. /include/boost/capy /write.hpp
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1   // 1   //
2   // Copyright (c) 2025 Vinnie Falco (vinnie.falco@gmail.com) 2   // Copyright (c) 2025 Vinnie Falco (vinnie.falco@gmail.com)
3   // 3   //
4   // Distributed under the Boost Software License, Version 1.0. (See accompanying 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) 5   // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
6   // 6   //
7   // Official repository: https://github.com/cppalliance/capy 7   // Official repository: https://github.com/cppalliance/capy
8   // 8   //
9   9  
10   #ifndef BOOST_CAPY_WRITE_HPP 10   #ifndef BOOST_CAPY_WRITE_HPP
11   #define BOOST_CAPY_WRITE_HPP 11   #define BOOST_CAPY_WRITE_HPP
12   12  
13   #include <boost/capy/detail/config.hpp> 13   #include <boost/capy/detail/config.hpp>
14   #include <boost/capy/io_task.hpp> 14   #include <boost/capy/io_task.hpp>
15   #include <boost/capy/buffers.hpp> 15   #include <boost/capy/buffers.hpp>
16   #include <boost/capy/buffers/buffer_slice.hpp> 16   #include <boost/capy/buffers/buffer_slice.hpp>
17   #include <boost/capy/concept/write_stream.hpp> 17   #include <boost/capy/concept/write_stream.hpp>
18   #include <system_error> 18   #include <system_error>
19   19  
20   #include <cstddef> 20   #include <cstddef>
21   21  
22   namespace boost { 22   namespace boost {
23   namespace capy { 23   namespace capy {
24   24  
25   /** Write an entire buffer sequence to a stream. 25   /** Write an entire buffer sequence to a stream.
26   26  
27   @par Await-effects 27   @par Await-effects
28   28  
29   Writes the contents of `buffers` to `stream` via awaiting 29   Writes the contents of `buffers` to `stream` via awaiting
30   `stream.write_some` with consecutive portions of data from `buffers` 30   `stream.write_some` with consecutive portions of data from `buffers`
31   until: 31   until:
32   32  
33   @li either the full content of @c buffers is processed, 33   @li either the full content of @c buffers is processed,
34   @li or a contingency occurs. 34   @li or a contingency occurs.
35   35  
36   If `buffer_size(buffers) == 0` then no awaiting `stream.write_some` 36   If `buffer_size(buffers) == 0` then no awaiting `stream.write_some`
37   is performed. This is not a contingency. 37   is performed. This is not a contingency.
38   38  
39   39  
40   @par Await-returns 40   @par Await-returns
41   41  
42   An object of type `io_result<std::size_t>` destructuring as `[ec, n]`. 42   An object of type `io_result<std::size_t>` destructuring as `[ec, n]`.
43   43  
44   Upon a contingency, `n` represents the number of bytes written 44   Upon a contingency, `n` represents the number of bytes written
45   so far. 45   so far.
46   46  
47   Otherwise `n` represents the number of bytes written. 47   Otherwise `n` represents the number of bytes written.
48   48  
49   Contingencies: 49   Contingencies:
50   50  
51   @li The first contingency reported from 51   @li The first contingency reported from
52   awaiting @c stream.write_some . 52   awaiting @c stream.write_some .
53   53  
54   Notable conditions: 54   Notable conditions:
55   55  
56   @li @c cond::canceled — Operation was cancelled, 56   @li @c cond::canceled — Operation was cancelled,
57   @li @c std::errc::broken_pipe — Peer closed connection. 57   @li @c std::errc::broken_pipe — Peer closed connection.
58   58  
59   59  
60   @par Await-postcondition 60   @par Await-postcondition
61   61  
62   `ec || n == buffer_size(buffers)`. 62   `ec || n == buffer_size(buffers)`.
63   63  
64   64  
65   @param stream The stream to write to. If the lifetime of `stream` ends 65   @param stream The stream to write to. If the lifetime of `stream` ends
66   before the coroutine finishes, the behavior is undefined. 66   before the coroutine finishes, the behavior is undefined.
67   67  
68   @param buffers The buffer sequence to write. If the lifetime of the buffer 68   @param buffers The buffer sequence to write. If the lifetime of the buffer
69   sequence represented by `buffers` ends 69   sequence represented by `buffers` ends
70   before the coroutine finishes, the behavior is undefined. 70   before the coroutine finishes, the behavior is undefined.
71   71  
72   @par Remarks 72   @par Remarks
73   73  
74   Supports _IoAwaitable cancellation_. 74   Supports _IoAwaitable cancellation_.
75   75  
76   @par Example 76   @par Example
77   77  
78   @code 78   @code
79   capy::task<> send_response(capy::WriteStream auto& stream, std::string_view body) 79   capy::task<> send_response(capy::WriteStream auto& stream, std::string_view body)
80   { 80   {
81   auto [ec, n] = co_await capy::write(stream, capy::make_buffer(body)); 81   auto [ec, n] = co_await capy::write(stream, capy::make_buffer(body));
82   if (ec) 82   if (ec)
83   throw std::system_error(ec); 83   throw std::system_error(ec);
84   84  
85   // All bytes written successfully 85   // All bytes written successfully
86   } 86   }
87   @endcode 87   @endcode
88   88  
89   @see WriteStream, ConstBufferSequence, IoAwaitable, io_result, cond. 89   @see WriteStream, ConstBufferSequence, IoAwaitable, io_result, cond.
90   */ 90   */
91   template <WriteStream S, ConstBufferSequence CB> 91   template <WriteStream S, ConstBufferSequence CB>
HITCBC 92   50 auto write(S& stream, CB buffers) -> io_task<std::size_t> 92   50 auto write(S& stream, CB buffers) -> io_task<std::size_t>
93   { 93   {
94   auto consuming = buffer_slice(buffers); 94   auto consuming = buffer_slice(buffers);
95   std::size_t const total_size = buffer_size(buffers); 95   std::size_t const total_size = buffer_size(buffers);
96   std::size_t total_written = 0; 96   std::size_t total_written = 0;
97   97  
98   while(total_written < total_size) 98   while(total_written < total_size)
99   { 99   {
100   auto [ec, n] = co_await stream.write_some(consuming.data()); 100   auto [ec, n] = co_await stream.write_some(consuming.data());
101   consuming.remove_prefix(n); 101   consuming.remove_prefix(n);
102   total_written += n; 102   total_written += n;
103   if(ec) 103   if(ec)
104   co_return {ec, total_written}; 104   co_return {ec, total_written};
105   } 105   }
106   106  
107   co_return {{}, total_written}; 107   co_return {{}, total_written};
HITCBC 108   100 } 108   100 }
109   109  
110   } // namespace capy 110   } // namespace capy
111   } // namespace boost 111   } // namespace boost
112   112  
113   #endif 113   #endif