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 <iterator> // 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/core/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 std::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