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This change adds a new set of type requirements for dynamic buffers,
DynamicBuffer_v2, which supports copy construction. These new type
requirements enable dynamic buffers to be used as arguments to
user-defined composed operations, where the same dynamic buffer object
is used repeatedly for multiple underlying operations. For example:
template <typename DynamicBuffer>
void echo_line(tcp::socket& sock, DynamicBuffer buf)
{
n = boost::asio::read_until(sock, buf, '\n');
boost::asio::write(sock, buf, boost::asio::transfer_exactly(n));
}
The original DynamicBuffer type requirements have been renamed to
DynamicBuffer_v1.
New type traits is_dynamic_buffer_v1 and is_dynamic_buffer_v2 have been
added to test for conformance to DynamicBuffer_v1 and DynamicBuffer_v2
respectively. The existing is_dynamic_buffer trait has been retained and
delegates to is_dynamic_buffer_v1, unless BOOST_ASIO_NO_DYNAMIC_BUFFER_V1
is defined, in which case it delegates to is_dynamic_buffer_v2.
The dynamic_string_buffer and dynamic_vector buffer classes conform to
both DynamicBuffer_v1 and DynamicBuffer_v2 requirements.
When BOOST_ASIO_NO_DYNAMIC_BUFFER_V1 is defined, all support for
DynamicBuffer_v1 types and functions is #ifdef-ed out. Support for using
basic_streambuf with the read, async_read, read_until, async_read_until,
write, and async_write functions is also disabled as a consequence.
This change should have no impact on existing source code that simply
uses dynamic buffers in conjunction with asio's composed operations,
such as:
string data;
// ...
size_t n = boost::asio::read_until(my_socket
boost::asio::dynamic_buffer(data, MY_MAX),
'\n');
17 lines
488 B
Plaintext
17 lines
488 B
Plaintext
[/
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/ Copyright (c) 2003-2019 Christopher M. Kohlhoff (chris at kohlhoff dot com)
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/
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/ Distributed under the Boost Software License, Version 1.0. (See accompanying
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/ file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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/]
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[section:DynamicBuffer Dynamic buffer requirements]
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See:
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* [link boost_asio.reference.DynamicBuffer_v1 Dynamic buffer requirements (version 1)]
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* [link boost_asio.reference.DynamicBuffer_v2 Dynamic buffer requirements (version 2)]
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[endsect]
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