Sync to dtolnay/ryu master (#17)

.clippy.toml

@@ -1 +1 @@
-msrv = "1.31.0"
+msrv = "1.36.0"

.github/workflows/ci.yml

@@ -19,15 +19,16 @@ jobs:
         with:
           toolchain: ${{matrix.rust}}
       - run: cargo test
+      - run: cargo test --features small
       - run: cargo build --tests --features no-panic --release
         if: matrix.rust == 'nightly'
 
   msrv:
-    name: Rust 1.31.0
+    name: Rust 1.36.0
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v2
-      - uses: dtolnay/rust-toolchain@1.31.0
+      - uses: dtolnay/rust-toolchain@1.36.0
       - run: cargo build
       - run: cargo build --features small
 
@@ -40,11 +41,23 @@ jobs:
         with:
           components: miri
       - run: cargo miri test
+        env:
+          MIRIFLAGS: "-Zmiri-tag-raw-pointers"
 
   clippy:
     name: Clippy
     runs-on: ubuntu-latest
+    if: github.event_name != 'pull_request'
     steps:
       - uses: actions/checkout@v2
       - uses: dtolnay/rust-toolchain@clippy
-      - run: cargo clippy -- -Dclippy::all -Dclippy::pedantic
+      - run: cargo clippy --tests --benches -- -Dclippy::all -Dclippy::pedantic
+
+  outdated:
+    name: Outdated
+    runs-on: ubuntu-latest
+    if: github.event_name != 'pull_request'
+    steps:
+      - uses: actions/checkout@v2
+      - uses: dtolnay/install@cargo-outdated
+      - run: cargo outdated --exit-code 1

Cargo.toml

@@ -6,8 +6,11 @@ license = "Apache-2.0 OR BSL-1.0"
 description = "Fast floating point to string conversion, ECMAScript compliant."
 repository = "https://github.com/boa-dev/ryu-js"
 documentation = "https://docs.rs/ryu-js"
+categories = ["value-formatting"]
 readme = "README.md"
+exclude = ["performance.png", "chart/**"]
 edition = "2018"
+rust-version = "1.36"
 
 [features]
 # Use smaller lookup tables. Instead of storing every required power of
@@ -21,8 +24,8 @@ no-panic = { version = "0.1", optional = true }
 
 [dev-dependencies]
 num_cpus = "1.8"
-rand = "0.7"
-rand_xorshift = "0.2"
+rand = "0.8"
+rand_xorshift = "0.3"
 
 [package.metadata.docs.rs]
 targets = ["x86_64-unknown-linux-gnu"]

README.md

@@ -17,7 +17,7 @@ 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].
 
-*Requirements: this crate supports any compiler version back to rustc 1.31; it
+*Requirements: this crate supports any compiler version back to rustc 1.36; it
 uses nothing from the Rust standard library so is usable from no_std crates.*
 
 [paper]: https://dl.acm.org/citation.cfm?id=3192369
@@ -28,6 +28,8 @@ uses nothing from the Rust standard library so is usable from no_std crates.*
 ryu-js = "0.2"
 ```
 
+<br>
+
 ## Example
 
 ```rust
@@ -38,7 +40,27 @@ fn main() {
 }
 ```
 
-## Performance
+<br>
+
+## Performance (lower is better)
+
+![performance](https://raw.githubusercontent.com/boa-dev/ryu-js/master/performance.png)
+
+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:ryu_benchmark --
+```
+
+And the same benchmark against our implementation with:
+
+```console
+$ git clone https://github.com/boa-dev/ryu-js rust-ryu
+$ cd rust-ryu
+$ cargo run --example upstream_benchmark --release
+```
 
 The 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
@@ -55,20 +77,10 @@ standard library which you can run with:
 $ cargo bench
 ```
 
-The benchmark shows Ryū approximately 4-10x faster than the standard library
+The benchmark shows Ryū approximately 2-5x 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

benches/bench.rs

@@ -1,6 +1,11 @@
 // cargo bench
 
 #![feature(test)]
+#![allow(
+    clippy::approx_constant,
+    clippy::excessive_precision,
+    clippy::unreadable_literal
+)]
 
 extern crate test;
 

chart/.gitignore

@@ -0,0 +1,7 @@
+*.aux
+*.fdb_latexmk
+*.fls
+*.log
+*.pdf
+*.png
+*.svg

chart/performance.tex

@@ -0,0 +1,80 @@
+\documentclass{standalone}
+\usepackage{pgfplots}
+\usepackage{sansmath}
+\pgfplotsset{compat=1.16}
+\definecolor{ryu}{HTML}{3366FF}
+\definecolor{std}{HTML}{949494}
+\definecolor{bg}{HTML}{CFCFCF}
+\begin{document}
+\pagecolor{white}
+\begin{tikzpicture}
+\edef\entries{
+  "$0.0$",
+  "$0.1234$",
+  "$2.718281828459045$",
+  "$1.7976931348623157e308$",
+}
+\begin{axis}[
+  width=5in,
+  height=3.5in,
+  ybar,
+  ymin=0,
+  bar width=24pt,
+  enlarge x limits={abs=39pt},
+  ylabel={nanos for one call to write},
+  legend style={
+    anchor=north west,
+    at={(0.025,0.975)},
+    legend columns=1,
+    draw=none,
+    fill=none,
+  },
+  legend entries={
+    ryu::Buffer::new().format\_finite(value)\\
+    std::write!(\&mut buf, ``\{\}'', value)\\
+  },
+  legend cell align=left,
+  xtick={-0.5,0.5,1.5,2.5,3.5,4.5},
+  xticklabels={},
+  xtick pos=left,
+  visualization depends on={y \as \rawy},
+  every node near coord/.append style={
+    shift={(axis direction cs:0,-\rawy/2)},
+    rotate=90,
+    anchor=center,
+    font=\sansmath\sffamily,
+  },
+  axis background/.style={fill=bg},
+  tick label style={font=\sansmath\sffamily},
+  every axis label={font=\sansmath\sffamily},
+  legend style={font=\sansmath\sffamily},
+  label style={font=\sansmath\sffamily},
+]
+  \addplot[
+    black,
+    fill=ryu,
+    area legend,
+    nodes near coords={},
+  ] coordinates {
+    (0, 3)
+    (1, 40)
+    (2, 27)
+    (3, 28)
+  };
+  \addplot[
+    black,
+    fill=std,
+    area legend,
+    nodes near coords=\pgfmathsetmacro{\input}{{\entries}[\coordindex]}\input,
+  ] coordinates {
+    (0, 20)
+    (1, 66)
+    (2, 88)
+    (3, 114)
+  };
+\end{axis}
+\pgfresetboundingbox\path
+  (current axis.south west) -- ++(-0.44in,-0.09in)
+  rectangle (current axis.north east) -- ++(0.05in,0.05in);
+\end{tikzpicture}
+\end{document}

src/buffer/mod.rs

@@ -1,7 +1,4 @@
 use crate::raw;
-#[cfg(not(maybe_uninit))]
-use core::mem;
-#[cfg(maybe_uninit)]
 use core::mem::MaybeUninit;
 use core::{slice, str};
 #[cfg(feature = "no-panic")]
@@ -21,10 +18,7 @@ const NEG_INFINITY: &str = "-Infinity";
 /// assert_eq!(printed, "1.234");
 /// ```
 pub struct Buffer {
-    #[cfg(maybe_uninit)]
     bytes: [MaybeUninit<u8>; 25],
-    #[cfg(not(maybe_uninit))]
-    bytes: [u8; 25],
 }
 
 impl Buffer {
@@ -33,12 +27,7 @@ impl Buffer {
     #[inline]
     #[cfg_attr(feature = "no-panic", no_panic)]
     pub fn new() -> Self {
-        // assume_init is safe here, since this is an array of MaybeUninit, which does not need
-        // to be initialized.
-        #[cfg(maybe_uninit)]
         let bytes = [MaybeUninit::<u8>::uninit(); 25];
-        #[cfg(not(maybe_uninit))]
-        let bytes = unsafe { core::mem::uninitialized() };
 
         Buffer { bytes }
     }