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Diffstat (limited to 'third_party/rust/bytes/src/lib.rs')
-rw-r--r-- | third_party/rust/bytes/src/lib.rs | 117 |
1 files changed, 117 insertions, 0 deletions
diff --git a/third_party/rust/bytes/src/lib.rs b/third_party/rust/bytes/src/lib.rs new file mode 100644 index 0000000000..af436b3162 --- /dev/null +++ b/third_party/rust/bytes/src/lib.rs @@ -0,0 +1,117 @@ +#![warn(missing_docs, missing_debug_implementations, rust_2018_idioms)] +#![doc(test( + no_crate_inject, + attr(deny(warnings, rust_2018_idioms), allow(dead_code, unused_variables)) +))] +#![no_std] +#![cfg_attr(docsrs, feature(doc_cfg))] + +//! Provides abstractions for working with bytes. +//! +//! The `bytes` crate provides an efficient byte buffer structure +//! ([`Bytes`](struct.Bytes.html)) and traits for working with buffer +//! implementations ([`Buf`], [`BufMut`]). +//! +//! [`Buf`]: trait.Buf.html +//! [`BufMut`]: trait.BufMut.html +//! +//! # `Bytes` +//! +//! `Bytes` is an efficient container for storing and operating on contiguous +//! slices of memory. It is intended for use primarily in networking code, but +//! could have applications elsewhere as well. +//! +//! `Bytes` values facilitate zero-copy network programming by allowing multiple +//! `Bytes` objects to point to the same underlying memory. This is managed by +//! using a reference count to track when the memory is no longer needed and can +//! be freed. +//! +//! A `Bytes` handle can be created directly from an existing byte store (such as `&[u8]` +//! or `Vec<u8>`), but usually a `BytesMut` is used first and written to. For +//! example: +//! +//! ```rust +//! use bytes::{BytesMut, BufMut}; +//! +//! let mut buf = BytesMut::with_capacity(1024); +//! buf.put(&b"hello world"[..]); +//! buf.put_u16(1234); +//! +//! let a = buf.split(); +//! assert_eq!(a, b"hello world\x04\xD2"[..]); +//! +//! buf.put(&b"goodbye world"[..]); +//! +//! let b = buf.split(); +//! assert_eq!(b, b"goodbye world"[..]); +//! +//! assert_eq!(buf.capacity(), 998); +//! ``` +//! +//! In the above example, only a single buffer of 1024 is allocated. The handles +//! `a` and `b` will share the underlying buffer and maintain indices tracking +//! the view into the buffer represented by the handle. +//! +//! See the [struct docs] for more details. +//! +//! [struct docs]: struct.Bytes.html +//! +//! # `Buf`, `BufMut` +//! +//! These two traits provide read and write access to buffers. The underlying +//! storage may or may not be in contiguous memory. For example, `Bytes` is a +//! buffer that guarantees contiguous memory, but a [rope] stores the bytes in +//! disjoint chunks. `Buf` and `BufMut` maintain cursors tracking the current +//! position in the underlying byte storage. When bytes are read or written, the +//! cursor is advanced. +//! +//! [rope]: https://en.wikipedia.org/wiki/Rope_(data_structure) +//! +//! ## Relation with `Read` and `Write` +//! +//! At first glance, it may seem that `Buf` and `BufMut` overlap in +//! functionality with `std::io::Read` and `std::io::Write`. However, they +//! serve different purposes. A buffer is the value that is provided as an +//! argument to `Read::read` and `Write::write`. `Read` and `Write` may then +//! perform a syscall, which has the potential of failing. Operations on `Buf` +//! and `BufMut` are infallible. + +extern crate alloc; + +#[cfg(feature = "std")] +extern crate std; + +pub mod buf; +pub use crate::buf::{Buf, BufMut}; + +mod bytes; +mod bytes_mut; +mod fmt; +mod loom; +pub use crate::bytes::Bytes; +pub use crate::bytes_mut::BytesMut; + +// Optional Serde support +#[cfg(feature = "serde")] +mod serde; + +#[inline(never)] +#[cold] +fn abort() -> ! { + #[cfg(feature = "std")] + { + std::process::abort(); + } + + #[cfg(not(feature = "std"))] + { + struct Abort; + impl Drop for Abort { + fn drop(&mut self) { + panic!(); + } + } + let _a = Abort; + panic!("abort"); + } +} |