The way BufMut uses MaybeUninit can lead to unsoundness. This replaces
MaybeUnit with a type owned by bytes so we can ensure the usage patterns
are sound.
Refs: #328
- The return type of `BufMut::bytes_mut` is now
`&mut [MaybeUninit<u8>]`.
- The argument type of `BufMut::bytes_vectored_mut` is now
`&mut [bytes::buf::IoSliceMut]`.
- `bytes::buf::IoSliceMut` is a `repr(transparent)` wrapper around an
`std::io::IoSliceMut`, but does not expose the inner bytes with a safe
API, since they might be uninitialized.
- `BufMut::bytesMut` and `BufMut::bytes_vectored_mut` are no longer
`unsafe fn`, since the types encapsulate the unsafety instead.
To make the library work as `no_std` we add an `std` feature which
is on by default. When it is off, we compile as `no_std` and make
parts of the API that require `std::io` conditional on the `std`
feature.
As consequence Buf::collect is removed as well, which is replaced with `Buf::into_bytes`. The advantage of `Buf::into_bytes` is that it can be optimized in cases where converting a `T: Buf` into a `Bytes` instance is efficient.
The `Source` trait was essentially covering the same case as `IntoBuf`,
so remove it.
While technically a breaking change, this should not have any impact due
to:
1) There are no reverse dependencies that currently depend on `bytes`
2) Source was not supposed to be implemented externally
3) IntoBuf provides the same implementations as `Source`
Given these points, the change should be safe to apply.
This commit is a significant overhaul of the library in an effort to head
towards a stable API. The rope implementation as well as a number of buffer
implementations have been removed from the library and will live at
https://github.com/carllerche/bytes-more while they incubate.
**Bytes / BytesMut**
`Bytes` is now an atomic ref counted byte slice. As it is contigous, it offers
a richer API than before.
`BytesMut` is a mutable variant. It is safe by ensuring that it is the only
handle to a given byte slice.
**AppendBuf -> ByteBuf**
`AppendBuf` has been replaced by `ByteBuf`. The API is not identical, but is
close enough to be considered a suitable replacement.
**Removed types**
The following types have been removed in favor of living in bytes-more
* RingBuf
* BlockBuf
* `Bytes` as a rope implementation
* ReadExt
* WriteExt
