forked from boostorg/beast
Vinnie Falco
f9f6e1e0cc
* FieldsReader now requires chunked() and keep_alive() * serializer logic calls into the reader to calculate the message metadata * Removed some of the previous requirements of FieldsReader Actions Required: * Implement chunked() and keep_alive() for user defined FieldsReader types.
128 lines
3.6 KiB
Plaintext
128 lines
3.6 KiB
Plaintext
[/
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Copyright (c) 2013-2017 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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]
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[section:FieldsReader FieldsReader]
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A [*FieldsReader] provides a algorithm to obtain a sequence of buffers
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representing the complete serialized HTTP/1 header for a set of fields.
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The implementation constructs an instance of this type when needed, and
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calls into it once to retrieve the buffers.
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In this table:
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* `X` denotes a type that meets the requirements of [*FieldsReader].
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* `F` denotes a __Fields__ where
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`std::is_same<X, F::reader>::value == `true`.
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* `a` is a value of type `X`.
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* `f` is a value of type `F`.
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* `v` is an `unsigned` value representing the HTTP version.
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* `c` is an `unsigned` representing the HTTP status-code.
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* `m` is a value of type [link beast.ref.beast__http__verb `verb`].
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[table FieldsReader requirements
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[[expression][type][semantics, pre/post-conditions]]
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[
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[`X::const_buffers_type`]
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[]
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[
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A type which meets the requirements of __ConstBufferSequence__.
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This is the type of buffer returned by `X::get`.
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]
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][
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[`X(f,v,m)`]
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[]
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[
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The implementation calls this constructor to indicate
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that the fields being serialized form part of an HTTP
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request. The lifetime of `f` is guaranteed
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to end no earlier than after the `X` is destroyed.
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]
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][
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[`X(f,v,c)`]
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[]
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[
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The implementation calls this constructor to indicate
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that the fields being serialized form part of an HTTP
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response. The lifetime of `f` is guaranteed
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to end no earlier than after the `X` is destroyed.
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]
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][
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[`a.chunked()`]
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[`bool`]
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[
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Called once after construction, this function returns `true`
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if the [*Transfer-Encoding] field is present, and the last
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token in its value is [*"chunked"].
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]
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][
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[`a.keep_alive()`]
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[`bool`]
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[
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Called once after construction, this function returns `true`
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if the semantics of the mesage indicate that the connection
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should remain open after processing the message. When the
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HTTP version is below 1.1, `keep_alive` returns `true` when
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the [*Connection] field is present, and its value contains the
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"keep-alive" token. Otherwise, `keep_alive` returns `true`
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when either the [*Connection] field is absent, or if the
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value does not contain the "close" token.
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]
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][
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[`a.get()`]
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[X::const_buffers_type]
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[
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Called once after construction, this function returns
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a constant buffer sequence containing the serialized
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representation of the HTTP request or response including
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the final carriage return linefeed sequence (`"\r\n"`).
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]
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][
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[`is_fields_reader<F>`]
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[`std::true_type`]
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[
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An alias for `std::true_type` for `F`, otherwise an alias
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for `std::false_type`.
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]
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]
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]
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[heading Exemplar]
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```
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struct FieldsReader
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{
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// The type of buffers returned by `get`
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using const_buffers_type = implementation-defined;
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// Constructor for requests
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FieldsReader(F const& f, unsigned version, verb method);
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// Constructor for responses
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FieldsReader(F const& f, unsigned version, unsigned status);
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// Returns `true` if the payload uses the chunked Transfer-Encoding
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bool
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chunked();
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// Returns `true` if keep-alive is indicated
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bool
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keep_alive();
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// Returns the serialized header buffers
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const_buffers_type
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get();
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};
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```
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[endsect]
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