[/
    Copyright (c) 2013-2016 Vinnie Falco (vinnie dot falco at gmail dot com)

    Distributed under the Boost Software License, Version 1.0. (See accompanying
    file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
]

[section:Reader Reader requirements]

Parsers provided by the implementation will construct the corresponding
`reader` object during parsing. This customization point allows the
Body to determine the strategy for storing incoming message body data.

In this table:

* `X` denotes a type meeting the requirements of [*`Reader`].

* `a` denotes a value of type `X`.

* `n` is a value convertible to `std::size_t`.

* `p` is a `void const*` to valid memory of at least `n` bytes.

* `ec` is a value of type [link beast.ref.error_code `error_code&`].

* `m` denotes a value of type `message&` where
    `std::is_same<decltype(m.body), Body::value_type>::value == true`.

[table Reader requirements
[[operation] [type] [semantics, pre/post-conditions]]
[
    [`X a(m);`]
    []
    [
        `a` is constructible from `m`. The lifetime of `m` is guaranteed
        to end no earlier than after `a` is destroyed. The constructor
        will be called after all headers have been stored in `m`, and
        before any body data is deserialized. This function must be
        `noexcept`.
    ]
]
[
    [`a.init(ec)`]
    [`void`]
    [
        Called immediately after construction. If the function sets
        an error code in `ec`, the parse is aborted and the error is
        propagated to the caller. This function must be `noexcept`.
    ]
]
[
    [`a.write(p, n, ec)`]
    [`void`]
    [
        Deserializes the input sequence into the body. If `ec` is set,
        the deserialization is aborted and the error is propagated to
        the caller. If the message headers specify a chunked transfer
        encoding, the reader will receive the decoded version of the
        body. This function must be `noexcept`.
    ]
]
]

[note
    Definitions for required `Reader` member functions should be declared
    inline so the generated code can become part of the implementation.
]

[endsect]