| <!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/itertools-0.10.5/src/size_hint.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>size_hint.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="../../itertools/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="../../itertools/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">//! Arithmetic on `Iterator.size_hint()` values. |
| //! |
| |
| </span><span class="kw">use </span>std::usize; |
| <span class="kw">use </span>std::cmp; |
| <span class="kw">use </span>std::u32; |
| |
| <span class="doccomment">/// `SizeHint` is the return type of `Iterator::size_hint()`. |
| </span><span class="kw">pub type </span>SizeHint = (usize, <span class="prelude-ty">Option</span><usize>); |
| |
| <span class="doccomment">/// Add `SizeHint` correctly. |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub fn </span>add(a: SizeHint, b: SizeHint) -> SizeHint { |
| <span class="kw">let </span>min = a.<span class="number">0</span>.saturating_add(b.<span class="number">0</span>); |
| <span class="kw">let </span>max = <span class="kw">match </span>(a.<span class="number">1</span>, b.<span class="number">1</span>) { |
| (<span class="prelude-val">Some</span>(x), <span class="prelude-val">Some</span>(y)) => x.checked_add(y), |
| <span class="kw">_ </span>=> <span class="prelude-val">None</span>, |
| }; |
| |
| (min, max) |
| } |
| |
| <span class="doccomment">/// Add `x` correctly to a `SizeHint`. |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub fn </span>add_scalar(sh: SizeHint, x: usize) -> SizeHint { |
| <span class="kw">let </span>(<span class="kw-2">mut </span>low, <span class="kw-2">mut </span>hi) = sh; |
| low = low.saturating_add(x); |
| hi = hi.and_then(|elt| elt.checked_add(x)); |
| (low, hi) |
| } |
| |
| <span class="doccomment">/// Subtract `x` correctly from a `SizeHint`. |
| </span><span class="attribute">#[inline] |
| #[allow(dead_code)] |
| </span><span class="kw">pub fn </span>sub_scalar(sh: SizeHint, x: usize) -> SizeHint { |
| <span class="kw">let </span>(<span class="kw-2">mut </span>low, <span class="kw-2">mut </span>hi) = sh; |
| low = low.saturating_sub(x); |
| hi = hi.map(|elt| elt.saturating_sub(x)); |
| (low, hi) |
| } |
| |
| |
| <span class="doccomment">/// Multiply `SizeHint` correctly |
| /// |
| /// ```ignore |
| /// use std::usize; |
| /// use itertools::size_hint; |
| /// |
| /// assert_eq!(size_hint::mul((3, Some(4)), (3, Some(4))), |
| /// (9, Some(16))); |
| /// |
| /// assert_eq!(size_hint::mul((3, Some(4)), (usize::MAX, None)), |
| /// (usize::MAX, None)); |
| /// |
| /// assert_eq!(size_hint::mul((3, None), (0, Some(0))), |
| /// (0, Some(0))); |
| /// ``` |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub fn </span>mul(a: SizeHint, b: SizeHint) -> SizeHint { |
| <span class="kw">let </span>low = a.<span class="number">0</span>.saturating_mul(b.<span class="number">0</span>); |
| <span class="kw">let </span>hi = <span class="kw">match </span>(a.<span class="number">1</span>, b.<span class="number">1</span>) { |
| (<span class="prelude-val">Some</span>(x), <span class="prelude-val">Some</span>(y)) => x.checked_mul(y), |
| (<span class="prelude-val">Some</span>(<span class="number">0</span>), <span class="prelude-val">None</span>) | (<span class="prelude-val">None</span>, <span class="prelude-val">Some</span>(<span class="number">0</span>)) => <span class="prelude-val">Some</span>(<span class="number">0</span>), |
| <span class="kw">_ </span>=> <span class="prelude-val">None</span>, |
| }; |
| (low, hi) |
| } |
| |
| <span class="doccomment">/// Multiply `x` correctly with a `SizeHint`. |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub fn </span>mul_scalar(sh: SizeHint, x: usize) -> SizeHint { |
| <span class="kw">let </span>(<span class="kw-2">mut </span>low, <span class="kw-2">mut </span>hi) = sh; |
| low = low.saturating_mul(x); |
| hi = hi.and_then(|elt| elt.checked_mul(x)); |
| (low, hi) |
| } |
| |
| <span class="doccomment">/// Raise `base` correctly by a `SizeHint` exponent. |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub fn </span>pow_scalar_base(base: usize, exp: SizeHint) -> SizeHint { |
| <span class="kw">let </span>exp_low = cmp::min(exp.<span class="number">0</span>, u32::MAX <span class="kw">as </span>usize) <span class="kw">as </span>u32; |
| <span class="kw">let </span>low = base.saturating_pow(exp_low); |
| |
| <span class="kw">let </span>hi = exp.<span class="number">1</span>.and_then(|exp| { |
| <span class="kw">let </span>exp_hi = cmp::min(exp, u32::MAX <span class="kw">as </span>usize) <span class="kw">as </span>u32; |
| base.checked_pow(exp_hi) |
| }); |
| |
| (low, hi) |
| } |
| |
| <span class="doccomment">/// Return the maximum |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub fn </span>max(a: SizeHint, b: SizeHint) -> SizeHint { |
| <span class="kw">let </span>(a_lower, a_upper) = a; |
| <span class="kw">let </span>(b_lower, b_upper) = b; |
| |
| <span class="kw">let </span>lower = cmp::max(a_lower, b_lower); |
| |
| <span class="kw">let </span>upper = <span class="kw">match </span>(a_upper, b_upper) { |
| (<span class="prelude-val">Some</span>(x), <span class="prelude-val">Some</span>(y)) => <span class="prelude-val">Some</span>(cmp::max(x, y)), |
| <span class="kw">_ </span>=> <span class="prelude-val">None</span>, |
| }; |
| |
| (lower, upper) |
| } |
| |
| <span class="doccomment">/// Return the minimum |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub fn </span>min(a: SizeHint, b: SizeHint) -> SizeHint { |
| <span class="kw">let </span>(a_lower, a_upper) = a; |
| <span class="kw">let </span>(b_lower, b_upper) = b; |
| <span class="kw">let </span>lower = cmp::min(a_lower, b_lower); |
| <span class="kw">let </span>upper = <span class="kw">match </span>(a_upper, b_upper) { |
| (<span class="prelude-val">Some</span>(u1), <span class="prelude-val">Some</span>(u2)) => <span class="prelude-val">Some</span>(cmp::min(u1, u2)), |
| <span class="kw">_ </span>=> a_upper.or(b_upper), |
| }; |
| (lower, upper) |
| } |
| </code></pre></div> |
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