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1 : //
2 : // Copyright (c) 2019 Vinnie Falco (vinnie.falco@gmail.com)
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 : // Official repository: https://github.com/cppalliance/http_proto
8 : //
9 :
10 : #ifndef BOOST_HTTP_PROTO_SOURCE_HPP
11 : #define BOOST_HTTP_PROTO_SOURCE_HPP
12 :
13 : #include <boost/http_proto/detail/config.hpp>
14 : #include <boost/http_proto/buffered_base.hpp>
15 : #include <boost/buffers/mutable_buffer_span.hpp>
16 : #include <boost/buffers/type_traits.hpp>
17 : #include <boost/system/error_code.hpp>
18 : #include <cstddef>
19 : #include <type_traits>
20 :
21 : namespace boost {
22 : namespace http_proto {
23 :
24 : /** An algorithm for producing buffers of data.
25 :
26 : This interface abstracts the production of
27 : a finite stream of data, returned by writing
28 : into caller-provided buffers until there
29 : is no more output data.
30 :
31 : @par Thread Safety
32 : Non-const member functions may not be
33 : called concurrently on the same instance.
34 : */
35 : struct BOOST_HTTP_PROTO_DECL
36 : source
37 : {
38 : /** The results of producing data.
39 : */
40 : struct results
41 : {
42 : /** The error, if any occurred.
43 : */
44 : system::error_code ec;
45 :
46 : /** The number of bytes produced in the output.
47 : */
48 : std::size_t bytes = 0;
49 :
50 : /** True if there will be no more output.
51 : */
52 : bool finished = false;
53 :
54 : /** Accumulate results.
55 : */
56 : results&
57 : operator+=(
58 : results const& rv) noexcept;
59 : };
60 :
61 : /** Produce data.
62 :
63 : This function attempts to read from the
64 : source, placing the data into the given
65 : mutable buffer sequence.
66 : The return value indicates the number of
67 : bytes placed into the buffers, the error
68 : if any occurred, and a `bool` indicating
69 : whether or not there is more data
70 : remaining in the source.
71 :
72 : @par Preconditions
73 : @li @ref init was called, and
74 : @li There is more data remaining.
75 :
76 : @return The result of the operation.
77 :
78 : @param bs The buffers to use.
79 : Each buffer in the sequence will
80 : be filled completely before data
81 : is placed in the next buffer.
82 : */
83 : template<class MutableBufferSequence>
84 : results
85 24 : read(MutableBufferSequence const& bs)
86 : {
87 : static_assert(
88 : buffers::is_mutable_buffer_sequence<
89 : MutableBufferSequence>::value,
90 : "Type requirements not met");
91 :
92 24 : return read_impl(bs);
93 : }
94 :
95 : #ifdef BOOST_HTTP_PROTO_DOCS
96 : protected:
97 : #else
98 : private:
99 : #endif
100 : /** Derived class override.
101 :
102 : This pure virtual function is called by
103 : the implementation and must be overriden.
104 : The callee should attempt to place data
105 : into the given mutable buffer.
106 : The return value must be set to indicate
107 : the number of bytes placed into the
108 : buffers, the error if any occurred,
109 : and a `bool` indicating whether or
110 : not there is more data remaining
111 : in the source.
112 :
113 : @par Preconditions
114 : @li @ref init was called, and
115 : @li There is more data remaining.
116 :
117 : @return The result of the operation.
118 :
119 : @param b The buffer to use.
120 : If this is not filled completely,
121 : then the result must indicate failure
122 : or that no more data remains (or both).
123 : */
124 : virtual
125 : results
126 : on_read(
127 : buffers::mutable_buffer b) = 0;
128 :
129 : /** Derived class override.
130 :
131 : This pure virtual function is called by
132 : the implementation and must be overriden.
133 : The callee should attempt to place data
134 : into the given mutable buffer sequence.
135 : The return value must be set to indicate
136 : the number of bytes placed into the
137 : buffers, the error if any occurred,
138 : and a `bool` indicating whether or
139 : not there is more data remaining
140 : in the source.
141 :
142 : @par Preconditions
143 : @li @ref init was called, and
144 : @li There is more data remaining.
145 :
146 : @return The result of the operation.
147 :
148 : @param bs The buffer sequence to use.
149 : Each buffer in the sequence must
150 : be filled completely before data
151 : is placed in the next buffer.
152 : If the buffers are not filled
153 : completely, then the result must
154 : indicate failure or that no more
155 : data remains (or both).
156 : */
157 : virtual
158 : results
159 : on_read(
160 : buffers::mutable_buffer_span bs);
161 :
162 : private:
163 : results
164 2 : read_impl(
165 : buffers::mutable_buffer const& b)
166 : {
167 2 : return on_read(b);
168 : }
169 :
170 : results
171 5 : read_impl(
172 : buffers::mutable_buffer_span const& bs)
173 : {
174 5 : return on_read(bs);
175 : }
176 :
177 : template<class T>
178 : results
179 : read_impl(T const&);
180 : };
181 :
182 : //------------------------------------------------
183 :
184 : /** Metafunction which determines if T is a source
185 :
186 : @see
187 : @ref source.
188 : */
189 : #ifdef BOOST_HTTP_PROTO_DOCS
190 : template<class T>
191 : using is_source = __see_below__;
192 : #else
193 : template<class T>
194 : using is_source =
195 : std::is_convertible<
196 : typename std::decay<T>::type*,
197 : source*>;
198 : #endif
199 :
200 : } // http_proto
201 : } // boost
202 :
203 : #include <boost/http_proto/impl/source.hpp>
204 :
205 : #endif
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