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<section id='main' class="content"><pre class="line-numbers"><span id="1"> 1</span>
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</pre><pre class="rust ">
<span class="comment">// Copyright 2013-2016 The Rust Project Developers. See the COPYRIGHT</span>
<span class="comment">// file at the top-level directory of this distribution and at</span>
<span class="comment">// http://rust-lang.org/COPYRIGHT.</span>
<span class="comment">//</span>
<span class="comment">// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or</span>
<span class="comment">// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license</span>
<span class="comment">// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your</span>
<span class="comment">// option. This file may not be copied, modified, or distributed</span>
<span class="comment">// except according to those terms.</span>
<span class="doccomment">//! Composable external iteration.</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! If you've found yourself with a collection of some kind, and needed to</span>
<span class="doccomment">//! perform an operation on the elements of said collection, you'll quickly run</span>
<span class="doccomment">//! into 'iterators'. Iterators are heavily used in idiomatic Rust code, so</span>
<span class="doccomment">//! it's worth becoming familiar with them.</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! Before explaining more, let's talk about how this module is structured:</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! # Organization</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! This module is largely organized by type:</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! * [Traits] are the core portion: these traits define what kind of iterators</span>
<span class="doccomment">//! exist and what you can do with them. The methods of these traits are worth</span>
<span class="doccomment">//! putting some extra study time into.</span>
<span class="doccomment">//! * [Functions] provide some helpful ways to create some basic iterators.</span>
<span class="doccomment">//! * [Structs] are often the return types of the various methods on this</span>
<span class="doccomment">//! module's traits. You'll usually want to look at the method that creates</span>
<span class="doccomment">//! the `struct`, rather than the `struct` itself. For more detail about why,</span>
<span class="doccomment">//! see '[Implementing Iterator](#implementing-iterator)'.</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! [Traits]: #traits</span>
<span class="doccomment">//! [Functions]: #functions</span>
<span class="doccomment">//! [Structs]: #structs</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! That's it! Let's dig into iterators.</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! # Iterator</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! The heart and soul of this module is the [`Iterator`] trait. The core of</span>
<span class="doccomment">//! [`Iterator`] looks like this:</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! ```</span>
<span class="doccomment">//! trait Iterator {</span>
<span class="doccomment">//! type Item;</span>
<span class="doccomment">//! fn next(&mut self) -> Option<Self::Item>;</span>
<span class="doccomment">//! }</span>
<span class="doccomment">//! ```</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! An iterator has a method, [`next`], which when called, returns an</span>
<span class="doccomment">//! [`Option`]`<Item>`. [`next`] will return `Some(Item)` as long as there</span>
<span class="doccomment">//! are elements, and once they've all been exhausted, will return `None` to</span>
<span class="doccomment">//! indicate that iteration is finished. Individual iterators may choose to</span>
<span class="doccomment">//! resume iteration, and so calling [`next`] again may or may not eventually</span>
<span class="doccomment">//! start returning `Some(Item)` again at some point.</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! [`Iterator`]'s full definition includes a number of other methods as well,</span>
<span class="doccomment">//! but they are default methods, built on top of [`next`], and so you get</span>
<span class="doccomment">//! them for free.</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! Iterators are also composable, and it's common to chain them together to do</span>
<span class="doccomment">//! more complex forms of processing. See the [Adapters](#adapters) section</span>
<span class="doccomment">//! below for more details.</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! [`Iterator`]: trait.Iterator.html</span>
<span class="doccomment">//! [`next`]: trait.Iterator.html#tymethod.next</span>
<span class="doccomment">//! [`Option`]: ../../std/option/enum.Option.html</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! # The three forms of iteration</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! There are three common methods which can create iterators from a collection:</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! * `iter()`, which iterates over `&T`.</span>
<span class="doccomment">//! * `iter_mut()`, which iterates over `&mut T`.</span>
<span class="doccomment">//! * `into_iter()`, which iterates over `T`.</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! Various things in the standard library may implement one or more of the</span>
<span class="doccomment">//! three, where appropriate.</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! # Implementing Iterator</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! Creating an iterator of your own involves two steps: creating a `struct` to</span>
<span class="doccomment">//! hold the iterator's state, and then `impl`ementing [`Iterator`] for that</span>
<span class="doccomment">//! `struct`. This is why there are so many `struct`s in this module: there is</span>
<span class="doccomment">//! one for each iterator and iterator adapter.</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! Let's make an iterator named `Counter` which counts from `1` to `5`:</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! ```</span>
<span class="doccomment">//! // First, the struct:</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! /// An iterator which counts from one to five</span>
<span class="doccomment">//! struct Counter {</span>
<span class="doccomment">//! count: usize,</span>
<span class="doccomment">//! }</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! // we want our count to start at one, so let's add a new() method to help.</span>
<span class="doccomment">//! // This isn't strictly necessary, but is convenient. Note that we start</span>
<span class="doccomment">//! // `count` at zero, we'll see why in `next()`'s implementation below.</span>
<span class="doccomment">//! impl Counter {</span>
<span class="doccomment">//! fn new() -> Counter {</span>
<span class="doccomment">//! Counter { count: 0 }</span>
<span class="doccomment">//! }</span>
<span class="doccomment">//! }</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! // Then, we implement `Iterator` for our `Counter`:</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! impl Iterator for Counter {</span>
<span class="doccomment">//! // we will be counting with usize</span>
<span class="doccomment">//! type Item = usize;</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! // next() is the only required method</span>
<span class="doccomment">//! fn next(&mut self) -> Option<usize> {</span>
<span class="doccomment">//! // increment our count. This is why we started at zero.</span>
<span class="doccomment">//! self.count += 1;</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! // check to see if we've finished counting or not.</span>
<span class="doccomment">//! if self.count < 6 {</span>
<span class="doccomment">//! Some(self.count)</span>
<span class="doccomment">//! } else {</span>
<span class="doccomment">//! None</span>
<span class="doccomment">//! }</span>
<span class="doccomment">//! }</span>
<span class="doccomment">//! }</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! // And now we can use it!</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! let mut counter = Counter::new();</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! let x = counter.next().unwrap();</span>
<span class="doccomment">//! println!("{}", x);</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! let x = counter.next().unwrap();</span>
<span class="doccomment">//! println!("{}", x);</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! let x = counter.next().unwrap();</span>
<span class="doccomment">//! println!("{}", x);</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! let x = counter.next().unwrap();</span>
<span class="doccomment">//! println!("{}", x);</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! let x = counter.next().unwrap();</span>
<span class="doccomment">//! println!("{}", x);</span>
<span class="doccomment">//! ```</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! This will print `1` through `5`, each on their own line.</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! Calling `next()` this way gets repetitive. Rust has a construct which can</span>
<span class="doccomment">//! call `next()` on your iterator, until it reaches `None`. Let's go over that</span>
<span class="doccomment">//! next.</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! # for Loops and IntoIterator</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! Rust's `for` loop syntax is actually sugar for iterators. Here's a basic</span>
<span class="doccomment">//! example of `for`:</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! ```</span>
<span class="doccomment">//! let values = vec![1, 2, 3, 4, 5];</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! for x in values {</span>
<span class="doccomment">//! println!("{}", x);</span>
<span class="doccomment">//! }</span>
<span class="doccomment">//! ```</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! This will print the numbers one through five, each on their own line. But</span>
<span class="doccomment">//! you'll notice something here: we never called anything on our vector to</span>
<span class="doccomment">//! produce an iterator. What gives?</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! There's a trait in the standard library for converting something into an</span>
<span class="doccomment">//! iterator: [`IntoIterator`]. This trait has one method, [`into_iter`],</span>
<span class="doccomment">//! which converts the thing implementing [`IntoIterator`] into an iterator.</span>
<span class="doccomment">//! Let's take a look at that `for` loop again, and what the compiler converts</span>
<span class="doccomment">//! it into:</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! [`IntoIterator`]: trait.IntoIterator.html</span>
<span class="doccomment">//! [`into_iter`]: trait.IntoIterator.html#tymethod.into_iter</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! ```</span>
<span class="doccomment">//! let values = vec![1, 2, 3, 4, 5];</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! for x in values {</span>
<span class="doccomment">//! println!("{}", x);</span>
<span class="doccomment">//! }</span>
<span class="doccomment">//! ```</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! Rust de-sugars this into:</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! ```</span>
<span class="doccomment">//! let values = vec![1, 2, 3, 4, 5];</span>
<span class="doccomment">//! {</span>
<span class="doccomment">//! let result = match IntoIterator::into_iter(values) {</span>
<span class="doccomment">//! mut iter => loop {</span>
<span class="doccomment">//! let next;</span>
<span class="doccomment">//! match iter.next() {</span>
<span class="doccomment">//! Some(val) => next = val,</span>
<span class="doccomment">//! None => break,</span>
<span class="doccomment">//! };</span>
<span class="doccomment">//! let x = next;</span>
<span class="doccomment">//! let () = { println!("{}", x); };</span>
<span class="doccomment">//! },</span>
<span class="doccomment">//! };</span>
<span class="doccomment">//! result</span>
<span class="doccomment">//! }</span>
<span class="doccomment">//! ```</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! First, we call `into_iter()` on the value. Then, we match on the iterator</span>
<span class="doccomment">//! that returns, calling [`next`] over and over until we see a `None`. At</span>
<span class="doccomment">//! that point, we `break` out of the loop, and we're done iterating.</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! There's one more subtle bit here: the standard library contains an</span>
<span class="doccomment">//! interesting implementation of [`IntoIterator`]:</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! ```ignore</span>
<span class="doccomment">//! impl<I: Iterator> IntoIterator for I</span>
<span class="doccomment">//! ```</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! In other words, all [`Iterator`]s implement [`IntoIterator`], by just</span>
<span class="doccomment">//! returning themselves. This means two things:</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! 1. If you're writing an [`Iterator`], you can use it with a `for` loop.</span>
<span class="doccomment">//! 2. If you're creating a collection, implementing [`IntoIterator`] for it</span>
<span class="doccomment">//! will allow your collection to be used with the `for` loop.</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! # Adapters</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! Functions which take an [`Iterator`] and return another [`Iterator`] are</span>
<span class="doccomment">//! often called 'iterator adapters', as they're a form of the 'adapter</span>
<span class="doccomment">//! pattern'.</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! Common iterator adapters include [`map`], [`take`], and [`filter`].</span>
<span class="doccomment">//! For more, see their documentation.</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! [`map`]: trait.Iterator.html#method.map</span>
<span class="doccomment">//! [`take`]: trait.Iterator.html#method.take</span>
<span class="doccomment">//! [`filter`]: trait.Iterator.html#method.filter</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! # Laziness</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! Iterators (and iterator [adapters](#adapters)) are *lazy*. This means that</span>
<span class="doccomment">//! just creating an iterator doesn't _do_ a whole lot. Nothing really happens</span>
<span class="doccomment">//! until you call [`next`]. This is sometimes a source of confusion when</span>
<span class="doccomment">//! creating an iterator solely for its side effects. For example, the [`map`]</span>
<span class="doccomment">//! method calls a closure on each element it iterates over:</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! ```</span>
<span class="doccomment">//! # #![allow(unused_must_use)]</span>
<span class="doccomment">//! let v = vec![1, 2, 3, 4, 5];</span>
<span class="doccomment">//! v.iter().map(|x| println!("{}", x));</span>
<span class="doccomment">//! ```</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! This will not print any values, as we only created an iterator, rather than</span>
<span class="doccomment">//! using it. The compiler will warn us about this kind of behavior:</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! ```text</span>
<span class="doccomment">//! warning: unused result which must be used: iterator adaptors are lazy and</span>
<span class="doccomment">//! do nothing unless consumed</span>
<span class="doccomment">//! ```</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! The idiomatic way to write a [`map`] for its side effects is to use a</span>
<span class="doccomment">//! `for` loop instead:</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! ```</span>
<span class="doccomment">//! let v = vec![1, 2, 3, 4, 5];</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! for x in &v {</span>
<span class="doccomment">//! println!("{}", x);</span>
<span class="doccomment">//! }</span>
<span class="doccomment">//! ```</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! [`map`]: trait.Iterator.html#method.map</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! The two most common ways to evaluate an iterator are to use a `for` loop</span>
<span class="doccomment">//! like this, or using the [`collect`] method to produce a new collection.</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! [`collect`]: trait.Iterator.html#method.collect</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! # Infinity</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! Iterators do not have to be finite. As an example, an open-ended range is</span>
<span class="doccomment">//! an infinite iterator:</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! ```</span>
<span class="doccomment">//! let numbers = 0..;</span>
<span class="doccomment">//! ```</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! It is common to use the [`take`] iterator adapter to turn an infinite</span>
<span class="doccomment">//! iterator into a finite one:</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! ```</span>
<span class="doccomment">//! let numbers = 0..;</span>
<span class="doccomment">//! let five_numbers = numbers.take(5);</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! for number in five_numbers {</span>
<span class="doccomment">//! println!("{}", number);</span>
<span class="doccomment">//! }</span>
<span class="doccomment">//! ```</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! This will print the numbers `0` through `4`, each on their own line.</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! [`take`]: trait.Iterator.html#method.take</span>
<span class="attribute">#<span class="op">!</span>[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">use</span> <span class="ident">cmp</span>;
<span class="kw">use</span> <span class="ident">fmt</span>;
<span class="kw">use</span> <span class="ident">iter_private</span>::<span class="ident">TrustedRandomAccess</span>;
<span class="kw">use</span> <span class="ident">usize</span>;
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">pub</span> <span class="kw">use</span> <span class="self">self</span>::<span class="ident">iterator</span>::<span class="ident">Iterator</span>;
<span class="attribute">#[<span class="ident">unstable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"step_trait"</span>,
<span class="ident">reason</span> <span class="op">=</span> <span class="string">"likely to be replaced by finer-grained traits"</span>,
<span class="ident">issue</span> <span class="op">=</span> <span class="string">"42168"</span>)]</span>
<span class="kw">pub</span> <span class="kw">use</span> <span class="self">self</span>::<span class="ident">range</span>::<span class="ident">Step</span>;
<span class="attribute">#[<span class="ident">unstable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"step_by"</span>, <span class="ident">reason</span> <span class="op">=</span> <span class="string">"recent addition"</span>,
<span class="ident">issue</span> <span class="op">=</span> <span class="string">"27741"</span>)]</span>
<span class="attribute">#[<span class="ident">rustc_deprecated</span>(<span class="ident">since</span> <span class="op">=</span> <span class="string">"1.19.0"</span>,
<span class="ident">reason</span> <span class="op">=</span> <span class="string">"replaced by `iter::StepBy`"</span>)]</span>
<span class="attribute">#[<span class="ident">allow</span>(<span class="ident">deprecated</span>)]</span>
<span class="kw">pub</span> <span class="kw">use</span> <span class="self">self</span>::<span class="ident">range</span>::<span class="ident">StepBy</span> <span class="kw">as</span> <span class="ident">DeprecatedStepBy</span>;
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">pub</span> <span class="kw">use</span> <span class="self">self</span>::<span class="ident">sources</span>::{<span class="ident">Repeat</span>, <span class="ident">repeat</span>};
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"iter_empty"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.2.0"</span>)]</span>
<span class="kw">pub</span> <span class="kw">use</span> <span class="self">self</span>::<span class="ident">sources</span>::{<span class="ident">Empty</span>, <span class="ident">empty</span>};
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"iter_once"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.2.0"</span>)]</span>
<span class="kw">pub</span> <span class="kw">use</span> <span class="self">self</span>::<span class="ident">sources</span>::{<span class="ident">Once</span>, <span class="ident">once</span>};
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">pub</span> <span class="kw">use</span> <span class="self">self</span>::<span class="ident">traits</span>::{<span class="ident">FromIterator</span>, <span class="ident">IntoIterator</span>, <span class="ident">DoubleEndedIterator</span>, <span class="ident">Extend</span>};
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">pub</span> <span class="kw">use</span> <span class="self">self</span>::<span class="ident">traits</span>::{<span class="ident">ExactSizeIterator</span>, <span class="ident">Sum</span>, <span class="ident">Product</span>};
<span class="attribute">#[<span class="ident">unstable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"fused"</span>, <span class="ident">issue</span> <span class="op">=</span> <span class="string">"35602"</span>)]</span>
<span class="kw">pub</span> <span class="kw">use</span> <span class="self">self</span>::<span class="ident">traits</span>::<span class="ident">FusedIterator</span>;
<span class="attribute">#[<span class="ident">unstable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"trusted_len"</span>, <span class="ident">issue</span> <span class="op">=</span> <span class="string">"37572"</span>)]</span>
<span class="kw">pub</span> <span class="kw">use</span> <span class="self">self</span>::<span class="ident">traits</span>::<span class="ident">TrustedLen</span>;
<span class="kw">mod</span> <span class="ident">iterator</span>;
<span class="kw">mod</span> <span class="ident">range</span>;
<span class="kw">mod</span> <span class="ident">sources</span>;
<span class="kw">mod</span> <span class="ident">traits</span>;
<span class="doccomment">/// A double-ended iterator with the direction inverted.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This `struct` is created by the [`rev`] method on [`Iterator`]. See its</span>
<span class="doccomment">/// documentation for more.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// [`rev`]: trait.Iterator.html#method.rev</span>
<span class="doccomment">/// [`Iterator`]: trait.Iterator.html</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Clone</span>, <span class="ident">Debug</span>)]</span>
<span class="attribute">#[<span class="ident">must_use</span> <span class="op">=</span> <span class="string">"iterator adaptors are lazy and do nothing unless consumed"</span>]</span>
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">Rev</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="ident">iter</span>: <span class="ident">T</span>
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">I</span><span class="op">></span> <span class="ident">Iterator</span> <span class="kw">for</span> <span class="ident">Rev</span><span class="op"><</span><span class="ident">I</span><span class="op">></span> <span class="kw">where</span> <span class="ident">I</span>: <span class="ident">DoubleEndedIterator</span> {
<span class="kw">type</span> <span class="ident">Item</span> <span class="op">=</span> <span class="op"><</span><span class="ident">I</span> <span class="kw">as</span> <span class="ident">Iterator</span><span class="op">></span>::<span class="ident">Item</span>;
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">next</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><<</span><span class="ident">I</span> <span class="kw">as</span> <span class="ident">Iterator</span><span class="op">></span>::<span class="ident">Item</span><span class="op">></span> { <span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">next_back</span>() }
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">size_hint</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> (<span class="ident">usize</span>, <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">usize</span><span class="op">></span>) { <span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">size_hint</span>() }
<span class="kw">fn</span> <span class="ident">find</span><span class="op"><</span><span class="ident">P</span><span class="op">></span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">predicate</span>: <span class="ident">P</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="self">Self</span>::<span class="ident">Item</span><span class="op">></span>
<span class="kw">where</span> <span class="ident">P</span>: <span class="ident">FnMut</span>(<span class="kw-2">&</span><span class="self">Self</span>::<span class="ident">Item</span>) <span class="op">-></span> <span class="ident">bool</span>
{
<span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">rfind</span>(<span class="ident">predicate</span>)
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">I</span><span class="op">></span> <span class="ident">DoubleEndedIterator</span> <span class="kw">for</span> <span class="ident">Rev</span><span class="op"><</span><span class="ident">I</span><span class="op">></span> <span class="kw">where</span> <span class="ident">I</span>: <span class="ident">DoubleEndedIterator</span> {
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">next_back</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><<</span><span class="ident">I</span> <span class="kw">as</span> <span class="ident">Iterator</span><span class="op">></span>::<span class="ident">Item</span><span class="op">></span> { <span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">next</span>() }
<span class="kw">fn</span> <span class="ident">rfind</span><span class="op"><</span><span class="ident">P</span><span class="op">></span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">predicate</span>: <span class="ident">P</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="self">Self</span>::<span class="ident">Item</span><span class="op">></span>
<span class="kw">where</span> <span class="ident">P</span>: <span class="ident">FnMut</span>(<span class="kw-2">&</span><span class="self">Self</span>::<span class="ident">Item</span>) <span class="op">-></span> <span class="ident">bool</span>
{
<span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">find</span>(<span class="ident">predicate</span>)
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">I</span><span class="op">></span> <span class="ident">ExactSizeIterator</span> <span class="kw">for</span> <span class="ident">Rev</span><span class="op"><</span><span class="ident">I</span><span class="op">></span>
<span class="kw">where</span> <span class="ident">I</span>: <span class="ident">ExactSizeIterator</span> <span class="op">+</span> <span class="ident">DoubleEndedIterator</span>
{
<span class="kw">fn</span> <span class="ident">len</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="ident">usize</span> {
<span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">len</span>()
}
<span class="kw">fn</span> <span class="ident">is_empty</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="ident">bool</span> {
<span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">is_empty</span>()
}
}
<span class="attribute">#[<span class="ident">unstable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"fused"</span>, <span class="ident">issue</span> <span class="op">=</span> <span class="string">"35602"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">I</span><span class="op">></span> <span class="ident">FusedIterator</span> <span class="kw">for</span> <span class="ident">Rev</span><span class="op"><</span><span class="ident">I</span><span class="op">></span>
<span class="kw">where</span> <span class="ident">I</span>: <span class="ident">FusedIterator</span> <span class="op">+</span> <span class="ident">DoubleEndedIterator</span> {}
<span class="attribute">#[<span class="ident">unstable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"trusted_len"</span>, <span class="ident">issue</span> <span class="op">=</span> <span class="string">"37572"</span>)]</span>
<span class="kw">unsafe</span> <span class="kw">impl</span><span class="op"><</span><span class="ident">I</span><span class="op">></span> <span class="ident">TrustedLen</span> <span class="kw">for</span> <span class="ident">Rev</span><span class="op"><</span><span class="ident">I</span><span class="op">></span>
<span class="kw">where</span> <span class="ident">I</span>: <span class="ident">TrustedLen</span> <span class="op">+</span> <span class="ident">DoubleEndedIterator</span> {}
<span class="doccomment">/// An iterator that clones the elements of an underlying iterator.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This `struct` is created by the [`cloned`] method on [`Iterator`]. See its</span>
<span class="doccomment">/// documentation for more.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// [`cloned`]: trait.Iterator.html#method.cloned</span>
<span class="doccomment">/// [`Iterator`]: trait.Iterator.html</span>
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"iter_cloned"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.1.0"</span>)]</span>
<span class="attribute">#[<span class="ident">must_use</span> <span class="op">=</span> <span class="string">"iterator adaptors are lazy and do nothing unless consumed"</span>]</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Clone</span>, <span class="ident">Debug</span>)]</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">Cloned</span><span class="op"><</span><span class="ident">I</span><span class="op">></span> {
<span class="ident">it</span>: <span class="ident">I</span>,
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"iter_cloned"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.1.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="lifetime">'a</span>, <span class="ident">I</span>, <span class="ident">T</span>: <span class="lifetime">'a</span><span class="op">></span> <span class="ident">Iterator</span> <span class="kw">for</span> <span class="ident">Cloned</span><span class="op"><</span><span class="ident">I</span><span class="op">></span>
<span class="kw">where</span> <span class="ident">I</span>: <span class="ident">Iterator</span><span class="op"><</span><span class="ident">Item</span><span class="op">=</span><span class="kw-2">&</span><span class="lifetime">'a</span> <span class="ident">T</span><span class="op">></span>, <span class="ident">T</span>: <span class="ident">Clone</span>
{
<span class="kw">type</span> <span class="ident">Item</span> <span class="op">=</span> <span class="ident">T</span>;
<span class="kw">fn</span> <span class="ident">next</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="self">self</span>.<span class="ident">it</span>.<span class="ident">next</span>().<span class="ident">cloned</span>()
}
<span class="kw">fn</span> <span class="ident">size_hint</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> (<span class="ident">usize</span>, <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">usize</span><span class="op">></span>) {
<span class="self">self</span>.<span class="ident">it</span>.<span class="ident">size_hint</span>()
}
<span class="kw">fn</span> <span class="ident">fold</span><span class="op"><</span><span class="ident">Acc</span>, <span class="ident">F</span><span class="op">></span>(<span class="self">self</span>, <span class="ident">init</span>: <span class="ident">Acc</span>, <span class="kw-2">mut</span> <span class="ident">f</span>: <span class="ident">F</span>) <span class="op">-></span> <span class="ident">Acc</span>
<span class="kw">where</span> <span class="ident">F</span>: <span class="ident">FnMut</span>(<span class="ident">Acc</span>, <span class="self">Self</span>::<span class="ident">Item</span>) <span class="op">-></span> <span class="ident">Acc</span>,
{
<span class="self">self</span>.<span class="ident">it</span>.<span class="ident">fold</span>(<span class="ident">init</span>, <span class="kw">move</span> <span class="op">|</span><span class="ident">acc</span>, <span class="ident">elt</span><span class="op">|</span> <span class="ident">f</span>(<span class="ident">acc</span>, <span class="ident">elt</span>.<span class="ident">clone</span>()))
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"iter_cloned"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.1.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="lifetime">'a</span>, <span class="ident">I</span>, <span class="ident">T</span>: <span class="lifetime">'a</span><span class="op">></span> <span class="ident">DoubleEndedIterator</span> <span class="kw">for</span> <span class="ident">Cloned</span><span class="op"><</span><span class="ident">I</span><span class="op">></span>
<span class="kw">where</span> <span class="ident">I</span>: <span class="ident">DoubleEndedIterator</span><span class="op"><</span><span class="ident">Item</span><span class="op">=</span><span class="kw-2">&</span><span class="lifetime">'a</span> <span class="ident">T</span><span class="op">></span>, <span class="ident">T</span>: <span class="ident">Clone</span>
{
<span class="kw">fn</span> <span class="ident">next_back</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="self">self</span>.<span class="ident">it</span>.<span class="ident">next_back</span>().<span class="ident">cloned</span>()
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"iter_cloned"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.1.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="lifetime">'a</span>, <span class="ident">I</span>, <span class="ident">T</span>: <span class="lifetime">'a</span><span class="op">></span> <span class="ident">ExactSizeIterator</span> <span class="kw">for</span> <span class="ident">Cloned</span><span class="op"><</span><span class="ident">I</span><span class="op">></span>
<span class="kw">where</span> <span class="ident">I</span>: <span class="ident">ExactSizeIterator</span><span class="op"><</span><span class="ident">Item</span><span class="op">=</span><span class="kw-2">&</span><span class="lifetime">'a</span> <span class="ident">T</span><span class="op">></span>, <span class="ident">T</span>: <span class="ident">Clone</span>
{
<span class="kw">fn</span> <span class="ident">len</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="ident">usize</span> {
<span class="self">self</span>.<span class="ident">it</span>.<span class="ident">len</span>()
}
<span class="kw">fn</span> <span class="ident">is_empty</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="ident">bool</span> {
<span class="self">self</span>.<span class="ident">it</span>.<span class="ident">is_empty</span>()
}
}
<span class="attribute">#[<span class="ident">unstable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"fused"</span>, <span class="ident">issue</span> <span class="op">=</span> <span class="string">"35602"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="lifetime">'a</span>, <span class="ident">I</span>, <span class="ident">T</span>: <span class="lifetime">'a</span><span class="op">></span> <span class="ident">FusedIterator</span> <span class="kw">for</span> <span class="ident">Cloned</span><span class="op"><</span><span class="ident">I</span><span class="op">></span>
<span class="kw">where</span> <span class="ident">I</span>: <span class="ident">FusedIterator</span><span class="op"><</span><span class="ident">Item</span><span class="op">=</span><span class="kw-2">&</span><span class="lifetime">'a</span> <span class="ident">T</span><span class="op">></span>, <span class="ident">T</span>: <span class="ident">Clone</span>
{}
<span class="attribute">#[<span class="ident">doc</span>(<span class="ident">hidden</span>)]</span>
<span class="kw">unsafe</span> <span class="kw">impl</span><span class="op"><</span><span class="lifetime">'a</span>, <span class="ident">I</span>, <span class="ident">T</span>: <span class="lifetime">'a</span><span class="op">></span> <span class="ident">TrustedRandomAccess</span> <span class="kw">for</span> <span class="ident">Cloned</span><span class="op"><</span><span class="ident">I</span><span class="op">></span>
<span class="kw">where</span> <span class="ident">I</span>: <span class="ident">TrustedRandomAccess</span><span class="op"><</span><span class="ident">Item</span><span class="op">=</span><span class="kw-2">&</span><span class="lifetime">'a</span> <span class="ident">T</span><span class="op">></span>, <span class="ident">T</span>: <span class="ident">Clone</span>
{
<span class="kw">unsafe</span> <span class="kw">fn</span> <span class="ident">get_unchecked</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">i</span>: <span class="ident">usize</span>) <span class="op">-></span> <span class="self">Self</span>::<span class="ident">Item</span> {
<span class="self">self</span>.<span class="ident">it</span>.<span class="ident">get_unchecked</span>(<span class="ident">i</span>).<span class="ident">clone</span>()
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">may_have_side_effect</span>() <span class="op">-></span> <span class="ident">bool</span> { <span class="bool-val">true</span> }
}
<span class="attribute">#[<span class="ident">unstable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"trusted_len"</span>, <span class="ident">issue</span> <span class="op">=</span> <span class="string">"37572"</span>)]</span>
<span class="kw">unsafe</span> <span class="kw">impl</span><span class="op"><</span><span class="lifetime">'a</span>, <span class="ident">I</span>, <span class="ident">T</span>: <span class="lifetime">'a</span><span class="op">></span> <span class="ident">TrustedLen</span> <span class="kw">for</span> <span class="ident">Cloned</span><span class="op"><</span><span class="ident">I</span><span class="op">></span>
<span class="kw">where</span> <span class="ident">I</span>: <span class="ident">TrustedLen</span><span class="op"><</span><span class="ident">Item</span><span class="op">=</span><span class="kw-2">&</span><span class="lifetime">'a</span> <span class="ident">T</span><span class="op">></span>,
<span class="ident">T</span>: <span class="ident">Clone</span>
{}
<span class="doccomment">/// An iterator that repeats endlessly.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This `struct` is created by the [`cycle`] method on [`Iterator`]. See its</span>
<span class="doccomment">/// documentation for more.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// [`cycle`]: trait.Iterator.html#method.cycle</span>
<span class="doccomment">/// [`Iterator`]: trait.Iterator.html</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Clone</span>, <span class="ident">Debug</span>)]</span>
<span class="attribute">#[<span class="ident">must_use</span> <span class="op">=</span> <span class="string">"iterator adaptors are lazy and do nothing unless consumed"</span>]</span>
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">Cycle</span><span class="op"><</span><span class="ident">I</span><span class="op">></span> {
<span class="ident">orig</span>: <span class="ident">I</span>,
<span class="ident">iter</span>: <span class="ident">I</span>,
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">I</span><span class="op">></span> <span class="ident">Iterator</span> <span class="kw">for</span> <span class="ident">Cycle</span><span class="op"><</span><span class="ident">I</span><span class="op">></span> <span class="kw">where</span> <span class="ident">I</span>: <span class="ident">Clone</span> <span class="op">+</span> <span class="ident">Iterator</span> {
<span class="kw">type</span> <span class="ident">Item</span> <span class="op">=</span> <span class="op"><</span><span class="ident">I</span> <span class="kw">as</span> <span class="ident">Iterator</span><span class="op">></span>::<span class="ident">Item</span>;
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">next</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><<</span><span class="ident">I</span> <span class="kw">as</span> <span class="ident">Iterator</span><span class="op">></span>::<span class="ident">Item</span><span class="op">></span> {
<span class="kw">match</span> <span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">next</span>() {
<span class="prelude-val">None</span> <span class="op">=></span> { <span class="self">self</span>.<span class="ident">iter</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">orig</span>.<span class="ident">clone</span>(); <span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">next</span>() }
<span class="ident">y</span> <span class="op">=></span> <span class="ident">y</span>
}
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">size_hint</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> (<span class="ident">usize</span>, <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">usize</span><span class="op">></span>) {
<span class="comment">// the cycle iterator is either empty or infinite</span>
<span class="kw">match</span> <span class="self">self</span>.<span class="ident">orig</span>.<span class="ident">size_hint</span>() {
<span class="ident">sz</span> @ (<span class="number">0</span>, <span class="prelude-val">Some</span>(<span class="number">0</span>)) <span class="op">=></span> <span class="ident">sz</span>,
(<span class="number">0</span>, _) <span class="op">=></span> (<span class="number">0</span>, <span class="prelude-val">None</span>),
_ <span class="op">=></span> (<span class="ident">usize</span>::<span class="ident">MAX</span>, <span class="prelude-val">None</span>)
}
}
}
<span class="attribute">#[<span class="ident">unstable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"fused"</span>, <span class="ident">issue</span> <span class="op">=</span> <span class="string">"35602"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">I</span><span class="op">></span> <span class="ident">FusedIterator</span> <span class="kw">for</span> <span class="ident">Cycle</span><span class="op"><</span><span class="ident">I</span><span class="op">></span> <span class="kw">where</span> <span class="ident">I</span>: <span class="ident">Clone</span> <span class="op">+</span> <span class="ident">Iterator</span> {}
<span class="doccomment">/// An adapter for stepping iterators by a custom amount.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This `struct` is created by the [`step_by`] method on [`Iterator`]. See</span>
<span class="doccomment">/// its documentation for more.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// [`step_by`]: trait.Iterator.html#method.step_by</span>
<span class="doccomment">/// [`Iterator`]: trait.Iterator.html</span>
<span class="attribute">#[<span class="ident">must_use</span> <span class="op">=</span> <span class="string">"iterator adaptors are lazy and do nothing unless consumed"</span>]</span>
<span class="attribute">#[<span class="ident">unstable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"iterator_step_by"</span>,
<span class="ident">reason</span> <span class="op">=</span> <span class="string">"unstable replacement of Range::step_by"</span>,
<span class="ident">issue</span> <span class="op">=</span> <span class="string">"27741"</span>)]</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Clone</span>, <span class="ident">Debug</span>)]</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">StepBy</span><span class="op"><</span><span class="ident">I</span><span class="op">></span> {
<span class="ident">iter</span>: <span class="ident">I</span>,
<span class="ident">step</span>: <span class="ident">usize</span>,
<span class="ident">first_take</span>: <span class="ident">bool</span>,
}
<span class="attribute">#[<span class="ident">unstable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"iterator_step_by"</span>,
<span class="ident">reason</span> <span class="op">=</span> <span class="string">"unstable replacement of Range::step_by"</span>,
<span class="ident">issue</span> <span class="op">=</span> <span class="string">"27741"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">I</span><span class="op">></span> <span class="ident">Iterator</span> <span class="kw">for</span> <span class="ident">StepBy</span><span class="op"><</span><span class="ident">I</span><span class="op">></span> <span class="kw">where</span> <span class="ident">I</span>: <span class="ident">Iterator</span> {
<span class="kw">type</span> <span class="ident">Item</span> <span class="op">=</span> <span class="ident">I</span>::<span class="ident">Item</span>;
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">next</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="self">Self</span>::<span class="ident">Item</span><span class="op">></span> {
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">first_take</span> {
<span class="self">self</span>.<span class="ident">first_take</span> <span class="op">=</span> <span class="bool-val">false</span>;
<span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">next</span>()
} <span class="kw">else</span> {
<span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">nth</span>(<span class="self">self</span>.<span class="ident">step</span>)
}
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">size_hint</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> (<span class="ident">usize</span>, <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">usize</span><span class="op">></span>) {
<span class="kw">let</span> <span class="ident">inner_hint</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">size_hint</span>();
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">first_take</span> {
<span class="kw">let</span> <span class="ident">f</span> <span class="op">=</span> <span class="op">|</span><span class="ident">n</span><span class="op">|</span> <span class="kw">if</span> <span class="ident">n</span> <span class="op">==</span> <span class="number">0</span> { <span class="number">0</span> } <span class="kw">else</span> { <span class="number">1</span> <span class="op">+</span> (<span class="ident">n</span><span class="op">-</span><span class="number">1</span>)<span class="op">/</span>(<span class="self">self</span>.<span class="ident">step</span><span class="op">+</span><span class="number">1</span>) };
(<span class="ident">f</span>(<span class="ident">inner_hint</span>.<span class="number">0</span>), <span class="ident">inner_hint</span>.<span class="number">1</span>.<span class="ident">map</span>(<span class="ident">f</span>))
} <span class="kw">else</span> {
<span class="kw">let</span> <span class="ident">f</span> <span class="op">=</span> <span class="op">|</span><span class="ident">n</span><span class="op">|</span> <span class="ident">n</span> <span class="op">/</span> (<span class="self">self</span>.<span class="ident">step</span><span class="op">+</span><span class="number">1</span>);
(<span class="ident">f</span>(<span class="ident">inner_hint</span>.<span class="number">0</span>), <span class="ident">inner_hint</span>.<span class="number">1</span>.<span class="ident">map</span>(<span class="ident">f</span>))
}
}
}
<span class="comment">// StepBy can only make the iterator shorter, so the len will still fit.</span>
<span class="attribute">#[<span class="ident">unstable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"iterator_step_by"</span>,
<span class="ident">reason</span> <span class="op">=</span> <span class="string">"unstable replacement of Range::step_by"</span>,
<span class="ident">issue</span> <span class="op">=</span> <span class="string">"27741"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">I</span><span class="op">></span> <span class="ident">ExactSizeIterator</span> <span class="kw">for</span> <span class="ident">StepBy</span><span class="op"><</span><span class="ident">I</span><span class="op">></span> <span class="kw">where</span> <span class="ident">I</span>: <span class="ident">ExactSizeIterator</span> {}
<span class="doccomment">/// An iterator that strings two iterators together.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This `struct` is created by the [`chain`] method on [`Iterator`]. See its</span>
<span class="doccomment">/// documentation for more.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// [`chain`]: trait.Iterator.html#method.chain</span>
<span class="doccomment">/// [`Iterator`]: trait.Iterator.html</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Clone</span>, <span class="ident">Debug</span>)]</span>
<span class="attribute">#[<span class="ident">must_use</span> <span class="op">=</span> <span class="string">"iterator adaptors are lazy and do nothing unless consumed"</span>]</span>
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">Chain</span><span class="op"><</span><span class="ident">A</span>, <span class="ident">B</span><span class="op">></span> {
<span class="ident">a</span>: <span class="ident">A</span>,
<span class="ident">b</span>: <span class="ident">B</span>,
<span class="ident">state</span>: <span class="ident">ChainState</span>,
}
<span class="comment">// The iterator protocol specifies that iteration ends with the return value</span>
<span class="comment">// `None` from `.next()` (or `.next_back()`) and it is unspecified what</span>
<span class="comment">// further calls return. The chain adaptor must account for this since it uses</span>
<span class="comment">// two subiterators.</span>
<span class="comment">//</span>
<span class="comment">// It uses three states:</span>
<span class="comment">//</span>
<span class="comment">// - Both: `a` and `b` are remaining</span>
<span class="comment">// - Front: `a` remaining</span>
<span class="comment">// - Back: `b` remaining</span>
<span class="comment">//</span>
<span class="comment">// The fourth state (neither iterator is remaining) only occurs after Chain has</span>
<span class="comment">// returned None once, so we don't need to store this state.</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Clone</span>, <span class="ident">Debug</span>)]</span>
<span class="kw">enum</span> <span class="ident">ChainState</span> {
<span class="comment">// both front and back iterator are remaining</span>
<span class="ident">Both</span>,
<span class="comment">// only front is remaining</span>
<span class="ident">Front</span>,
<span class="comment">// only back is remaining</span>
<span class="ident">Back</span>,
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">A</span>, <span class="ident">B</span><span class="op">></span> <span class="ident">Iterator</span> <span class="kw">for</span> <span class="ident">Chain</span><span class="op"><</span><span class="ident">A</span>, <span class="ident">B</span><span class="op">></span> <span class="kw">where</span>
<span class="ident">A</span>: <span class="ident">Iterator</span>,
<span class="ident">B</span>: <span class="ident">Iterator</span><span class="op"><</span><span class="ident">Item</span> <span class="op">=</span> <span class="ident">A</span>::<span class="ident">Item</span><span class="op">></span>
{
<span class="kw">type</span> <span class="ident">Item</span> <span class="op">=</span> <span class="ident">A</span>::<span class="ident">Item</span>;
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">next</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">A</span>::<span class="ident">Item</span><span class="op">></span> {
<span class="kw">match</span> <span class="self">self</span>.<span class="ident">state</span> {
<span class="ident">ChainState</span>::<span class="ident">Both</span> <span class="op">=></span> <span class="kw">match</span> <span class="self">self</span>.<span class="ident">a</span>.<span class="ident">next</span>() {
<span class="ident">elt</span> @ <span class="prelude-val">Some</span>(..) <span class="op">=></span> <span class="ident">elt</span>,
<span class="prelude-val">None</span> <span class="op">=></span> {
<span class="self">self</span>.<span class="ident">state</span> <span class="op">=</span> <span class="ident">ChainState</span>::<span class="ident">Back</span>;
<span class="self">self</span>.<span class="ident">b</span>.<span class="ident">next</span>()
}
},
<span class="ident">ChainState</span>::<span class="ident">Front</span> <span class="op">=></span> <span class="self">self</span>.<span class="ident">a</span>.<span class="ident">next</span>(),
<span class="ident">ChainState</span>::<span class="ident">Back</span> <span class="op">=></span> <span class="self">self</span>.<span class="ident">b</span>.<span class="ident">next</span>(),
}
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="attribute">#[<span class="ident">rustc_inherit_overflow_checks</span>]</span>
<span class="kw">fn</span> <span class="ident">count</span>(<span class="self">self</span>) <span class="op">-></span> <span class="ident">usize</span> {
<span class="kw">match</span> <span class="self">self</span>.<span class="ident">state</span> {
<span class="ident">ChainState</span>::<span class="ident">Both</span> <span class="op">=></span> <span class="self">self</span>.<span class="ident">a</span>.<span class="ident">count</span>() <span class="op">+</span> <span class="self">self</span>.<span class="ident">b</span>.<span class="ident">count</span>(),
<span class="ident">ChainState</span>::<span class="ident">Front</span> <span class="op">=></span> <span class="self">self</span>.<span class="ident">a</span>.<span class="ident">count</span>(),
<span class="ident">ChainState</span>::<span class="ident">Back</span> <span class="op">=></span> <span class="self">self</span>.<span class="ident">b</span>.<span class="ident">count</span>(),
}
}
<span class="kw">fn</span> <span class="ident">fold</span><span class="op"><</span><span class="ident">Acc</span>, <span class="ident">F</span><span class="op">></span>(<span class="self">self</span>, <span class="ident">init</span>: <span class="ident">Acc</span>, <span class="kw-2">mut</span> <span class="ident">f</span>: <span class="ident">F</span>) <span class="op">-></span> <span class="ident">Acc</span>
<span class="kw">where</span> <span class="ident">F</span>: <span class="ident">FnMut</span>(<span class="ident">Acc</span>, <span class="self">Self</span>::<span class="ident">Item</span>) <span class="op">-></span> <span class="ident">Acc</span>,
{
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">accum</span> <span class="op">=</span> <span class="ident">init</span>;
<span class="kw">match</span> <span class="self">self</span>.<span class="ident">state</span> {
<span class="ident">ChainState</span>::<span class="ident">Both</span> <span class="op">|</span> <span class="ident">ChainState</span>::<span class="ident">Front</span> <span class="op">=></span> {
<span class="ident">accum</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">a</span>.<span class="ident">fold</span>(<span class="ident">accum</span>, <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">f</span>);
}
_ <span class="op">=></span> { }
}
<span class="kw">match</span> <span class="self">self</span>.<span class="ident">state</span> {
<span class="ident">ChainState</span>::<span class="ident">Both</span> <span class="op">|</span> <span class="ident">ChainState</span>::<span class="ident">Back</span> <span class="op">=></span> {
<span class="ident">accum</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">b</span>.<span class="ident">fold</span>(<span class="ident">accum</span>, <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">f</span>);
}
_ <span class="op">=></span> { }
}
<span class="ident">accum</span>
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">nth</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="kw-2">mut</span> <span class="ident">n</span>: <span class="ident">usize</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">A</span>::<span class="ident">Item</span><span class="op">></span> {
<span class="kw">match</span> <span class="self">self</span>.<span class="ident">state</span> {
<span class="ident">ChainState</span>::<span class="ident">Both</span> <span class="op">|</span> <span class="ident">ChainState</span>::<span class="ident">Front</span> <span class="op">=></span> {
<span class="kw">for</span> <span class="ident">x</span> <span class="kw">in</span> <span class="self">self</span>.<span class="ident">a</span>.<span class="ident">by_ref</span>() {
<span class="kw">if</span> <span class="ident">n</span> <span class="op">==</span> <span class="number">0</span> {
<span class="kw">return</span> <span class="prelude-val">Some</span>(<span class="ident">x</span>)
}
<span class="ident">n</span> <span class="op">-=</span> <span class="number">1</span>;
}
<span class="kw">if</span> <span class="kw">let</span> <span class="ident">ChainState</span>::<span class="ident">Both</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">state</span> {
<span class="self">self</span>.<span class="ident">state</span> <span class="op">=</span> <span class="ident">ChainState</span>::<span class="ident">Back</span>;
}
}
<span class="ident">ChainState</span>::<span class="ident">Back</span> <span class="op">=></span> {}
}
<span class="kw">if</span> <span class="kw">let</span> <span class="ident">ChainState</span>::<span class="ident">Back</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">state</span> {
<span class="self">self</span>.<span class="ident">b</span>.<span class="ident">nth</span>(<span class="ident">n</span>)
} <span class="kw">else</span> {
<span class="prelude-val">None</span>
}
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">find</span><span class="op"><</span><span class="ident">P</span><span class="op">></span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="kw-2">mut</span> <span class="ident">predicate</span>: <span class="ident">P</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="self">Self</span>::<span class="ident">Item</span><span class="op">></span> <span class="kw">where</span>
<span class="ident">P</span>: <span class="ident">FnMut</span>(<span class="kw-2">&</span><span class="self">Self</span>::<span class="ident">Item</span>) <span class="op">-></span> <span class="ident">bool</span>,
{
<span class="kw">match</span> <span class="self">self</span>.<span class="ident">state</span> {
<span class="ident">ChainState</span>::<span class="ident">Both</span> <span class="op">=></span> <span class="kw">match</span> <span class="self">self</span>.<span class="ident">a</span>.<span class="ident">find</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">predicate</span>) {
<span class="prelude-val">None</span> <span class="op">=></span> {
<span class="self">self</span>.<span class="ident">state</span> <span class="op">=</span> <span class="ident">ChainState</span>::<span class="ident">Back</span>;
<span class="self">self</span>.<span class="ident">b</span>.<span class="ident">find</span>(<span class="ident">predicate</span>)
}
<span class="ident">v</span> <span class="op">=></span> <span class="ident">v</span>
},
<span class="ident">ChainState</span>::<span class="ident">Front</span> <span class="op">=></span> <span class="self">self</span>.<span class="ident">a</span>.<span class="ident">find</span>(<span class="ident">predicate</span>),
<span class="ident">ChainState</span>::<span class="ident">Back</span> <span class="op">=></span> <span class="self">self</span>.<span class="ident">b</span>.<span class="ident">find</span>(<span class="ident">predicate</span>),
}
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">last</span>(<span class="self">self</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">A</span>::<span class="ident">Item</span><span class="op">></span> {
<span class="kw">match</span> <span class="self">self</span>.<span class="ident">state</span> {
<span class="ident">ChainState</span>::<span class="ident">Both</span> <span class="op">=></span> {
<span class="comment">// Must exhaust a before b.</span>
<span class="kw">let</span> <span class="ident">a_last</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">a</span>.<span class="ident">last</span>();
<span class="kw">let</span> <span class="ident">b_last</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">b</span>.<span class="ident">last</span>();
<span class="ident">b_last</span>.<span class="ident">or</span>(<span class="ident">a_last</span>)
},
<span class="ident">ChainState</span>::<span class="ident">Front</span> <span class="op">=></span> <span class="self">self</span>.<span class="ident">a</span>.<span class="ident">last</span>(),
<span class="ident">ChainState</span>::<span class="ident">Back</span> <span class="op">=></span> <span class="self">self</span>.<span class="ident">b</span>.<span class="ident">last</span>()
}
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">size_hint</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> (<span class="ident">usize</span>, <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">usize</span><span class="op">></span>) {
<span class="kw">let</span> (<span class="ident">a_lower</span>, <span class="ident">a_upper</span>) <span class="op">=</span> <span class="self">self</span>.<span class="ident">a</span>.<span class="ident">size_hint</span>();
<span class="kw">let</span> (<span class="ident">b_lower</span>, <span class="ident">b_upper</span>) <span class="op">=</span> <span class="self">self</span>.<span class="ident">b</span>.<span class="ident">size_hint</span>();
<span class="kw">let</span> <span class="ident">lower</span> <span class="op">=</span> <span class="ident">a_lower</span>.<span class="ident">saturating_add</span>(<span class="ident">b_lower</span>);
<span class="kw">let</span> <span class="ident">upper</span> <span class="op">=</span> <span class="kw">match</span> (<span class="ident">a_upper</span>, <span class="ident">b_upper</span>) {
(<span class="prelude-val">Some</span>(<span class="ident">x</span>), <span class="prelude-val">Some</span>(<span class="ident">y</span>)) <span class="op">=></span> <span class="ident">x</span>.<span class="ident">checked_add</span>(<span class="ident">y</span>),
_ <span class="op">=></span> <span class="prelude-val">None</span>
};
(<span class="ident">lower</span>, <span class="ident">upper</span>)
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">A</span>, <span class="ident">B</span><span class="op">></span> <span class="ident">DoubleEndedIterator</span> <span class="kw">for</span> <span class="ident">Chain</span><span class="op"><</span><span class="ident">A</span>, <span class="ident">B</span><span class="op">></span> <span class="kw">where</span>
<span class="ident">A</span>: <span class="ident">DoubleEndedIterator</span>,
<span class="ident">B</span>: <span class="ident">DoubleEndedIterator</span><span class="op"><</span><span class="ident">Item</span><span class="op">=</span><span class="ident">A</span>::<span class="ident">Item</span><span class="op">></span>,
{
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">next_back</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">A</span>::<span class="ident">Item</span><span class="op">></span> {
<span class="kw">match</span> <span class="self">self</span>.<span class="ident">state</span> {
<span class="ident">ChainState</span>::<span class="ident">Both</span> <span class="op">=></span> <span class="kw">match</span> <span class="self">self</span>.<span class="ident">b</span>.<span class="ident">next_back</span>() {
<span class="ident">elt</span> @ <span class="prelude-val">Some</span>(..) <span class="op">=></span> <span class="ident">elt</span>,
<span class="prelude-val">None</span> <span class="op">=></span> {
<span class="self">self</span>.<span class="ident">state</span> <span class="op">=</span> <span class="ident">ChainState</span>::<span class="ident">Front</span>;
<span class="self">self</span>.<span class="ident">a</span>.<span class="ident">next_back</span>()
}
},
<span class="ident">ChainState</span>::<span class="ident">Front</span> <span class="op">=></span> <span class="self">self</span>.<span class="ident">a</span>.<span class="ident">next_back</span>(),
<span class="ident">ChainState</span>::<span class="ident">Back</span> <span class="op">=></span> <span class="self">self</span>.<span class="ident">b</span>.<span class="ident">next_back</span>(),
}
}
}
<span class="comment">// Note: *both* must be fused to handle double-ended iterators.</span>
<span class="attribute">#[<span class="ident">unstable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"fused"</span>, <span class="ident">issue</span> <span class="op">=</span> <span class="string">"35602"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">A</span>, <span class="ident">B</span><span class="op">></span> <span class="ident">FusedIterator</span> <span class="kw">for</span> <span class="ident">Chain</span><span class="op"><</span><span class="ident">A</span>, <span class="ident">B</span><span class="op">></span>
<span class="kw">where</span> <span class="ident">A</span>: <span class="ident">FusedIterator</span>,
<span class="ident">B</span>: <span class="ident">FusedIterator</span><span class="op"><</span><span class="ident">Item</span><span class="op">=</span><span class="ident">A</span>::<span class="ident">Item</span><span class="op">></span>,
{}
<span class="attribute">#[<span class="ident">unstable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"trusted_len"</span>, <span class="ident">issue</span> <span class="op">=</span> <span class="string">"37572"</span>)]</span>
<span class="kw">unsafe</span> <span class="kw">impl</span><span class="op"><</span><span class="ident">A</span>, <span class="ident">B</span><span class="op">></span> <span class="ident">TrustedLen</span> <span class="kw">for</span> <span class="ident">Chain</span><span class="op"><</span><span class="ident">A</span>, <span class="ident">B</span><span class="op">></span>
<span class="kw">where</span> <span class="ident">A</span>: <span class="ident">TrustedLen</span>, <span class="ident">B</span>: <span class="ident">TrustedLen</span><span class="op"><</span><span class="ident">Item</span><span class="op">=</span><span class="ident">A</span>::<span class="ident">Item</span><span class="op">></span>,
{}
<span class="doccomment">/// An iterator that iterates two other iterators simultaneously.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This `struct` is created by the [`zip`] method on [`Iterator`]. See its</span>
<span class="doccomment">/// documentation for more.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// [`zip`]: trait.Iterator.html#method.zip</span>
<span class="doccomment">/// [`Iterator`]: trait.Iterator.html</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Clone</span>, <span class="ident">Debug</span>)]</span>
<span class="attribute">#[<span class="ident">must_use</span> <span class="op">=</span> <span class="string">"iterator adaptors are lazy and do nothing unless consumed"</span>]</span>
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">Zip</span><span class="op"><</span><span class="ident">A</span>, <span class="ident">B</span><span class="op">></span> {
<span class="ident">a</span>: <span class="ident">A</span>,
<span class="ident">b</span>: <span class="ident">B</span>,
<span class="comment">// index and len are only used by the specialized version of zip</span>
<span class="ident">index</span>: <span class="ident">usize</span>,
<span class="ident">len</span>: <span class="ident">usize</span>,
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">A</span>, <span class="ident">B</span><span class="op">></span> <span class="ident">Iterator</span> <span class="kw">for</span> <span class="ident">Zip</span><span class="op"><</span><span class="ident">A</span>, <span class="ident">B</span><span class="op">></span> <span class="kw">where</span> <span class="ident">A</span>: <span class="ident">Iterator</span>, <span class="ident">B</span>: <span class="ident">Iterator</span>
{
<span class="kw">type</span> <span class="ident">Item</span> <span class="op">=</span> (<span class="ident">A</span>::<span class="ident">Item</span>, <span class="ident">B</span>::<span class="ident">Item</span>);
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">next</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="self">Self</span>::<span class="ident">Item</span><span class="op">></span> {
<span class="ident">ZipImpl</span>::<span class="ident">next</span>(<span class="self">self</span>)
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">size_hint</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> (<span class="ident">usize</span>, <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">usize</span><span class="op">></span>) {
<span class="ident">ZipImpl</span>::<span class="ident">size_hint</span>(<span class="self">self</span>)
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">A</span>, <span class="ident">B</span><span class="op">></span> <span class="ident">DoubleEndedIterator</span> <span class="kw">for</span> <span class="ident">Zip</span><span class="op"><</span><span class="ident">A</span>, <span class="ident">B</span><span class="op">></span> <span class="kw">where</span>
<span class="ident">A</span>: <span class="ident">DoubleEndedIterator</span> <span class="op">+</span> <span class="ident">ExactSizeIterator</span>,
<span class="ident">B</span>: <span class="ident">DoubleEndedIterator</span> <span class="op">+</span> <span class="ident">ExactSizeIterator</span>,
{
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">next_back</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span>(<span class="ident">A</span>::<span class="ident">Item</span>, <span class="ident">B</span>::<span class="ident">Item</span>)<span class="op">></span> {
<span class="ident">ZipImpl</span>::<span class="ident">next_back</span>(<span class="self">self</span>)
}
}
<span class="comment">// Zip specialization trait</span>
<span class="attribute">#[<span class="ident">doc</span>(<span class="ident">hidden</span>)]</span>
<span class="kw">trait</span> <span class="ident">ZipImpl</span><span class="op"><</span><span class="ident">A</span>, <span class="ident">B</span><span class="op">></span> {
<span class="kw">type</span> <span class="ident">Item</span>;
<span class="kw">fn</span> <span class="ident">new</span>(<span class="ident">a</span>: <span class="ident">A</span>, <span class="ident">b</span>: <span class="ident">B</span>) <span class="op">-></span> <span class="self">Self</span>;
<span class="kw">fn</span> <span class="ident">next</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="self">Self</span>::<span class="ident">Item</span><span class="op">></span>;
<span class="kw">fn</span> <span class="ident">size_hint</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> (<span class="ident">usize</span>, <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">usize</span><span class="op">></span>);
<span class="kw">fn</span> <span class="ident">next_back</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="self">Self</span>::<span class="ident">Item</span><span class="op">></span>
<span class="kw">where</span> <span class="ident">A</span>: <span class="ident">DoubleEndedIterator</span> <span class="op">+</span> <span class="ident">ExactSizeIterator</span>,
<span class="ident">B</span>: <span class="ident">DoubleEndedIterator</span> <span class="op">+</span> <span class="ident">ExactSizeIterator</span>;
}
<span class="comment">// General Zip impl</span>
<span class="attribute">#[<span class="ident">doc</span>(<span class="ident">hidden</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">A</span>, <span class="ident">B</span><span class="op">></span> <span class="ident">ZipImpl</span><span class="op"><</span><span class="ident">A</span>, <span class="ident">B</span><span class="op">></span> <span class="kw">for</span> <span class="ident">Zip</span><span class="op"><</span><span class="ident">A</span>, <span class="ident">B</span><span class="op">></span>
<span class="kw">where</span> <span class="ident">A</span>: <span class="ident">Iterator</span>, <span class="ident">B</span>: <span class="ident">Iterator</span>
{
<span class="kw">type</span> <span class="ident">Item</span> <span class="op">=</span> (<span class="ident">A</span>::<span class="ident">Item</span>, <span class="ident">B</span>::<span class="ident">Item</span>);
<span class="ident">default</span> <span class="kw">fn</span> <span class="ident">new</span>(<span class="ident">a</span>: <span class="ident">A</span>, <span class="ident">b</span>: <span class="ident">B</span>) <span class="op">-></span> <span class="self">Self</span> {
<span class="ident">Zip</span> {
<span class="ident">a</span>: <span class="ident">a</span>,
<span class="ident">b</span>: <span class="ident">b</span>,
<span class="ident">index</span>: <span class="number">0</span>, <span class="comment">// unused</span>
<span class="ident">len</span>: <span class="number">0</span>, <span class="comment">// unused</span>
}
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="ident">default</span> <span class="kw">fn</span> <span class="ident">next</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span>(<span class="ident">A</span>::<span class="ident">Item</span>, <span class="ident">B</span>::<span class="ident">Item</span>)<span class="op">></span> {
<span class="self">self</span>.<span class="ident">a</span>.<span class="ident">next</span>().<span class="ident">and_then</span>(<span class="op">|</span><span class="ident">x</span><span class="op">|</span> {
<span class="self">self</span>.<span class="ident">b</span>.<span class="ident">next</span>().<span class="ident">and_then</span>(<span class="op">|</span><span class="ident">y</span><span class="op">|</span> {
<span class="prelude-val">Some</span>((<span class="ident">x</span>, <span class="ident">y</span>))
})
})
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="ident">default</span> <span class="kw">fn</span> <span class="ident">next_back</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span>(<span class="ident">A</span>::<span class="ident">Item</span>, <span class="ident">B</span>::<span class="ident">Item</span>)<span class="op">></span>
<span class="kw">where</span> <span class="ident">A</span>: <span class="ident">DoubleEndedIterator</span> <span class="op">+</span> <span class="ident">ExactSizeIterator</span>,
<span class="ident">B</span>: <span class="ident">DoubleEndedIterator</span> <span class="op">+</span> <span class="ident">ExactSizeIterator</span>
{
<span class="kw">let</span> <span class="ident">a_sz</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">a</span>.<span class="ident">len</span>();
<span class="kw">let</span> <span class="ident">b_sz</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">b</span>.<span class="ident">len</span>();
<span class="kw">if</span> <span class="ident">a_sz</span> <span class="op">!=</span> <span class="ident">b_sz</span> {
<span class="comment">// Adjust a, b to equal length</span>
<span class="kw">if</span> <span class="ident">a_sz</span> <span class="op">></span> <span class="ident">b_sz</span> {
<span class="kw">for</span> _ <span class="kw">in</span> <span class="number">0</span>..<span class="ident">a_sz</span> <span class="op">-</span> <span class="ident">b_sz</span> { <span class="self">self</span>.<span class="ident">a</span>.<span class="ident">next_back</span>(); }
} <span class="kw">else</span> {
<span class="kw">for</span> _ <span class="kw">in</span> <span class="number">0</span>..<span class="ident">b_sz</span> <span class="op">-</span> <span class="ident">a_sz</span> { <span class="self">self</span>.<span class="ident">b</span>.<span class="ident">next_back</span>(); }
}
}
<span class="kw">match</span> (<span class="self">self</span>.<span class="ident">a</span>.<span class="ident">next_back</span>(), <span class="self">self</span>.<span class="ident">b</span>.<span class="ident">next_back</span>()) {
(<span class="prelude-val">Some</span>(<span class="ident">x</span>), <span class="prelude-val">Some</span>(<span class="ident">y</span>)) <span class="op">=></span> <span class="prelude-val">Some</span>((<span class="ident">x</span>, <span class="ident">y</span>)),
(<span class="prelude-val">None</span>, <span class="prelude-val">None</span>) <span class="op">=></span> <span class="prelude-val">None</span>,
_ <span class="op">=></span> <span class="macro">unreachable</span><span class="macro">!</span>(),
}
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="ident">default</span> <span class="kw">fn</span> <span class="ident">size_hint</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> (<span class="ident">usize</span>, <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">usize</span><span class="op">></span>) {
<span class="kw">let</span> (<span class="ident">a_lower</span>, <span class="ident">a_upper</span>) <span class="op">=</span> <span class="self">self</span>.<span class="ident">a</span>.<span class="ident">size_hint</span>();
<span class="kw">let</span> (<span class="ident">b_lower</span>, <span class="ident">b_upper</span>) <span class="op">=</span> <span class="self">self</span>.<span class="ident">b</span>.<span class="ident">size_hint</span>();
<span class="kw">let</span> <span class="ident">lower</span> <span class="op">=</span> <span class="ident">cmp</span>::<span class="ident">min</span>(<span class="ident">a_lower</span>, <span class="ident">b_lower</span>);
<span class="kw">let</span> <span class="ident">upper</span> <span class="op">=</span> <span class="kw">match</span> (<span class="ident">a_upper</span>, <span class="ident">b_upper</span>) {
(<span class="prelude-val">Some</span>(<span class="ident">x</span>), <span class="prelude-val">Some</span>(<span class="ident">y</span>)) <span class="op">=></span> <span class="prelude-val">Some</span>(<span class="ident">cmp</span>::<span class="ident">min</span>(<span class="ident">x</span>,<span class="ident">y</span>)),
(<span class="prelude-val">Some</span>(<span class="ident">x</span>), <span class="prelude-val">None</span>) <span class="op">=></span> <span class="prelude-val">Some</span>(<span class="ident">x</span>),
(<span class="prelude-val">None</span>, <span class="prelude-val">Some</span>(<span class="ident">y</span>)) <span class="op">=></span> <span class="prelude-val">Some</span>(<span class="ident">y</span>),
(<span class="prelude-val">None</span>, <span class="prelude-val">None</span>) <span class="op">=></span> <span class="prelude-val">None</span>
};
(<span class="ident">lower</span>, <span class="ident">upper</span>)
}
}
<span class="attribute">#[<span class="ident">doc</span>(<span class="ident">hidden</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">A</span>, <span class="ident">B</span><span class="op">></span> <span class="ident">ZipImpl</span><span class="op"><</span><span class="ident">A</span>, <span class="ident">B</span><span class="op">></span> <span class="kw">for</span> <span class="ident">Zip</span><span class="op"><</span><span class="ident">A</span>, <span class="ident">B</span><span class="op">></span>
<span class="kw">where</span> <span class="ident">A</span>: <span class="ident">TrustedRandomAccess</span>, <span class="ident">B</span>: <span class="ident">TrustedRandomAccess</span>
{
<span class="kw">fn</span> <span class="ident">new</span>(<span class="ident">a</span>: <span class="ident">A</span>, <span class="ident">b</span>: <span class="ident">B</span>) <span class="op">-></span> <span class="self">Self</span> {
<span class="kw">let</span> <span class="ident">len</span> <span class="op">=</span> <span class="ident">cmp</span>::<span class="ident">min</span>(<span class="ident">a</span>.<span class="ident">len</span>(), <span class="ident">b</span>.<span class="ident">len</span>());
<span class="ident">Zip</span> {
<span class="ident">a</span>: <span class="ident">a</span>,
<span class="ident">b</span>: <span class="ident">b</span>,
<span class="ident">index</span>: <span class="number">0</span>,
<span class="ident">len</span>: <span class="ident">len</span>,
}
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">next</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span>(<span class="ident">A</span>::<span class="ident">Item</span>, <span class="ident">B</span>::<span class="ident">Item</span>)<span class="op">></span> {
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">index</span> <span class="op"><</span> <span class="self">self</span>.<span class="ident">len</span> {
<span class="kw">let</span> <span class="ident">i</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">index</span>;
<span class="self">self</span>.<span class="ident">index</span> <span class="op">+=</span> <span class="number">1</span>;
<span class="kw">unsafe</span> {
<span class="prelude-val">Some</span>((<span class="self">self</span>.<span class="ident">a</span>.<span class="ident">get_unchecked</span>(<span class="ident">i</span>), <span class="self">self</span>.<span class="ident">b</span>.<span class="ident">get_unchecked</span>(<span class="ident">i</span>)))
}
} <span class="kw">else</span> <span class="kw">if</span> <span class="ident">A</span>::<span class="ident">may_have_side_effect</span>() <span class="op">&&</span> <span class="self">self</span>.<span class="ident">index</span> <span class="op"><</span> <span class="self">self</span>.<span class="ident">a</span>.<span class="ident">len</span>() {
<span class="comment">// match the base implementation's potential side effects</span>
<span class="kw">unsafe</span> {
<span class="self">self</span>.<span class="ident">a</span>.<span class="ident">get_unchecked</span>(<span class="self">self</span>.<span class="ident">index</span>);
}
<span class="self">self</span>.<span class="ident">index</span> <span class="op">+=</span> <span class="number">1</span>;
<span class="prelude-val">None</span>
} <span class="kw">else</span> {
<span class="prelude-val">None</span>
}
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">size_hint</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> (<span class="ident">usize</span>, <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">usize</span><span class="op">></span>) {
<span class="kw">let</span> <span class="ident">len</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">len</span> <span class="op">-</span> <span class="self">self</span>.<span class="ident">index</span>;
(<span class="ident">len</span>, <span class="prelude-val">Some</span>(<span class="ident">len</span>))
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">next_back</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span>(<span class="ident">A</span>::<span class="ident">Item</span>, <span class="ident">B</span>::<span class="ident">Item</span>)<span class="op">></span>
<span class="kw">where</span> <span class="ident">A</span>: <span class="ident">DoubleEndedIterator</span> <span class="op">+</span> <span class="ident">ExactSizeIterator</span>,
<span class="ident">B</span>: <span class="ident">DoubleEndedIterator</span> <span class="op">+</span> <span class="ident">ExactSizeIterator</span>
{
<span class="comment">// Adjust a, b to equal length</span>
<span class="kw">if</span> <span class="ident">A</span>::<span class="ident">may_have_side_effect</span>() {
<span class="kw">let</span> <span class="ident">sz</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">a</span>.<span class="ident">len</span>();
<span class="kw">if</span> <span class="ident">sz</span> <span class="op">></span> <span class="self">self</span>.<span class="ident">len</span> {
<span class="kw">for</span> _ <span class="kw">in</span> <span class="number">0</span>..<span class="ident">sz</span> <span class="op">-</span> <span class="ident">cmp</span>::<span class="ident">max</span>(<span class="self">self</span>.<span class="ident">len</span>, <span class="self">self</span>.<span class="ident">index</span>) {
<span class="self">self</span>.<span class="ident">a</span>.<span class="ident">next_back</span>();
}
}
}
<span class="kw">if</span> <span class="ident">B</span>::<span class="ident">may_have_side_effect</span>() {
<span class="kw">let</span> <span class="ident">sz</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">b</span>.<span class="ident">len</span>();
<span class="kw">if</span> <span class="ident">sz</span> <span class="op">></span> <span class="self">self</span>.<span class="ident">len</span> {
<span class="kw">for</span> _ <span class="kw">in</span> <span class="number">0</span>..<span class="ident">sz</span> <span class="op">-</span> <span class="self">self</span>.<span class="ident">len</span> {
<span class="self">self</span>.<span class="ident">b</span>.<span class="ident">next_back</span>();
}
}
}
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">index</span> <span class="op"><</span> <span class="self">self</span>.<span class="ident">len</span> {
<span class="self">self</span>.<span class="ident">len</span> <span class="op">-=</span> <span class="number">1</span>;
<span class="kw">let</span> <span class="ident">i</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">len</span>;
<span class="kw">unsafe</span> {
<span class="prelude-val">Some</span>((<span class="self">self</span>.<span class="ident">a</span>.<span class="ident">get_unchecked</span>(<span class="ident">i</span>), <span class="self">self</span>.<span class="ident">b</span>.<span class="ident">get_unchecked</span>(<span class="ident">i</span>)))
}
} <span class="kw">else</span> {
<span class="prelude-val">None</span>
}
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">A</span>, <span class="ident">B</span><span class="op">></span> <span class="ident">ExactSizeIterator</span> <span class="kw">for</span> <span class="ident">Zip</span><span class="op"><</span><span class="ident">A</span>, <span class="ident">B</span><span class="op">></span>
<span class="kw">where</span> <span class="ident">A</span>: <span class="ident">ExactSizeIterator</span>, <span class="ident">B</span>: <span class="ident">ExactSizeIterator</span> {}
<span class="attribute">#[<span class="ident">doc</span>(<span class="ident">hidden</span>)]</span>
<span class="kw">unsafe</span> <span class="kw">impl</span><span class="op"><</span><span class="ident">A</span>, <span class="ident">B</span><span class="op">></span> <span class="ident">TrustedRandomAccess</span> <span class="kw">for</span> <span class="ident">Zip</span><span class="op"><</span><span class="ident">A</span>, <span class="ident">B</span><span class="op">></span>
<span class="kw">where</span> <span class="ident">A</span>: <span class="ident">TrustedRandomAccess</span>,
<span class="ident">B</span>: <span class="ident">TrustedRandomAccess</span>,
{
<span class="kw">unsafe</span> <span class="kw">fn</span> <span class="ident">get_unchecked</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">i</span>: <span class="ident">usize</span>) <span class="op">-></span> (<span class="ident">A</span>::<span class="ident">Item</span>, <span class="ident">B</span>::<span class="ident">Item</span>) {
(<span class="self">self</span>.<span class="ident">a</span>.<span class="ident">get_unchecked</span>(<span class="ident">i</span>), <span class="self">self</span>.<span class="ident">b</span>.<span class="ident">get_unchecked</span>(<span class="ident">i</span>))
}
<span class="kw">fn</span> <span class="ident">may_have_side_effect</span>() <span class="op">-></span> <span class="ident">bool</span> {
<span class="ident">A</span>::<span class="ident">may_have_side_effect</span>() <span class="op">||</span> <span class="ident">B</span>::<span class="ident">may_have_side_effect</span>()
}
}
<span class="attribute">#[<span class="ident">unstable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"fused"</span>, <span class="ident">issue</span> <span class="op">=</span> <span class="string">"35602"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">A</span>, <span class="ident">B</span><span class="op">></span> <span class="ident">FusedIterator</span> <span class="kw">for</span> <span class="ident">Zip</span><span class="op"><</span><span class="ident">A</span>, <span class="ident">B</span><span class="op">></span>
<span class="kw">where</span> <span class="ident">A</span>: <span class="ident">FusedIterator</span>, <span class="ident">B</span>: <span class="ident">FusedIterator</span>, {}
<span class="attribute">#[<span class="ident">unstable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"trusted_len"</span>, <span class="ident">issue</span> <span class="op">=</span> <span class="string">"37572"</span>)]</span>
<span class="kw">unsafe</span> <span class="kw">impl</span><span class="op"><</span><span class="ident">A</span>, <span class="ident">B</span><span class="op">></span> <span class="ident">TrustedLen</span> <span class="kw">for</span> <span class="ident">Zip</span><span class="op"><</span><span class="ident">A</span>, <span class="ident">B</span><span class="op">></span>
<span class="kw">where</span> <span class="ident">A</span>: <span class="ident">TrustedLen</span>, <span class="ident">B</span>: <span class="ident">TrustedLen</span>,
{}
<span class="doccomment">/// An iterator that maps the values of `iter` with `f`.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This `struct` is created by the [`map`] method on [`Iterator`]. See its</span>
<span class="doccomment">/// documentation for more.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// [`map`]: trait.Iterator.html#method.map</span>
<span class="doccomment">/// [`Iterator`]: trait.Iterator.html</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Notes about side effects</span>
<span class="doccomment">///</span>
<span class="doccomment">/// The [`map`] iterator implements [`DoubleEndedIterator`], meaning that</span>
<span class="doccomment">/// you can also [`map`] backwards:</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```rust</span>
<span class="doccomment">/// let v: Vec<i32> = vec![1, 2, 3].into_iter().map(|x| x + 1).rev().collect();</span>
<span class="doccomment">///</span>
<span class="doccomment">/// assert_eq!(v, [4, 3, 2]);</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">///</span>
<span class="doccomment">/// [`DoubleEndedIterator`]: trait.DoubleEndedIterator.html</span>
<span class="doccomment">///</span>
<span class="doccomment">/// But if your closure has state, iterating backwards may act in a way you do</span>
<span class="doccomment">/// not expect. Let's go through an example. First, in the forward direction:</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```rust</span>
<span class="doccomment">/// let mut c = 0;</span>
<span class="doccomment">///</span>
<span class="doccomment">/// for pair in vec!['a', 'b', 'c'].into_iter()</span>
<span class="doccomment">/// .map(|letter| { c += 1; (letter, c) }) {</span>
<span class="doccomment">/// println!("{:?}", pair);</span>
<span class="doccomment">/// }</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This will print "('a', 1), ('b', 2), ('c', 3)".</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Now consider this twist where we add a call to `rev`. This version will</span>
<span class="doccomment">/// print `('c', 1), ('b', 2), ('a', 3)`. Note that the letters are reversed,</span>
<span class="doccomment">/// but the values of the counter still go in order. This is because `map()` is</span>
<span class="doccomment">/// still being called lazilly on each item, but we are popping items off the</span>
<span class="doccomment">/// back of the vector now, instead of shifting them from the front.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```rust</span>
<span class="doccomment">/// let mut c = 0;</span>
<span class="doccomment">///</span>
<span class="doccomment">/// for pair in vec!['a', 'b', 'c'].into_iter()</span>
<span class="doccomment">/// .map(|letter| { c += 1; (letter, c) })</span>
<span class="doccomment">/// .rev() {</span>
<span class="doccomment">/// println!("{:?}", pair);</span>
<span class="doccomment">/// }</span>
<span class="doccomment">/// ```</span>
<span class="attribute">#[<span class="ident">must_use</span> <span class="op">=</span> <span class="string">"iterator adaptors are lazy and do nothing unless consumed"</span>]</span>
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Clone</span>)]</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">Map</span><span class="op"><</span><span class="ident">I</span>, <span class="ident">F</span><span class="op">></span> {
<span class="ident">iter</span>: <span class="ident">I</span>,
<span class="ident">f</span>: <span class="ident">F</span>,
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"core_impl_debug"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.9.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">I</span>: <span class="ident">fmt</span>::<span class="ident">Debug</span>, <span class="ident">F</span><span class="op">></span> <span class="ident">fmt</span>::<span class="ident">Debug</span> <span class="kw">for</span> <span class="ident">Map</span><span class="op"><</span><span class="ident">I</span>, <span class="ident">F</span><span class="op">></span> {
<span class="kw">fn</span> <span class="ident">fmt</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">f</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">fmt</span>::<span class="ident">Formatter</span>) <span class="op">-></span> <span class="ident">fmt</span>::<span class="prelude-ty">Result</span> {
<span class="ident">f</span>.<span class="ident">debug_struct</span>(<span class="string">"Map"</span>)
.<span class="ident">field</span>(<span class="string">"iter"</span>, <span class="kw-2">&</span><span class="self">self</span>.<span class="ident">iter</span>)
.<span class="ident">finish</span>()
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">B</span>, <span class="ident">I</span>: <span class="ident">Iterator</span>, <span class="ident">F</span><span class="op">></span> <span class="ident">Iterator</span> <span class="kw">for</span> <span class="ident">Map</span><span class="op"><</span><span class="ident">I</span>, <span class="ident">F</span><span class="op">></span> <span class="kw">where</span> <span class="ident">F</span>: <span class="ident">FnMut</span>(<span class="ident">I</span>::<span class="ident">Item</span>) <span class="op">-></span> <span class="ident">B</span> {
<span class="kw">type</span> <span class="ident">Item</span> <span class="op">=</span> <span class="ident">B</span>;
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">next</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">B</span><span class="op">></span> {
<span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">next</span>().<span class="ident">map</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>.<span class="ident">f</span>)
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">size_hint</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> (<span class="ident">usize</span>, <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">usize</span><span class="op">></span>) {
<span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">size_hint</span>()
}
<span class="kw">fn</span> <span class="ident">fold</span><span class="op"><</span><span class="ident">Acc</span>, <span class="ident">G</span><span class="op">></span>(<span class="self">self</span>, <span class="ident">init</span>: <span class="ident">Acc</span>, <span class="kw-2">mut</span> <span class="ident">g</span>: <span class="ident">G</span>) <span class="op">-></span> <span class="ident">Acc</span>
<span class="kw">where</span> <span class="ident">G</span>: <span class="ident">FnMut</span>(<span class="ident">Acc</span>, <span class="self">Self</span>::<span class="ident">Item</span>) <span class="op">-></span> <span class="ident">Acc</span>,
{
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">f</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">f</span>;
<span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">fold</span>(<span class="ident">init</span>, <span class="kw">move</span> <span class="op">|</span><span class="ident">acc</span>, <span class="ident">elt</span><span class="op">|</span> <span class="ident">g</span>(<span class="ident">acc</span>, <span class="ident">f</span>(<span class="ident">elt</span>)))
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">B</span>, <span class="ident">I</span>: <span class="ident">DoubleEndedIterator</span>, <span class="ident">F</span><span class="op">></span> <span class="ident">DoubleEndedIterator</span> <span class="kw">for</span> <span class="ident">Map</span><span class="op"><</span><span class="ident">I</span>, <span class="ident">F</span><span class="op">></span> <span class="kw">where</span>
<span class="ident">F</span>: <span class="ident">FnMut</span>(<span class="ident">I</span>::<span class="ident">Item</span>) <span class="op">-></span> <span class="ident">B</span>,
{
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">next_back</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">B</span><span class="op">></span> {
<span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">next_back</span>().<span class="ident">map</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>.<span class="ident">f</span>)
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">B</span>, <span class="ident">I</span>: <span class="ident">ExactSizeIterator</span>, <span class="ident">F</span><span class="op">></span> <span class="ident">ExactSizeIterator</span> <span class="kw">for</span> <span class="ident">Map</span><span class="op"><</span><span class="ident">I</span>, <span class="ident">F</span><span class="op">></span>
<span class="kw">where</span> <span class="ident">F</span>: <span class="ident">FnMut</span>(<span class="ident">I</span>::<span class="ident">Item</span>) <span class="op">-></span> <span class="ident">B</span>
{
<span class="kw">fn</span> <span class="ident">len</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="ident">usize</span> {
<span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">len</span>()
}
<span class="kw">fn</span> <span class="ident">is_empty</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="ident">bool</span> {
<span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">is_empty</span>()
}
}
<span class="attribute">#[<span class="ident">unstable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"fused"</span>, <span class="ident">issue</span> <span class="op">=</span> <span class="string">"35602"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">B</span>, <span class="ident">I</span>: <span class="ident">FusedIterator</span>, <span class="ident">F</span><span class="op">></span> <span class="ident">FusedIterator</span> <span class="kw">for</span> <span class="ident">Map</span><span class="op"><</span><span class="ident">I</span>, <span class="ident">F</span><span class="op">></span>
<span class="kw">where</span> <span class="ident">F</span>: <span class="ident">FnMut</span>(<span class="ident">I</span>::<span class="ident">Item</span>) <span class="op">-></span> <span class="ident">B</span> {}
<span class="attribute">#[<span class="ident">unstable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"trusted_len"</span>, <span class="ident">issue</span> <span class="op">=</span> <span class="string">"37572"</span>)]</span>
<span class="kw">unsafe</span> <span class="kw">impl</span><span class="op"><</span><span class="ident">B</span>, <span class="ident">I</span>, <span class="ident">F</span><span class="op">></span> <span class="ident">TrustedLen</span> <span class="kw">for</span> <span class="ident">Map</span><span class="op"><</span><span class="ident">I</span>, <span class="ident">F</span><span class="op">></span>
<span class="kw">where</span> <span class="ident">I</span>: <span class="ident">TrustedLen</span>,
<span class="ident">F</span>: <span class="ident">FnMut</span>(<span class="ident">I</span>::<span class="ident">Item</span>) <span class="op">-></span> <span class="ident">B</span> {}
<span class="attribute">#[<span class="ident">doc</span>(<span class="ident">hidden</span>)]</span>
<span class="kw">unsafe</span> <span class="kw">impl</span><span class="op"><</span><span class="ident">B</span>, <span class="ident">I</span>, <span class="ident">F</span><span class="op">></span> <span class="ident">TrustedRandomAccess</span> <span class="kw">for</span> <span class="ident">Map</span><span class="op"><</span><span class="ident">I</span>, <span class="ident">F</span><span class="op">></span>
<span class="kw">where</span> <span class="ident">I</span>: <span class="ident">TrustedRandomAccess</span>,
<span class="ident">F</span>: <span class="ident">FnMut</span>(<span class="ident">I</span>::<span class="ident">Item</span>) <span class="op">-></span> <span class="ident">B</span>,
{
<span class="kw">unsafe</span> <span class="kw">fn</span> <span class="ident">get_unchecked</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">i</span>: <span class="ident">usize</span>) <span class="op">-></span> <span class="self">Self</span>::<span class="ident">Item</span> {
(<span class="self">self</span>.<span class="ident">f</span>)(<span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">get_unchecked</span>(<span class="ident">i</span>))
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">may_have_side_effect</span>() <span class="op">-></span> <span class="ident">bool</span> { <span class="bool-val">true</span> }
}
<span class="doccomment">/// An iterator that filters the elements of `iter` with `predicate`.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This `struct` is created by the [`filter`] method on [`Iterator`]. See its</span>
<span class="doccomment">/// documentation for more.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// [`filter`]: trait.Iterator.html#method.filter</span>
<span class="doccomment">/// [`Iterator`]: trait.Iterator.html</span>
<span class="attribute">#[<span class="ident">must_use</span> <span class="op">=</span> <span class="string">"iterator adaptors are lazy and do nothing unless consumed"</span>]</span>
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Clone</span>)]</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">Filter</span><span class="op"><</span><span class="ident">I</span>, <span class="ident">P</span><span class="op">></span> {
<span class="ident">iter</span>: <span class="ident">I</span>,
<span class="ident">predicate</span>: <span class="ident">P</span>,
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"core_impl_debug"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.9.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">I</span>: <span class="ident">fmt</span>::<span class="ident">Debug</span>, <span class="ident">P</span><span class="op">></span> <span class="ident">fmt</span>::<span class="ident">Debug</span> <span class="kw">for</span> <span class="ident">Filter</span><span class="op"><</span><span class="ident">I</span>, <span class="ident">P</span><span class="op">></span> {
<span class="kw">fn</span> <span class="ident">fmt</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">f</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">fmt</span>::<span class="ident">Formatter</span>) <span class="op">-></span> <span class="ident">fmt</span>::<span class="prelude-ty">Result</span> {
<span class="ident">f</span>.<span class="ident">debug_struct</span>(<span class="string">"Filter"</span>)
.<span class="ident">field</span>(<span class="string">"iter"</span>, <span class="kw-2">&</span><span class="self">self</span>.<span class="ident">iter</span>)
.<span class="ident">finish</span>()
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">I</span>: <span class="ident">Iterator</span>, <span class="ident">P</span><span class="op">></span> <span class="ident">Iterator</span> <span class="kw">for</span> <span class="ident">Filter</span><span class="op"><</span><span class="ident">I</span>, <span class="ident">P</span><span class="op">></span> <span class="kw">where</span> <span class="ident">P</span>: <span class="ident">FnMut</span>(<span class="kw-2">&</span><span class="ident">I</span>::<span class="ident">Item</span>) <span class="op">-></span> <span class="ident">bool</span> {
<span class="kw">type</span> <span class="ident">Item</span> <span class="op">=</span> <span class="ident">I</span>::<span class="ident">Item</span>;
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">next</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">I</span>::<span class="ident">Item</span><span class="op">></span> {
<span class="kw">for</span> <span class="ident">x</span> <span class="kw">in</span> <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>.<span class="ident">iter</span> {
<span class="kw">if</span> (<span class="self">self</span>.<span class="ident">predicate</span>)(<span class="kw-2">&</span><span class="ident">x</span>) {
<span class="kw">return</span> <span class="prelude-val">Some</span>(<span class="ident">x</span>);
}
}
<span class="prelude-val">None</span>
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">size_hint</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> (<span class="ident">usize</span>, <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">usize</span><span class="op">></span>) {
<span class="kw">let</span> (_, <span class="ident">upper</span>) <span class="op">=</span> <span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">size_hint</span>();
(<span class="number">0</span>, <span class="ident">upper</span>) <span class="comment">// can't know a lower bound, due to the predicate</span>
}
<span class="comment">// this special case allows the compiler to make `.filter(_).count()`</span>
<span class="comment">// branchless. Barring perfect branch prediction (which is unattainable in</span>
<span class="comment">// the general case), this will be much faster in >90% of cases (containing</span>
<span class="comment">// virtually all real workloads) and only a tiny bit slower in the rest.</span>
<span class="comment">//</span>
<span class="comment">// Having this specialization thus allows us to write `.filter(p).count()`</span>
<span class="comment">// where we would otherwise write `.map(|x| p(x) as usize).sum()`, which is</span>
<span class="comment">// less readable and also less backwards-compatible to Rust before 1.10.</span>
<span class="comment">//</span>
<span class="comment">// Using the branchless version will also simplify the LLVM byte code, thus</span>
<span class="comment">// leaving more budget for LLVM optimizations.</span>
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">count</span>(<span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="ident">usize</span> {
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">count</span> <span class="op">=</span> <span class="number">0</span>;
<span class="kw">for</span> <span class="ident">x</span> <span class="kw">in</span> <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>.<span class="ident">iter</span> {
<span class="ident">count</span> <span class="op">+=</span> (<span class="self">self</span>.<span class="ident">predicate</span>)(<span class="kw-2">&</span><span class="ident">x</span>) <span class="kw">as</span> <span class="ident">usize</span>;
}
<span class="ident">count</span>
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">I</span>: <span class="ident">DoubleEndedIterator</span>, <span class="ident">P</span><span class="op">></span> <span class="ident">DoubleEndedIterator</span> <span class="kw">for</span> <span class="ident">Filter</span><span class="op"><</span><span class="ident">I</span>, <span class="ident">P</span><span class="op">></span>
<span class="kw">where</span> <span class="ident">P</span>: <span class="ident">FnMut</span>(<span class="kw-2">&</span><span class="ident">I</span>::<span class="ident">Item</span>) <span class="op">-></span> <span class="ident">bool</span>,
{
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">next_back</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">I</span>::<span class="ident">Item</span><span class="op">></span> {
<span class="kw">for</span> <span class="ident">x</span> <span class="kw">in</span> <span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">by_ref</span>().<span class="ident">rev</span>() {
<span class="kw">if</span> (<span class="self">self</span>.<span class="ident">predicate</span>)(<span class="kw-2">&</span><span class="ident">x</span>) {
<span class="kw">return</span> <span class="prelude-val">Some</span>(<span class="ident">x</span>);
}
}
<span class="prelude-val">None</span>
}
}
<span class="attribute">#[<span class="ident">unstable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"fused"</span>, <span class="ident">issue</span> <span class="op">=</span> <span class="string">"35602"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">I</span>: <span class="ident">FusedIterator</span>, <span class="ident">P</span><span class="op">></span> <span class="ident">FusedIterator</span> <span class="kw">for</span> <span class="ident">Filter</span><span class="op"><</span><span class="ident">I</span>, <span class="ident">P</span><span class="op">></span>
<span class="kw">where</span> <span class="ident">P</span>: <span class="ident">FnMut</span>(<span class="kw-2">&</span><span class="ident">I</span>::<span class="ident">Item</span>) <span class="op">-></span> <span class="ident">bool</span> {}
<span class="doccomment">/// An iterator that uses `f` to both filter and map elements from `iter`.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This `struct` is created by the [`filter_map`] method on [`Iterator`]. See its</span>
<span class="doccomment">/// documentation for more.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// [`filter_map`]: trait.Iterator.html#method.filter_map</span>
<span class="doccomment">/// [`Iterator`]: trait.Iterator.html</span>
<span class="attribute">#[<span class="ident">must_use</span> <span class="op">=</span> <span class="string">"iterator adaptors are lazy and do nothing unless consumed"</span>]</span>
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Clone</span>)]</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">FilterMap</span><span class="op"><</span><span class="ident">I</span>, <span class="ident">F</span><span class="op">></span> {
<span class="ident">iter</span>: <span class="ident">I</span>,
<span class="ident">f</span>: <span class="ident">F</span>,
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"core_impl_debug"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.9.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">I</span>: <span class="ident">fmt</span>::<span class="ident">Debug</span>, <span class="ident">F</span><span class="op">></span> <span class="ident">fmt</span>::<span class="ident">Debug</span> <span class="kw">for</span> <span class="ident">FilterMap</span><span class="op"><</span><span class="ident">I</span>, <span class="ident">F</span><span class="op">></span> {
<span class="kw">fn</span> <span class="ident">fmt</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">f</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">fmt</span>::<span class="ident">Formatter</span>) <span class="op">-></span> <span class="ident">fmt</span>::<span class="prelude-ty">Result</span> {
<span class="ident">f</span>.<span class="ident">debug_struct</span>(<span class="string">"FilterMap"</span>)
.<span class="ident">field</span>(<span class="string">"iter"</span>, <span class="kw-2">&</span><span class="self">self</span>.<span class="ident">iter</span>)
.<span class="ident">finish</span>()
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">B</span>, <span class="ident">I</span>: <span class="ident">Iterator</span>, <span class="ident">F</span><span class="op">></span> <span class="ident">Iterator</span> <span class="kw">for</span> <span class="ident">FilterMap</span><span class="op"><</span><span class="ident">I</span>, <span class="ident">F</span><span class="op">></span>
<span class="kw">where</span> <span class="ident">F</span>: <span class="ident">FnMut</span>(<span class="ident">I</span>::<span class="ident">Item</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">B</span><span class="op">></span>,
{
<span class="kw">type</span> <span class="ident">Item</span> <span class="op">=</span> <span class="ident">B</span>;
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">next</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">B</span><span class="op">></span> {
<span class="kw">for</span> <span class="ident">x</span> <span class="kw">in</span> <span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">by_ref</span>() {
<span class="kw">if</span> <span class="kw">let</span> <span class="prelude-val">Some</span>(<span class="ident">y</span>) <span class="op">=</span> (<span class="self">self</span>.<span class="ident">f</span>)(<span class="ident">x</span>) {
<span class="kw">return</span> <span class="prelude-val">Some</span>(<span class="ident">y</span>);
}
}
<span class="prelude-val">None</span>
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">size_hint</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> (<span class="ident">usize</span>, <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">usize</span><span class="op">></span>) {
<span class="kw">let</span> (_, <span class="ident">upper</span>) <span class="op">=</span> <span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">size_hint</span>();
(<span class="number">0</span>, <span class="ident">upper</span>) <span class="comment">// can't know a lower bound, due to the predicate</span>
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">B</span>, <span class="ident">I</span>: <span class="ident">DoubleEndedIterator</span>, <span class="ident">F</span><span class="op">></span> <span class="ident">DoubleEndedIterator</span> <span class="kw">for</span> <span class="ident">FilterMap</span><span class="op"><</span><span class="ident">I</span>, <span class="ident">F</span><span class="op">></span>
<span class="kw">where</span> <span class="ident">F</span>: <span class="ident">FnMut</span>(<span class="ident">I</span>::<span class="ident">Item</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">B</span><span class="op">></span>,
{
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">next_back</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">B</span><span class="op">></span> {
<span class="kw">for</span> <span class="ident">x</span> <span class="kw">in</span> <span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">by_ref</span>().<span class="ident">rev</span>() {
<span class="kw">if</span> <span class="kw">let</span> <span class="prelude-val">Some</span>(<span class="ident">y</span>) <span class="op">=</span> (<span class="self">self</span>.<span class="ident">f</span>)(<span class="ident">x</span>) {
<span class="kw">return</span> <span class="prelude-val">Some</span>(<span class="ident">y</span>);
}
}
<span class="prelude-val">None</span>
}
}
<span class="attribute">#[<span class="ident">unstable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"fused"</span>, <span class="ident">issue</span> <span class="op">=</span> <span class="string">"35602"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">B</span>, <span class="ident">I</span>: <span class="ident">FusedIterator</span>, <span class="ident">F</span><span class="op">></span> <span class="ident">FusedIterator</span> <span class="kw">for</span> <span class="ident">FilterMap</span><span class="op"><</span><span class="ident">I</span>, <span class="ident">F</span><span class="op">></span>
<span class="kw">where</span> <span class="ident">F</span>: <span class="ident">FnMut</span>(<span class="ident">I</span>::<span class="ident">Item</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">B</span><span class="op">></span> {}
<span class="doccomment">/// An iterator that yields the current count and the element during iteration.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This `struct` is created by the [`enumerate`] method on [`Iterator`]. See its</span>
<span class="doccomment">/// documentation for more.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// [`enumerate`]: trait.Iterator.html#method.enumerate</span>
<span class="doccomment">/// [`Iterator`]: trait.Iterator.html</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Clone</span>, <span class="ident">Debug</span>)]</span>
<span class="attribute">#[<span class="ident">must_use</span> <span class="op">=</span> <span class="string">"iterator adaptors are lazy and do nothing unless consumed"</span>]</span>
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">Enumerate</span><span class="op"><</span><span class="ident">I</span><span class="op">></span> {
<span class="ident">iter</span>: <span class="ident">I</span>,
<span class="ident">count</span>: <span class="ident">usize</span>,
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">I</span><span class="op">></span> <span class="ident">Iterator</span> <span class="kw">for</span> <span class="ident">Enumerate</span><span class="op"><</span><span class="ident">I</span><span class="op">></span> <span class="kw">where</span> <span class="ident">I</span>: <span class="ident">Iterator</span> {
<span class="kw">type</span> <span class="ident">Item</span> <span class="op">=</span> (<span class="ident">usize</span>, <span class="op"><</span><span class="ident">I</span> <span class="kw">as</span> <span class="ident">Iterator</span><span class="op">></span>::<span class="ident">Item</span>);
<span class="doccomment">/// # Overflow Behavior</span>
<span class="doccomment">///</span>
<span class="doccomment">/// The method does no guarding against overflows, so enumerating more than</span>
<span class="doccomment">/// `usize::MAX` elements either produces the wrong result or panics. If</span>
<span class="doccomment">/// debug assertions are enabled, a panic is guaranteed.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Panics</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Might panic if the index of the element overflows a `usize`.</span>
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="attribute">#[<span class="ident">rustc_inherit_overflow_checks</span>]</span>
<span class="kw">fn</span> <span class="ident">next</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span>(<span class="ident">usize</span>, <span class="op"><</span><span class="ident">I</span> <span class="kw">as</span> <span class="ident">Iterator</span><span class="op">></span>::<span class="ident">Item</span>)<span class="op">></span> {
<span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">next</span>().<span class="ident">map</span>(<span class="op">|</span><span class="ident">a</span><span class="op">|</span> {
<span class="kw">let</span> <span class="ident">ret</span> <span class="op">=</span> (<span class="self">self</span>.<span class="ident">count</span>, <span class="ident">a</span>);
<span class="comment">// Possible undefined overflow.</span>
<span class="self">self</span>.<span class="ident">count</span> <span class="op">+=</span> <span class="number">1</span>;
<span class="ident">ret</span>
})
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">size_hint</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> (<span class="ident">usize</span>, <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">usize</span><span class="op">></span>) {
<span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">size_hint</span>()
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="attribute">#[<span class="ident">rustc_inherit_overflow_checks</span>]</span>
<span class="kw">fn</span> <span class="ident">nth</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">n</span>: <span class="ident">usize</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span>(<span class="ident">usize</span>, <span class="ident">I</span>::<span class="ident">Item</span>)<span class="op">></span> {
<span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">nth</span>(<span class="ident">n</span>).<span class="ident">map</span>(<span class="op">|</span><span class="ident">a</span><span class="op">|</span> {
<span class="kw">let</span> <span class="ident">i</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">count</span> <span class="op">+</span> <span class="ident">n</span>;
<span class="self">self</span>.<span class="ident">count</span> <span class="op">=</span> <span class="ident">i</span> <span class="op">+</span> <span class="number">1</span>;
(<span class="ident">i</span>, <span class="ident">a</span>)
})
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">count</span>(<span class="self">self</span>) <span class="op">-></span> <span class="ident">usize</span> {
<span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">count</span>()
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">I</span><span class="op">></span> <span class="ident">DoubleEndedIterator</span> <span class="kw">for</span> <span class="ident">Enumerate</span><span class="op"><</span><span class="ident">I</span><span class="op">></span> <span class="kw">where</span>
<span class="ident">I</span>: <span class="ident">ExactSizeIterator</span> <span class="op">+</span> <span class="ident">DoubleEndedIterator</span>
{
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">next_back</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span>(<span class="ident">usize</span>, <span class="op"><</span><span class="ident">I</span> <span class="kw">as</span> <span class="ident">Iterator</span><span class="op">></span>::<span class="ident">Item</span>)<span class="op">></span> {
<span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">next_back</span>().<span class="ident">map</span>(<span class="op">|</span><span class="ident">a</span><span class="op">|</span> {
<span class="kw">let</span> <span class="ident">len</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">len</span>();
<span class="comment">// Can safely add, `ExactSizeIterator` promises that the number of</span>
<span class="comment">// elements fits into a `usize`.</span>
(<span class="self">self</span>.<span class="ident">count</span> <span class="op">+</span> <span class="ident">len</span>, <span class="ident">a</span>)
})
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">I</span><span class="op">></span> <span class="ident">ExactSizeIterator</span> <span class="kw">for</span> <span class="ident">Enumerate</span><span class="op"><</span><span class="ident">I</span><span class="op">></span> <span class="kw">where</span> <span class="ident">I</span>: <span class="ident">ExactSizeIterator</span> {
<span class="kw">fn</span> <span class="ident">len</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="ident">usize</span> {
<span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">len</span>()
}
<span class="kw">fn</span> <span class="ident">is_empty</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="ident">bool</span> {
<span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">is_empty</span>()
}
}
<span class="attribute">#[<span class="ident">doc</span>(<span class="ident">hidden</span>)]</span>
<span class="kw">unsafe</span> <span class="kw">impl</span><span class="op"><</span><span class="ident">I</span><span class="op">></span> <span class="ident">TrustedRandomAccess</span> <span class="kw">for</span> <span class="ident">Enumerate</span><span class="op"><</span><span class="ident">I</span><span class="op">></span>
<span class="kw">where</span> <span class="ident">I</span>: <span class="ident">TrustedRandomAccess</span>
{
<span class="kw">unsafe</span> <span class="kw">fn</span> <span class="ident">get_unchecked</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">i</span>: <span class="ident">usize</span>) <span class="op">-></span> (<span class="ident">usize</span>, <span class="ident">I</span>::<span class="ident">Item</span>) {
(<span class="self">self</span>.<span class="ident">count</span> <span class="op">+</span> <span class="ident">i</span>, <span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">get_unchecked</span>(<span class="ident">i</span>))
}
<span class="kw">fn</span> <span class="ident">may_have_side_effect</span>() <span class="op">-></span> <span class="ident">bool</span> {
<span class="ident">I</span>::<span class="ident">may_have_side_effect</span>()
}
}
<span class="attribute">#[<span class="ident">unstable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"fused"</span>, <span class="ident">issue</span> <span class="op">=</span> <span class="string">"35602"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">I</span><span class="op">></span> <span class="ident">FusedIterator</span> <span class="kw">for</span> <span class="ident">Enumerate</span><span class="op"><</span><span class="ident">I</span><span class="op">></span> <span class="kw">where</span> <span class="ident">I</span>: <span class="ident">FusedIterator</span> {}
<span class="attribute">#[<span class="ident">unstable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"trusted_len"</span>, <span class="ident">issue</span> <span class="op">=</span> <span class="string">"37572"</span>)]</span>
<span class="kw">unsafe</span> <span class="kw">impl</span><span class="op"><</span><span class="ident">I</span><span class="op">></span> <span class="ident">TrustedLen</span> <span class="kw">for</span> <span class="ident">Enumerate</span><span class="op"><</span><span class="ident">I</span><span class="op">></span>
<span class="kw">where</span> <span class="ident">I</span>: <span class="ident">TrustedLen</span>,
{}
<span class="doccomment">/// An iterator with a `peek()` that returns an optional reference to the next</span>
<span class="doccomment">/// element.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This `struct` is created by the [`peekable`] method on [`Iterator`]. See its</span>
<span class="doccomment">/// documentation for more.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// [`peekable`]: trait.Iterator.html#method.peekable</span>
<span class="doccomment">/// [`Iterator`]: trait.Iterator.html</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Clone</span>, <span class="ident">Debug</span>)]</span>
<span class="attribute">#[<span class="ident">must_use</span> <span class="op">=</span> <span class="string">"iterator adaptors are lazy and do nothing unless consumed"</span>]</span>
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">Peekable</span><span class="op"><</span><span class="ident">I</span>: <span class="ident">Iterator</span><span class="op">></span> {
<span class="ident">iter</span>: <span class="ident">I</span>,
<span class="doccomment">/// Remember a peeked value, even if it was None.</span>
<span class="ident">peeked</span>: <span class="prelude-ty">Option</span><span class="op"><</span><span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">I</span>::<span class="ident">Item</span><span class="op">>></span>,
}
<span class="comment">// Peekable must remember if a None has been seen in the `.peek()` method.</span>
<span class="comment">// It ensures that `.peek(); .peek();` or `.peek(); .next();` only advances the</span>
<span class="comment">// underlying iterator at most once. This does not by itself make the iterator</span>
<span class="comment">// fused.</span>
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">I</span>: <span class="ident">Iterator</span><span class="op">></span> <span class="ident">Iterator</span> <span class="kw">for</span> <span class="ident">Peekable</span><span class="op"><</span><span class="ident">I</span><span class="op">></span> {
<span class="kw">type</span> <span class="ident">Item</span> <span class="op">=</span> <span class="ident">I</span>::<span class="ident">Item</span>;
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">next</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">I</span>::<span class="ident">Item</span><span class="op">></span> {
<span class="kw">match</span> <span class="self">self</span>.<span class="ident">peeked</span>.<span class="ident">take</span>() {
<span class="prelude-val">Some</span>(<span class="ident">v</span>) <span class="op">=></span> <span class="ident">v</span>,
<span class="prelude-val">None</span> <span class="op">=></span> <span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">next</span>(),
}
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="attribute">#[<span class="ident">rustc_inherit_overflow_checks</span>]</span>
<span class="kw">fn</span> <span class="ident">count</span>(<span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="ident">usize</span> {
<span class="kw">match</span> <span class="self">self</span>.<span class="ident">peeked</span>.<span class="ident">take</span>() {
<span class="prelude-val">Some</span>(<span class="prelude-val">None</span>) <span class="op">=></span> <span class="number">0</span>,
<span class="prelude-val">Some</span>(<span class="prelude-val">Some</span>(_)) <span class="op">=></span> <span class="number">1</span> <span class="op">+</span> <span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">count</span>(),
<span class="prelude-val">None</span> <span class="op">=></span> <span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">count</span>(),
}
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">nth</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">n</span>: <span class="ident">usize</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">I</span>::<span class="ident">Item</span><span class="op">></span> {
<span class="kw">match</span> <span class="self">self</span>.<span class="ident">peeked</span>.<span class="ident">take</span>() {
<span class="comment">// the .take() below is just to avoid "move into pattern guard"</span>
<span class="prelude-val">Some</span>(<span class="kw-2">ref</span> <span class="kw-2">mut</span> <span class="ident">v</span>) <span class="kw">if</span> <span class="ident">n</span> <span class="op">==</span> <span class="number">0</span> <span class="op">=></span> <span class="ident">v</span>.<span class="ident">take</span>(),
<span class="prelude-val">Some</span>(<span class="prelude-val">None</span>) <span class="op">=></span> <span class="prelude-val">None</span>,
<span class="prelude-val">Some</span>(<span class="prelude-val">Some</span>(_)) <span class="op">=></span> <span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">nth</span>(<span class="ident">n</span> <span class="op">-</span> <span class="number">1</span>),
<span class="prelude-val">None</span> <span class="op">=></span> <span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">nth</span>(<span class="ident">n</span>),
}
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">last</span>(<span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">I</span>::<span class="ident">Item</span><span class="op">></span> {
<span class="kw">let</span> <span class="ident">peek_opt</span> <span class="op">=</span> <span class="kw">match</span> <span class="self">self</span>.<span class="ident">peeked</span>.<span class="ident">take</span>() {
<span class="prelude-val">Some</span>(<span class="prelude-val">None</span>) <span class="op">=></span> <span class="kw">return</span> <span class="prelude-val">None</span>,
<span class="prelude-val">Some</span>(<span class="ident">v</span>) <span class="op">=></span> <span class="ident">v</span>,
<span class="prelude-val">None</span> <span class="op">=></span> <span class="prelude-val">None</span>,
};
<span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">last</span>().<span class="ident">or</span>(<span class="ident">peek_opt</span>)
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">size_hint</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> (<span class="ident">usize</span>, <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">usize</span><span class="op">></span>) {
<span class="kw">let</span> <span class="ident">peek_len</span> <span class="op">=</span> <span class="kw">match</span> <span class="self">self</span>.<span class="ident">peeked</span> {
<span class="prelude-val">Some</span>(<span class="prelude-val">None</span>) <span class="op">=></span> <span class="kw">return</span> (<span class="number">0</span>, <span class="prelude-val">Some</span>(<span class="number">0</span>)),
<span class="prelude-val">Some</span>(<span class="prelude-val">Some</span>(_)) <span class="op">=></span> <span class="number">1</span>,
<span class="prelude-val">None</span> <span class="op">=></span> <span class="number">0</span>,
};
<span class="kw">let</span> (<span class="ident">lo</span>, <span class="ident">hi</span>) <span class="op">=</span> <span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">size_hint</span>();
<span class="kw">let</span> <span class="ident">lo</span> <span class="op">=</span> <span class="ident">lo</span>.<span class="ident">saturating_add</span>(<span class="ident">peek_len</span>);
<span class="kw">let</span> <span class="ident">hi</span> <span class="op">=</span> <span class="ident">hi</span>.<span class="ident">and_then</span>(<span class="op">|</span><span class="ident">x</span><span class="op">|</span> <span class="ident">x</span>.<span class="ident">checked_add</span>(<span class="ident">peek_len</span>));
(<span class="ident">lo</span>, <span class="ident">hi</span>)
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">I</span>: <span class="ident">ExactSizeIterator</span><span class="op">></span> <span class="ident">ExactSizeIterator</span> <span class="kw">for</span> <span class="ident">Peekable</span><span class="op"><</span><span class="ident">I</span><span class="op">></span> {}
<span class="attribute">#[<span class="ident">unstable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"fused"</span>, <span class="ident">issue</span> <span class="op">=</span> <span class="string">"35602"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">I</span>: <span class="ident">FusedIterator</span><span class="op">></span> <span class="ident">FusedIterator</span> <span class="kw">for</span> <span class="ident">Peekable</span><span class="op"><</span><span class="ident">I</span><span class="op">></span> {}
<span class="kw">impl</span><span class="op"><</span><span class="ident">I</span>: <span class="ident">Iterator</span><span class="op">></span> <span class="ident">Peekable</span><span class="op"><</span><span class="ident">I</span><span class="op">></span> {
<span class="doccomment">/// Returns a reference to the next() value without advancing the iterator.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Like [`next`], if there is a value, it is wrapped in a `Some(T)`.</span>
<span class="doccomment">/// But if the iteration is over, `None` is returned.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// [`next`]: trait.Iterator.html#tymethod.next</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Because `peek()` returns a reference, and many iterators iterate over</span>
<span class="doccomment">/// references, there can be a possibly confusing situation where the</span>
<span class="doccomment">/// return value is a double reference. You can see this effect in the</span>
<span class="doccomment">/// examples below.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Examples</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Basic usage:</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">/// let xs = [1, 2, 3];</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let mut iter = xs.iter().peekable();</span>
<span class="doccomment">///</span>
<span class="doccomment">/// // peek() lets us see into the future</span>
<span class="doccomment">/// assert_eq!(iter.peek(), Some(&&1));</span>
<span class="doccomment">/// assert_eq!(iter.next(), Some(&1));</span>
<span class="doccomment">///</span>
<span class="doccomment">/// assert_eq!(iter.next(), Some(&2));</span>
<span class="doccomment">///</span>
<span class="doccomment">/// // The iterator does not advance even if we `peek` multiple times</span>
<span class="doccomment">/// assert_eq!(iter.peek(), Some(&&3));</span>
<span class="doccomment">/// assert_eq!(iter.peek(), Some(&&3));</span>
<span class="doccomment">///</span>
<span class="doccomment">/// assert_eq!(iter.next(), Some(&3));</span>
<span class="doccomment">///</span>
<span class="doccomment">/// // After the iterator is finished, so is `peek()`</span>
<span class="doccomment">/// assert_eq!(iter.peek(), None);</span>
<span class="doccomment">/// assert_eq!(iter.next(), None);</span>
<span class="doccomment">/// ```</span>
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">peek</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="kw-2">&</span><span class="ident">I</span>::<span class="ident">Item</span><span class="op">></span> {
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">peeked</span>.<span class="ident">is_none</span>() {
<span class="self">self</span>.<span class="ident">peeked</span> <span class="op">=</span> <span class="prelude-val">Some</span>(<span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">next</span>());
}
<span class="kw">match</span> <span class="self">self</span>.<span class="ident">peeked</span> {
<span class="prelude-val">Some</span>(<span class="prelude-val">Some</span>(<span class="kw-2">ref</span> <span class="ident">value</span>)) <span class="op">=></span> <span class="prelude-val">Some</span>(<span class="ident">value</span>),
<span class="prelude-val">Some</span>(<span class="prelude-val">None</span>) <span class="op">=></span> <span class="prelude-val">None</span>,
_ <span class="op">=></span> <span class="macro">unreachable</span><span class="macro">!</span>(),
}
}
}
<span class="doccomment">/// An iterator that rejects elements while `predicate` is true.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This `struct` is created by the [`skip_while`] method on [`Iterator`]. See its</span>
<span class="doccomment">/// documentation for more.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// [`skip_while`]: trait.Iterator.html#method.skip_while</span>
<span class="doccomment">/// [`Iterator`]: trait.Iterator.html</span>
<span class="attribute">#[<span class="ident">must_use</span> <span class="op">=</span> <span class="string">"iterator adaptors are lazy and do nothing unless consumed"</span>]</span>
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Clone</span>)]</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">SkipWhile</span><span class="op"><</span><span class="ident">I</span>, <span class="ident">P</span><span class="op">></span> {
<span class="ident">iter</span>: <span class="ident">I</span>,
<span class="ident">flag</span>: <span class="ident">bool</span>,
<span class="ident">predicate</span>: <span class="ident">P</span>,
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"core_impl_debug"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.9.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">I</span>: <span class="ident">fmt</span>::<span class="ident">Debug</span>, <span class="ident">P</span><span class="op">></span> <span class="ident">fmt</span>::<span class="ident">Debug</span> <span class="kw">for</span> <span class="ident">SkipWhile</span><span class="op"><</span><span class="ident">I</span>, <span class="ident">P</span><span class="op">></span> {
<span class="kw">fn</span> <span class="ident">fmt</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">f</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">fmt</span>::<span class="ident">Formatter</span>) <span class="op">-></span> <span class="ident">fmt</span>::<span class="prelude-ty">Result</span> {
<span class="ident">f</span>.<span class="ident">debug_struct</span>(<span class="string">"SkipWhile"</span>)
.<span class="ident">field</span>(<span class="string">"iter"</span>, <span class="kw-2">&</span><span class="self">self</span>.<span class="ident">iter</span>)
.<span class="ident">field</span>(<span class="string">"flag"</span>, <span class="kw-2">&</span><span class="self">self</span>.<span class="ident">flag</span>)
.<span class="ident">finish</span>()
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">I</span>: <span class="ident">Iterator</span>, <span class="ident">P</span><span class="op">></span> <span class="ident">Iterator</span> <span class="kw">for</span> <span class="ident">SkipWhile</span><span class="op"><</span><span class="ident">I</span>, <span class="ident">P</span><span class="op">></span>
<span class="kw">where</span> <span class="ident">P</span>: <span class="ident">FnMut</span>(<span class="kw-2">&</span><span class="ident">I</span>::<span class="ident">Item</span>) <span class="op">-></span> <span class="ident">bool</span>
{
<span class="kw">type</span> <span class="ident">Item</span> <span class="op">=</span> <span class="ident">I</span>::<span class="ident">Item</span>;
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">next</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">I</span>::<span class="ident">Item</span><span class="op">></span> {
<span class="kw">for</span> <span class="ident">x</span> <span class="kw">in</span> <span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">by_ref</span>() {
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">flag</span> <span class="op">||</span> <span class="op">!</span>(<span class="self">self</span>.<span class="ident">predicate</span>)(<span class="kw-2">&</span><span class="ident">x</span>) {
<span class="self">self</span>.<span class="ident">flag</span> <span class="op">=</span> <span class="bool-val">true</span>;
<span class="kw">return</span> <span class="prelude-val">Some</span>(<span class="ident">x</span>);
}
}
<span class="prelude-val">None</span>
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">size_hint</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> (<span class="ident">usize</span>, <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">usize</span><span class="op">></span>) {
<span class="kw">let</span> (_, <span class="ident">upper</span>) <span class="op">=</span> <span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">size_hint</span>();
(<span class="number">0</span>, <span class="ident">upper</span>) <span class="comment">// can't know a lower bound, due to the predicate</span>
}
}
<span class="attribute">#[<span class="ident">unstable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"fused"</span>, <span class="ident">issue</span> <span class="op">=</span> <span class="string">"35602"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">I</span>, <span class="ident">P</span><span class="op">></span> <span class="ident">FusedIterator</span> <span class="kw">for</span> <span class="ident">SkipWhile</span><span class="op"><</span><span class="ident">I</span>, <span class="ident">P</span><span class="op">></span>
<span class="kw">where</span> <span class="ident">I</span>: <span class="ident">FusedIterator</span>, <span class="ident">P</span>: <span class="ident">FnMut</span>(<span class="kw-2">&</span><span class="ident">I</span>::<span class="ident">Item</span>) <span class="op">-></span> <span class="ident">bool</span> {}
<span class="doccomment">/// An iterator that only accepts elements while `predicate` is true.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This `struct` is created by the [`take_while`] method on [`Iterator`]. See its</span>
<span class="doccomment">/// documentation for more.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// [`take_while`]: trait.Iterator.html#method.take_while</span>
<span class="doccomment">/// [`Iterator`]: trait.Iterator.html</span>
<span class="attribute">#[<span class="ident">must_use</span> <span class="op">=</span> <span class="string">"iterator adaptors are lazy and do nothing unless consumed"</span>]</span>
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Clone</span>)]</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">TakeWhile</span><span class="op"><</span><span class="ident">I</span>, <span class="ident">P</span><span class="op">></span> {
<span class="ident">iter</span>: <span class="ident">I</span>,
<span class="ident">flag</span>: <span class="ident">bool</span>,
<span class="ident">predicate</span>: <span class="ident">P</span>,
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"core_impl_debug"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.9.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">I</span>: <span class="ident">fmt</span>::<span class="ident">Debug</span>, <span class="ident">P</span><span class="op">></span> <span class="ident">fmt</span>::<span class="ident">Debug</span> <span class="kw">for</span> <span class="ident">TakeWhile</span><span class="op"><</span><span class="ident">I</span>, <span class="ident">P</span><span class="op">></span> {
<span class="kw">fn</span> <span class="ident">fmt</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">f</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">fmt</span>::<span class="ident">Formatter</span>) <span class="op">-></span> <span class="ident">fmt</span>::<span class="prelude-ty">Result</span> {
<span class="ident">f</span>.<span class="ident">debug_struct</span>(<span class="string">"TakeWhile"</span>)
.<span class="ident">field</span>(<span class="string">"iter"</span>, <span class="kw-2">&</span><span class="self">self</span>.<span class="ident">iter</span>)
.<span class="ident">field</span>(<span class="string">"flag"</span>, <span class="kw-2">&</span><span class="self">self</span>.<span class="ident">flag</span>)
.<span class="ident">finish</span>()
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">I</span>: <span class="ident">Iterator</span>, <span class="ident">P</span><span class="op">></span> <span class="ident">Iterator</span> <span class="kw">for</span> <span class="ident">TakeWhile</span><span class="op"><</span><span class="ident">I</span>, <span class="ident">P</span><span class="op">></span>
<span class="kw">where</span> <span class="ident">P</span>: <span class="ident">FnMut</span>(<span class="kw-2">&</span><span class="ident">I</span>::<span class="ident">Item</span>) <span class="op">-></span> <span class="ident">bool</span>
{
<span class="kw">type</span> <span class="ident">Item</span> <span class="op">=</span> <span class="ident">I</span>::<span class="ident">Item</span>;
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">next</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">I</span>::<span class="ident">Item</span><span class="op">></span> {
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">flag</span> {
<span class="prelude-val">None</span>
} <span class="kw">else</span> {
<span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">next</span>().<span class="ident">and_then</span>(<span class="op">|</span><span class="ident">x</span><span class="op">|</span> {
<span class="kw">if</span> (<span class="self">self</span>.<span class="ident">predicate</span>)(<span class="kw-2">&</span><span class="ident">x</span>) {
<span class="prelude-val">Some</span>(<span class="ident">x</span>)
} <span class="kw">else</span> {
<span class="self">self</span>.<span class="ident">flag</span> <span class="op">=</span> <span class="bool-val">true</span>;
<span class="prelude-val">None</span>
}
})
}
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">size_hint</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> (<span class="ident">usize</span>, <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">usize</span><span class="op">></span>) {
<span class="kw">let</span> (_, <span class="ident">upper</span>) <span class="op">=</span> <span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">size_hint</span>();
(<span class="number">0</span>, <span class="ident">upper</span>) <span class="comment">// can't know a lower bound, due to the predicate</span>
}
}
<span class="attribute">#[<span class="ident">unstable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"fused"</span>, <span class="ident">issue</span> <span class="op">=</span> <span class="string">"35602"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">I</span>, <span class="ident">P</span><span class="op">></span> <span class="ident">FusedIterator</span> <span class="kw">for</span> <span class="ident">TakeWhile</span><span class="op"><</span><span class="ident">I</span>, <span class="ident">P</span><span class="op">></span>
<span class="kw">where</span> <span class="ident">I</span>: <span class="ident">FusedIterator</span>, <span class="ident">P</span>: <span class="ident">FnMut</span>(<span class="kw-2">&</span><span class="ident">I</span>::<span class="ident">Item</span>) <span class="op">-></span> <span class="ident">bool</span> {}
<span class="doccomment">/// An iterator that skips over `n` elements of `iter`.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This `struct` is created by the [`skip`] method on [`Iterator`]. See its</span>
<span class="doccomment">/// documentation for more.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// [`skip`]: trait.Iterator.html#method.skip</span>
<span class="doccomment">/// [`Iterator`]: trait.Iterator.html</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Clone</span>, <span class="ident">Debug</span>)]</span>
<span class="attribute">#[<span class="ident">must_use</span> <span class="op">=</span> <span class="string">"iterator adaptors are lazy and do nothing unless consumed"</span>]</span>
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">Skip</span><span class="op"><</span><span class="ident">I</span><span class="op">></span> {
<span class="ident">iter</span>: <span class="ident">I</span>,
<span class="ident">n</span>: <span class="ident">usize</span>
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">I</span><span class="op">></span> <span class="ident">Iterator</span> <span class="kw">for</span> <span class="ident">Skip</span><span class="op"><</span><span class="ident">I</span><span class="op">></span> <span class="kw">where</span> <span class="ident">I</span>: <span class="ident">Iterator</span> {
<span class="kw">type</span> <span class="ident">Item</span> <span class="op">=</span> <span class="op"><</span><span class="ident">I</span> <span class="kw">as</span> <span class="ident">Iterator</span><span class="op">></span>::<span class="ident">Item</span>;
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">next</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">I</span>::<span class="ident">Item</span><span class="op">></span> {
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">n</span> <span class="op">==</span> <span class="number">0</span> {
<span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">next</span>()
} <span class="kw">else</span> {
<span class="kw">let</span> <span class="ident">old_n</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">n</span>;
<span class="self">self</span>.<span class="ident">n</span> <span class="op">=</span> <span class="number">0</span>;
<span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">nth</span>(<span class="ident">old_n</span>)
}
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">nth</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">n</span>: <span class="ident">usize</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">I</span>::<span class="ident">Item</span><span class="op">></span> {
<span class="comment">// Can't just add n + self.n due to overflow.</span>
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">n</span> <span class="op">==</span> <span class="number">0</span> {
<span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">nth</span>(<span class="ident">n</span>)
} <span class="kw">else</span> {
<span class="kw">let</span> <span class="ident">to_skip</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">n</span>;
<span class="self">self</span>.<span class="ident">n</span> <span class="op">=</span> <span class="number">0</span>;
<span class="comment">// nth(n) skips n+1</span>
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">nth</span>(<span class="ident">to_skip</span><span class="op">-</span><span class="number">1</span>).<span class="ident">is_none</span>() {
<span class="kw">return</span> <span class="prelude-val">None</span>;
}
<span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">nth</span>(<span class="ident">n</span>)
}
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">count</span>(<span class="self">self</span>) <span class="op">-></span> <span class="ident">usize</span> {
<span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">count</span>().<span class="ident">saturating_sub</span>(<span class="self">self</span>.<span class="ident">n</span>)
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">last</span>(<span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">I</span>::<span class="ident">Item</span><span class="op">></span> {
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">n</span> <span class="op">==</span> <span class="number">0</span> {
<span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">last</span>()
} <span class="kw">else</span> {
<span class="kw">let</span> <span class="ident">next</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">next</span>();
<span class="kw">if</span> <span class="ident">next</span>.<span class="ident">is_some</span>() {
<span class="comment">// recurse. n should be 0.</span>
<span class="self">self</span>.<span class="ident">last</span>().<span class="ident">or</span>(<span class="ident">next</span>)
} <span class="kw">else</span> {
<span class="prelude-val">None</span>
}
}
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">size_hint</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> (<span class="ident">usize</span>, <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">usize</span><span class="op">></span>) {
<span class="kw">let</span> (<span class="ident">lower</span>, <span class="ident">upper</span>) <span class="op">=</span> <span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">size_hint</span>();
<span class="kw">let</span> <span class="ident">lower</span> <span class="op">=</span> <span class="ident">lower</span>.<span class="ident">saturating_sub</span>(<span class="self">self</span>.<span class="ident">n</span>);
<span class="kw">let</span> <span class="ident">upper</span> <span class="op">=</span> <span class="ident">upper</span>.<span class="ident">map</span>(<span class="op">|</span><span class="ident">x</span><span class="op">|</span> <span class="ident">x</span>.<span class="ident">saturating_sub</span>(<span class="self">self</span>.<span class="ident">n</span>));
(<span class="ident">lower</span>, <span class="ident">upper</span>)
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">I</span><span class="op">></span> <span class="ident">ExactSizeIterator</span> <span class="kw">for</span> <span class="ident">Skip</span><span class="op"><</span><span class="ident">I</span><span class="op">></span> <span class="kw">where</span> <span class="ident">I</span>: <span class="ident">ExactSizeIterator</span> {}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"double_ended_skip_iterator"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.9.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">I</span><span class="op">></span> <span class="ident">DoubleEndedIterator</span> <span class="kw">for</span> <span class="ident">Skip</span><span class="op"><</span><span class="ident">I</span><span class="op">></span> <span class="kw">where</span> <span class="ident">I</span>: <span class="ident">DoubleEndedIterator</span> <span class="op">+</span> <span class="ident">ExactSizeIterator</span> {
<span class="kw">fn</span> <span class="ident">next_back</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="self">Self</span>::<span class="ident">Item</span><span class="op">></span> {
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">len</span>() <span class="op">></span> <span class="number">0</span> {
<span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">next_back</span>()
} <span class="kw">else</span> {
<span class="prelude-val">None</span>
}
}
}
<span class="attribute">#[<span class="ident">unstable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"fused"</span>, <span class="ident">issue</span> <span class="op">=</span> <span class="string">"35602"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">I</span><span class="op">></span> <span class="ident">FusedIterator</span> <span class="kw">for</span> <span class="ident">Skip</span><span class="op"><</span><span class="ident">I</span><span class="op">></span> <span class="kw">where</span> <span class="ident">I</span>: <span class="ident">FusedIterator</span> {}
<span class="doccomment">/// An iterator that only iterates over the first `n` iterations of `iter`.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This `struct` is created by the [`take`] method on [`Iterator`]. See its</span>
<span class="doccomment">/// documentation for more.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// [`take`]: trait.Iterator.html#method.take</span>
<span class="doccomment">/// [`Iterator`]: trait.Iterator.html</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Clone</span>, <span class="ident">Debug</span>)]</span>
<span class="attribute">#[<span class="ident">must_use</span> <span class="op">=</span> <span class="string">"iterator adaptors are lazy and do nothing unless consumed"</span>]</span>
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">Take</span><span class="op"><</span><span class="ident">I</span><span class="op">></span> {
<span class="ident">iter</span>: <span class="ident">I</span>,
<span class="ident">n</span>: <span class="ident">usize</span>
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">I</span><span class="op">></span> <span class="ident">Iterator</span> <span class="kw">for</span> <span class="ident">Take</span><span class="op"><</span><span class="ident">I</span><span class="op">></span> <span class="kw">where</span> <span class="ident">I</span>: <span class="ident">Iterator</span>{
<span class="kw">type</span> <span class="ident">Item</span> <span class="op">=</span> <span class="op"><</span><span class="ident">I</span> <span class="kw">as</span> <span class="ident">Iterator</span><span class="op">></span>::<span class="ident">Item</span>;
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">next</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><<</span><span class="ident">I</span> <span class="kw">as</span> <span class="ident">Iterator</span><span class="op">></span>::<span class="ident">Item</span><span class="op">></span> {
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">n</span> <span class="op">!=</span> <span class="number">0</span> {
<span class="self">self</span>.<span class="ident">n</span> <span class="op">-=</span> <span class="number">1</span>;
<span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">next</span>()
} <span class="kw">else</span> {
<span class="prelude-val">None</span>
}
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">nth</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">n</span>: <span class="ident">usize</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">I</span>::<span class="ident">Item</span><span class="op">></span> {
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">n</span> <span class="op">></span> <span class="ident">n</span> {
<span class="self">self</span>.<span class="ident">n</span> <span class="op">-=</span> <span class="ident">n</span> <span class="op">+</span> <span class="number">1</span>;
<span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">nth</span>(<span class="ident">n</span>)
} <span class="kw">else</span> {
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">n</span> <span class="op">></span> <span class="number">0</span> {
<span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">nth</span>(<span class="self">self</span>.<span class="ident">n</span> <span class="op">-</span> <span class="number">1</span>);
<span class="self">self</span>.<span class="ident">n</span> <span class="op">=</span> <span class="number">0</span>;
}
<span class="prelude-val">None</span>
}
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">size_hint</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> (<span class="ident">usize</span>, <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">usize</span><span class="op">></span>) {
<span class="kw">let</span> (<span class="ident">lower</span>, <span class="ident">upper</span>) <span class="op">=</span> <span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">size_hint</span>();
<span class="kw">let</span> <span class="ident">lower</span> <span class="op">=</span> <span class="ident">cmp</span>::<span class="ident">min</span>(<span class="ident">lower</span>, <span class="self">self</span>.<span class="ident">n</span>);
<span class="kw">let</span> <span class="ident">upper</span> <span class="op">=</span> <span class="kw">match</span> <span class="ident">upper</span> {
<span class="prelude-val">Some</span>(<span class="ident">x</span>) <span class="kw">if</span> <span class="ident">x</span> <span class="op"><</span> <span class="self">self</span>.<span class="ident">n</span> <span class="op">=></span> <span class="prelude-val">Some</span>(<span class="ident">x</span>),
_ <span class="op">=></span> <span class="prelude-val">Some</span>(<span class="self">self</span>.<span class="ident">n</span>)
};
(<span class="ident">lower</span>, <span class="ident">upper</span>)
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">I</span><span class="op">></span> <span class="ident">ExactSizeIterator</span> <span class="kw">for</span> <span class="ident">Take</span><span class="op"><</span><span class="ident">I</span><span class="op">></span> <span class="kw">where</span> <span class="ident">I</span>: <span class="ident">ExactSizeIterator</span> {}
<span class="attribute">#[<span class="ident">unstable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"fused"</span>, <span class="ident">issue</span> <span class="op">=</span> <span class="string">"35602"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">I</span><span class="op">></span> <span class="ident">FusedIterator</span> <span class="kw">for</span> <span class="ident">Take</span><span class="op"><</span><span class="ident">I</span><span class="op">></span> <span class="kw">where</span> <span class="ident">I</span>: <span class="ident">FusedIterator</span> {}
<span class="doccomment">/// An iterator to maintain state while iterating another iterator.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This `struct` is created by the [`scan`] method on [`Iterator`]. See its</span>
<span class="doccomment">/// documentation for more.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// [`scan`]: trait.Iterator.html#method.scan</span>
<span class="doccomment">/// [`Iterator`]: trait.Iterator.html</span>
<span class="attribute">#[<span class="ident">must_use</span> <span class="op">=</span> <span class="string">"iterator adaptors are lazy and do nothing unless consumed"</span>]</span>
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Clone</span>)]</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">Scan</span><span class="op"><</span><span class="ident">I</span>, <span class="ident">St</span>, <span class="ident">F</span><span class="op">></span> {
<span class="ident">iter</span>: <span class="ident">I</span>,
<span class="ident">f</span>: <span class="ident">F</span>,
<span class="ident">state</span>: <span class="ident">St</span>,
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"core_impl_debug"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.9.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">I</span>: <span class="ident">fmt</span>::<span class="ident">Debug</span>, <span class="ident">St</span>: <span class="ident">fmt</span>::<span class="ident">Debug</span>, <span class="ident">F</span><span class="op">></span> <span class="ident">fmt</span>::<span class="ident">Debug</span> <span class="kw">for</span> <span class="ident">Scan</span><span class="op"><</span><span class="ident">I</span>, <span class="ident">St</span>, <span class="ident">F</span><span class="op">></span> {
<span class="kw">fn</span> <span class="ident">fmt</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">f</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">fmt</span>::<span class="ident">Formatter</span>) <span class="op">-></span> <span class="ident">fmt</span>::<span class="prelude-ty">Result</span> {
<span class="ident">f</span>.<span class="ident">debug_struct</span>(<span class="string">"Scan"</span>)
.<span class="ident">field</span>(<span class="string">"iter"</span>, <span class="kw-2">&</span><span class="self">self</span>.<span class="ident">iter</span>)
.<span class="ident">field</span>(<span class="string">"state"</span>, <span class="kw-2">&</span><span class="self">self</span>.<span class="ident">state</span>)
.<span class="ident">finish</span>()
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">B</span>, <span class="ident">I</span>, <span class="ident">St</span>, <span class="ident">F</span><span class="op">></span> <span class="ident">Iterator</span> <span class="kw">for</span> <span class="ident">Scan</span><span class="op"><</span><span class="ident">I</span>, <span class="ident">St</span>, <span class="ident">F</span><span class="op">></span> <span class="kw">where</span>
<span class="ident">I</span>: <span class="ident">Iterator</span>,
<span class="ident">F</span>: <span class="ident">FnMut</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">St</span>, <span class="ident">I</span>::<span class="ident">Item</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">B</span><span class="op">></span>,
{
<span class="kw">type</span> <span class="ident">Item</span> <span class="op">=</span> <span class="ident">B</span>;
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">next</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">B</span><span class="op">></span> {
<span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">next</span>().<span class="ident">and_then</span>(<span class="op">|</span><span class="ident">a</span><span class="op">|</span> (<span class="self">self</span>.<span class="ident">f</span>)(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>.<span class="ident">state</span>, <span class="ident">a</span>))
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">size_hint</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> (<span class="ident">usize</span>, <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">usize</span><span class="op">></span>) {
<span class="kw">let</span> (_, <span class="ident">upper</span>) <span class="op">=</span> <span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">size_hint</span>();
(<span class="number">0</span>, <span class="ident">upper</span>) <span class="comment">// can't know a lower bound, due to the scan function</span>
}
}
<span class="doccomment">/// An iterator that maps each element to an iterator, and yields the elements</span>
<span class="doccomment">/// of the produced iterators.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This `struct` is created by the [`flat_map`] method on [`Iterator`]. See its</span>
<span class="doccomment">/// documentation for more.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// [`flat_map`]: trait.Iterator.html#method.flat_map</span>
<span class="doccomment">/// [`Iterator`]: trait.Iterator.html</span>
<span class="attribute">#[<span class="ident">must_use</span> <span class="op">=</span> <span class="string">"iterator adaptors are lazy and do nothing unless consumed"</span>]</span>
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Clone</span>)]</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">FlatMap</span><span class="op"><</span><span class="ident">I</span>, <span class="ident">U</span>: <span class="ident">IntoIterator</span>, <span class="ident">F</span><span class="op">></span> {
<span class="ident">iter</span>: <span class="ident">I</span>,
<span class="ident">f</span>: <span class="ident">F</span>,
<span class="ident">frontiter</span>: <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">U</span>::<span class="ident">IntoIter</span><span class="op">></span>,
<span class="ident">backiter</span>: <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">U</span>::<span class="ident">IntoIter</span><span class="op">></span>,
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"core_impl_debug"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.9.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">I</span>: <span class="ident">fmt</span>::<span class="ident">Debug</span>, <span class="ident">U</span>: <span class="ident">IntoIterator</span>, <span class="ident">F</span><span class="op">></span> <span class="ident">fmt</span>::<span class="ident">Debug</span> <span class="kw">for</span> <span class="ident">FlatMap</span><span class="op"><</span><span class="ident">I</span>, <span class="ident">U</span>, <span class="ident">F</span><span class="op">></span>
<span class="kw">where</span> <span class="ident">U</span>::<span class="ident">IntoIter</span>: <span class="ident">fmt</span>::<span class="ident">Debug</span>
{
<span class="kw">fn</span> <span class="ident">fmt</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">f</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">fmt</span>::<span class="ident">Formatter</span>) <span class="op">-></span> <span class="ident">fmt</span>::<span class="prelude-ty">Result</span> {
<span class="ident">f</span>.<span class="ident">debug_struct</span>(<span class="string">"FlatMap"</span>)
.<span class="ident">field</span>(<span class="string">"iter"</span>, <span class="kw-2">&</span><span class="self">self</span>.<span class="ident">iter</span>)
.<span class="ident">field</span>(<span class="string">"frontiter"</span>, <span class="kw-2">&</span><span class="self">self</span>.<span class="ident">frontiter</span>)
.<span class="ident">field</span>(<span class="string">"backiter"</span>, <span class="kw-2">&</span><span class="self">self</span>.<span class="ident">backiter</span>)
.<span class="ident">finish</span>()
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">I</span>: <span class="ident">Iterator</span>, <span class="ident">U</span>: <span class="ident">IntoIterator</span>, <span class="ident">F</span><span class="op">></span> <span class="ident">Iterator</span> <span class="kw">for</span> <span class="ident">FlatMap</span><span class="op"><</span><span class="ident">I</span>, <span class="ident">U</span>, <span class="ident">F</span><span class="op">></span>
<span class="kw">where</span> <span class="ident">F</span>: <span class="ident">FnMut</span>(<span class="ident">I</span>::<span class="ident">Item</span>) <span class="op">-></span> <span class="ident">U</span>,
{
<span class="kw">type</span> <span class="ident">Item</span> <span class="op">=</span> <span class="ident">U</span>::<span class="ident">Item</span>;
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">next</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">U</span>::<span class="ident">Item</span><span class="op">></span> {
<span class="kw">loop</span> {
<span class="kw">if</span> <span class="kw">let</span> <span class="prelude-val">Some</span>(<span class="kw-2">ref</span> <span class="kw-2">mut</span> <span class="ident">inner</span>) <span class="op">=</span> <span class="self">self</span>.<span class="ident">frontiter</span> {
<span class="kw">if</span> <span class="kw">let</span> <span class="prelude-val">Some</span>(<span class="ident">x</span>) <span class="op">=</span> <span class="ident">inner</span>.<span class="ident">by_ref</span>().<span class="ident">next</span>() {
<span class="kw">return</span> <span class="prelude-val">Some</span>(<span class="ident">x</span>)
}
}
<span class="kw">match</span> <span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">next</span>().<span class="ident">map</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>.<span class="ident">f</span>) {
<span class="prelude-val">None</span> <span class="op">=></span> <span class="kw">return</span> <span class="self">self</span>.<span class="ident">backiter</span>.<span class="ident">as_mut</span>().<span class="ident">and_then</span>(<span class="op">|</span><span class="ident">it</span><span class="op">|</span> <span class="ident">it</span>.<span class="ident">next</span>()),
<span class="ident">next</span> <span class="op">=></span> <span class="self">self</span>.<span class="ident">frontiter</span> <span class="op">=</span> <span class="ident">next</span>.<span class="ident">map</span>(<span class="ident">IntoIterator</span>::<span class="ident">into_iter</span>),
}
}
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">size_hint</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> (<span class="ident">usize</span>, <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">usize</span><span class="op">></span>) {
<span class="kw">let</span> (<span class="ident">flo</span>, <span class="ident">fhi</span>) <span class="op">=</span> <span class="self">self</span>.<span class="ident">frontiter</span>.<span class="ident">as_ref</span>().<span class="ident">map_or</span>((<span class="number">0</span>, <span class="prelude-val">Some</span>(<span class="number">0</span>)), <span class="op">|</span><span class="ident">it</span><span class="op">|</span> <span class="ident">it</span>.<span class="ident">size_hint</span>());
<span class="kw">let</span> (<span class="ident">blo</span>, <span class="ident">bhi</span>) <span class="op">=</span> <span class="self">self</span>.<span class="ident">backiter</span>.<span class="ident">as_ref</span>().<span class="ident">map_or</span>((<span class="number">0</span>, <span class="prelude-val">Some</span>(<span class="number">0</span>)), <span class="op">|</span><span class="ident">it</span><span class="op">|</span> <span class="ident">it</span>.<span class="ident">size_hint</span>());
<span class="kw">let</span> <span class="ident">lo</span> <span class="op">=</span> <span class="ident">flo</span>.<span class="ident">saturating_add</span>(<span class="ident">blo</span>);
<span class="kw">match</span> (<span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">size_hint</span>(), <span class="ident">fhi</span>, <span class="ident">bhi</span>) {
((<span class="number">0</span>, <span class="prelude-val">Some</span>(<span class="number">0</span>)), <span class="prelude-val">Some</span>(<span class="ident">a</span>), <span class="prelude-val">Some</span>(<span class="ident">b</span>)) <span class="op">=></span> (<span class="ident">lo</span>, <span class="ident">a</span>.<span class="ident">checked_add</span>(<span class="ident">b</span>)),
_ <span class="op">=></span> (<span class="ident">lo</span>, <span class="prelude-val">None</span>)
}
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">I</span>: <span class="ident">DoubleEndedIterator</span>, <span class="ident">U</span>, <span class="ident">F</span><span class="op">></span> <span class="ident">DoubleEndedIterator</span> <span class="kw">for</span> <span class="ident">FlatMap</span><span class="op"><</span><span class="ident">I</span>, <span class="ident">U</span>, <span class="ident">F</span><span class="op">></span> <span class="kw">where</span>
<span class="ident">F</span>: <span class="ident">FnMut</span>(<span class="ident">I</span>::<span class="ident">Item</span>) <span class="op">-></span> <span class="ident">U</span>,
<span class="ident">U</span>: <span class="ident">IntoIterator</span>,
<span class="ident">U</span>::<span class="ident">IntoIter</span>: <span class="ident">DoubleEndedIterator</span>
{
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">next_back</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">U</span>::<span class="ident">Item</span><span class="op">></span> {
<span class="kw">loop</span> {
<span class="kw">if</span> <span class="kw">let</span> <span class="prelude-val">Some</span>(<span class="kw-2">ref</span> <span class="kw-2">mut</span> <span class="ident">inner</span>) <span class="op">=</span> <span class="self">self</span>.<span class="ident">backiter</span> {
<span class="kw">if</span> <span class="kw">let</span> <span class="prelude-val">Some</span>(<span class="ident">y</span>) <span class="op">=</span> <span class="ident">inner</span>.<span class="ident">next_back</span>() {
<span class="kw">return</span> <span class="prelude-val">Some</span>(<span class="ident">y</span>)
}
}
<span class="kw">match</span> <span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">next_back</span>().<span class="ident">map</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>.<span class="ident">f</span>) {
<span class="prelude-val">None</span> <span class="op">=></span> <span class="kw">return</span> <span class="self">self</span>.<span class="ident">frontiter</span>.<span class="ident">as_mut</span>().<span class="ident">and_then</span>(<span class="op">|</span><span class="ident">it</span><span class="op">|</span> <span class="ident">it</span>.<span class="ident">next_back</span>()),
<span class="ident">next</span> <span class="op">=></span> <span class="self">self</span>.<span class="ident">backiter</span> <span class="op">=</span> <span class="ident">next</span>.<span class="ident">map</span>(<span class="ident">IntoIterator</span>::<span class="ident">into_iter</span>),
}
}
}
}
<span class="attribute">#[<span class="ident">unstable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"fused"</span>, <span class="ident">issue</span> <span class="op">=</span> <span class="string">"35602"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">I</span>, <span class="ident">U</span>, <span class="ident">F</span><span class="op">></span> <span class="ident">FusedIterator</span> <span class="kw">for</span> <span class="ident">FlatMap</span><span class="op"><</span><span class="ident">I</span>, <span class="ident">U</span>, <span class="ident">F</span><span class="op">></span>
<span class="kw">where</span> <span class="ident">I</span>: <span class="ident">FusedIterator</span>, <span class="ident">U</span>: <span class="ident">IntoIterator</span>, <span class="ident">F</span>: <span class="ident">FnMut</span>(<span class="ident">I</span>::<span class="ident">Item</span>) <span class="op">-></span> <span class="ident">U</span> {}
<span class="doccomment">/// An iterator that yields `None` forever after the underlying iterator</span>
<span class="doccomment">/// yields `None` once.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This `struct` is created by the [`fuse`] method on [`Iterator`]. See its</span>
<span class="doccomment">/// documentation for more.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// [`fuse`]: trait.Iterator.html#method.fuse</span>
<span class="doccomment">/// [`Iterator`]: trait.Iterator.html</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Clone</span>, <span class="ident">Debug</span>)]</span>
<span class="attribute">#[<span class="ident">must_use</span> <span class="op">=</span> <span class="string">"iterator adaptors are lazy and do nothing unless consumed"</span>]</span>
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">Fuse</span><span class="op"><</span><span class="ident">I</span><span class="op">></span> {
<span class="ident">iter</span>: <span class="ident">I</span>,
<span class="ident">done</span>: <span class="ident">bool</span>
}
<span class="attribute">#[<span class="ident">unstable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"fused"</span>, <span class="ident">issue</span> <span class="op">=</span> <span class="string">"35602"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">I</span><span class="op">></span> <span class="ident">FusedIterator</span> <span class="kw">for</span> <span class="ident">Fuse</span><span class="op"><</span><span class="ident">I</span><span class="op">></span> <span class="kw">where</span> <span class="ident">I</span>: <span class="ident">Iterator</span> {}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">I</span><span class="op">></span> <span class="ident">Iterator</span> <span class="kw">for</span> <span class="ident">Fuse</span><span class="op"><</span><span class="ident">I</span><span class="op">></span> <span class="kw">where</span> <span class="ident">I</span>: <span class="ident">Iterator</span> {
<span class="kw">type</span> <span class="ident">Item</span> <span class="op">=</span> <span class="op"><</span><span class="ident">I</span> <span class="kw">as</span> <span class="ident">Iterator</span><span class="op">></span>::<span class="ident">Item</span>;
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="ident">default</span> <span class="kw">fn</span> <span class="ident">next</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><<</span><span class="ident">I</span> <span class="kw">as</span> <span class="ident">Iterator</span><span class="op">></span>::<span class="ident">Item</span><span class="op">></span> {
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">done</span> {
<span class="prelude-val">None</span>
} <span class="kw">else</span> {
<span class="kw">let</span> <span class="ident">next</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">next</span>();
<span class="self">self</span>.<span class="ident">done</span> <span class="op">=</span> <span class="ident">next</span>.<span class="ident">is_none</span>();
<span class="ident">next</span>
}
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="ident">default</span> <span class="kw">fn</span> <span class="ident">nth</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">n</span>: <span class="ident">usize</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">I</span>::<span class="ident">Item</span><span class="op">></span> {
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">done</span> {
<span class="prelude-val">None</span>
} <span class="kw">else</span> {
<span class="kw">let</span> <span class="ident">nth</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">nth</span>(<span class="ident">n</span>);
<span class="self">self</span>.<span class="ident">done</span> <span class="op">=</span> <span class="ident">nth</span>.<span class="ident">is_none</span>();
<span class="ident">nth</span>
}
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="ident">default</span> <span class="kw">fn</span> <span class="ident">last</span>(<span class="self">self</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">I</span>::<span class="ident">Item</span><span class="op">></span> {
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">done</span> {
<span class="prelude-val">None</span>
} <span class="kw">else</span> {
<span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">last</span>()
}
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="ident">default</span> <span class="kw">fn</span> <span class="ident">count</span>(<span class="self">self</span>) <span class="op">-></span> <span class="ident">usize</span> {
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">done</span> {
<span class="number">0</span>
} <span class="kw">else</span> {
<span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">count</span>()
}
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="ident">default</span> <span class="kw">fn</span> <span class="ident">size_hint</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> (<span class="ident">usize</span>, <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">usize</span><span class="op">></span>) {
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">done</span> {
(<span class="number">0</span>, <span class="prelude-val">Some</span>(<span class="number">0</span>))
} <span class="kw">else</span> {
<span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">size_hint</span>()
}
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">I</span><span class="op">></span> <span class="ident">DoubleEndedIterator</span> <span class="kw">for</span> <span class="ident">Fuse</span><span class="op"><</span><span class="ident">I</span><span class="op">></span> <span class="kw">where</span> <span class="ident">I</span>: <span class="ident">DoubleEndedIterator</span> {
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="ident">default</span> <span class="kw">fn</span> <span class="ident">next_back</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><<</span><span class="ident">I</span> <span class="kw">as</span> <span class="ident">Iterator</span><span class="op">></span>::<span class="ident">Item</span><span class="op">></span> {
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">done</span> {
<span class="prelude-val">None</span>
} <span class="kw">else</span> {
<span class="kw">let</span> <span class="ident">next</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">next_back</span>();
<span class="self">self</span>.<span class="ident">done</span> <span class="op">=</span> <span class="ident">next</span>.<span class="ident">is_none</span>();
<span class="ident">next</span>
}
}
}
<span class="kw">unsafe</span> <span class="kw">impl</span><span class="op"><</span><span class="ident">I</span><span class="op">></span> <span class="ident">TrustedRandomAccess</span> <span class="kw">for</span> <span class="ident">Fuse</span><span class="op"><</span><span class="ident">I</span><span class="op">></span>
<span class="kw">where</span> <span class="ident">I</span>: <span class="ident">TrustedRandomAccess</span>,
{
<span class="kw">unsafe</span> <span class="kw">fn</span> <span class="ident">get_unchecked</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">i</span>: <span class="ident">usize</span>) <span class="op">-></span> <span class="ident">I</span>::<span class="ident">Item</span> {
<span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">get_unchecked</span>(<span class="ident">i</span>)
}
<span class="kw">fn</span> <span class="ident">may_have_side_effect</span>() <span class="op">-></span> <span class="ident">bool</span> {
<span class="ident">I</span>::<span class="ident">may_have_side_effect</span>()
}
}
<span class="attribute">#[<span class="ident">unstable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"fused"</span>, <span class="ident">issue</span> <span class="op">=</span> <span class="string">"35602"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">I</span><span class="op">></span> <span class="ident">Iterator</span> <span class="kw">for</span> <span class="ident">Fuse</span><span class="op"><</span><span class="ident">I</span><span class="op">></span> <span class="kw">where</span> <span class="ident">I</span>: <span class="ident">FusedIterator</span> {
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">next</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><<</span><span class="ident">I</span> <span class="kw">as</span> <span class="ident">Iterator</span><span class="op">></span>::<span class="ident">Item</span><span class="op">></span> {
<span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">next</span>()
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">nth</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">n</span>: <span class="ident">usize</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">I</span>::<span class="ident">Item</span><span class="op">></span> {
<span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">nth</span>(<span class="ident">n</span>)
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">last</span>(<span class="self">self</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">I</span>::<span class="ident">Item</span><span class="op">></span> {
<span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">last</span>()
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">count</span>(<span class="self">self</span>) <span class="op">-></span> <span class="ident">usize</span> {
<span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">count</span>()
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">size_hint</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> (<span class="ident">usize</span>, <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">usize</span><span class="op">></span>) {
<span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">size_hint</span>()
}
}
<span class="attribute">#[<span class="ident">unstable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"fused"</span>, <span class="ident">reason</span> <span class="op">=</span> <span class="string">"recently added"</span>, <span class="ident">issue</span> <span class="op">=</span> <span class="string">"35602"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">I</span><span class="op">></span> <span class="ident">DoubleEndedIterator</span> <span class="kw">for</span> <span class="ident">Fuse</span><span class="op"><</span><span class="ident">I</span><span class="op">></span>
<span class="kw">where</span> <span class="ident">I</span>: <span class="ident">DoubleEndedIterator</span> <span class="op">+</span> <span class="ident">FusedIterator</span>
{
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">next_back</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><<</span><span class="ident">I</span> <span class="kw">as</span> <span class="ident">Iterator</span><span class="op">></span>::<span class="ident">Item</span><span class="op">></span> {
<span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">next_back</span>()
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">I</span><span class="op">></span> <span class="ident">ExactSizeIterator</span> <span class="kw">for</span> <span class="ident">Fuse</span><span class="op"><</span><span class="ident">I</span><span class="op">></span> <span class="kw">where</span> <span class="ident">I</span>: <span class="ident">ExactSizeIterator</span> {
<span class="kw">fn</span> <span class="ident">len</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="ident">usize</span> {
<span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">len</span>()
}
<span class="kw">fn</span> <span class="ident">is_empty</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="ident">bool</span> {
<span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">is_empty</span>()
}
}
<span class="doccomment">/// An iterator that calls a function with a reference to each element before</span>
<span class="doccomment">/// yielding it.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This `struct` is created by the [`inspect`] method on [`Iterator`]. See its</span>
<span class="doccomment">/// documentation for more.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// [`inspect`]: trait.Iterator.html#method.inspect</span>
<span class="doccomment">/// [`Iterator`]: trait.Iterator.html</span>
<span class="attribute">#[<span class="ident">must_use</span> <span class="op">=</span> <span class="string">"iterator adaptors are lazy and do nothing unless consumed"</span>]</span>
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Clone</span>)]</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">Inspect</span><span class="op"><</span><span class="ident">I</span>, <span class="ident">F</span><span class="op">></span> {
<span class="ident">iter</span>: <span class="ident">I</span>,
<span class="ident">f</span>: <span class="ident">F</span>,
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"core_impl_debug"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.9.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">I</span>: <span class="ident">fmt</span>::<span class="ident">Debug</span>, <span class="ident">F</span><span class="op">></span> <span class="ident">fmt</span>::<span class="ident">Debug</span> <span class="kw">for</span> <span class="ident">Inspect</span><span class="op"><</span><span class="ident">I</span>, <span class="ident">F</span><span class="op">></span> {
<span class="kw">fn</span> <span class="ident">fmt</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">f</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">fmt</span>::<span class="ident">Formatter</span>) <span class="op">-></span> <span class="ident">fmt</span>::<span class="prelude-ty">Result</span> {
<span class="ident">f</span>.<span class="ident">debug_struct</span>(<span class="string">"Inspect"</span>)
.<span class="ident">field</span>(<span class="string">"iter"</span>, <span class="kw-2">&</span><span class="self">self</span>.<span class="ident">iter</span>)
.<span class="ident">finish</span>()
}
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">I</span>: <span class="ident">Iterator</span>, <span class="ident">F</span><span class="op">></span> <span class="ident">Inspect</span><span class="op"><</span><span class="ident">I</span>, <span class="ident">F</span><span class="op">></span> <span class="kw">where</span> <span class="ident">F</span>: <span class="ident">FnMut</span>(<span class="kw-2">&</span><span class="ident">I</span>::<span class="ident">Item</span>) {
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">do_inspect</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">elt</span>: <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">I</span>::<span class="ident">Item</span><span class="op">></span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">I</span>::<span class="ident">Item</span><span class="op">></span> {
<span class="kw">if</span> <span class="kw">let</span> <span class="prelude-val">Some</span>(<span class="kw-2">ref</span> <span class="ident">a</span>) <span class="op">=</span> <span class="ident">elt</span> {
(<span class="self">self</span>.<span class="ident">f</span>)(<span class="ident">a</span>);
}
<span class="ident">elt</span>
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">I</span>: <span class="ident">Iterator</span>, <span class="ident">F</span><span class="op">></span> <span class="ident">Iterator</span> <span class="kw">for</span> <span class="ident">Inspect</span><span class="op"><</span><span class="ident">I</span>, <span class="ident">F</span><span class="op">></span> <span class="kw">where</span> <span class="ident">F</span>: <span class="ident">FnMut</span>(<span class="kw-2">&</span><span class="ident">I</span>::<span class="ident">Item</span>) {
<span class="kw">type</span> <span class="ident">Item</span> <span class="op">=</span> <span class="ident">I</span>::<span class="ident">Item</span>;
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">next</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">I</span>::<span class="ident">Item</span><span class="op">></span> {
<span class="kw">let</span> <span class="ident">next</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">next</span>();
<span class="self">self</span>.<span class="ident">do_inspect</span>(<span class="ident">next</span>)
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">size_hint</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> (<span class="ident">usize</span>, <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">usize</span><span class="op">></span>) {
<span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">size_hint</span>()
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">I</span>: <span class="ident">DoubleEndedIterator</span>, <span class="ident">F</span><span class="op">></span> <span class="ident">DoubleEndedIterator</span> <span class="kw">for</span> <span class="ident">Inspect</span><span class="op"><</span><span class="ident">I</span>, <span class="ident">F</span><span class="op">></span>
<span class="kw">where</span> <span class="ident">F</span>: <span class="ident">FnMut</span>(<span class="kw-2">&</span><span class="ident">I</span>::<span class="ident">Item</span>),
{
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">next_back</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">I</span>::<span class="ident">Item</span><span class="op">></span> {
<span class="kw">let</span> <span class="ident">next</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">next_back</span>();
<span class="self">self</span>.<span class="ident">do_inspect</span>(<span class="ident">next</span>)
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">I</span>: <span class="ident">ExactSizeIterator</span>, <span class="ident">F</span><span class="op">></span> <span class="ident">ExactSizeIterator</span> <span class="kw">for</span> <span class="ident">Inspect</span><span class="op"><</span><span class="ident">I</span>, <span class="ident">F</span><span class="op">></span>
<span class="kw">where</span> <span class="ident">F</span>: <span class="ident">FnMut</span>(<span class="kw-2">&</span><span class="ident">I</span>::<span class="ident">Item</span>)
{
<span class="kw">fn</span> <span class="ident">len</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="ident">usize</span> {
<span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">len</span>()
}
<span class="kw">fn</span> <span class="ident">is_empty</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="ident">bool</span> {
<span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">is_empty</span>()
}
}
<span class="attribute">#[<span class="ident">unstable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"fused"</span>, <span class="ident">issue</span> <span class="op">=</span> <span class="string">"35602"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">I</span>: <span class="ident">FusedIterator</span>, <span class="ident">F</span><span class="op">></span> <span class="ident">FusedIterator</span> <span class="kw">for</span> <span class="ident">Inspect</span><span class="op"><</span><span class="ident">I</span>, <span class="ident">F</span><span class="op">></span>
<span class="kw">where</span> <span class="ident">F</span>: <span class="ident">FnMut</span>(<span class="kw-2">&</span><span class="ident">I</span>::<span class="ident">Item</span>) {}
</pre>
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