| <!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/duplicates_impl.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>duplicates_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> |
| <span id="2">2</span> |
| <span id="3">3</span> |
| <span id="4">4</span> |
| <span id="5">5</span> |
| <span id="6">6</span> |
| <span id="7">7</span> |
| <span id="8">8</span> |
| <span id="9">9</span> |
| <span id="10">10</span> |
| <span id="11">11</span> |
| <span id="12">12</span> |
| <span id="13">13</span> |
| <span id="14">14</span> |
| <span id="15">15</span> |
| <span id="16">16</span> |
| <span id="17">17</span> |
| <span id="18">18</span> |
| <span id="19">19</span> |
| <span id="20">20</span> |
| <span id="21">21</span> |
| <span id="22">22</span> |
| <span id="23">23</span> |
| <span id="24">24</span> |
| <span id="25">25</span> |
| <span id="26">26</span> |
| <span id="27">27</span> |
| <span id="28">28</span> |
| <span id="29">29</span> |
| <span id="30">30</span> |
| <span id="31">31</span> |
| <span id="32">32</span> |
| <span id="33">33</span> |
| <span id="34">34</span> |
| <span id="35">35</span> |
| <span id="36">36</span> |
| <span id="37">37</span> |
| <span id="38">38</span> |
| <span id="39">39</span> |
| <span id="40">40</span> |
| <span id="41">41</span> |
| <span id="42">42</span> |
| <span id="43">43</span> |
| <span id="44">44</span> |
| <span id="45">45</span> |
| <span id="46">46</span> |
| <span id="47">47</span> |
| <span id="48">48</span> |
| <span id="49">49</span> |
| <span id="50">50</span> |
| <span id="51">51</span> |
| <span id="52">52</span> |
| <span id="53">53</span> |
| <span id="54">54</span> |
| <span id="55">55</span> |
| <span id="56">56</span> |
| <span id="57">57</span> |
| <span id="58">58</span> |
| <span id="59">59</span> |
| <span id="60">60</span> |
| <span id="61">61</span> |
| <span id="62">62</span> |
| <span id="63">63</span> |
| <span id="64">64</span> |
| <span id="65">65</span> |
| <span id="66">66</span> |
| <span id="67">67</span> |
| <span id="68">68</span> |
| <span id="69">69</span> |
| <span id="70">70</span> |
| <span id="71">71</span> |
| <span id="72">72</span> |
| <span id="73">73</span> |
| <span id="74">74</span> |
| <span id="75">75</span> |
| <span id="76">76</span> |
| <span id="77">77</span> |
| <span id="78">78</span> |
| <span id="79">79</span> |
| <span id="80">80</span> |
| <span id="81">81</span> |
| <span id="82">82</span> |
| <span id="83">83</span> |
| <span id="84">84</span> |
| <span id="85">85</span> |
| <span id="86">86</span> |
| <span id="87">87</span> |
| <span id="88">88</span> |
| <span id="89">89</span> |
| <span id="90">90</span> |
| <span id="91">91</span> |
| <span id="92">92</span> |
| <span id="93">93</span> |
| <span id="94">94</span> |
| <span id="95">95</span> |
| <span id="96">96</span> |
| <span id="97">97</span> |
| <span id="98">98</span> |
| <span id="99">99</span> |
| <span id="100">100</span> |
| <span id="101">101</span> |
| <span id="102">102</span> |
| <span id="103">103</span> |
| <span id="104">104</span> |
| <span id="105">105</span> |
| <span id="106">106</span> |
| <span id="107">107</span> |
| <span id="108">108</span> |
| <span id="109">109</span> |
| <span id="110">110</span> |
| <span id="111">111</span> |
| <span id="112">112</span> |
| <span id="113">113</span> |
| <span id="114">114</span> |
| <span id="115">115</span> |
| <span id="116">116</span> |
| <span id="117">117</span> |
| <span id="118">118</span> |
| <span id="119">119</span> |
| <span id="120">120</span> |
| <span id="121">121</span> |
| <span id="122">122</span> |
| <span id="123">123</span> |
| <span id="124">124</span> |
| <span id="125">125</span> |
| <span id="126">126</span> |
| <span id="127">127</span> |
| <span id="128">128</span> |
| <span id="129">129</span> |
| <span id="130">130</span> |
| <span id="131">131</span> |
| <span id="132">132</span> |
| <span id="133">133</span> |
| <span id="134">134</span> |
| <span id="135">135</span> |
| <span id="136">136</span> |
| <span id="137">137</span> |
| <span id="138">138</span> |
| <span id="139">139</span> |
| <span id="140">140</span> |
| <span id="141">141</span> |
| <span id="142">142</span> |
| <span id="143">143</span> |
| <span id="144">144</span> |
| <span id="145">145</span> |
| <span id="146">146</span> |
| <span id="147">147</span> |
| <span id="148">148</span> |
| <span id="149">149</span> |
| <span id="150">150</span> |
| <span id="151">151</span> |
| <span id="152">152</span> |
| <span id="153">153</span> |
| <span id="154">154</span> |
| <span id="155">155</span> |
| <span id="156">156</span> |
| <span id="157">157</span> |
| <span id="158">158</span> |
| <span id="159">159</span> |
| <span id="160">160</span> |
| <span id="161">161</span> |
| <span id="162">162</span> |
| <span id="163">163</span> |
| <span id="164">164</span> |
| <span id="165">165</span> |
| <span id="166">166</span> |
| <span id="167">167</span> |
| <span id="168">168</span> |
| <span id="169">169</span> |
| <span id="170">170</span> |
| <span id="171">171</span> |
| <span id="172">172</span> |
| <span id="173">173</span> |
| <span id="174">174</span> |
| <span id="175">175</span> |
| <span id="176">176</span> |
| <span id="177">177</span> |
| <span id="178">178</span> |
| <span id="179">179</span> |
| <span id="180">180</span> |
| <span id="181">181</span> |
| <span id="182">182</span> |
| <span id="183">183</span> |
| <span id="184">184</span> |
| <span id="185">185</span> |
| <span id="186">186</span> |
| <span id="187">187</span> |
| <span id="188">188</span> |
| <span id="189">189</span> |
| <span id="190">190</span> |
| <span id="191">191</span> |
| <span id="192">192</span> |
| <span id="193">193</span> |
| <span id="194">194</span> |
| <span id="195">195</span> |
| <span id="196">196</span> |
| <span id="197">197</span> |
| <span id="198">198</span> |
| <span id="199">199</span> |
| <span id="200">200</span> |
| <span id="201">201</span> |
| <span id="202">202</span> |
| <span id="203">203</span> |
| <span id="204">204</span> |
| <span id="205">205</span> |
| <span id="206">206</span> |
| <span id="207">207</span> |
| <span id="208">208</span> |
| <span id="209">209</span> |
| <span id="210">210</span> |
| <span id="211">211</span> |
| <span id="212">212</span> |
| <span id="213">213</span> |
| <span id="214">214</span> |
| <span id="215">215</span> |
| <span id="216">216</span> |
| </pre><pre class="rust"><code><span class="kw">use </span>std::hash::Hash; |
| |
| <span class="kw">mod </span>private { |
| <span class="kw">use </span>std::collections::HashMap; |
| <span class="kw">use </span>std::hash::Hash; |
| <span class="kw">use </span>std::fmt; |
| |
| <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>DuplicatesBy<I: Iterator, Key, F> { |
| <span class="kw">pub</span>(<span class="kw">crate</span>) iter: I, |
| <span class="kw">pub</span>(<span class="kw">crate</span>) meta: Meta<Key, F>, |
| } |
| |
| <span class="kw">impl</span><I, V, F> fmt::Debug <span class="kw">for </span>DuplicatesBy<I, V, F> |
| <span class="kw">where |
| </span>I: Iterator + fmt::Debug, |
| V: fmt::Debug + Hash + Eq, |
| { |
| <span class="macro">debug_fmt_fields!</span>(DuplicatesBy, iter, meta.used); |
| } |
| |
| <span class="kw">impl</span><I: Iterator, Key: Eq + Hash, F> DuplicatesBy<I, Key, F> { |
| <span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>new(iter: I, key_method: F) -> <span class="self">Self </span>{ |
| DuplicatesBy { |
| iter, |
| meta: Meta { |
| used: HashMap::new(), |
| pending: <span class="number">0</span>, |
| key_method, |
| }, |
| } |
| } |
| } |
| |
| <span class="attribute">#[derive(Clone)] |
| </span><span class="kw">pub struct </span>Meta<Key, F> { |
| used: HashMap<Key, bool>, |
| pending: usize, |
| key_method: F, |
| } |
| |
| <span class="kw">impl</span><Key, F> Meta<Key, F> |
| <span class="kw">where |
| </span>Key: Eq + Hash, |
| { |
| <span class="doccomment">/// Takes an item and returns it back to the caller if it's the second time we see it. |
| /// Otherwise the item is consumed and None is returned |
| </span><span class="attribute">#[inline(always)] |
| </span><span class="kw">fn </span>filter<I>(<span class="kw-2">&mut </span><span class="self">self</span>, item: I) -> <span class="prelude-ty">Option</span><I> |
| <span class="kw">where |
| </span>F: KeyMethod<Key, I>, |
| { |
| <span class="kw">let </span>kv = <span class="self">self</span>.key_method.make(item); |
| <span class="kw">match </span><span class="self">self</span>.used.get_mut(kv.key_ref()) { |
| <span class="prelude-val">None </span>=> { |
| <span class="self">self</span>.used.insert(kv.key(), <span class="bool-val">false</span>); |
| <span class="self">self</span>.pending += <span class="number">1</span>; |
| <span class="prelude-val">None |
| </span>} |
| <span class="prelude-val">Some</span>(<span class="bool-val">true</span>) => <span class="prelude-val">None</span>, |
| <span class="prelude-val">Some</span>(produced) => { |
| <span class="kw-2">*</span>produced = <span class="bool-val">true</span>; |
| <span class="self">self</span>.pending -= <span class="number">1</span>; |
| <span class="prelude-val">Some</span>(kv.value()) |
| } |
| } |
| } |
| } |
| |
| <span class="kw">impl</span><I, Key, F> Iterator <span class="kw">for </span>DuplicatesBy<I, Key, F> |
| <span class="kw">where |
| </span>I: Iterator, |
| Key: Eq + Hash, |
| F: KeyMethod<Key, I::Item>, |
| { |
| <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">let </span>DuplicatesBy { iter, meta } = <span class="self">self</span>; |
| iter.find_map(|v| meta.filter(v)) |
| } |
| |
| <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>(<span class="kw">_</span>, hi) = <span class="self">self</span>.iter.size_hint(); |
| <span class="kw">let </span>hi = hi.map(|hi| { |
| <span class="kw">if </span>hi <= <span class="self">self</span>.meta.pending { |
| <span class="comment">// fewer or equally many iter-remaining elements than pending elements |
| // => at most, each iter-remaining element is matched |
| </span>hi |
| } <span class="kw">else </span>{ |
| <span class="comment">// fewer pending elements than iter-remaining elements |
| // => at most: |
| // * each pending element is matched |
| // * the other iter-remaining elements come in pairs |
| </span><span class="self">self</span>.meta.pending + (hi - <span class="self">self</span>.meta.pending) / <span class="number">2 |
| </span>} |
| }); |
| <span class="comment">// The lower bound is always 0 since we might only get unique items from now on |
| </span>(<span class="number">0</span>, hi) |
| } |
| } |
| |
| <span class="kw">impl</span><I, Key, F> DoubleEndedIterator <span class="kw">for </span>DuplicatesBy<I, Key, F> |
| <span class="kw">where |
| </span>I: DoubleEndedIterator, |
| Key: Eq + Hash, |
| F: KeyMethod<Key, I::Item>, |
| { |
| <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">let </span>DuplicatesBy { iter, meta } = <span class="self">self</span>; |
| iter.rev().find_map(|v| meta.filter(v)) |
| } |
| } |
| |
| <span class="doccomment">/// A keying method for use with `DuplicatesBy` |
| </span><span class="kw">pub trait </span>KeyMethod<K, V> { |
| <span class="kw">type </span>Container: KeyXorValue<K, V>; |
| |
| <span class="kw">fn </span>make(<span class="kw-2">&mut </span><span class="self">self</span>, value: V) -> <span class="self">Self</span>::Container; |
| } |
| |
| <span class="doccomment">/// Apply the identity function to elements before checking them for equality. |
| </span><span class="attribute">#[derive(Debug)] |
| </span><span class="kw">pub struct </span>ById; |
| <span class="kw">impl</span><V> KeyMethod<V, V> <span class="kw">for </span>ById { |
| <span class="kw">type </span>Container = JustValue<V>; |
| |
| <span class="kw">fn </span>make(<span class="kw-2">&mut </span><span class="self">self</span>, v: V) -> <span class="self">Self</span>::Container { |
| JustValue(v) |
| } |
| } |
| |
| <span class="doccomment">/// Apply a user-supplied function to elements before checking them for equality. |
| </span><span class="kw">pub struct </span>ByFn<F>(<span class="kw">pub</span>(<span class="kw">crate</span>) F); |
| <span class="kw">impl</span><F> fmt::Debug <span class="kw">for </span>ByFn<F> { |
| <span class="macro">debug_fmt_fields!</span>(ByFn,); |
| } |
| <span class="kw">impl</span><K, V, F> KeyMethod<K, V> <span class="kw">for </span>ByFn<F> |
| <span class="kw">where |
| </span>F: FnMut(<span class="kw-2">&</span>V) -> K, |
| { |
| <span class="kw">type </span>Container = KeyValue<K, V>; |
| |
| <span class="kw">fn </span>make(<span class="kw-2">&mut </span><span class="self">self</span>, v: V) -> <span class="self">Self</span>::Container { |
| KeyValue((<span class="self">self</span>.<span class="number">0</span>)(<span class="kw-2">&</span>v), v) |
| } |
| } |
| |
| <span class="comment">// Implementors of this trait can hold onto a key and a value but only give access to one of them |
| // at a time. This allows the key and the value to be the same value internally |
| </span><span class="kw">pub trait </span>KeyXorValue<K, V> { |
| <span class="kw">fn </span>key_ref(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="kw-2">&</span>K; |
| <span class="kw">fn </span>key(<span class="self">self</span>) -> K; |
| <span class="kw">fn </span>value(<span class="self">self</span>) -> V; |
| } |
| |
| <span class="attribute">#[derive(Debug)] |
| </span><span class="kw">pub struct </span>KeyValue<K, V>(K, V); |
| <span class="kw">impl</span><K, V> KeyXorValue<K, V> <span class="kw">for </span>KeyValue<K, V> { |
| <span class="kw">fn </span>key_ref(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="kw-2">&</span>K { |
| <span class="kw-2">&</span><span class="self">self</span>.<span class="number">0 |
| </span>} |
| <span class="kw">fn </span>key(<span class="self">self</span>) -> K { |
| <span class="self">self</span>.<span class="number">0 |
| </span>} |
| <span class="kw">fn </span>value(<span class="self">self</span>) -> V { |
| <span class="self">self</span>.<span class="number">1 |
| </span>} |
| } |
| |
| <span class="attribute">#[derive(Debug)] |
| </span><span class="kw">pub struct </span>JustValue<V>(V); |
| <span class="kw">impl</span><V> KeyXorValue<V, V> <span class="kw">for </span>JustValue<V> { |
| <span class="kw">fn </span>key_ref(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="kw-2">&</span>V { |
| <span class="kw-2">&</span><span class="self">self</span>.<span class="number">0 |
| </span>} |
| <span class="kw">fn </span>key(<span class="self">self</span>) -> V { |
| <span class="self">self</span>.<span class="number">0 |
| </span>} |
| <span class="kw">fn </span>value(<span class="self">self</span>) -> V { |
| <span class="self">self</span>.<span class="number">0 |
| </span>} |
| } |
| } |
| |
| <span class="doccomment">/// An iterator adapter to filter for duplicate elements. |
| /// |
| /// See [`.duplicates_by()`](crate::Itertools::duplicates_by) for more information. |
| </span><span class="kw">pub type </span>DuplicatesBy<I, V, F> = private::DuplicatesBy<I, V, private::ByFn<F>>; |
| |
| <span class="doccomment">/// Create a new `DuplicatesBy` iterator. |
| </span><span class="kw">pub fn </span>duplicates_by<I, Key, F>(iter: I, f: F) -> DuplicatesBy<I, Key, F> |
| <span class="kw">where |
| </span>Key: Eq + Hash, |
| F: FnMut(<span class="kw-2">&</span>I::Item) -> Key, |
| I: Iterator, |
| { |
| DuplicatesBy::new(iter, private::ByFn(f)) |
| } |
| |
| <span class="doccomment">/// An iterator adapter to filter out duplicate elements. |
| /// |
| /// See [`.duplicates()`](crate::Itertools::duplicates) for more information. |
| </span><span class="kw">pub type </span>Duplicates<I> = private::DuplicatesBy<I, <I <span class="kw">as </span>Iterator>::Item, private::ById>; |
| |
| <span class="doccomment">/// Create a new `Duplicates` iterator. |
| </span><span class="kw">pub fn </span>duplicates<I>(iter: I) -> Duplicates<I> |
| <span class="kw">where |
| </span>I: Iterator, |
| I::Item: Eq + Hash, |
| { |
| Duplicates::new(iter, private::ById) |
| } |
| |
| </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> |
