Home - News ( United States | United Kingdom | Italy | Germany ) - Football scores

Showing content from https://github.com/rust-lang/libs-team/issues/417 below:

peek · Issue #417 · rust-lang/libs-team · GitHub

It is often desirable to look ahead a small amount in an unseekable stream, such as a unix pipe.

the main usecase is inspecting the magic number of a file, such as is trying to be done here, but it could also be useful for some simple parsers.

add a method BufReader::peek that has the signature fn peek(&mut self, n: usize) -> io::Result<&[u8]>

the method would work as followed:

1. clear from the front of the buffer any consumed bytes
2. do read calls on the underlying Read object to fill the buffer until it reaches any of: the length requested, the BufReader's capacity, or end of file
3. return the slice of this new buffer

1. give it the same signature as Read::read (adds an extra copy, but has nice parity)
2. a Peek trait that abstracts over all streams that can do a limited lookahead
3. instead of limiting the lookahead to the capacity of the buffer, automatically grow the buffer if a larger lookahead is requested (less performant and more complexity)
4. leave this up to other crates (this would require those other crates to reimplement basically all of BufReader)

original thread linked previously

This issue contains an API change proposal (or ACP) and is part of the libs-api team feature lifecycle. Once this issue is filed, the libs-api team will review open proposals as capability becomes available. Current response times do not have a clear estimate, but may be up to several months.

The libs team may respond in various different ways. First, the team will consider the problem (this doesn't require any concrete solution or alternatives to have been proposed):

• We think this problem seems worth solving, and the standard library might be the right place to solve it.
• We think that this probably doesn't belong in the standard library.

Second, if there's a concrete solution:

• We think this specific solution looks roughly right, approved, you or someone else should implement this. (Further review will still happen on the subsequent implementation PR.)
• We're not sure this is the right solution, and the alternatives or other materials don't give us enough information to be sure about that. Here are some questions we have that aren't answered, or rough ideas about alternatives we'd want to see discussed.

RetroSearch is an open source project built by @garambo | Open a GitHub Issue

Search and Browse the WWW like it's 1997 | Search results from DuckDuckGo

HTML: 3.2 | Encoding: UTF-8 | Version: 0.7.4