| <!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/unique_impl.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>unique_impl.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="kw">use </span>std::collections::HashMap; |
| <span class="kw">use </span>std::collections::hash_map::Entry; |
| <span class="kw">use </span>std::hash::Hash; |
| <span class="kw">use </span>std::fmt; |
| <span class="kw">use </span>std::iter::FusedIterator; |
| |
| <span class="doccomment">/// An iterator adapter to filter out duplicate elements. |
| /// |
| /// See [`.unique_by()`](crate::Itertools::unique) for more information. |
| </span><span class="attribute">#[derive(Clone)] |
| #[must_use = <span class="string">"iterator adaptors are lazy and do nothing unless consumed"</span>] |
| </span><span class="kw">pub struct </span>UniqueBy<I: Iterator, V, F> { |
| iter: I, |
| <span class="comment">// Use a Hashmap for the Entry API in order to prevent hashing twice. |
| // This can maybe be replaced with a HashSet once `get_or_insert_with` |
| // or a proper Entry API for Hashset is stable and meets this msrv |
| </span>used: HashMap<V, ()>, |
| f: F, |
| } |
| |
| <span class="kw">impl</span><I, V, F> fmt::Debug <span class="kw">for </span>UniqueBy<I, V, F> |
| <span class="kw">where </span>I: Iterator + fmt::Debug, |
| V: fmt::Debug + Hash + Eq, |
| { |
| <span class="macro">debug_fmt_fields!</span>(UniqueBy, iter, used); |
| } |
| |
| <span class="doccomment">/// Create a new `UniqueBy` iterator. |
| </span><span class="kw">pub fn </span>unique_by<I, V, F>(iter: I, f: F) -> UniqueBy<I, V, F> |
| <span class="kw">where </span>V: Eq + Hash, |
| F: FnMut(<span class="kw-2">&</span>I::Item) -> V, |
| I: Iterator, |
| { |
| UniqueBy { |
| iter, |
| used: HashMap::new(), |
| f, |
| } |
| } |
| |
| <span class="comment">// count the number of new unique keys in iterable (`used` is the set already seen) |
| </span><span class="kw">fn </span>count_new_keys<I, K>(<span class="kw-2">mut </span>used: HashMap<K, ()>, iterable: I) -> usize |
| <span class="kw">where </span>I: IntoIterator<Item=K>, |
| K: Hash + Eq, |
| { |
| <span class="kw">let </span>iter = iterable.into_iter(); |
| <span class="kw">let </span>current_used = used.len(); |
| used.extend(iter.map(|key| (key, ()))); |
| used.len() - current_used |
| } |
| |
| <span class="kw">impl</span><I, V, F> Iterator <span class="kw">for </span>UniqueBy<I, V, F> |
| <span class="kw">where </span>I: Iterator, |
| V: Eq + Hash, |
| F: FnMut(<span class="kw-2">&</span>I::Item) -> V |
| { |
| <span class="kw">type </span>Item = I::Item; |
| |
| <span class="kw">fn </span>next(<span class="kw-2">&mut </span><span class="self">self</span>) -> <span class="prelude-ty">Option</span><<span class="self">Self</span>::Item> { |
| <span class="kw">while let </span><span class="prelude-val">Some</span>(v) = <span class="self">self</span>.iter.next() { |
| <span class="kw">let </span>key = (<span class="self">self</span>.f)(<span class="kw-2">&</span>v); |
| <span class="kw">if </span><span class="self">self</span>.used.insert(key, ()).is_none() { |
| <span class="kw">return </span><span class="prelude-val">Some</span>(v); |
| } |
| } |
| <span class="prelude-val">None |
| </span>} |
| |
| <span class="attribute">#[inline] |
| </span><span class="kw">fn </span>size_hint(<span class="kw-2">&</span><span class="self">self</span>) -> (usize, <span class="prelude-ty">Option</span><usize>) { |
| <span class="kw">let </span>(low, hi) = <span class="self">self</span>.iter.size_hint(); |
| ((low > <span class="number">0 </span>&& <span class="self">self</span>.used.is_empty()) <span class="kw">as </span>usize, hi) |
| } |
| |
| <span class="kw">fn </span>count(<span class="self">self</span>) -> usize { |
| <span class="kw">let </span><span class="kw-2">mut </span>key_f = <span class="self">self</span>.f; |
| count_new_keys(<span class="self">self</span>.used, <span class="self">self</span>.iter.map(<span class="kw">move </span>|elt| key_f(<span class="kw-2">&</span>elt))) |
| } |
| } |
| |
| <span class="kw">impl</span><I, V, F> DoubleEndedIterator <span class="kw">for </span>UniqueBy<I, V, F> |
| <span class="kw">where </span>I: DoubleEndedIterator, |
| V: Eq + Hash, |
| F: FnMut(<span class="kw-2">&</span>I::Item) -> V |
| { |
| <span class="kw">fn </span>next_back(<span class="kw-2">&mut </span><span class="self">self</span>) -> <span class="prelude-ty">Option</span><<span class="self">Self</span>::Item> { |
| <span class="kw">while let </span><span class="prelude-val">Some</span>(v) = <span class="self">self</span>.iter.next_back() { |
| <span class="kw">let </span>key = (<span class="self">self</span>.f)(<span class="kw-2">&</span>v); |
| <span class="kw">if </span><span class="self">self</span>.used.insert(key, ()).is_none() { |
| <span class="kw">return </span><span class="prelude-val">Some</span>(v); |
| } |
| } |
| <span class="prelude-val">None |
| </span>} |
| } |
| |
| <span class="kw">impl</span><I, V, F> FusedIterator <span class="kw">for </span>UniqueBy<I, V, F> |
| <span class="kw">where </span>I: FusedIterator, |
| V: Eq + Hash, |
| F: FnMut(<span class="kw-2">&</span>I::Item) -> V |
| {} |
| |
| <span class="kw">impl</span><I> Iterator <span class="kw">for </span>Unique<I> |
| <span class="kw">where </span>I: Iterator, |
| I::Item: Eq + Hash + Clone |
| { |
| <span class="kw">type </span>Item = I::Item; |
| |
| <span class="kw">fn </span>next(<span class="kw-2">&mut </span><span class="self">self</span>) -> <span class="prelude-ty">Option</span><<span class="self">Self</span>::Item> { |
| <span class="kw">while let </span><span class="prelude-val">Some</span>(v) = <span class="self">self</span>.iter.iter.next() { |
| <span class="kw">if let </span>Entry::Vacant(entry) = <span class="self">self</span>.iter.used.entry(v) { |
| <span class="kw">let </span>elt = entry.key().clone(); |
| entry.insert(()); |
| <span class="kw">return </span><span class="prelude-val">Some</span>(elt); |
| } |
| } |
| <span class="prelude-val">None |
| </span>} |
| |
| <span class="attribute">#[inline] |
| </span><span class="kw">fn </span>size_hint(<span class="kw-2">&</span><span class="self">self</span>) -> (usize, <span class="prelude-ty">Option</span><usize>) { |
| <span class="kw">let </span>(low, hi) = <span class="self">self</span>.iter.iter.size_hint(); |
| ((low > <span class="number">0 </span>&& <span class="self">self</span>.iter.used.is_empty()) <span class="kw">as </span>usize, hi) |
| } |
| |
| <span class="kw">fn </span>count(<span class="self">self</span>) -> usize { |
| count_new_keys(<span class="self">self</span>.iter.used, <span class="self">self</span>.iter.iter) |
| } |
| } |
| |
| <span class="kw">impl</span><I> DoubleEndedIterator <span class="kw">for </span>Unique<I> |
| <span class="kw">where </span>I: DoubleEndedIterator, |
| I::Item: Eq + Hash + Clone |
| { |
| <span class="kw">fn </span>next_back(<span class="kw-2">&mut </span><span class="self">self</span>) -> <span class="prelude-ty">Option</span><<span class="self">Self</span>::Item> { |
| <span class="kw">while let </span><span class="prelude-val">Some</span>(v) = <span class="self">self</span>.iter.iter.next_back() { |
| <span class="kw">if let </span>Entry::Vacant(entry) = <span class="self">self</span>.iter.used.entry(v) { |
| <span class="kw">let </span>elt = entry.key().clone(); |
| entry.insert(()); |
| <span class="kw">return </span><span class="prelude-val">Some</span>(elt); |
| } |
| } |
| <span class="prelude-val">None |
| </span>} |
| } |
| |
| <span class="kw">impl</span><I> FusedIterator <span class="kw">for </span>Unique<I> |
| <span class="kw">where </span>I: FusedIterator, |
| I::Item: Eq + Hash + Clone |
| {} |
| |
| <span class="doccomment">/// An iterator adapter to filter out duplicate elements. |
| /// |
| /// See [`.unique()`](crate::Itertools::unique) for more information. |
| </span><span class="attribute">#[derive(Clone)] |
| #[must_use = <span class="string">"iterator adaptors are lazy and do nothing unless consumed"</span>] |
| </span><span class="kw">pub struct </span>Unique<I: Iterator> { |
| iter: UniqueBy<I, I::Item, ()>, |
| } |
| |
| <span class="kw">impl</span><I> fmt::Debug <span class="kw">for </span>Unique<I> |
| <span class="kw">where </span>I: Iterator + fmt::Debug, |
| I::Item: Hash + Eq + fmt::Debug, |
| { |
| <span class="macro">debug_fmt_fields!</span>(Unique, iter); |
| } |
| |
| <span class="kw">pub fn </span>unique<I>(iter: I) -> Unique<I> |
| <span class="kw">where </span>I: Iterator, |
| I::Item: Eq + Hash, |
| { |
| Unique { |
| iter: UniqueBy { |
| iter, |
| used: HashMap::new(), |
| f: (), |
| } |
| } |
| } |
| </code></pre></div> |
| </section></div></main><div id="rustdoc-vars" data-root-path="../../" data-current-crate="itertools" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |