117 lines
3.4 KiB
Plaintext
117 lines
3.4 KiB
Plaintext
[/
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Copyright (c) 2016-2019 Vinnie Falco (vinnie dot falco at gmail dot com)
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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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Official repository: https://github.com/boostorg/beast
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]
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[section:stream_types Streams]
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A __Stream__ is a communication channel where data is reliably transferred as
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an ordered sequence of bytes. Streams are either synchronous or asynchronous,
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and may allow reading, writing, or both. Note that a particular type may model
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more than one concept. For example, the networking types __socket__ and
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__ssl_stream__ support both __SyncStream__ and __AsyncStream__. All stream
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algorithms in Beast are declared as template functions using these concepts:
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[table Stream Concepts
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[[Concept][Description]]
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[
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[__SyncReadStream__]
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[
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Supports buffer-oriented blocking reads.
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]
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][
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[__SyncWriteStream__]
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[
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Supports buffer-oriented blocking writes.
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]
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][
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[__SyncStream__]
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[
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A stream supporting buffer-oriented blocking reads and writes.
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]
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][
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[__AsyncReadStream__]
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[
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Supports buffer-oriented asynchronous reads.
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]
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][
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[__AsyncWriteStream__]
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[
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Supports buffer-oriented asynchronous writes.
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]
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][
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[__AsyncStream__]
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[
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A stream supporting buffer-oriented asynchronous reads and writes.
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]
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]
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]
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These template metafunctions check whether a given type meets the
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requirements for the various stream concepts, and some additional
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useful utilities. The library uses these type checks internally
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and also provides them as public interfaces so users may use the
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same techniques to augment their own code. The use of these type
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checks helps provide more concise errors during compilation:
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[table Type Traits and Metafunctions
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[[Name][Description]]
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[[
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[link beast.ref.boost__beast__executor_type `executor_type`]
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][
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An alias for the type of object returned by `get_executor`.
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]]
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[[
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[link beast.ref.boost__beast__has_get_executor `has_get_executor`]
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][
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Determine if the `get_executor` member function is present.
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]]
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[[
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[link beast.ref.boost__beast__is_async_read_stream `is_async_read_stream`]
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][
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Determine if a type meets the requirements of __AsyncReadStream__.
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]]
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[[
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[link beast.ref.boost__beast__is_async_stream `is_async_stream`]
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][
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Determine if a type meets the requirements of both __AsyncReadStream__
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and __AsyncWriteStream__.
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]]
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[[
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[link beast.ref.boost__beast__is_async_write_stream `is_async_write_stream`]
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][
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Determine if a type meets the requirements of __AsyncWriteStream__.
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]]
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[[
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[link beast.ref.boost__beast__is_sync_read_stream `is_sync_read_stream`]
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][
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Determine if a type meets the requirements of __SyncReadStream__.
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]]
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[[
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[link beast.ref.boost__beast__is_sync_stream `is_sync_stream`]
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][
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Determine if a type meets the requirements of both __SyncReadStream__
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and __SyncWriteStream__.
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]]
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[[
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[link beast.ref.boost__beast__is_sync_write_stream `is_sync_write_stream`]
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][
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Determine if a type meets the requirements of __SyncWriteStream__.
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]]
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]
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Using the type checks with `static_assert` on function or class template
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types will provide users with helpful error messages and prevent undefined
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behaviors. This example shows how a template function which writes to a
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synchronous stream may check its argument:
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[snippet_core_3]
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[endsect]
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