Bytes::drain

[stepancheg]

[carllerche]

Could we provide this w/ a drain API to mirror std?

[stepancheg]

What should be a result of drain?

[carllerche]

Basically copy this but have our own RangeArgument trait until that becomes stable: https://doc.rust-lang.org/std/vec/struct.Vec.html#method.drain

[stepancheg]

Vec::drain returns an iterator. Do you think Bytes::drain should return an iterator too?

[carllerche]

Yeah, we should copy it. If the iterator is dropped the compiler should be able to optimize the work fairly easily. Benchmarks should reflect this.

[stepancheg]

I mean I doubt result of drain on Bytes will ever be used as iterator, but OK.

[stepancheg]

I've updated the PR with huge patch.

I believe it is mostly OK, however, there's an issue: Drain is the same for Bytes and BytesMut. And it contains a field to distinguish between Bytes and BytesMut to enable optimization for BytesMut later.

Probably Bytes should have two different Drain types, but I couldn't think of good names for the types.

[stepancheg]

Compilation is failed because Bound is not available in 0.1.10. Should I reimplement RangeParameter without Bound?

[stepancheg]

Updated the PR with Bound copied to bytes.