//! Pure Rust implementation of Ryū, an algorithm to quickly convert floating //! point numbers to decimal strings. //! //! The PLDI'18 paper [*Ryū: fast float-to-string conversion*][paper] by Ulf //! Adams includes a complete correctness proof of the algorithm. The paper is //! available under the creative commons CC-BY-SA license. //! //! This Rust implementation is a line-by-line port of Ulf Adams' implementation //! in C, [https://github.com/ulfjack/ryu][upstream]. //! //! [paper]: https://dl.acm.org/citation.cfm?id=3192369 //! [upstream]: https://github.com/ulfjack/ryu //! //! # Example //! //! ```edition2018 //! fn main() { //! let mut buffer = ryu::Buffer::new(); //! let printed = buffer.format(1.234); //! assert_eq!(printed, "1.234"); //! } //! ``` //! //! ## Performance //! //! You can run upstream's benchmarks with: //! //! ```console //! $ git clone https://github.com/ulfjack/ryu c-ryu //! $ cd c-ryu //! $ bazel run -c opt //ryu/benchmark //! ``` //! //! And the same benchmark against our implementation with: //! //! ```console //! $ git clone https://github.com/dtolnay/ryu rust-ryu //! $ cd rust-ryu //! $ cargo run --example upstream_benchmark --release //! ``` //! //! These benchmarks measure the average time to print a 32-bit float and average //! time to print a 64-bit float, where the inputs are distributed as uniform random //! bit patterns 32 and 64 bits wide. //! //! The upstream C code, the unsafe direct Rust port, and the safe pretty Rust API //! all perform the same, taking around 21 nanoseconds to format a 32-bit float and //! 31 nanoseconds to format a 64-bit float. //! //! There is also a Rust-specific benchmark comparing this implementation to the //! standard library which you can run with: //! //! ```console //! $ cargo bench //! ``` //! //! The benchmark shows Ryu approximately 4-10x faster than the standard library //! across a range of f32 and f64 inputs. Measurements are in nanoseconds per //! iteration; smaller is better. //! //! | type=f32 | 0.0 | 0.1234 | 2.718281828459045 | f32::MAX | //! |:--------:|:----:|:------:|:-----------------:|:--------:| //! | RYU | 3ns | 28ns | 23ns | 22ns | //! | STD | 40ns | 106ns | 128ns | 110ns | //! //! | type=f64 | 0.0 | 0.1234 | 2.718281828459045 | f64::MAX | //! |:--------:|:----:|:------:|:-----------------:|:--------:| //! | RYU | 3ns | 50ns | 35ns | 32ns | //! | STD | 39ns | 105ns | 128ns | 202ns | //! //! ## Formatting //! //! This library tends to produce more human-readable output than the standard //! library's to\_string, which never uses scientific notation. Here are two //! examples: //! //! - *ryu:* 1.23e40, *std:* 12300000000000000000000000000000000000000 //! - *ryu:* 1.23e-40, *std:* 0.000000000000000000000000000000000000000123 //! //! Both libraries print short decimals such as 0.0000123 without scientific //! notation. #![no_std] #![doc(html_root_url = "https://docs.rs/ryu/1.0.2")] #![cfg_attr(feature = "cargo-clippy", allow(renamed_and_removed_lints))] #![cfg_attr( feature = "cargo-clippy", allow(cast_lossless, many_single_char_names, unreadable_literal,) )] #[cfg(feature = "no-panic")] extern crate no_panic; mod buffer; mod common; mod d2s; #[cfg(not(feature = "small"))] mod d2s_full_table; mod d2s_intrinsics; #[cfg(feature = "small")] mod d2s_small_table; mod digit_table; mod f2s; mod pretty; pub use buffer::{Buffer, Float}; /// Unsafe functions that mirror the API of the C implementation of Ryū. pub mod raw { pub use pretty::{format32, format64}; }