iterator;
47     typedef boost::detail::iterator_traits<iterator>  iter_traits;
48     typedef typename iter_traits::iterator_category   iter_cat;
49 public:
50     typedef typename Range::value_type                char_type;
51     struct category : Mode, device_tag { };
52     typedef typename
53             mpl::if_<
54                 is_convertible<
55                     iter_cat,
56                     std::random_access_iterator_tag
57                 >,
58                 std::random_access_iterator_tag,
59                 std::forward_iterator_tag
60             >::type                                   tag;
61     typedef range_adapter_impl<tag>                   impl;
62 
63     explicit range_adapter(const Range& rng);
64     range_adapter(iterator first, iterator last);
65     std::streamsize read(char_type* s, std::streamsize n);
66     std::streamsize write(const char_type* s, std::streamsize n);
67     std::streampos seek(stream_offset off, BOOST_IOS::seekdir way);
68 private:
69     iterator first_, cur_, last_;
70 };
71 
72 //------------------Implementation of range_adapter---------------------------//
73 
74 template<typename Mode, typename Range>
range_adapter(const Range & rng)75 range_adapter<Mode, Range>::range_adapter(const Range& rng)
76     : first_(rng.begin()), cur_(rng.begin()), last_(rng.end()) { }
77 
78 template<typename Mode, typename Range>
range_adapter(iterator first,iterator last)79 range_adapter<Mode, Range>::range_adapter(iterator first, iterator last)
80     : first_(first), cur_(first), last_(last) { }
81 
82 template<typename Mode, typename Range>
read(char_type * s,std::streamsize n)83 inline std::streamsize range_adapter<Mode, Range>::read
84     (char_type* s, std::streamsize n)
85 { return impl::read(cur_, last_, s, n); }
86 
87 template<typename Mode, typename Range>
write(const char_type * s,std::streamsize n)88 inline std::streamsize range_adapter<Mode, Range>::write
89     (const char_type* s, std::streamsize n)
90 { return impl::write(cur_, last_, s, n); }
91 
92 
93 template<typename Mode, typename Range>
seek(stream_offset off,BOOST_IOS::seekdir way)94 std::streampos range_adapter<Mode, Range>::seek
95     (stream_offset off, BOOST_IOS::seekdir way)
96 {
97     impl::seek(first_, cur_, last_, off, way);
98     return offset_to_position(cur_ - first_);
99 }
100 
101 //------------------Implementation of range_adapter_impl----------------------//
102 
103 template<>
104 struct range_adapter_impl<std::forward_iterator_tag> {
105     template<typename Iter, typename Ch>
readboost::iostreams::detail::range_adapter_impl106     static std::streamsize read
107         (Iter& cur, Iter& last, Ch* s,std::streamsize n)
108     {
109         std::streamsize rem = n; // No. of chars remaining.
110         while (cur != last && rem-- > 0) *s++ = *cur++;
111         return n - rem != 0 ? n - rem : -1;
112     }
113 
114     template<typename Iter, typename Ch>
writeboost::iostreams::detail::range_adapter_impl115     static std::streamsize write
116         (Iter& cur, Iter& last, const Ch* s, std::streamsize n)
117     {
118         while (cur != last && n-- > 0) *cur++ = *s++;
119         if (cur == last && n > 0)
120             boost::throw_exception(write_area_exhausted());
121         return n;
122     }
123 };
124 
125 template<>
126 struct range_adapter_impl<std::random_access_iterator_tag> {
127     template<typename Iter, typename Ch>
readboost::iostreams::detail::range_adapter_impl128     static std::streamsize read
129         (Iter& cur, Iter& last, Ch* s,std::streamsize n)
130     {
131         std::streamsize result =
132             (std::min)(static_cast<std::streamsize>(last - cur), n);
133         if (result)
134             std::copy(cur, cur + result, s);
135         cur += result;
136         return result != 0 ? result : -1;
137     }
138 
139     template<typename Iter, typename Ch>
writeboost::iostreams::detail::range_adapter_impl140     static std::streamsize write
141         (Iter& cur, Iter& last, const Ch* s, std::streamsize n)
142     {
143         std::streamsize count =
144             (std::min)(static_cast<std::streamsize>(last - cur), n);
145         std::copy(s, s + count, cur);
146         cur += count;
147         if (count < n)
148             boost::throw_exception(write_area_exhausted());
149         return n;
150     }
151 
152     template<typename Iter>
seekboost::iostreams::detail::range_adapter_impl153     static void seek
154         ( Iter& first, Iter& cur, Iter& last, stream_offset off,
155           BOOST_IOS::seekdir way )
156     {
157         using namespace std;
158         switch (way) {
159         case BOOST_IOS::beg:
160             if (off > last - first || off < 0)
161                 boost::throw_exception(bad_seek());
162             cur = first + off;
163             break;
164         case BOOST_IOS::cur:
165             {
166                 std::ptrdiff_t newoff = cur - first + off;
167                 if (newoff > last - first || newoff < 0)
168                     boost::throw_exception(bad_seek());
169                 cur += off;
170                 break;
171             }
172         case BOOST_IOS::end:
173             if (last - first + off < 0 || off > 0)
174                 boost::throw_exception(bad_seek());
175             cur = last + off;
176             break;
177         default:
178             BOOST_ASSERT(0);
179         }
180     }
181 };
182 
183 } } } // End namespaces detail, iostreams, boost.
184 
185 #include <boost/iostreams/detail/config/enable_warnings.hpp>  // MSVC.
186 
187 #endif // #ifndef BOOST_IOSTREAMS_DETAIL_RANGE_ADAPTER_HPP_INCLUDED //---------------//
188