# bZipper bZipper is a Rust crate for cheaply serialising (encoding) and deserialising (decoding) data structures into binary streams What separates this crate from others such as [Bincode](https://crates.io/crates/bincode/) or [Postcard](https://crates.io/crates/postcard/) is that this crate is extensively optimised for *just* binary encodings (whilst the mentioned crates specifically use Serde and build on a more abstract data model). The original goal of this project was specifically to guarantee size constraints for encodings on a per-type basis at compile-time. Therefore, this crate may be more suited for networking or other cases where many allocations are unwanted. Keep in mind that this project is still work-in-progress. Until the interfaces are stabilised, different facilities may be replaced, removed, or altered in a breaking way. This crate is compatible with `no_std`. ## Performance As bZipper is optimised exclusively for a single, binary format, it may outperform other libraries that are more generic in nature. The `bzipper_benchmarks` binary compares multiple scenarios using bZipper and other, similar crates. According to my runs on an AMD Ryzen 7 3700X, these benchmarks indicate that bZipper outperform all of the tested crates -- as demonstrated in the following table: | Benchmark | [Bincode] | [Borsh] | bZipper | [Ciborium] | [Postcard] | | :--------------------------------- | --------: | ------: | ------: | ---------: | ---------: | | `encode_u8` | 1.262 | 1.271 | 1.153 | 2.854 | 1.270 | | `encode_struct_unit` | 0.000 | 0.000 | 0.000 | 0.447 | 0.000 | | `encode_struct_unnamed` | 1.270 | 1.102 | 0.998 | 1.948 | 1.182 | | `encode_struct_named` | 4.205 | 1.186 | 1.136 | 10.395 | 1.168 | | `encode_enum_unit` | 0.328 | 0.008 | 0.000 | 2.293 | 0.004 | | **Total time** → | 7.065 | 3.567 | 3.286 | 17.937 | 3.625 | | **Total deviation (p.c.)** → | +115 | +9 | ±0 | +446 | +10 | [Bincode]: https://crates.io/crates/bincode/ [Borsh]: https://crates.io/crates/borsh/ [Ciborium]: https://crates.io/crates/ciborium/ [Postcard]: https://crates.io/crates/postcard/ All quantities are measured in seconds unless otherwise noted. Please feel free to conduct your own tests of bZipper. ## Data model Most primitives encode losslessly, with the main exceptions being `usize` and `isize`. These are instead first cast as `u16` and `i16`, respectively, due to portability concerns (with respect to embedded systems). See specific types' implementations for notes on their data models. **Note that the data model is currently not stabilised,** and may not necessarily be in the near future (before [specialisation](https://github.com/rust-lang/rust/issues/31844/)). It may therefore be undesired to store encodings long-term. ## Usage This crate revolves around the `Encode` and `Decode` traits which both handle conversions to and from byte streams. Many standard types come implemented with bZipper, including most primitives as well as some standard library types such as `Option` and `Result`. Some [features](#features-flags) enable an extended set of implementations. It is recommended in most cases to simply derive these two traits for custom types (although this is only supported with enumerations and structures – not untagged unions). Here, each field is *chained* according to declaration order: ```rust use bzipper::{Buf, Decode, Encode, SizedEncode}; #[derive(Debug, Decode, PartialEq, SizedEncode)] struct IoRegister { addr: u32, value: u16, } let mut buf = Buf::new(); buf.write(IoRegister { addr: 0x04000000, value: 0x0402 }).unwrap(); assert_eq!(buf.len(), 0x6); assert_eq!(buf, [0x04, 0x00, 0x00, 0x00, 0x04, 0x02].as_slice()); assert_eq!(buf.read().unwrap(), IoRegister { addr: 0x04000000, value: 0x0402 }); ``` ### Buffer types The `Encode` and `Decode` traits both rely on streams for carrying the manipulated byte streams. These streams are separated into two type: *O-streams* (output streams) and *i-streams* (input streams). Often, but not always, the `Buf` type is preferred over directly calling the `encode` and `decode` methods. ### Encoding To encode an object directly using the `Encode` trait, simply allocate a buffer for the encoding and wrap it in an `OStream` object: ```rust use bzipper::{Encode, OStream, SizedEncode}; let mut buf = [0x00; char::MAX_ENCODED_SIZE]; let mut stream = OStream::new(&mut buf); 'Ж'.encode(&mut stream).unwrap(); assert_eq!(buf, [0x00, 0x00, 0x04, 0x16].as_slice()); ``` Streams can also be used to chain multiple objects together: ```rust use bzipper::{Encode, OStream, SizedEncode}; let mut buf = [0x0; char::MAX_ENCODED_SIZE * 0x5]; let mut stream = OStream::new(&mut buf); // Note: For serialising multiple characters, the // `String` and `SizedStr` types are usually // preferred. 'ل'.encode(&mut stream).unwrap(); 'ا'.encode(&mut stream).unwrap(); 'م'.encode(&mut stream).unwrap(); 'د'.encode(&mut stream).unwrap(); 'ا'.encode(&mut stream).unwrap(); assert_eq!(buf, [ 0x00, 0x00, 0x06, 0x44, 0x00, 0x00, 0x06, 0x27, 0x00, 0x00, 0x06, 0x45, 0x00, 0x00, 0x06, 0x2F, 0x00, 0x00, 0x06, 0x27 ]); ``` If the encoded type additionally implements `SizedEncode`, then the maximum size of any encoding is guaranteed with the `MAX_ENCODED_SIZE` constant. Numerical primitives are encoded in big endian (a.k.a. [network order](https://en.wikipedia.org/wiki/Endianness#Networking)) for... reasons. It is recommended for implementors to follow this convention as well. ### Decoding Decoding works with a similar syntax to encoding. To decode a byte array, simply call the `decode` method with an `IStream` object: ```rust use bzipper::{Decode, IStream}; let data = [0x45, 0x54]; let mut stream = IStream::new(&data); assert_eq!(u16::decode(&mut stream).unwrap(), 0x4554); // Data can theoretically be reinterpretred: stream = IStream::new(&data); assert_eq!(u8::decode(&mut stream).unwrap(), 0x45); assert_eq!(u8::decode(&mut stream).unwrap(), 0x54); // Including as tuples: stream = IStream::new(&data); assert_eq!(<(u8, u8)>::decode(&mut stream).unwrap(), (0x45, 0x54)); ``` ## Examples A UDP server/client for geographic data: ```rust use bzipper::{Buf, Decode, SizedEncode}; use std::io; use std::net::{SocketAddr, ToSocketAddrs, UdpSocket}; use std::thread::spawn; // City, region, etc.: #[derive(Clone, Copy, Debug, Decode, Eq, PartialEq, SizedEncode)] enum Area { AlQuds, Byzantion, Cusco, Tenochtitlan, // ... } // Client-to-server message: #[derive(Debug, Decode, PartialEq, SizedEncode)] enum Request { AtmosphericHumidity { area: Area }, AtmosphericPressure { area: Area }, AtmosphericTemperature { area: Area }, // ... } // Server-to-client message: #[derive(Debug, Decode, PartialEq, SizedEncode)] enum Response { AtmosphericHumidity(f64), AtmosphericPressure(f64), // Pascal AtmosphericTemperature(f64), // Kelvin // ... } struct Party { pub socket: UdpSocket, pub request_buf: Buf::, pub response_buf: Buf::, } impl Party { pub fn new(addr: A) -> io::Result { let socket = UdpSocket::bind(addr)?; let this = Self { socket, request_buf: Buf::new(), response_buf: Buf::new(), }; Ok(this) } } let mut server = Party::new("127.0.0.1:27015").unwrap(); let mut client = Party::new("0.0.0.0:0").unwrap(); spawn(move || { let Party { socket, mut request_buf, mut response_buf } = server; // Recieve initial request from client. let (len, addr) = socket.recv_from(&mut request_buf).unwrap(); request_buf.set_len(len); let request = request_buf.read().unwrap(); assert_eq!(request, Request::AtmosphericTemperature { area: Area::AlQuds }); // Handle request and respond back to client. let response = Response::AtmosphericTemperature(44.4); // For demonstration's sake. response_buf.write(response).unwrap(); socket.send_to(&response_buf, addr).unwrap(); }); spawn(move || { let Party { socket, mut request_buf, mut response_buf } = client; // Send initial request to server. socket.connect("127.0.0.1:27015").unwrap(); let request = Request::AtmosphericTemperature { area: Area::AlQuds }; request_buf.write(request); socket.send(&request_buf).unwrap(); // Recieve final response from server. socket.recv(&mut response_buf).unwrap(); let response = response_buf.read().unwrap(); assert_eq!(response, Response::AtmosphericTemperature(44.4)); }); ``` ## Feature flags bZipper defines the following features: * `alloc` (default): Enables the `Buf` type and implementations for e.g. `Box` and `Arc` * `std` (default): Enables implementations for types such as `Mutex` and `RwLock` ## Documentation bZipper has its documentation written in-source for use by `rustdoc`. See [Docs.rs](https://docs.rs/bzipper/latest/bzipper/) for an on-line, rendered instance. Currently, these docs make use of some unstable features for the sake of readability. The nightly toolchain is therefore required when rendering them. ## Contribution bZipper does not accept source code contributions at the moment. This is a personal choice by the maintainer and may be undone in the future. Do however feel free to open up an issue on [`GitLab`](https://gitlab.com/bjoernager/bzipper/issues/) or (preferably) [`GitHub`](https://github.com/bjoernager/bzipper/issues/) if you feel the need to express any concerns over the project. ## Copyright & Licence Copyright 2024 Gabriel Bjørnager Jensen. This program is free software: you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with this program. If not, see .