1// (C) Copyright 2008 CodeRage, LLC (turkanis at coderage dot com)
2// (C) Copyright 2005-2007 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_READ_HPP_INCLUDED
9#define BOOST_IOSTREAMS_READ_HPP_INCLUDED
10
11#if defined(_MSC_VER)
12# pragma once
13#endif
14
15#include <boost/config.hpp> // DEDUCED_TYPENAME, MSVC.
16#include <boost/detail/workaround.hpp>
17#include <boost/iostreams/char_traits.hpp>
18#include <boost/iostreams/detail/char_traits.hpp>
19#include <boost/iostreams/detail/dispatch.hpp>
20#include <boost/iostreams/detail/ios.hpp> // streamsize.
21#include <boost/iostreams/detail/streambuf.hpp>
22#include <boost/iostreams/detail/wrap_unwrap.hpp>
23#include <boost/iostreams/operations_fwd.hpp>
24#include <boost/mpl/if.hpp>
25
26// Must come last.
27#include <boost/iostreams/detail/config/disable_warnings.hpp>
28
29namespace boost { namespace iostreams {
30
31namespace detail {
32
33template<typename T>
34struct read_device_impl;
35
36template<typename T>
37struct read_filter_impl;
38
39} // End namespace detail.
40
41template<typename T>
42typename int_type_of<T>::type get(T& t)
43{ return detail::read_device_impl<T>::get(detail::unwrap(t)); }
44
45template<typename T>
46inline std::streamsize
47read(T& t, typename char_type_of<T>::type* s, std::streamsize n)
48{ return detail::read_device_impl<T>::read(detail::unwrap(t), s, n); }
49
50template<typename T, typename Source>
51std::streamsize
52read(T& t, Source& src, typename char_type_of<T>::type* s, std::streamsize n)
53{ return detail::read_filter_impl<T>::read(detail::unwrap(t), src, s, n); }
54
55template<typename T>
56bool putback(T& t, typename char_type_of<T>::type c)
57{ return detail::read_device_impl<T>::putback(detail::unwrap(t), c); }
58
59//----------------------------------------------------------------------------//
60
61namespace detail {
62
63// Helper function for adding -1 as EOF indicator.
64inline std::streamsize check_eof(std::streamsize n) { return n != 0 ? n : -1; }
65
66// Helper templates for reading from streambufs.
67template<bool IsLinked>
68struct true_eof_impl;
69
70template<>
71struct true_eof_impl<true> {
72 template<typename T>
73 static bool true_eof(T& t) { return t.true_eof(); }
74};
75
76template<>
77struct true_eof_impl<false> {
78 template<typename T>
79 static bool true_eof(T&) { return true; }
80};
81
82template<typename T>
83inline bool true_eof(T& t)
84{
85 const bool linked = is_linked<T>::value;
86 return true_eof_impl<linked>::true_eof(t);
87}
88
89//------------------Definition of read_device_impl----------------------------//
90
91template<typename T>
92struct read_device_impl
93 : mpl::if_<
94 detail::is_custom<T>,
95 operations<T>,
96 read_device_impl<
97 BOOST_DEDUCED_TYPENAME
98 detail::dispatch<
99 T, istream_tag, streambuf_tag, input
100 >::type
101 >
102 >::type
103 { };
104
105template<>
106struct read_device_impl<istream_tag> {
107 template<typename T>
108 static typename int_type_of<T>::type get(T& t)
109 { return t.get(); }
110
111 template<typename T>
112 static std::streamsize
113 read(T& t, typename char_type_of<T>::type* s, std::streamsize n)
114 { return check_eof(t.rdbuf()->sgetn(s, n)); }
115
116 template<typename T>
117 static bool putback(T& t, typename char_type_of<T>::type c)
118 {
119 typedef typename char_type_of<T>::type char_type;
120 typedef BOOST_IOSTREAMS_CHAR_TRAITS(char_type) traits_type;
121 return !traits_type::eq_int_type( t.rdbuf()->sputbackc(c),
122 traits_type::eof() );
123 }
124};
125
126template<>
127struct read_device_impl<streambuf_tag> {
128 template<typename T>
129 static typename int_type_of<T>::type
130 get(T& t)
131 { // gcc 2.95 needs namespace qualification for char_traits.
132 typedef typename char_type_of<T>::type char_type;
133 typedef iostreams::char_traits<char_type> traits_type;
134 typename int_type_of<T>::type c;
135 return !traits_type::is_eof(c = t.sbumpc()) ||
136 detail::true_eof(t)
137 ?
138 c : traits_type::would_block();
139 }
140
141 template<typename T>
142 static std::streamsize
143 read(T& t, typename char_type_of<T>::type* s, std::streamsize n)
144 {
145 std::streamsize amt;
146 return (amt = t.sgetn(s, n)) != 0 ?
147 amt :
148 detail::true_eof(t) ?
149 -1 :
150 0;
151 }
152
153 template<typename T>
154 static bool putback(T& t, typename char_type_of<T>::type c)
155 { // gcc 2.95 needs namespace qualification for char_traits.
156 typedef typename char_type_of<T>::type char_type;
157 typedef iostreams::char_traits<char_type> traits_type;
158 return !traits_type::is_eof(t.sputbackc(c));
159 }
160};
161
162template<>
163struct read_device_impl<input> {
164 template<typename T>
165 static typename int_type_of<T>::type
166 get(T& t)
167 { // gcc 2.95 needs namespace qualification for char_traits.
168 typedef typename char_type_of<T>::type char_type;
169 typedef iostreams::char_traits<char_type> traits_type;
170 char_type c;
171 std::streamsize amt;
172 return (amt = t.read(&c, 1)) == 1 ?
173 traits_type::to_int_type(c) :
174 amt == -1 ?
175 traits_type::eof() :
176 traits_type::would_block();
177 }
178
179 template<typename T>
180 static std::streamsize
181 read(T& t, typename char_type_of<T>::type* s, std::streamsize n)
182 { return t.read(s, n); }
183
184 template<typename T>
185 static bool putback(T& t, typename char_type_of<T>::type c)
186 { // T must be Peekable.
187 return t.putback(c);
188 }
189};
190
191//------------------Definition of read_filter_impl----------------------------//
192
193template<typename T>
194struct read_filter_impl
195 : mpl::if_<
196 detail::is_custom<T>,
197 operations<T>,
198 read_filter_impl<
199 BOOST_DEDUCED_TYPENAME
200 detail::dispatch<
201 T, multichar_tag, any_tag
202 >::type
203 >
204 >::type
205 { };
206
207template<>
208struct read_filter_impl<multichar_tag> {
209 template<typename T, typename Source>
210 static std::streamsize read
211 (T& t, Source& src, typename char_type_of<T>::type* s, std::streamsize n)
212 { return t.read(src, s, n); }
213};
214
215template<>
216struct read_filter_impl<any_tag> {
217 template<typename T, typename Source>
218 static std::streamsize read
219 (T& t, Source& src, typename char_type_of<T>::type* s, std::streamsize n)
220 { // gcc 2.95 needs namespace qualification for char_traits.
221 typedef typename char_type_of<T>::type char_type;
222 typedef iostreams::char_traits<char_type> traits_type;
223 for (std::streamsize off = 0; off < n; ++off) {
224 typename traits_type::int_type c = t.get(src);
225 if (traits_type::is_eof(c))
226 return check_eof(n: off);
227 if (traits_type::would_block(c))
228 return off;
229 s[off] = traits_type::to_char_type(c);
230 }
231 return n;
232 }
233};
234
235} // End namespace detail.
236
237} } // End namespaces iostreams, boost.
238
239#include <boost/iostreams/detail/config/enable_warnings.hpp>
240
241#endif // #ifndef BOOST_IOSTREAMS_READ_HPP_INCLUDED
242

source code of boost/libs/iostreams/include/boost/iostreams/read.hpp