| <!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/groupbylazy.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>groupbylazy.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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| <span id="522">522</span> |
| <span id="523">523</span> |
| <span id="524">524</span> |
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| <span id="526">526</span> |
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| <span id="536">536</span> |
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| <span id="538">538</span> |
| <span id="539">539</span> |
| <span id="540">540</span> |
| <span id="541">541</span> |
| <span id="542">542</span> |
| <span id="543">543</span> |
| <span id="544">544</span> |
| <span id="545">545</span> |
| <span id="546">546</span> |
| <span id="547">547</span> |
| <span id="548">548</span> |
| <span id="549">549</span> |
| <span id="550">550</span> |
| <span id="551">551</span> |
| <span id="552">552</span> |
| <span id="553">553</span> |
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| <span id="556">556</span> |
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| <span id="559">559</span> |
| <span id="560">560</span> |
| <span id="561">561</span> |
| <span id="562">562</span> |
| <span id="563">563</span> |
| <span id="564">564</span> |
| <span id="565">565</span> |
| <span id="566">566</span> |
| <span id="567">567</span> |
| <span id="568">568</span> |
| <span id="569">569</span> |
| <span id="570">570</span> |
| <span id="571">571</span> |
| </pre><pre class="rust"><code><span class="kw">use </span>std::cell::{Cell, RefCell}; |
| <span class="kw">use </span>alloc::vec::{<span class="self">self</span>, Vec}; |
| |
| <span class="doccomment">/// A trait to unify `FnMut` for `GroupBy` with the chunk key in `IntoChunks` |
| </span><span class="kw">trait </span>KeyFunction<A> { |
| <span class="kw">type </span>Key; |
| <span class="kw">fn </span>call_mut(<span class="kw-2">&mut </span><span class="self">self</span>, arg: A) -> <span class="self">Self</span>::Key; |
| } |
| |
| <span class="kw">impl</span><A, K, F: <span class="question-mark">?</span>Sized> KeyFunction<A> <span class="kw">for </span>F |
| <span class="kw">where </span>F: FnMut(A) -> K |
| { |
| <span class="kw">type </span>Key = K; |
| <span class="attribute">#[inline] |
| </span><span class="kw">fn </span>call_mut(<span class="kw-2">&mut </span><span class="self">self</span>, arg: A) -> <span class="self">Self</span>::Key { |
| (<span class="kw-2">*</span><span class="self">self</span>)(arg) |
| } |
| } |
| |
| |
| <span class="doccomment">/// `ChunkIndex` acts like the grouping key function for `IntoChunks` |
| </span><span class="attribute">#[derive(Debug)] |
| </span><span class="kw">struct </span>ChunkIndex { |
| size: usize, |
| index: usize, |
| key: usize, |
| } |
| |
| <span class="kw">impl </span>ChunkIndex { |
| <span class="attribute">#[inline(always)] |
| </span><span class="kw">fn </span>new(size: usize) -> <span class="self">Self </span>{ |
| ChunkIndex { |
| size, |
| index: <span class="number">0</span>, |
| key: <span class="number">0</span>, |
| } |
| } |
| } |
| |
| <span class="kw">impl</span><A> KeyFunction<A> <span class="kw">for </span>ChunkIndex { |
| <span class="kw">type </span>Key = usize; |
| <span class="attribute">#[inline(always)] |
| </span><span class="kw">fn </span>call_mut(<span class="kw-2">&mut </span><span class="self">self</span>, _arg: A) -> <span class="self">Self</span>::Key { |
| <span class="kw">if </span><span class="self">self</span>.index == <span class="self">self</span>.size { |
| <span class="self">self</span>.key += <span class="number">1</span>; |
| <span class="self">self</span>.index = <span class="number">0</span>; |
| } |
| <span class="self">self</span>.index += <span class="number">1</span>; |
| <span class="self">self</span>.key |
| } |
| } |
| |
| |
| <span class="kw">struct </span>GroupInner<K, I, F> |
| <span class="kw">where </span>I: Iterator |
| { |
| key: F, |
| iter: I, |
| current_key: <span class="prelude-ty">Option</span><K>, |
| current_elt: <span class="prelude-ty">Option</span><I::Item>, |
| <span class="doccomment">/// flag set if iterator is exhausted |
| </span>done: bool, |
| <span class="doccomment">/// Index of group we are currently buffering or visiting |
| </span>top_group: usize, |
| <span class="doccomment">/// Least index for which we still have elements buffered |
| </span>oldest_buffered_group: usize, |
| <span class="doccomment">/// Group index for `buffer[0]` -- the slots |
| /// bottom_group..oldest_buffered_group are unused and will be erased when |
| /// that range is large enough. |
| </span>bottom_group: usize, |
| <span class="doccomment">/// Buffered groups, from `bottom_group` (index 0) to `top_group`. |
| </span>buffer: Vec<vec::IntoIter<I::Item>>, |
| <span class="doccomment">/// index of last group iter that was dropped, usize::MAX == none |
| </span>dropped_group: usize, |
| } |
| |
| <span class="kw">impl</span><K, I, F> GroupInner<K, I, F> |
| <span class="kw">where </span>I: Iterator, |
| F: <span class="kw">for</span><<span class="lifetime">'a</span>> KeyFunction<<span class="kw-2">&</span><span class="lifetime">'a </span>I::Item, Key=K>, |
| K: PartialEq, |
| { |
| <span class="doccomment">/// `client`: Index of group that requests next element |
| </span><span class="attribute">#[inline(always)] |
| </span><span class="kw">fn </span>step(<span class="kw-2">&mut </span><span class="self">self</span>, client: usize) -> <span class="prelude-ty">Option</span><I::Item> { |
| <span class="comment">/* |
| println!("client={}, bottom_group={}, oldest_buffered_group={}, top_group={}, buffers=[{}]", |
| client, self.bottom_group, self.oldest_buffered_group, |
| self.top_group, |
| self.buffer.iter().map(|elt| elt.len()).format(", ")); |
| */ |
| </span><span class="kw">if </span>client < <span class="self">self</span>.oldest_buffered_group { |
| <span class="prelude-val">None |
| </span>} <span class="kw">else if </span>client < <span class="self">self</span>.top_group || |
| (client == <span class="self">self</span>.top_group && |
| <span class="self">self</span>.buffer.len() > <span class="self">self</span>.top_group - <span class="self">self</span>.bottom_group) |
| { |
| <span class="self">self</span>.lookup_buffer(client) |
| } <span class="kw">else if </span><span class="self">self</span>.done { |
| <span class="prelude-val">None |
| </span>} <span class="kw">else if </span><span class="self">self</span>.top_group == client { |
| <span class="self">self</span>.step_current() |
| } <span class="kw">else </span>{ |
| <span class="self">self</span>.step_buffering(client) |
| } |
| } |
| |
| <span class="attribute">#[inline(never)] |
| </span><span class="kw">fn </span>lookup_buffer(<span class="kw-2">&mut </span><span class="self">self</span>, client: usize) -> <span class="prelude-ty">Option</span><I::Item> { |
| <span class="comment">// if `bufidx` doesn't exist in self.buffer, it might be empty |
| </span><span class="kw">let </span>bufidx = client - <span class="self">self</span>.bottom_group; |
| <span class="kw">if </span>client < <span class="self">self</span>.oldest_buffered_group { |
| <span class="kw">return </span><span class="prelude-val">None</span>; |
| } |
| <span class="kw">let </span>elt = <span class="self">self</span>.buffer.get_mut(bufidx).and_then(|queue| queue.next()); |
| <span class="kw">if </span>elt.is_none() && client == <span class="self">self</span>.oldest_buffered_group { |
| <span class="comment">// FIXME: VecDeque is unfortunately not zero allocation when empty, |
| // so we do this job manually. |
| // `bottom_group..oldest_buffered_group` is unused, and if it's large enough, erase it. |
| </span><span class="self">self</span>.oldest_buffered_group += <span class="number">1</span>; |
| <span class="comment">// skip forward further empty queues too |
| </span><span class="kw">while </span><span class="self">self</span>.buffer.get(<span class="self">self</span>.oldest_buffered_group - <span class="self">self</span>.bottom_group) |
| .map_or(<span class="bool-val">false</span>, |buf| buf.len() == <span class="number">0</span>) |
| { |
| <span class="self">self</span>.oldest_buffered_group += <span class="number">1</span>; |
| } |
| |
| <span class="kw">let </span>nclear = <span class="self">self</span>.oldest_buffered_group - <span class="self">self</span>.bottom_group; |
| <span class="kw">if </span>nclear > <span class="number">0 </span>&& nclear >= <span class="self">self</span>.buffer.len() / <span class="number">2 </span>{ |
| <span class="kw">let </span><span class="kw-2">mut </span>i = <span class="number">0</span>; |
| <span class="self">self</span>.buffer.retain(|buf| { |
| i += <span class="number">1</span>; |
| <span class="macro">debug_assert!</span>(buf.len() == <span class="number">0 </span>|| i > nclear); |
| i > nclear |
| }); |
| <span class="self">self</span>.bottom_group = <span class="self">self</span>.oldest_buffered_group; |
| } |
| } |
| elt |
| } |
| |
| <span class="doccomment">/// Take the next element from the iterator, and set the done |
| /// flag if exhausted. Must not be called after done. |
| </span><span class="attribute">#[inline(always)] |
| </span><span class="kw">fn </span>next_element(<span class="kw-2">&mut </span><span class="self">self</span>) -> <span class="prelude-ty">Option</span><I::Item> { |
| <span class="macro">debug_assert!</span>(!<span class="self">self</span>.done); |
| <span class="kw">match </span><span class="self">self</span>.iter.next() { |
| <span class="prelude-val">None </span>=> { <span class="self">self</span>.done = <span class="bool-val">true</span>; <span class="prelude-val">None </span>} |
| otherwise => otherwise, |
| } |
| } |
| |
| |
| <span class="attribute">#[inline(never)] |
| </span><span class="kw">fn </span>step_buffering(<span class="kw-2">&mut </span><span class="self">self</span>, client: usize) -> <span class="prelude-ty">Option</span><I::Item> { |
| <span class="comment">// requested a later group -- walk through the current group up to |
| // the requested group index, and buffer the elements (unless |
| // the group is marked as dropped). |
| // Because the `Groups` iterator is always the first to request |
| // each group index, client is the next index efter top_group. |
| </span><span class="macro">debug_assert!</span>(<span class="self">self</span>.top_group + <span class="number">1 </span>== client); |
| <span class="kw">let </span><span class="kw-2">mut </span>group = Vec::new(); |
| |
| <span class="kw">if let </span><span class="prelude-val">Some</span>(elt) = <span class="self">self</span>.current_elt.take() { |
| <span class="kw">if </span><span class="self">self</span>.top_group != <span class="self">self</span>.dropped_group { |
| group.push(elt); |
| } |
| } |
| <span class="kw">let </span><span class="kw-2">mut </span>first_elt = <span class="prelude-val">None</span>; <span class="comment">// first element of the next group |
| |
| </span><span class="kw">while let </span><span class="prelude-val">Some</span>(elt) = <span class="self">self</span>.next_element() { |
| <span class="kw">let </span>key = <span class="self">self</span>.key.call_mut(<span class="kw-2">&</span>elt); |
| <span class="kw">match </span><span class="self">self</span>.current_key.take() { |
| <span class="prelude-val">None </span>=> {} |
| <span class="prelude-val">Some</span>(old_key) => <span class="kw">if </span>old_key != key { |
| <span class="self">self</span>.current_key = <span class="prelude-val">Some</span>(key); |
| first_elt = <span class="prelude-val">Some</span>(elt); |
| <span class="kw">break</span>; |
| }, |
| } |
| <span class="self">self</span>.current_key = <span class="prelude-val">Some</span>(key); |
| <span class="kw">if </span><span class="self">self</span>.top_group != <span class="self">self</span>.dropped_group { |
| group.push(elt); |
| } |
| } |
| |
| <span class="kw">if </span><span class="self">self</span>.top_group != <span class="self">self</span>.dropped_group { |
| <span class="self">self</span>.push_next_group(group); |
| } |
| <span class="kw">if </span>first_elt.is_some() { |
| <span class="self">self</span>.top_group += <span class="number">1</span>; |
| <span class="macro">debug_assert!</span>(<span class="self">self</span>.top_group == client); |
| } |
| first_elt |
| } |
| |
| <span class="kw">fn </span>push_next_group(<span class="kw-2">&mut </span><span class="self">self</span>, group: Vec<I::Item>) { |
| <span class="comment">// When we add a new buffered group, fill up slots between oldest_buffered_group and top_group |
| </span><span class="kw">while </span><span class="self">self</span>.top_group - <span class="self">self</span>.bottom_group > <span class="self">self</span>.buffer.len() { |
| <span class="kw">if </span><span class="self">self</span>.buffer.is_empty() { |
| <span class="self">self</span>.bottom_group += <span class="number">1</span>; |
| <span class="self">self</span>.oldest_buffered_group += <span class="number">1</span>; |
| } <span class="kw">else </span>{ |
| <span class="self">self</span>.buffer.push(Vec::new().into_iter()); |
| } |
| } |
| <span class="self">self</span>.buffer.push(group.into_iter()); |
| <span class="macro">debug_assert!</span>(<span class="self">self</span>.top_group + <span class="number">1 </span>- <span class="self">self</span>.bottom_group == <span class="self">self</span>.buffer.len()); |
| } |
| |
| <span class="doccomment">/// This is the immediate case, where we use no buffering |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">fn </span>step_current(<span class="kw-2">&mut </span><span class="self">self</span>) -> <span class="prelude-ty">Option</span><I::Item> { |
| <span class="macro">debug_assert!</span>(!<span class="self">self</span>.done); |
| <span class="kw">if let </span>elt @ <span class="prelude-val">Some</span>(..) = <span class="self">self</span>.current_elt.take() { |
| <span class="kw">return </span>elt; |
| } |
| <span class="kw">match </span><span class="self">self</span>.next_element() { |
| <span class="prelude-val">None </span>=> <span class="prelude-val">None</span>, |
| <span class="prelude-val">Some</span>(elt) => { |
| <span class="kw">let </span>key = <span class="self">self</span>.key.call_mut(<span class="kw-2">&</span>elt); |
| <span class="kw">match </span><span class="self">self</span>.current_key.take() { |
| <span class="prelude-val">None </span>=> {} |
| <span class="prelude-val">Some</span>(old_key) => <span class="kw">if </span>old_key != key { |
| <span class="self">self</span>.current_key = <span class="prelude-val">Some</span>(key); |
| <span class="self">self</span>.current_elt = <span class="prelude-val">Some</span>(elt); |
| <span class="self">self</span>.top_group += <span class="number">1</span>; |
| <span class="kw">return </span><span class="prelude-val">None</span>; |
| }, |
| } |
| <span class="self">self</span>.current_key = <span class="prelude-val">Some</span>(key); |
| <span class="prelude-val">Some</span>(elt) |
| } |
| } |
| } |
| |
| <span class="doccomment">/// Request the just started groups' key. |
| /// |
| /// `client`: Index of group |
| /// |
| /// **Panics** if no group key is available. |
| </span><span class="kw">fn </span>group_key(<span class="kw-2">&mut </span><span class="self">self</span>, client: usize) -> K { |
| <span class="comment">// This can only be called after we have just returned the first |
| // element of a group. |
| // Perform this by simply buffering one more element, grabbing the |
| // next key. |
| </span><span class="macro">debug_assert!</span>(!<span class="self">self</span>.done); |
| <span class="macro">debug_assert!</span>(client == <span class="self">self</span>.top_group); |
| <span class="macro">debug_assert!</span>(<span class="self">self</span>.current_key.is_some()); |
| <span class="macro">debug_assert!</span>(<span class="self">self</span>.current_elt.is_none()); |
| <span class="kw">let </span>old_key = <span class="self">self</span>.current_key.take().unwrap(); |
| <span class="kw">if let </span><span class="prelude-val">Some</span>(elt) = <span class="self">self</span>.next_element() { |
| <span class="kw">let </span>key = <span class="self">self</span>.key.call_mut(<span class="kw-2">&</span>elt); |
| <span class="kw">if </span>old_key != key { |
| <span class="self">self</span>.top_group += <span class="number">1</span>; |
| } |
| <span class="self">self</span>.current_key = <span class="prelude-val">Some</span>(key); |
| <span class="self">self</span>.current_elt = <span class="prelude-val">Some</span>(elt); |
| } |
| old_key |
| } |
| } |
| |
| <span class="kw">impl</span><K, I, F> GroupInner<K, I, F> |
| <span class="kw">where </span>I: Iterator, |
| { |
| <span class="doccomment">/// Called when a group is dropped |
| </span><span class="kw">fn </span>drop_group(<span class="kw-2">&mut </span><span class="self">self</span>, client: usize) { |
| <span class="comment">// It's only useful to track the maximal index |
| </span><span class="kw">if </span><span class="self">self</span>.dropped_group == !<span class="number">0 </span>|| client > <span class="self">self</span>.dropped_group { |
| <span class="self">self</span>.dropped_group = client; |
| } |
| } |
| } |
| |
| <span class="doccomment">/// `GroupBy` is the storage for the lazy grouping operation. |
| /// |
| /// If the groups are consumed in their original order, or if each |
| /// group is dropped without keeping it around, then `GroupBy` uses |
| /// no allocations. It needs allocations only if several group iterators |
| /// are alive at the same time. |
| /// |
| /// This type implements [`IntoIterator`] (it is **not** an iterator |
| /// itself), because the group iterators need to borrow from this |
| /// value. It should be stored in a local variable or temporary and |
| /// iterated. |
| /// |
| /// See [`.group_by()`](crate::Itertools::group_by) for more information. |
| </span><span class="attribute">#[must_use = <span class="string">"iterator adaptors are lazy and do nothing unless consumed"</span>] |
| </span><span class="kw">pub struct </span>GroupBy<K, I, F> |
| <span class="kw">where </span>I: Iterator, |
| { |
| inner: RefCell<GroupInner<K, I, F>>, |
| <span class="comment">// the group iterator's current index. Keep this in the main value |
| // so that simultaneous iterators all use the same state. |
| </span>index: Cell<usize>, |
| } |
| |
| <span class="doccomment">/// Create a new |
| </span><span class="kw">pub fn </span>new<K, J, F>(iter: J, f: F) -> GroupBy<K, J::IntoIter, F> |
| <span class="kw">where </span>J: IntoIterator, |
| F: FnMut(<span class="kw-2">&</span>J::Item) -> K, |
| { |
| GroupBy { |
| inner: RefCell::new(GroupInner { |
| key: f, |
| iter: iter.into_iter(), |
| current_key: <span class="prelude-val">None</span>, |
| current_elt: <span class="prelude-val">None</span>, |
| done: <span class="bool-val">false</span>, |
| top_group: <span class="number">0</span>, |
| oldest_buffered_group: <span class="number">0</span>, |
| bottom_group: <span class="number">0</span>, |
| buffer: Vec::new(), |
| dropped_group: !<span class="number">0</span>, |
| }), |
| index: Cell::new(<span class="number">0</span>), |
| } |
| } |
| |
| <span class="kw">impl</span><K, I, F> GroupBy<K, I, F> |
| <span class="kw">where </span>I: Iterator, |
| { |
| <span class="doccomment">/// `client`: Index of group that requests next element |
| </span><span class="kw">fn </span>step(<span class="kw-2">&</span><span class="self">self</span>, client: usize) -> <span class="prelude-ty">Option</span><I::Item> |
| <span class="kw">where </span>F: FnMut(<span class="kw-2">&</span>I::Item) -> K, |
| K: PartialEq, |
| { |
| <span class="self">self</span>.inner.borrow_mut().step(client) |
| } |
| |
| <span class="doccomment">/// `client`: Index of group |
| </span><span class="kw">fn </span>drop_group(<span class="kw-2">&</span><span class="self">self</span>, client: usize) { |
| <span class="self">self</span>.inner.borrow_mut().drop_group(client); |
| } |
| } |
| |
| <span class="kw">impl</span><<span class="lifetime">'a</span>, K, I, F> IntoIterator <span class="kw">for </span><span class="kw-2">&</span><span class="lifetime">'a </span>GroupBy<K, I, F> |
| <span class="kw">where </span>I: Iterator, |
| I::Item: <span class="lifetime">'a</span>, |
| F: FnMut(<span class="kw-2">&</span>I::Item) -> K, |
| K: PartialEq |
| { |
| <span class="kw">type </span>Item = (K, Group<<span class="lifetime">'a</span>, K, I, F>); |
| <span class="kw">type </span>IntoIter = Groups<<span class="lifetime">'a</span>, K, I, F>; |
| |
| <span class="kw">fn </span>into_iter(<span class="self">self</span>) -> <span class="self">Self</span>::IntoIter { |
| Groups { parent: <span class="self">self </span>} |
| } |
| } |
| |
| |
| <span class="doccomment">/// An iterator that yields the Group iterators. |
| /// |
| /// Iterator element type is `(K, Group)`: |
| /// the group's key `K` and the group's iterator. |
| /// |
| /// See [`.group_by()`](crate::Itertools::group_by) for more information. |
| </span><span class="attribute">#[must_use = <span class="string">"iterator adaptors are lazy and do nothing unless consumed"</span>] |
| </span><span class="kw">pub struct </span>Groups<<span class="lifetime">'a</span>, K: <span class="lifetime">'a</span>, I: <span class="lifetime">'a</span>, F: <span class="lifetime">'a</span>> |
| <span class="kw">where </span>I: Iterator, |
| I::Item: <span class="lifetime">'a |
| </span>{ |
| parent: <span class="kw-2">&</span><span class="lifetime">'a </span>GroupBy<K, I, F>, |
| } |
| |
| <span class="kw">impl</span><<span class="lifetime">'a</span>, K, I, F> Iterator <span class="kw">for </span>Groups<<span class="lifetime">'a</span>, K, I, F> |
| <span class="kw">where </span>I: Iterator, |
| I::Item: <span class="lifetime">'a</span>, |
| F: FnMut(<span class="kw-2">&</span>I::Item) -> K, |
| K: PartialEq |
| { |
| <span class="kw">type </span>Item = (K, Group<<span class="lifetime">'a</span>, K, I, F>); |
| |
| <span class="attribute">#[inline] |
| </span><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>index = <span class="self">self</span>.parent.index.get(); |
| <span class="self">self</span>.parent.index.set(index + <span class="number">1</span>); |
| <span class="kw">let </span>inner = <span class="kw-2">&mut *</span><span class="self">self</span>.parent.inner.borrow_mut(); |
| inner.step(index).map(|elt| { |
| <span class="kw">let </span>key = inner.group_key(index); |
| (key, Group { |
| parent: <span class="self">self</span>.parent, |
| index, |
| first: <span class="prelude-val">Some</span>(elt), |
| }) |
| }) |
| } |
| } |
| |
| <span class="doccomment">/// An iterator for the elements in a single group. |
| /// |
| /// Iterator element type is `I::Item`. |
| </span><span class="kw">pub struct </span>Group<<span class="lifetime">'a</span>, K: <span class="lifetime">'a</span>, I: <span class="lifetime">'a</span>, F: <span class="lifetime">'a</span>> |
| <span class="kw">where </span>I: Iterator, |
| I::Item: <span class="lifetime">'a</span>, |
| { |
| parent: <span class="kw-2">&</span><span class="lifetime">'a </span>GroupBy<K, I, F>, |
| index: usize, |
| first: <span class="prelude-ty">Option</span><I::Item>, |
| } |
| |
| <span class="kw">impl</span><<span class="lifetime">'a</span>, K, I, F> Drop <span class="kw">for </span>Group<<span class="lifetime">'a</span>, K, I, F> |
| <span class="kw">where </span>I: Iterator, |
| I::Item: <span class="lifetime">'a</span>, |
| { |
| <span class="kw">fn </span>drop(<span class="kw-2">&mut </span><span class="self">self</span>) { |
| <span class="self">self</span>.parent.drop_group(<span class="self">self</span>.index); |
| } |
| } |
| |
| <span class="kw">impl</span><<span class="lifetime">'a</span>, K, I, F> Iterator <span class="kw">for </span>Group<<span class="lifetime">'a</span>, K, I, F> |
| <span class="kw">where </span>I: Iterator, |
| I::Item: <span class="lifetime">'a</span>, |
| F: FnMut(<span class="kw-2">&</span>I::Item) -> K, |
| K: PartialEq, |
| { |
| <span class="kw">type </span>Item = I::Item; |
| <span class="attribute">#[inline] |
| </span><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">if let </span>elt @ <span class="prelude-val">Some</span>(..) = <span class="self">self</span>.first.take() { |
| <span class="kw">return </span>elt; |
| } |
| <span class="self">self</span>.parent.step(<span class="self">self</span>.index) |
| } |
| } |
| |
| <span class="comment">///// IntoChunks ///// |
| |
| </span><span class="doccomment">/// Create a new |
| </span><span class="kw">pub fn </span>new_chunks<J>(iter: J, size: usize) -> IntoChunks<J::IntoIter> |
| <span class="kw">where </span>J: IntoIterator, |
| { |
| IntoChunks { |
| inner: RefCell::new(GroupInner { |
| key: ChunkIndex::new(size), |
| iter: iter.into_iter(), |
| current_key: <span class="prelude-val">None</span>, |
| current_elt: <span class="prelude-val">None</span>, |
| done: <span class="bool-val">false</span>, |
| top_group: <span class="number">0</span>, |
| oldest_buffered_group: <span class="number">0</span>, |
| bottom_group: <span class="number">0</span>, |
| buffer: Vec::new(), |
| dropped_group: !<span class="number">0</span>, |
| }), |
| index: Cell::new(<span class="number">0</span>), |
| } |
| } |
| |
| |
| <span class="doccomment">/// `ChunkLazy` is the storage for a lazy chunking operation. |
| /// |
| /// `IntoChunks` behaves just like `GroupBy`: it is iterable, and |
| /// it only buffers if several chunk iterators are alive at the same time. |
| /// |
| /// This type implements [`IntoIterator`] (it is **not** an iterator |
| /// itself), because the chunk iterators need to borrow from this |
| /// value. It should be stored in a local variable or temporary and |
| /// iterated. |
| /// |
| /// Iterator element type is `Chunk`, each chunk's iterator. |
| /// |
| /// See [`.chunks()`](crate::Itertools::chunks) for more information. |
| </span><span class="attribute">#[must_use = <span class="string">"iterator adaptors are lazy and do nothing unless consumed"</span>] |
| </span><span class="kw">pub struct </span>IntoChunks<I> |
| <span class="kw">where </span>I: Iterator, |
| { |
| inner: RefCell<GroupInner<usize, I, ChunkIndex>>, |
| <span class="comment">// the chunk iterator's current index. Keep this in the main value |
| // so that simultaneous iterators all use the same state. |
| </span>index: Cell<usize>, |
| } |
| |
| |
| <span class="kw">impl</span><I> IntoChunks<I> |
| <span class="kw">where </span>I: Iterator, |
| { |
| <span class="doccomment">/// `client`: Index of chunk that requests next element |
| </span><span class="kw">fn </span>step(<span class="kw-2">&</span><span class="self">self</span>, client: usize) -> <span class="prelude-ty">Option</span><I::Item> { |
| <span class="self">self</span>.inner.borrow_mut().step(client) |
| } |
| |
| <span class="doccomment">/// `client`: Index of chunk |
| </span><span class="kw">fn </span>drop_group(<span class="kw-2">&</span><span class="self">self</span>, client: usize) { |
| <span class="self">self</span>.inner.borrow_mut().drop_group(client); |
| } |
| } |
| |
| <span class="kw">impl</span><<span class="lifetime">'a</span>, I> IntoIterator <span class="kw">for </span><span class="kw-2">&</span><span class="lifetime">'a </span>IntoChunks<I> |
| <span class="kw">where </span>I: Iterator, |
| I::Item: <span class="lifetime">'a</span>, |
| { |
| <span class="kw">type </span>Item = Chunk<<span class="lifetime">'a</span>, I>; |
| <span class="kw">type </span>IntoIter = Chunks<<span class="lifetime">'a</span>, I>; |
| |
| <span class="kw">fn </span>into_iter(<span class="self">self</span>) -> <span class="self">Self</span>::IntoIter { |
| Chunks { |
| parent: <span class="self">self</span>, |
| } |
| } |
| } |
| |
| |
| <span class="doccomment">/// An iterator that yields the Chunk iterators. |
| /// |
| /// Iterator element type is `Chunk`. |
| /// |
| /// See [`.chunks()`](crate::Itertools::chunks) for more information. |
| </span><span class="attribute">#[must_use = <span class="string">"iterator adaptors are lazy and do nothing unless consumed"</span>] |
| </span><span class="kw">pub struct </span>Chunks<<span class="lifetime">'a</span>, I: <span class="lifetime">'a</span>> |
| <span class="kw">where </span>I: Iterator, |
| I::Item: <span class="lifetime">'a</span>, |
| { |
| parent: <span class="kw-2">&</span><span class="lifetime">'a </span>IntoChunks<I>, |
| } |
| |
| <span class="kw">impl</span><<span class="lifetime">'a</span>, I> Iterator <span class="kw">for </span>Chunks<<span class="lifetime">'a</span>, I> |
| <span class="kw">where </span>I: Iterator, |
| I::Item: <span class="lifetime">'a</span>, |
| { |
| <span class="kw">type </span>Item = Chunk<<span class="lifetime">'a</span>, I>; |
| |
| <span class="attribute">#[inline] |
| </span><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>index = <span class="self">self</span>.parent.index.get(); |
| <span class="self">self</span>.parent.index.set(index + <span class="number">1</span>); |
| <span class="kw">let </span>inner = <span class="kw-2">&mut *</span><span class="self">self</span>.parent.inner.borrow_mut(); |
| inner.step(index).map(|elt| { |
| Chunk { |
| parent: <span class="self">self</span>.parent, |
| index, |
| first: <span class="prelude-val">Some</span>(elt), |
| } |
| }) |
| } |
| } |
| |
| <span class="doccomment">/// An iterator for the elements in a single chunk. |
| /// |
| /// Iterator element type is `I::Item`. |
| </span><span class="kw">pub struct </span>Chunk<<span class="lifetime">'a</span>, I: <span class="lifetime">'a</span>> |
| <span class="kw">where </span>I: Iterator, |
| I::Item: <span class="lifetime">'a</span>, |
| { |
| parent: <span class="kw-2">&</span><span class="lifetime">'a </span>IntoChunks<I>, |
| index: usize, |
| first: <span class="prelude-ty">Option</span><I::Item>, |
| } |
| |
| <span class="kw">impl</span><<span class="lifetime">'a</span>, I> Drop <span class="kw">for </span>Chunk<<span class="lifetime">'a</span>, I> |
| <span class="kw">where </span>I: Iterator, |
| I::Item: <span class="lifetime">'a</span>, |
| { |
| <span class="kw">fn </span>drop(<span class="kw-2">&mut </span><span class="self">self</span>) { |
| <span class="self">self</span>.parent.drop_group(<span class="self">self</span>.index); |
| } |
| } |
| |
| <span class="kw">impl</span><<span class="lifetime">'a</span>, I> Iterator <span class="kw">for </span>Chunk<<span class="lifetime">'a</span>, I> |
| <span class="kw">where </span>I: Iterator, |
| I::Item: <span class="lifetime">'a</span>, |
| { |
| <span class="kw">type </span>Item = I::Item; |
| <span class="attribute">#[inline] |
| </span><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">if let </span>elt @ <span class="prelude-val">Some</span>(..) = <span class="self">self</span>.first.take() { |
| <span class="kw">return </span>elt; |
| } |
| <span class="self">self</span>.parent.step(<span class="self">self</span>.index) |
| } |
| } |
| </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> |
