libs/capy/include/boost/capy/io/push_to.hpp

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1			//
2			// Copyright (c) 2025 Vinnie Falco (vinnie dot falco at gmail dot 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/capy
8			//
9
10			#ifndef BOOST_CAPY_IO_PUSH_TO_HPP
11			#define BOOST_CAPY_IO_PUSH_TO_HPP
12
13			#include <boost/capy/detail/config.hpp>
14			#include <boost/capy/buffers.hpp>
15			#include <boost/capy/concept/buffer_source.hpp>
16			#include <boost/capy/concept/write_sink.hpp>
17			#include <boost/capy/concept/write_stream.hpp>
18			#include <boost/capy/io_result.hpp>
19			#include <boost/capy/task.hpp>
20
21			#include <cstddef>
22			#include <span>
23
24			namespace boost {
25			namespace capy {
26
27			/** Transfer data from a BufferSource to a WriteSink.
28
29			This function pulls data from the source and writes it to the
30			sink until the source is exhausted or an error occurs. When
31			the source signals completion, `write_eof()` is called on the
32			sink to finalize the transfer.
33
34			@tparam Src The source type, must satisfy @ref BufferSource.
35			@tparam Sink The sink type, must satisfy @ref WriteSink.
36
37			@param source The source to pull data from.
38			@param sink The sink to write data to.
39
40			@return A task that yields `(std::error_code, std::size_t)`.
41			On success, `ec` is default-constructed (no error) and `n` is
42			the total number of bytes transferred. On error, `ec` contains
43			the error code and `n` is the total number of bytes transferred
44			before the error.
45
46			@par Example
47			@code
48			task<void> transfer_body(BufferSource auto& source, WriteSink auto& sink)
49			{
50			auto [ec, n] = co_await push_to(source, sink);
51			if (ec)
52			{
53			// Handle error
54			}
55			// n bytes were transferred
56			}
57			@endcode
58
59			@see BufferSource, WriteSink
60			*/
61			template<BufferSource Src, WriteSink Sink>
62			task<io_result<std::size_t>>
63	1/1 ✓ Branch 1 taken 140 times.	140	push_to(Src& source, Sink& sink)
64			{
65			const_buffer arr[detail::max_iovec_];
66			std::size_t total = 0;
67
68			for(;;)
69			{
70			auto [ec, bufs] = co_await source.pull(arr);
71			if(ec)
72			co_return {ec, total};
73
74			if(bufs.empty())
75			{
76			auto [eof_ec] = co_await sink.write_eof();
77			co_return {eof_ec, total};
78			}
79
80			auto [write_ec, n] = co_await sink.write(bufs);
81			total += n;
82			source.consume(n);
83			if(write_ec)
84			co_return {write_ec, total};
85			}
86		280	}
87
88			/** Transfer data from a BufferSource to a WriteStream.
89
90			This function pulls data from the source and writes it to the
91			stream until the source is exhausted or an error occurs. The
92			stream uses `write_some()` which may perform partial writes,
93			so this function loops until all pulled data is consumed.
94
95			Unlike the WriteSink overload, this function does not signal
96			EOF explicitly since WriteStream does not provide a write_eof
97			method. The transfer completes when the source is exhausted.
98
99			@tparam Src The source type, must satisfy @ref BufferSource.
100			@tparam Stream The stream type, must satisfy @ref WriteStream.
101
102			@param source The source to pull data from.
103			@param stream The stream to write data to.
104
105			@return A task that yields `(std::error_code, std::size_t)`.
106			On success, `ec` is default-constructed (no error) and `n` is
107			the total number of bytes transferred. On error, `ec` contains
108			the error code and `n` is the total number of bytes transferred
109			before the error.
110
111			@par Example
112			@code
113			task<void> transfer_body(BufferSource auto& source, WriteStream auto& stream)
114			{
115			auto [ec, n] = co_await push_to(source, stream);
116			if (ec)
117			{
118			// Handle error
119			}
120			// n bytes were transferred
121			}
122			@endcode
123
124			@see BufferSource, WriteStream, pull_from
125			*/
126			template<BufferSource Src, WriteStream Stream>
127			task<io_result<std::size_t>>
128	1/1 ✓ Branch 1 taken 104 times.	104	push_to(Src& source, Stream& stream)
129			{
130			const_buffer arr[detail::max_iovec_];
131			std::size_t total = 0;
132
133			for(;;)
134			{
135			auto [ec, bufs] = co_await source.pull(arr);
136			if(ec)
137			co_return {ec, total};
138
139			if(bufs.empty())
140			co_return {{}, total};
141
142			auto [write_ec, n] = co_await stream.write_some(bufs);
143			if(write_ec)
144			co_return {write_ec, total};
145
146			total += n;
147			source.consume(n);
148			}
149		208	}
150
151			} // namespace capy
152			} // namespace boost
153
154			#endif
155