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chromium / external / github.com / dtolnay / ryu / refs/tags/upstream/0.2.7
tag959ffba6ae1b31d1354766afee43634fe47234cf
taggerDavid Tolnay <dtolnay@gmail.com>Sat Nov 10 22:05:33 2018
object5edafe24373c9884609fc2e04c0eba0770df47a8 
Release 0.2.7
commit5edafe24373c9884609fc2e04c0eba0770df47a8[log] [tgz]
authorDavid Tolnay <dtolnay@gmail.com>Sat Nov 10 22:05:33 2018
committerDavid Tolnay <dtolnay@gmail.com>Sat Nov 10 22:33:44 2018
treeda932f2197dcb4734fdbbfe8e60bb18d95a9e48b
parent0cc666d12762bfb5b4288d23c5d54940c1df2992 [diff]
Release 0.2.7
2 files changed
tree: da932f2197dcb4734fdbbfe8e60bb18d95a9e48b
  1. benchmark/
  2. src/
  3. tests/
  4. .gitignore
  5. .travis.yml
  6. build.rs
  7. Cargo.toml
  8. LICENSE-APACHE
  9. LICENSE-BOOST
  10. README.md
README.md

Ryū

Build Status Latest Version Rust Documentation Rustc Version 1.15+

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 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. The ryu::raw module exposes exactly the API and formatting of the C implementation as unsafe pure Rust functions. There is additionally a safe API as demonstrated in the example code below. The safe API uses the same underlying Ryū algorithm but diverges from the formatting of the C implementation to produce more human-readable output, for example 0.3 rather than 3E-1.

Requirements: this crate supports any compiler version back to rustc 1.15; it uses nothing from the Rust standard library so is usable from no_std crates.

[dependencies]
ryu = "0.2"

Examples

extern crate ryu;

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:

$ git clone https://github.com/ulfjack/ryu c-ryu
$ cd c-ryu
$ bazel run -c opt //ryu/benchmark

And our benchmarks with:

$ git clone https://github.com/ulfjack/ryu rust-ryu
$ cd rust-ryu
$ cargo run --example 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.

License

Licensed under either of the following at your option.