| <!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/num-traits-0.2.15/src/pow.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>pow.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="../../num_traits/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="../../num_traits/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="kw">use </span>core::num::Wrapping; |
| <span class="kw">use </span>core::ops::Mul; |
| <span class="kw">use </span>{CheckedMul, One}; |
| |
| <span class="doccomment">/// Binary operator for raising a value to a power. |
| </span><span class="kw">pub trait </span>Pow<RHS> { |
| <span class="doccomment">/// The result after applying the operator. |
| </span><span class="kw">type </span>Output; |
| |
| <span class="doccomment">/// Returns `self` to the power `rhs`. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use num_traits::Pow; |
| /// assert_eq!(Pow::pow(10u32, 2u32), 100); |
| /// ``` |
| </span><span class="kw">fn </span>pow(<span class="self">self</span>, rhs: RHS) -> <span class="self">Self</span>::Output; |
| } |
| |
| <span class="macro">macro_rules! </span>pow_impl { |
| (<span class="macro-nonterminal">$t</span>:ty) => { |
| <span class="macro">pow_impl!</span>(<span class="macro-nonterminal">$t</span>, u8); |
| <span class="macro">pow_impl!</span>(<span class="macro-nonterminal">$t</span>, usize); |
| |
| <span class="comment">// FIXME: these should be possible |
| // pow_impl!($t, u16); |
| // pow_impl!($t, u32); |
| // pow_impl!($t, u64); |
| </span>}; |
| (<span class="macro-nonterminal">$t</span>:ty, <span class="macro-nonterminal">$rhs</span>:ty) => { |
| <span class="macro">pow_impl!</span>(<span class="macro-nonterminal">$t</span>, <span class="macro-nonterminal">$rhs</span>, usize, pow); |
| }; |
| (<span class="macro-nonterminal">$t</span>:ty, <span class="macro-nonterminal">$rhs</span>:ty, <span class="macro-nonterminal">$desired_rhs</span>:ty, <span class="macro-nonterminal">$method</span>:expr) => { |
| <span class="kw">impl </span>Pow<<span class="macro-nonterminal">$rhs</span>> <span class="kw">for </span><span class="macro-nonterminal">$t </span>{ |
| <span class="kw">type </span>Output = <span class="macro-nonterminal">$t</span>; |
| <span class="attribute">#[inline] |
| </span><span class="kw">fn </span>pow(<span class="self">self</span>, rhs: <span class="macro-nonterminal">$rhs</span>) -> <span class="macro-nonterminal">$t </span>{ |
| (<span class="macro-nonterminal">$method</span>)(<span class="self">self</span>, <<span class="macro-nonterminal">$desired_rhs</span>>::from(rhs)) |
| } |
| } |
| |
| <span class="kw">impl</span><<span class="lifetime">'a</span>> Pow<<span class="kw-2">&</span><span class="lifetime">'a </span><span class="macro-nonterminal">$rhs</span>> <span class="kw">for </span><span class="macro-nonterminal">$t </span>{ |
| <span class="kw">type </span>Output = <span class="macro-nonterminal">$t</span>; |
| <span class="attribute">#[inline] |
| </span><span class="kw">fn </span>pow(<span class="self">self</span>, rhs: <span class="kw-2">&</span><span class="lifetime">'a </span><span class="macro-nonterminal">$rhs</span>) -> <span class="macro-nonterminal">$t </span>{ |
| (<span class="macro-nonterminal">$method</span>)(<span class="self">self</span>, <<span class="macro-nonterminal">$desired_rhs</span>>::from(<span class="kw-2">*</span>rhs)) |
| } |
| } |
| |
| <span class="kw">impl</span><<span class="lifetime">'a</span>> Pow<<span class="macro-nonterminal">$rhs</span>> <span class="kw">for </span><span class="kw-2">&</span><span class="lifetime">'a </span><span class="macro-nonterminal">$t </span>{ |
| <span class="kw">type </span>Output = <span class="macro-nonterminal">$t</span>; |
| <span class="attribute">#[inline] |
| </span><span class="kw">fn </span>pow(<span class="self">self</span>, rhs: <span class="macro-nonterminal">$rhs</span>) -> <span class="macro-nonterminal">$t </span>{ |
| (<span class="macro-nonterminal">$method</span>)(<span class="kw-2">*</span><span class="self">self</span>, <<span class="macro-nonterminal">$desired_rhs</span>>::from(rhs)) |
| } |
| } |
| |
| <span class="kw">impl</span><<span class="lifetime">'a</span>, <span class="lifetime">'b</span>> Pow<<span class="kw-2">&</span><span class="lifetime">'a </span><span class="macro-nonterminal">$rhs</span>> <span class="kw">for </span><span class="kw-2">&</span><span class="lifetime">'b </span><span class="macro-nonterminal">$t </span>{ |
| <span class="kw">type </span>Output = <span class="macro-nonterminal">$t</span>; |
| <span class="attribute">#[inline] |
| </span><span class="kw">fn </span>pow(<span class="self">self</span>, rhs: <span class="kw-2">&</span><span class="lifetime">'a </span><span class="macro-nonterminal">$rhs</span>) -> <span class="macro-nonterminal">$t </span>{ |
| (<span class="macro-nonterminal">$method</span>)(<span class="kw-2">*</span><span class="self">self</span>, <<span class="macro-nonterminal">$desired_rhs</span>>::from(<span class="kw-2">*</span>rhs)) |
| } |
| } |
| }; |
| } |
| |
| <span class="macro">pow_impl!</span>(u8, u8, u32, u8::pow); |
| <span class="macro">pow_impl!</span>(u8, u16, u32, u8::pow); |
| <span class="macro">pow_impl!</span>(u8, u32, u32, u8::pow); |
| <span class="macro">pow_impl!</span>(u8, usize); |
| <span class="macro">pow_impl!</span>(i8, u8, u32, i8::pow); |
| <span class="macro">pow_impl!</span>(i8, u16, u32, i8::pow); |
| <span class="macro">pow_impl!</span>(i8, u32, u32, i8::pow); |
| <span class="macro">pow_impl!</span>(i8, usize); |
| <span class="macro">pow_impl!</span>(u16, u8, u32, u16::pow); |
| <span class="macro">pow_impl!</span>(u16, u16, u32, u16::pow); |
| <span class="macro">pow_impl!</span>(u16, u32, u32, u16::pow); |
| <span class="macro">pow_impl!</span>(u16, usize); |
| <span class="macro">pow_impl!</span>(i16, u8, u32, i16::pow); |
| <span class="macro">pow_impl!</span>(i16, u16, u32, i16::pow); |
| <span class="macro">pow_impl!</span>(i16, u32, u32, i16::pow); |
| <span class="macro">pow_impl!</span>(i16, usize); |
| <span class="macro">pow_impl!</span>(u32, u8, u32, u32::pow); |
| <span class="macro">pow_impl!</span>(u32, u16, u32, u32::pow); |
| <span class="macro">pow_impl!</span>(u32, u32, u32, u32::pow); |
| <span class="macro">pow_impl!</span>(u32, usize); |
| <span class="macro">pow_impl!</span>(i32, u8, u32, i32::pow); |
| <span class="macro">pow_impl!</span>(i32, u16, u32, i32::pow); |
| <span class="macro">pow_impl!</span>(i32, u32, u32, i32::pow); |
| <span class="macro">pow_impl!</span>(i32, usize); |
| <span class="macro">pow_impl!</span>(u64, u8, u32, u64::pow); |
| <span class="macro">pow_impl!</span>(u64, u16, u32, u64::pow); |
| <span class="macro">pow_impl!</span>(u64, u32, u32, u64::pow); |
| <span class="macro">pow_impl!</span>(u64, usize); |
| <span class="macro">pow_impl!</span>(i64, u8, u32, i64::pow); |
| <span class="macro">pow_impl!</span>(i64, u16, u32, i64::pow); |
| <span class="macro">pow_impl!</span>(i64, u32, u32, i64::pow); |
| <span class="macro">pow_impl!</span>(i64, usize); |
| |
| <span class="attribute">#[cfg(has_i128)] |
| </span><span class="macro">pow_impl!</span>(u128, u8, u32, u128::pow); |
| <span class="attribute">#[cfg(has_i128)] |
| </span><span class="macro">pow_impl!</span>(u128, u16, u32, u128::pow); |
| <span class="attribute">#[cfg(has_i128)] |
| </span><span class="macro">pow_impl!</span>(u128, u32, u32, u128::pow); |
| <span class="attribute">#[cfg(has_i128)] |
| </span><span class="macro">pow_impl!</span>(u128, usize); |
| |
| <span class="attribute">#[cfg(has_i128)] |
| </span><span class="macro">pow_impl!</span>(i128, u8, u32, i128::pow); |
| <span class="attribute">#[cfg(has_i128)] |
| </span><span class="macro">pow_impl!</span>(i128, u16, u32, i128::pow); |
| <span class="attribute">#[cfg(has_i128)] |
| </span><span class="macro">pow_impl!</span>(i128, u32, u32, i128::pow); |
| <span class="attribute">#[cfg(has_i128)] |
| </span><span class="macro">pow_impl!</span>(i128, usize); |
| |
| <span class="macro">pow_impl!</span>(usize, u8, u32, usize::pow); |
| <span class="macro">pow_impl!</span>(usize, u16, u32, usize::pow); |
| <span class="macro">pow_impl!</span>(usize, u32, u32, usize::pow); |
| <span class="macro">pow_impl!</span>(usize, usize); |
| <span class="macro">pow_impl!</span>(isize, u8, u32, isize::pow); |
| <span class="macro">pow_impl!</span>(isize, u16, u32, isize::pow); |
| <span class="macro">pow_impl!</span>(isize, u32, u32, isize::pow); |
| <span class="macro">pow_impl!</span>(isize, usize); |
| <span class="macro">pow_impl!</span>(Wrapping<u8>); |
| <span class="macro">pow_impl!</span>(Wrapping<i8>); |
| <span class="macro">pow_impl!</span>(Wrapping<u16>); |
| <span class="macro">pow_impl!</span>(Wrapping<i16>); |
| <span class="macro">pow_impl!</span>(Wrapping<u32>); |
| <span class="macro">pow_impl!</span>(Wrapping<i32>); |
| <span class="macro">pow_impl!</span>(Wrapping<u64>); |
| <span class="macro">pow_impl!</span>(Wrapping<i64>); |
| <span class="attribute">#[cfg(has_i128)] |
| </span><span class="macro">pow_impl!</span>(Wrapping<u128>); |
| <span class="attribute">#[cfg(has_i128)] |
| </span><span class="macro">pow_impl!</span>(Wrapping<i128>); |
| <span class="macro">pow_impl!</span>(Wrapping<usize>); |
| <span class="macro">pow_impl!</span>(Wrapping<isize>); |
| |
| <span class="comment">// FIXME: these should be possible |
| // pow_impl!(u8, u64); |
| // pow_impl!(i16, u64); |
| // pow_impl!(i8, u64); |
| // pow_impl!(u16, u64); |
| // pow_impl!(u32, u64); |
| // pow_impl!(i32, u64); |
| // pow_impl!(u64, u64); |
| // pow_impl!(i64, u64); |
| // pow_impl!(usize, u64); |
| // pow_impl!(isize, u64); |
| |
| </span><span class="attribute">#[cfg(any(feature = <span class="string">"std"</span>, feature = <span class="string">"libm"</span>))] |
| </span><span class="kw">mod </span>float_impls { |
| <span class="kw">use </span><span class="kw">super</span>::Pow; |
| <span class="kw">use </span>Float; |
| |
| <span class="macro">pow_impl!</span>(f32, i8, i32, <f32 <span class="kw">as </span>Float>::powi); |
| <span class="macro">pow_impl!</span>(f32, u8, i32, <f32 <span class="kw">as </span>Float>::powi); |
| <span class="macro">pow_impl!</span>(f32, i16, i32, <f32 <span class="kw">as </span>Float>::powi); |
| <span class="macro">pow_impl!</span>(f32, u16, i32, <f32 <span class="kw">as </span>Float>::powi); |
| <span class="macro">pow_impl!</span>(f32, i32, i32, <f32 <span class="kw">as </span>Float>::powi); |
| <span class="macro">pow_impl!</span>(f64, i8, i32, <f64 <span class="kw">as </span>Float>::powi); |
| <span class="macro">pow_impl!</span>(f64, u8, i32, <f64 <span class="kw">as </span>Float>::powi); |
| <span class="macro">pow_impl!</span>(f64, i16, i32, <f64 <span class="kw">as </span>Float>::powi); |
| <span class="macro">pow_impl!</span>(f64, u16, i32, <f64 <span class="kw">as </span>Float>::powi); |
| <span class="macro">pow_impl!</span>(f64, i32, i32, <f64 <span class="kw">as </span>Float>::powi); |
| <span class="macro">pow_impl!</span>(f32, f32, f32, <f32 <span class="kw">as </span>Float>::powf); |
| <span class="macro">pow_impl!</span>(f64, f32, f64, <f64 <span class="kw">as </span>Float>::powf); |
| <span class="macro">pow_impl!</span>(f64, f64, f64, <f64 <span class="kw">as </span>Float>::powf); |
| } |
| |
| <span class="doccomment">/// Raises a value to the power of exp, using exponentiation by squaring. |
| /// |
| /// Note that `0⁰` (`pow(0, 0)`) returns `1`. Mathematically this is undefined. |
| /// |
| /// # Example |
| /// |
| /// ```rust |
| /// use num_traits::pow; |
| /// |
| /// assert_eq!(pow(2i8, 4), 16); |
| /// assert_eq!(pow(6u8, 3), 216); |
| /// assert_eq!(pow(0u8, 0), 1); // Be aware if this case affects you |
| /// ``` |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub fn </span>pow<T: Clone + One + Mul<T, Output = T>>(<span class="kw-2">mut </span>base: T, <span class="kw-2">mut </span>exp: usize) -> T { |
| <span class="kw">if </span>exp == <span class="number">0 </span>{ |
| <span class="kw">return </span>T::one(); |
| } |
| |
| <span class="kw">while </span>exp & <span class="number">1 </span>== <span class="number">0 </span>{ |
| base = base.clone() * base; |
| exp >>= <span class="number">1</span>; |
| } |
| <span class="kw">if </span>exp == <span class="number">1 </span>{ |
| <span class="kw">return </span>base; |
| } |
| |
| <span class="kw">let </span><span class="kw-2">mut </span>acc = base.clone(); |
| <span class="kw">while </span>exp > <span class="number">1 </span>{ |
| exp >>= <span class="number">1</span>; |
| base = base.clone() * base; |
| <span class="kw">if </span>exp & <span class="number">1 </span>== <span class="number">1 </span>{ |
| acc = acc * base.clone(); |
| } |
| } |
| acc |
| } |
| |
| <span class="doccomment">/// Raises a value to the power of exp, returning `None` if an overflow occurred. |
| /// |
| /// Note that `0⁰` (`checked_pow(0, 0)`) returns `Some(1)`. Mathematically this is undefined. |
| /// |
| /// Otherwise same as the `pow` function. |
| /// |
| /// # Example |
| /// |
| /// ```rust |
| /// use num_traits::checked_pow; |
| /// |
| /// assert_eq!(checked_pow(2i8, 4), Some(16)); |
| /// assert_eq!(checked_pow(7i8, 8), None); |
| /// assert_eq!(checked_pow(7u32, 8), Some(5_764_801)); |
| /// assert_eq!(checked_pow(0u32, 0), Some(1)); // Be aware if this case affect you |
| /// ``` |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub fn </span>checked_pow<T: Clone + One + CheckedMul>(<span class="kw-2">mut </span>base: T, <span class="kw-2">mut </span>exp: usize) -> <span class="prelude-ty">Option</span><T> { |
| <span class="kw">if </span>exp == <span class="number">0 </span>{ |
| <span class="kw">return </span><span class="prelude-val">Some</span>(T::one()); |
| } |
| |
| <span class="macro">macro_rules! </span>optry { |
| (<span class="macro-nonterminal">$expr</span>:expr) => { |
| <span class="kw">if let </span><span class="prelude-val">Some</span>(val) = <span class="macro-nonterminal">$expr </span>{ |
| val |
| } <span class="kw">else </span>{ |
| <span class="kw">return </span><span class="prelude-val">None</span>; |
| } |
| }; |
| } |
| |
| <span class="kw">while </span>exp & <span class="number">1 </span>== <span class="number">0 </span>{ |
| base = <span class="macro">optry!</span>(base.checked_mul(<span class="kw-2">&</span>base)); |
| exp >>= <span class="number">1</span>; |
| } |
| <span class="kw">if </span>exp == <span class="number">1 </span>{ |
| <span class="kw">return </span><span class="prelude-val">Some</span>(base); |
| } |
| |
| <span class="kw">let </span><span class="kw-2">mut </span>acc = base.clone(); |
| <span class="kw">while </span>exp > <span class="number">1 </span>{ |
| exp >>= <span class="number">1</span>; |
| base = <span class="macro">optry!</span>(base.checked_mul(<span class="kw-2">&</span>base)); |
| <span class="kw">if </span>exp & <span class="number">1 </span>== <span class="number">1 </span>{ |
| acc = <span class="macro">optry!</span>(acc.checked_mul(<span class="kw-2">&</span>base)); |
| } |
| } |
| <span class="prelude-val">Some</span>(acc) |
| } |
| </code></pre></div> |
| </section></div></main><div id="rustdoc-vars" data-root-path="../../" data-current-crate="num_traits" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |
