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### 3071. [networking.ts] `read_until` still refers to "input sequence"

Section: 17.9 [networking.ts::buffer.read.until] Status: WP Submitter: Christopher Kohlhoff Opened: 2018-02-26 Last modified: 2021-02-27

Priority: 0

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Discussion:

Addresses: networking.ts

When specifying `DynamicBuffers` and their related operations, early drafts of the Networking TS described the buffers in terms of their "input sequence" and "output sequence". This was changed to "readable bytes" and "writable bytes" respectively. Unfortunately, some instances of "input sequence" were missed in section 17.9 [networking.ts::buffer.read.until].

[ 2018-03-06 Moved to Tentatively Ready after 5 positive votes on c++std-lib. ]

[2018-06 Rapperswil: Adopted]

Proposed resolution:

This wording is relative to N4711.

1. Change 17.9 [networking.ts::buffer.read.until] as indicated:

   >     template<class SyncReadStream, class DynamicBuffer>
   >       size_t read_until(SyncReadStream& s, DynamicBuffer&& b, char delim);
   >     template<class SyncReadStream, class DynamicBuffer>
   >       size_t read_until(SyncReadStream& s, DynamicBuffer&& b,
   >                         char delim, error_code& ec);
   >     template<class SyncReadStream, class DynamicBuffer>
   >       size_t read_until(SyncReadStream& s, DynamicBuffer&& b, string_view delim);
   >     template<class SyncReadStream, class DynamicBuffer>
   >       size_t read_until(SyncReadStream& s, DynamicBuffer&& b,
   >                         string_view delim, error_code& ec);

   > > -1- Effects: Reads data from the buffer-oriented synchronous read stream (17.1.1 [networking.ts::buffer.stream.reqmts.syncreadstream]) object stream by performing zero or more calls to the stream's `read_some` member function, until the input sequence readable bytes of the dynamic buffer (16.2.4 [networking.ts::buffer.reqmts.dynamicbuffer]) object `b` contains the specified delimiter `delim`.

   > > -2- Data is placed into the dynamic buffer object b. A mutable buffer sequence (16.2.1) is obtained prior to each `read_some` call using `b.prepare(N)`, where `N` is an unspecified value such that `N <= max_size() - size()`. [Note: Implementations are encouraged to use `b.capacity()` when determining `N`, to minimize the number of `read_some` calls performed on the stream. — end note] After each `read_some` call, the implementation performs `b.commit(n)`, where `n` is the return value from `read_some`.

   > > -3- The synchronous `read_until` operation continues until:

   > > 1. (3.1) — the input sequence readable bytes of `b` contains the delimiter `delim`; or

   > > 2. (3.2) — `b.size() == b.max_size()`; or

   > > 3. (3.3) — an asynchronous `read_some` operation fails.

   > > -4- On exit, if the input sequence readable bytes of `b` contains the delimiter, `ec` is set such that `!ec` is `true`. Otherwise, if `b.size() == b.max_size()`, `ec` is set such that `ec == stream_errc::not_found`. If `b.size() < b.max_size()`, `ec` contains the `error_code` from the most recent `read_some` call.

   > > -5- Returns: The number of bytes in the input sequence of readable bytes in `b` up to and including the delimiter, if present. [Note: On completion, the buffer may contain additional bytes following the delimiter. — end note] Otherwise returns `0`.