| <!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta name="generator" content="rustdoc"><meta name="description" content="Source of the Rust file `/root/.cargo/registry/src/github.com-1ecc6299db9ec823/itoa-1.0.6/src/lib.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>lib.rs - source</title><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceSerif4-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../FiraSans-Regular.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../FiraSans-Medium.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceCodePro-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceSerif4-Bold.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceCodePro-Semibold.ttf.woff2"><link rel="stylesheet" href="../../normalize.css"><link rel="stylesheet" href="../../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" href="../../ayu.css" disabled><link rel="stylesheet" href="../../dark.css" disabled><link rel="stylesheet" href="../../light.css" id="themeStyle"><script id="default-settings" ></script><script src="../../storage.js"></script><script defer src="../../source-script.js"></script><script defer src="../../source-files.js"></script><script defer src="../../main.js"></script><noscript><link rel="stylesheet" href="../../noscript.css"></noscript><link rel="alternate icon" type="image/png" href="../../favicon-16x16.png"><link rel="alternate icon" type="image/png" href="../../favicon-32x32.png"><link rel="icon" type="image/svg+xml" href="../../favicon.svg"></head><body class="rustdoc source"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><a class="sidebar-logo" href="../../itoa/index.html"><div class="logo-container"><img class="rust-logo" src="../../rust-logo.svg" alt="logo"></div></a></nav><main><div class="width-limiter"><nav class="sub"><a class="sub-logo-container" href="../../itoa/index.html"><img class="rust-logo" src="../../rust-logo.svg" alt="logo"></a><form class="search-form"><div class="search-container"><span></span><input class="search-input" name="search" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><div id="help-button" title="help" tabindex="-1"><a href="../../help.html">?</a></div><div id="settings-menu" tabindex="-1"><a href="../../settings.html" title="settings"><img width="22" height="22" alt="Change settings" src="../../wheel.svg"></a></div></div></form></nav><section id="main-content" class="content"><div class="example-wrap"><pre class="src-line-numbers"><span id="1">1</span> |
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| </pre><pre class="rust"><code><span class="doccomment">//! [![github]](https://github.com/dtolnay/itoa)&ensp;[![crates-io]](https://crates.io/crates/itoa)&ensp;[![docs-rs]](https://docs.rs/itoa) |
| //! |
| //! [github]: https://img.shields.io/badge/github-8da0cb?style=for-the-badge&labelColor=555555&logo=github |
| //! [crates-io]: https://img.shields.io/badge/crates.io-fc8d62?style=for-the-badge&labelColor=555555&logo=rust |
| //! [docs-rs]: https://img.shields.io/badge/docs.rs-66c2a5?style=for-the-badge&labelColor=555555&logo=docs.rs |
| //! |
| //! <br> |
| //! |
| //! This crate provides a fast conversion of integer primitives to decimal |
| //! strings. The implementation comes straight from [libcore] but avoids the |
| //! performance penalty of going through [`core::fmt::Formatter`]. |
| //! |
| //! See also [`ryu`] for printing floating point primitives. |
| //! |
| //! [libcore]: https://github.com/rust-lang/rust/blob/b8214dc6c6fc20d0a660fb5700dca9ebf51ebe89/src/libcore/fmt/num.rs#L201-L254 |
| //! [`core::fmt::Formatter`]: https://doc.rust-lang.org/std/fmt/struct.Formatter.html |
| //! [`ryu`]: https://github.com/dtolnay/ryu |
| //! |
| //! # Example |
| //! |
| //! ``` |
| //! fn main() { |
| //! let mut buffer = itoa::Buffer::new(); |
| //! let printed = buffer.format(128u64); |
| //! assert_eq!(printed, "128"); |
| //! } |
| //! ``` |
| //! |
| //! # Performance (lower is better) |
| //! |
| //! ![performance](https://raw.githubusercontent.com/dtolnay/itoa/master/performance.png) |
| |
| </span><span class="attribute">#![doc(html_root_url = <span class="string">"https://docs.rs/itoa/1.0.6"</span>)] |
| #![no_std] |
| #![allow( |
| clippy::cast_lossless, |
| clippy::cast_possible_truncation, |
| clippy::must_use_candidate, |
| clippy::unreadable_literal |
| )] |
| |
| </span><span class="kw">mod </span>udiv128; |
| |
| <span class="kw">use </span>core::mem::{<span class="self">self</span>, MaybeUninit}; |
| <span class="kw">use </span>core::{ptr, slice, str}; |
| <span class="attribute">#[cfg(feature = <span class="string">"no-panic"</span>)] |
| </span><span class="kw">use </span>no_panic::no_panic; |
| |
| <span class="doccomment">/// A correctly sized stack allocation for the formatted integer to be written |
| /// into. |
| /// |
| /// # Example |
| /// |
| /// ``` |
| /// let mut buffer = itoa::Buffer::new(); |
| /// let printed = buffer.format(1234); |
| /// assert_eq!(printed, "1234"); |
| /// ``` |
| </span><span class="kw">pub struct </span>Buffer { |
| bytes: [MaybeUninit<u8>; I128_MAX_LEN], |
| } |
| |
| <span class="kw">impl </span>Default <span class="kw">for </span>Buffer { |
| <span class="attribute">#[inline] |
| </span><span class="kw">fn </span>default() -> Buffer { |
| Buffer::new() |
| } |
| } |
| |
| <span class="kw">impl </span>Clone <span class="kw">for </span>Buffer { |
| <span class="attribute">#[inline] |
| </span><span class="kw">fn </span>clone(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="self">Self </span>{ |
| Buffer::new() |
| } |
| } |
| |
| <span class="kw">impl </span>Buffer { |
| <span class="doccomment">/// This is a cheap operation; you don't need to worry about reusing buffers |
| /// for efficiency. |
| </span><span class="attribute">#[inline] |
| #[cfg_attr(feature = <span class="string">"no-panic"</span>, no_panic)] |
| </span><span class="kw">pub fn </span>new() -> Buffer { |
| <span class="kw">let </span>bytes = [MaybeUninit::<u8>::uninit(); I128_MAX_LEN]; |
| Buffer { bytes } |
| } |
| |
| <span class="doccomment">/// Print an integer into this buffer and return a reference to its string |
| /// representation within the buffer. |
| </span><span class="attribute">#[cfg_attr(feature = <span class="string">"no-panic"</span>, no_panic)] |
| </span><span class="kw">pub fn </span>format<I: Integer>(<span class="kw-2">&mut </span><span class="self">self</span>, i: I) -> <span class="kw-2">&</span>str { |
| i.write(<span class="kw">unsafe </span>{ |
| <span class="kw-2">&mut *</span>(<span class="kw-2">&mut </span><span class="self">self</span>.bytes <span class="kw">as </span><span class="kw-2">*mut </span>[MaybeUninit<u8>; I128_MAX_LEN] |
| <span class="kw">as </span><span class="kw-2">*mut </span><I <span class="kw">as </span>private::Sealed>::Buffer) |
| }) |
| } |
| } |
| |
| <span class="doccomment">/// An integer that can be written into an [`itoa::Buffer`][Buffer]. |
| /// |
| /// This trait is sealed and cannot be implemented for types outside of itoa. |
| </span><span class="kw">pub trait </span>Integer: private::Sealed {} |
| |
| <span class="comment">// Seal to prevent downstream implementations of the Integer trait. |
| </span><span class="kw">mod </span>private { |
| <span class="kw">pub trait </span>Sealed: Copy { |
| <span class="kw">type </span>Buffer: <span class="lifetime">'static</span>; |
| <span class="kw">fn </span>write(<span class="self">self</span>, buf: <span class="kw-2">&mut </span><span class="self">Self</span>::Buffer) -> <span class="kw-2">&</span>str; |
| } |
| } |
| |
| <span class="kw">const </span>DEC_DIGITS_LUT: <span class="kw-2">&</span>[u8] = <span class="string">b"\ |
| 0001020304050607080910111213141516171819\ |
| 2021222324252627282930313233343536373839\ |
| 4041424344454647484950515253545556575859\ |
| 6061626364656667686970717273747576777879\ |
| 8081828384858687888990919293949596979899"</span>; |
| |
| <span class="comment">// Adaptation of the original implementation at |
| // https://github.com/rust-lang/rust/blob/b8214dc6c6fc20d0a660fb5700dca9ebf51ebe89/src/libcore/fmt/num.rs#L188-L266 |
| </span><span class="macro">macro_rules! </span>impl_Integer { |
| ($(<span class="macro-nonterminal">$max_len</span>:expr => <span class="macro-nonterminal">$t</span>:ident),* <span class="kw">as </span><span class="macro-nonterminal">$conv_fn</span>:ident) => {$( |
| <span class="kw">impl </span>Integer <span class="kw">for </span><span class="macro-nonterminal">$t </span>{} |
| |
| <span class="kw">impl </span>private::Sealed <span class="kw">for </span><span class="macro-nonterminal">$t </span>{ |
| <span class="kw">type </span>Buffer = [MaybeUninit<u8>; <span class="macro-nonterminal">$max_len</span>]; |
| |
| <span class="attribute">#[allow(unused_comparisons)] |
| #[inline] |
| #[cfg_attr(feature = <span class="string">"no-panic"</span>, no_panic)] |
| </span><span class="kw">fn </span>write(<span class="self">self</span>, buf: <span class="kw-2">&mut </span>[MaybeUninit<u8>; <span class="macro-nonterminal">$max_len</span>]) -> <span class="kw-2">&</span>str { |
| <span class="kw">let </span>is_nonnegative = <span class="self">self </span>>= <span class="number">0</span>; |
| <span class="kw">let </span><span class="kw-2">mut </span>n = <span class="kw">if </span>is_nonnegative { |
| <span class="self">self </span><span class="kw">as </span><span class="macro-nonterminal">$conv_fn |
| </span>} <span class="kw">else </span>{ |
| <span class="comment">// convert the negative num to positive by summing 1 to it's 2 complement |
| </span>(!(<span class="self">self </span><span class="kw">as </span><span class="macro-nonterminal">$conv_fn</span>)).wrapping_add(<span class="number">1</span>) |
| }; |
| <span class="kw">let </span><span class="kw-2">mut </span>curr = buf.len() <span class="kw">as </span>isize; |
| <span class="kw">let </span>buf_ptr = buf.as_mut_ptr() <span class="kw">as </span><span class="kw-2">*mut </span>u8; |
| <span class="kw">let </span>lut_ptr = DEC_DIGITS_LUT.as_ptr(); |
| |
| <span class="kw">unsafe </span>{ |
| <span class="comment">// need at least 16 bits for the 4-characters-at-a-time to work. |
| </span><span class="kw">if </span>mem::size_of::<<span class="macro-nonterminal">$t</span>>() >= <span class="number">2 </span>{ |
| <span class="comment">// eagerly decode 4 characters at a time |
| </span><span class="kw">while </span>n >= <span class="number">10000 </span>{ |
| <span class="kw">let </span>rem = (n % <span class="number">10000</span>) <span class="kw">as </span>isize; |
| n /= <span class="number">10000</span>; |
| |
| <span class="kw">let </span>d1 = (rem / <span class="number">100</span>) << <span class="number">1</span>; |
| <span class="kw">let </span>d2 = (rem % <span class="number">100</span>) << <span class="number">1</span>; |
| curr -= <span class="number">4</span>; |
| ptr::copy_nonoverlapping(lut_ptr.offset(d1), buf_ptr.offset(curr), <span class="number">2</span>); |
| ptr::copy_nonoverlapping(lut_ptr.offset(d2), buf_ptr.offset(curr + <span class="number">2</span>), <span class="number">2</span>); |
| } |
| } |
| |
| <span class="comment">// if we reach here numbers are <= 9999, so at most 4 chars long |
| </span><span class="kw">let </span><span class="kw-2">mut </span>n = n <span class="kw">as </span>isize; <span class="comment">// possibly reduce 64bit math |
| |
| // decode 2 more chars, if > 2 chars |
| </span><span class="kw">if </span>n >= <span class="number">100 </span>{ |
| <span class="kw">let </span>d1 = (n % <span class="number">100</span>) << <span class="number">1</span>; |
| n /= <span class="number">100</span>; |
| curr -= <span class="number">2</span>; |
| ptr::copy_nonoverlapping(lut_ptr.offset(d1), buf_ptr.offset(curr), <span class="number">2</span>); |
| } |
| |
| <span class="comment">// decode last 1 or 2 chars |
| </span><span class="kw">if </span>n < <span class="number">10 </span>{ |
| curr -= <span class="number">1</span>; |
| <span class="kw-2">*</span>buf_ptr.offset(curr) = (n <span class="kw">as </span>u8) + <span class="string">b'0'</span>; |
| } <span class="kw">else </span>{ |
| <span class="kw">let </span>d1 = n << <span class="number">1</span>; |
| curr -= <span class="number">2</span>; |
| ptr::copy_nonoverlapping(lut_ptr.offset(d1), buf_ptr.offset(curr), <span class="number">2</span>); |
| } |
| |
| <span class="kw">if </span>!is_nonnegative { |
| curr -= <span class="number">1</span>; |
| <span class="kw-2">*</span>buf_ptr.offset(curr) = <span class="string">b'-'</span>; |
| } |
| } |
| |
| <span class="kw">let </span>len = buf.len() - curr <span class="kw">as </span>usize; |
| <span class="kw">let </span>bytes = <span class="kw">unsafe </span>{ slice::from_raw_parts(buf_ptr.offset(curr), len) }; |
| <span class="kw">unsafe </span>{ str::from_utf8_unchecked(bytes) } |
| } |
| } |
| )<span class="kw-2">*</span>}; |
| } |
| |
| <span class="kw">const </span>I8_MAX_LEN: usize = <span class="number">4</span>; |
| <span class="kw">const </span>U8_MAX_LEN: usize = <span class="number">3</span>; |
| <span class="kw">const </span>I16_MAX_LEN: usize = <span class="number">6</span>; |
| <span class="kw">const </span>U16_MAX_LEN: usize = <span class="number">5</span>; |
| <span class="kw">const </span>I32_MAX_LEN: usize = <span class="number">11</span>; |
| <span class="kw">const </span>U32_MAX_LEN: usize = <span class="number">10</span>; |
| <span class="kw">const </span>I64_MAX_LEN: usize = <span class="number">20</span>; |
| <span class="kw">const </span>U64_MAX_LEN: usize = <span class="number">20</span>; |
| |
| <span class="macro">impl_Integer!</span>( |
| I8_MAX_LEN => i8, |
| U8_MAX_LEN => u8, |
| I16_MAX_LEN => i16, |
| U16_MAX_LEN => u16, |
| I32_MAX_LEN => i32, |
| U32_MAX_LEN => u32 |
| <span class="kw">as </span>u32); |
| |
| <span class="macro">impl_Integer!</span>(I64_MAX_LEN => i64, U64_MAX_LEN => u64 <span class="kw">as </span>u64); |
| |
| <span class="attribute">#[cfg(target_pointer_width = <span class="string">"16"</span>)] |
| </span><span class="macro">impl_Integer!</span>(I16_MAX_LEN => isize, U16_MAX_LEN => usize <span class="kw">as </span>u16); |
| |
| <span class="attribute">#[cfg(target_pointer_width = <span class="string">"32"</span>)] |
| </span><span class="macro">impl_Integer!</span>(I32_MAX_LEN => isize, U32_MAX_LEN => usize <span class="kw">as </span>u32); |
| |
| <span class="attribute">#[cfg(target_pointer_width = <span class="string">"64"</span>)] |
| </span><span class="macro">impl_Integer!</span>(I64_MAX_LEN => isize, U64_MAX_LEN => usize <span class="kw">as </span>u64); |
| |
| <span class="macro">macro_rules! </span>impl_Integer128 { |
| ($(<span class="macro-nonterminal">$max_len</span>:expr => <span class="macro-nonterminal">$t</span>:ident),<span class="kw-2">*</span>) => {$( |
| <span class="kw">impl </span>Integer <span class="kw">for </span><span class="macro-nonterminal">$t </span>{} |
| |
| <span class="kw">impl </span>private::Sealed <span class="kw">for </span><span class="macro-nonterminal">$t </span>{ |
| <span class="kw">type </span>Buffer = [MaybeUninit<u8>; <span class="macro-nonterminal">$max_len</span>]; |
| |
| <span class="attribute">#[allow(unused_comparisons)] |
| #[inline] |
| #[cfg_attr(feature = <span class="string">"no-panic"</span>, no_panic)] |
| </span><span class="kw">fn </span>write(<span class="self">self</span>, buf: <span class="kw-2">&mut </span>[MaybeUninit<u8>; <span class="macro-nonterminal">$max_len</span>]) -> <span class="kw-2">&</span>str { |
| <span class="kw">let </span>is_nonnegative = <span class="self">self </span>>= <span class="number">0</span>; |
| <span class="kw">let </span>n = <span class="kw">if </span>is_nonnegative { |
| <span class="self">self </span><span class="kw">as </span>u128 |
| } <span class="kw">else </span>{ |
| <span class="comment">// convert the negative num to positive by summing 1 to it's 2 complement |
| </span>(!(<span class="self">self </span><span class="kw">as </span>u128)).wrapping_add(<span class="number">1</span>) |
| }; |
| <span class="kw">let </span><span class="kw-2">mut </span>curr = buf.len() <span class="kw">as </span>isize; |
| <span class="kw">let </span>buf_ptr = buf.as_mut_ptr() <span class="kw">as </span><span class="kw-2">*mut </span>u8; |
| |
| <span class="kw">unsafe </span>{ |
| <span class="comment">// Divide by 10^19 which is the highest power less than 2^64. |
| </span><span class="kw">let </span>(n, rem) = udiv128::udivmod_1e19(n); |
| <span class="kw">let </span>buf1 = buf_ptr.offset(curr - U64_MAX_LEN <span class="kw">as </span>isize) <span class="kw">as </span><span class="kw-2">*mut </span>[MaybeUninit<u8>; U64_MAX_LEN]; |
| curr -= rem.write(<span class="kw-2">&mut *</span>buf1).len() <span class="kw">as </span>isize; |
| |
| <span class="kw">if </span>n != <span class="number">0 </span>{ |
| <span class="comment">// Memset the base10 leading zeros of rem. |
| </span><span class="kw">let </span>target = buf.len() <span class="kw">as </span>isize - <span class="number">19</span>; |
| ptr::write_bytes(buf_ptr.offset(target), <span class="string">b'0'</span>, (curr - target) <span class="kw">as </span>usize); |
| curr = target; |
| |
| <span class="comment">// Divide by 10^19 again. |
| </span><span class="kw">let </span>(n, rem) = udiv128::udivmod_1e19(n); |
| <span class="kw">let </span>buf2 = buf_ptr.offset(curr - U64_MAX_LEN <span class="kw">as </span>isize) <span class="kw">as </span><span class="kw-2">*mut </span>[MaybeUninit<u8>; U64_MAX_LEN]; |
| curr -= rem.write(<span class="kw-2">&mut *</span>buf2).len() <span class="kw">as </span>isize; |
| |
| <span class="kw">if </span>n != <span class="number">0 </span>{ |
| <span class="comment">// Memset the leading zeros. |
| </span><span class="kw">let </span>target = buf.len() <span class="kw">as </span>isize - <span class="number">38</span>; |
| ptr::write_bytes(buf_ptr.offset(target), <span class="string">b'0'</span>, (curr - target) <span class="kw">as </span>usize); |
| curr = target; |
| |
| <span class="comment">// There is at most one digit left |
| // because u128::max / 10^19 / 10^19 is 3. |
| </span>curr -= <span class="number">1</span>; |
| <span class="kw-2">*</span>buf_ptr.offset(curr) = (n <span class="kw">as </span>u8) + <span class="string">b'0'</span>; |
| } |
| } |
| |
| <span class="kw">if </span>!is_nonnegative { |
| curr -= <span class="number">1</span>; |
| <span class="kw-2">*</span>buf_ptr.offset(curr) = <span class="string">b'-'</span>; |
| } |
| |
| <span class="kw">let </span>len = buf.len() - curr <span class="kw">as </span>usize; |
| <span class="kw">let </span>bytes = slice::from_raw_parts(buf_ptr.offset(curr), len); |
| str::from_utf8_unchecked(bytes) |
| } |
| } |
| } |
| )<span class="kw-2">*</span>}; |
| } |
| |
| <span class="kw">const </span>U128_MAX_LEN: usize = <span class="number">39</span>; |
| <span class="kw">const </span>I128_MAX_LEN: usize = <span class="number">40</span>; |
| |
| <span class="macro">impl_Integer128!</span>(I128_MAX_LEN => i128, U128_MAX_LEN => u128); |
| </code></pre></div> |
| </section></div></main><div id="rustdoc-vars" data-root-path="../../" data-current-crate="itoa" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |