| <!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta name="generator" content="rustdoc"><meta name="description" content="Source of the Rust file `/root/.cargo/registry/src/github.com-1ecc6299db9ec823/futures-util-0.3.28/src/stream/stream/peek.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>peek.rs - source</title><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../../SourceSerif4-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../../FiraSans-Regular.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../../FiraSans-Medium.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../../SourceCodePro-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../../SourceSerif4-Bold.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../../SourceCodePro-Semibold.ttf.woff2"><link rel="stylesheet" href="../../../../normalize.css"><link rel="stylesheet" href="../../../../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" href="../../../../ayu.css" disabled><link rel="stylesheet" href="../../../../dark.css" disabled><link rel="stylesheet" href="../../../../light.css" id="themeStyle"><script id="default-settings" ></script><script src="../../../../storage.js"></script><script defer src="../../../../source-script.js"></script><script defer src="../../../../source-files.js"></script><script defer src="../../../../main.js"></script><noscript><link rel="stylesheet" href="../../../../noscript.css"></noscript><link rel="alternate icon" type="image/png" href="../../../../favicon-16x16.png"><link rel="alternate icon" type="image/png" href="../../../../favicon-32x32.png"><link rel="icon" type="image/svg+xml" href="../../../../favicon.svg"></head><body class="rustdoc source"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><a class="sidebar-logo" href="../../../../futures_util/index.html"><div class="logo-container"><img class="rust-logo" src="../../../../rust-logo.svg" alt="logo"></div></a></nav><main><div class="width-limiter"><nav class="sub"><a class="sub-logo-container" href="../../../../futures_util/index.html"><img class="rust-logo" src="../../../../rust-logo.svg" alt="logo"></a><form class="search-form"><div class="search-container"><span></span><input class="search-input" name="search" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><div id="help-button" title="help" tabindex="-1"><a href="../../../../help.html">?</a></div><div id="settings-menu" tabindex="-1"><a href="../../../../settings.html" title="settings"><img width="22" height="22" alt="Change settings" src="../../../../wheel.svg"></a></div></div></form></nav><section id="main-content" class="content"><div class="example-wrap"><pre class="src-line-numbers"><span id="1">1</span> |
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| </pre><pre class="rust"><code><span class="kw">use </span><span class="kw">crate</span>::fns::FnOnce1; |
| <span class="kw">use </span><span class="kw">crate</span>::stream::{Fuse, StreamExt}; |
| <span class="kw">use </span>core::fmt; |
| <span class="kw">use </span>core::marker::PhantomData; |
| <span class="kw">use </span>core::pin::Pin; |
| <span class="kw">use </span>futures_core::future::{FusedFuture, Future}; |
| <span class="kw">use </span>futures_core::ready; |
| <span class="kw">use </span>futures_core::stream::{FusedStream, Stream}; |
| <span class="kw">use </span>futures_core::task::{Context, Poll}; |
| <span class="attribute">#[cfg(feature = <span class="string">"sink"</span>)] |
| </span><span class="kw">use </span>futures_sink::Sink; |
| <span class="kw">use </span>pin_project_lite::pin_project; |
| |
| <span class="macro">pin_project! </span>{ |
| <span class="doccomment">/// A `Stream` that implements a `peek` method. |
| /// |
| /// The `peek` method can be used to retrieve a reference |
| /// to the next `Stream::Item` if available. A subsequent |
| /// call to `poll` will return the owned item. |
| </span><span class="attribute">#[derive(Debug)] |
| #[must_use = <span class="string">"streams do nothing unless polled"</span>] |
| </span><span class="kw">pub struct </span>Peekable<St: Stream> { |
| <span class="attribute">#[pin] |
| </span>stream: Fuse<St>, |
| peeked: <span class="prelude-ty">Option</span><St::Item>, |
| } |
| } |
| |
| <span class="kw">impl</span><St: Stream> Peekable<St> { |
| <span class="kw">pub</span>(<span class="kw">super</span>) <span class="kw">fn </span>new(stream: St) -> <span class="self">Self </span>{ |
| <span class="self">Self </span>{ stream: stream.fuse(), peeked: <span class="prelude-val">None </span>} |
| } |
| |
| <span class="macro">delegate_access_inner!</span>(stream, St, (.)); |
| |
| <span class="doccomment">/// Produces a future which retrieves a reference to the next item |
| /// in the stream, or `None` if the underlying stream terminates. |
| </span><span class="kw">pub fn </span>peek(<span class="self">self</span>: Pin<<span class="kw-2">&mut </span><span class="self">Self</span>>) -> Peek<<span class="lifetime">'_</span>, St> { |
| Peek { inner: <span class="prelude-val">Some</span>(<span class="self">self</span>) } |
| } |
| |
| <span class="doccomment">/// Peek retrieves a reference to the next item in the stream. |
| /// |
| /// This method polls the underlying stream and return either a reference |
| /// to the next item if the stream is ready or passes through any errors. |
| </span><span class="kw">pub fn </span>poll_peek(<span class="self">self</span>: Pin<<span class="kw-2">&mut </span><span class="self">Self</span>>, cx: <span class="kw-2">&mut </span>Context<<span class="lifetime">'_</span>>) -> Poll<<span class="prelude-ty">Option</span><<span class="kw-2">&</span>St::Item>> { |
| <span class="kw">let </span><span class="kw-2">mut </span>this = <span class="self">self</span>.project(); |
| |
| Poll::Ready(<span class="kw">loop </span>{ |
| <span class="kw">if </span>this.peeked.is_some() { |
| <span class="kw">break </span>this.peeked.as_ref(); |
| } <span class="kw">else if let </span><span class="prelude-val">Some</span>(item) = <span class="macro">ready!</span>(this.stream.as_mut().poll_next(cx)) { |
| <span class="kw-2">*</span>this.peeked = <span class="prelude-val">Some</span>(item); |
| } <span class="kw">else </span>{ |
| <span class="kw">break </span><span class="prelude-val">None</span>; |
| } |
| }) |
| } |
| |
| <span class="doccomment">/// Produces a future which retrieves a mutable reference to the next item |
| /// in the stream, or `None` if the underlying stream terminates. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// # futures::executor::block_on(async { |
| /// use futures::stream::{self, StreamExt}; |
| /// use futures::pin_mut; |
| /// |
| /// let stream = stream::iter(vec![1, 2, 3]).peekable(); |
| /// pin_mut!(stream); |
| /// |
| /// assert_eq!(stream.as_mut().peek_mut().await, Some(&mut 1)); |
| /// assert_eq!(stream.as_mut().next().await, Some(1)); |
| /// |
| /// // Peek into the stream and modify the value which will be returned next |
| /// if let Some(p) = stream.as_mut().peek_mut().await { |
| /// if *p == 2 { |
| /// *p = 5; |
| /// } |
| /// } |
| /// |
| /// assert_eq!(stream.collect::<Vec<_>>().await, vec![5, 3]); |
| /// # }); |
| /// ``` |
| </span><span class="kw">pub fn </span>peek_mut(<span class="self">self</span>: Pin<<span class="kw-2">&mut </span><span class="self">Self</span>>) -> PeekMut<<span class="lifetime">'_</span>, St> { |
| PeekMut { inner: <span class="prelude-val">Some</span>(<span class="self">self</span>) } |
| } |
| |
| <span class="doccomment">/// Peek retrieves a mutable reference to the next item in the stream. |
| </span><span class="kw">pub fn </span>poll_peek_mut( |
| <span class="self">self</span>: Pin<<span class="kw-2">&mut </span><span class="self">Self</span>>, |
| cx: <span class="kw-2">&mut </span>Context<<span class="lifetime">'_</span>>, |
| ) -> Poll<<span class="prelude-ty">Option</span><<span class="kw-2">&mut </span>St::Item>> { |
| <span class="kw">let </span><span class="kw-2">mut </span>this = <span class="self">self</span>.project(); |
| |
| Poll::Ready(<span class="kw">loop </span>{ |
| <span class="kw">if </span>this.peeked.is_some() { |
| <span class="kw">break </span>this.peeked.as_mut(); |
| } <span class="kw">else if let </span><span class="prelude-val">Some</span>(item) = <span class="macro">ready!</span>(this.stream.as_mut().poll_next(cx)) { |
| <span class="kw-2">*</span>this.peeked = <span class="prelude-val">Some</span>(item); |
| } <span class="kw">else </span>{ |
| <span class="kw">break </span><span class="prelude-val">None</span>; |
| } |
| }) |
| } |
| |
| <span class="doccomment">/// Creates a future which will consume and return the next value of this |
| /// stream if a condition is true. |
| /// |
| /// If `func` returns `true` for the next value of this stream, consume and |
| /// return it. Otherwise, return `None`. |
| /// |
| /// # Examples |
| /// |
| /// Consume a number if it's equal to 0. |
| /// |
| /// ``` |
| /// # futures::executor::block_on(async { |
| /// use futures::stream::{self, StreamExt}; |
| /// use futures::pin_mut; |
| /// |
| /// let stream = stream::iter(0..5).peekable(); |
| /// pin_mut!(stream); |
| /// // The first item of the stream is 0; consume it. |
| /// assert_eq!(stream.as_mut().next_if(|&x| x == 0).await, Some(0)); |
| /// // The next item returned is now 1, so `consume` will return `false`. |
| /// assert_eq!(stream.as_mut().next_if(|&x| x == 0).await, None); |
| /// // `next_if` saves the value of the next item if it was not equal to `expected`. |
| /// assert_eq!(stream.next().await, Some(1)); |
| /// # }); |
| /// ``` |
| /// |
| /// Consume any number less than 10. |
| /// |
| /// ``` |
| /// # futures::executor::block_on(async { |
| /// use futures::stream::{self, StreamExt}; |
| /// use futures::pin_mut; |
| /// |
| /// let stream = stream::iter(1..20).peekable(); |
| /// pin_mut!(stream); |
| /// // Consume all numbers less than 10 |
| /// while stream.as_mut().next_if(|&x| x < 10).await.is_some() {} |
| /// // The next value returned will be 10 |
| /// assert_eq!(stream.next().await, Some(10)); |
| /// # }); |
| /// ``` |
| </span><span class="kw">pub fn </span>next_if<F>(<span class="self">self</span>: Pin<<span class="kw-2">&mut </span><span class="self">Self</span>>, func: F) -> NextIf<<span class="lifetime">'_</span>, St, F> |
| <span class="kw">where |
| </span>F: FnOnce(<span class="kw-2">&</span>St::Item) -> bool, |
| { |
| NextIf { inner: <span class="prelude-val">Some</span>((<span class="self">self</span>, func)) } |
| } |
| |
| <span class="doccomment">/// Creates a future which will consume and return the next item if it is |
| /// equal to `expected`. |
| /// |
| /// # Example |
| /// |
| /// Consume a number if it's equal to 0. |
| /// |
| /// ``` |
| /// # futures::executor::block_on(async { |
| /// use futures::stream::{self, StreamExt}; |
| /// use futures::pin_mut; |
| /// |
| /// let stream = stream::iter(0..5).peekable(); |
| /// pin_mut!(stream); |
| /// // The first item of the stream is 0; consume it. |
| /// assert_eq!(stream.as_mut().next_if_eq(&0).await, Some(0)); |
| /// // The next item returned is now 1, so `consume` will return `false`. |
| /// assert_eq!(stream.as_mut().next_if_eq(&0).await, None); |
| /// // `next_if_eq` saves the value of the next item if it was not equal to `expected`. |
| /// assert_eq!(stream.next().await, Some(1)); |
| /// # }); |
| /// ``` |
| </span><span class="kw">pub fn </span>next_if_eq<<span class="lifetime">'a</span>, T>(<span class="self">self</span>: Pin<<span class="kw-2">&</span><span class="lifetime">'a </span><span class="kw-2">mut </span><span class="self">Self</span>>, expected: <span class="kw-2">&</span><span class="lifetime">'a </span>T) -> NextIfEq<<span class="lifetime">'a</span>, St, T> |
| <span class="kw">where |
| </span>T: <span class="question-mark">?</span>Sized, |
| St::Item: PartialEq<T>, |
| { |
| NextIfEq { |
| inner: NextIf { inner: <span class="prelude-val">Some</span>((<span class="self">self</span>, NextIfEqFn { expected, _next: PhantomData })) }, |
| } |
| } |
| } |
| |
| <span class="kw">impl</span><St: Stream> FusedStream <span class="kw">for </span>Peekable<St> { |
| <span class="kw">fn </span>is_terminated(<span class="kw-2">&</span><span class="self">self</span>) -> bool { |
| <span class="self">self</span>.peeked.is_none() && <span class="self">self</span>.stream.is_terminated() |
| } |
| } |
| |
| <span class="kw">impl</span><S: Stream> Stream <span class="kw">for </span>Peekable<S> { |
| <span class="kw">type </span>Item = S::Item; |
| |
| <span class="kw">fn </span>poll_next(<span class="self">self</span>: Pin<<span class="kw-2">&mut </span><span class="self">Self</span>>, cx: <span class="kw-2">&mut </span>Context<<span class="lifetime">'_</span>>) -> Poll<<span class="prelude-ty">Option</span><<span class="self">Self</span>::Item>> { |
| <span class="kw">let </span>this = <span class="self">self</span>.project(); |
| <span class="kw">if let </span><span class="prelude-val">Some</span>(item) = this.peeked.take() { |
| <span class="kw">return </span>Poll::Ready(<span class="prelude-val">Some</span>(item)); |
| } |
| this.stream.poll_next(cx) |
| } |
| |
| <span class="kw">fn </span>size_hint(<span class="kw-2">&</span><span class="self">self</span>) -> (usize, <span class="prelude-ty">Option</span><usize>) { |
| <span class="kw">let </span>peek_len = usize::from(<span class="self">self</span>.peeked.is_some()); |
| <span class="kw">let </span>(lower, upper) = <span class="self">self</span>.stream.size_hint(); |
| <span class="kw">let </span>lower = lower.saturating_add(peek_len); |
| <span class="kw">let </span>upper = <span class="kw">match </span>upper { |
| <span class="prelude-val">Some</span>(x) => x.checked_add(peek_len), |
| <span class="prelude-val">None </span>=> <span class="prelude-val">None</span>, |
| }; |
| (lower, upper) |
| } |
| } |
| |
| <span class="comment">// Forwarding impl of Sink from the underlying stream |
| </span><span class="attribute">#[cfg(feature = <span class="string">"sink"</span>)] |
| </span><span class="kw">impl</span><S, Item> Sink<Item> <span class="kw">for </span>Peekable<S> |
| <span class="kw">where |
| </span>S: Sink<Item> + Stream, |
| { |
| <span class="kw">type </span>Error = S::Error; |
| |
| <span class="macro">delegate_sink!</span>(stream, Item); |
| } |
| |
| <span class="macro">pin_project! </span>{ |
| <span class="doccomment">/// Future for the [`Peekable::peek`](self::Peekable::peek) method. |
| </span><span class="attribute">#[must_use = <span class="string">"futures do nothing unless polled"</span>] |
| </span><span class="kw">pub struct </span>Peek<<span class="lifetime">'a</span>, St: Stream> { |
| inner: <span class="prelude-ty">Option</span><Pin<<span class="kw-2">&</span><span class="lifetime">'a </span><span class="kw-2">mut </span>Peekable<St>>>, |
| } |
| } |
| |
| <span class="kw">impl</span><St> fmt::Debug <span class="kw">for </span>Peek<<span class="lifetime">'_</span>, St> |
| <span class="kw">where |
| </span>St: Stream + fmt::Debug, |
| St::Item: fmt::Debug, |
| { |
| <span class="kw">fn </span>fmt(<span class="kw-2">&</span><span class="self">self</span>, f: <span class="kw-2">&mut </span>fmt::Formatter<<span class="lifetime">'_</span>>) -> fmt::Result { |
| f.debug_struct(<span class="string">"Peek"</span>).field(<span class="string">"inner"</span>, <span class="kw-2">&</span><span class="self">self</span>.inner).finish() |
| } |
| } |
| |
| <span class="kw">impl</span><St: Stream> FusedFuture <span class="kw">for </span>Peek<<span class="lifetime">'_</span>, St> { |
| <span class="kw">fn </span>is_terminated(<span class="kw-2">&</span><span class="self">self</span>) -> bool { |
| <span class="self">self</span>.inner.is_none() |
| } |
| } |
| |
| <span class="kw">impl</span><<span class="lifetime">'a</span>, St> Future <span class="kw">for </span>Peek<<span class="lifetime">'a</span>, St> |
| <span class="kw">where |
| </span>St: Stream, |
| { |
| <span class="kw">type </span>Output = <span class="prelude-ty">Option</span><<span class="kw-2">&</span><span class="lifetime">'a </span>St::Item>; |
| |
| <span class="kw">fn </span>poll(<span class="self">self</span>: Pin<<span class="kw-2">&mut </span><span class="self">Self</span>>, cx: <span class="kw-2">&mut </span>Context<<span class="lifetime">'_</span>>) -> Poll<<span class="self">Self</span>::Output> { |
| <span class="kw">let </span>inner = <span class="self">self</span>.project().inner; |
| <span class="kw">if let </span><span class="prelude-val">Some</span>(peekable) = inner { |
| <span class="macro">ready!</span>(peekable.as_mut().poll_peek(cx)); |
| |
| inner.take().unwrap().poll_peek(cx) |
| } <span class="kw">else </span>{ |
| <span class="macro">panic!</span>(<span class="string">"Peek polled after completion"</span>) |
| } |
| } |
| } |
| |
| <span class="macro">pin_project! </span>{ |
| <span class="doccomment">/// Future for the [`Peekable::peek_mut`](self::Peekable::peek_mut) method. |
| </span><span class="attribute">#[must_use = <span class="string">"futures do nothing unless polled"</span>] |
| </span><span class="kw">pub struct </span>PeekMut<<span class="lifetime">'a</span>, St: Stream> { |
| inner: <span class="prelude-ty">Option</span><Pin<<span class="kw-2">&</span><span class="lifetime">'a </span><span class="kw-2">mut </span>Peekable<St>>>, |
| } |
| } |
| |
| <span class="kw">impl</span><St> fmt::Debug <span class="kw">for </span>PeekMut<<span class="lifetime">'_</span>, St> |
| <span class="kw">where |
| </span>St: Stream + fmt::Debug, |
| St::Item: fmt::Debug, |
| { |
| <span class="kw">fn </span>fmt(<span class="kw-2">&</span><span class="self">self</span>, f: <span class="kw-2">&mut </span>fmt::Formatter<<span class="lifetime">'_</span>>) -> fmt::Result { |
| f.debug_struct(<span class="string">"PeekMut"</span>).field(<span class="string">"inner"</span>, <span class="kw-2">&</span><span class="self">self</span>.inner).finish() |
| } |
| } |
| |
| <span class="kw">impl</span><St: Stream> FusedFuture <span class="kw">for </span>PeekMut<<span class="lifetime">'_</span>, St> { |
| <span class="kw">fn </span>is_terminated(<span class="kw-2">&</span><span class="self">self</span>) -> bool { |
| <span class="self">self</span>.inner.is_none() |
| } |
| } |
| |
| <span class="kw">impl</span><<span class="lifetime">'a</span>, St> Future <span class="kw">for </span>PeekMut<<span class="lifetime">'a</span>, St> |
| <span class="kw">where |
| </span>St: Stream, |
| { |
| <span class="kw">type </span>Output = <span class="prelude-ty">Option</span><<span class="kw-2">&</span><span class="lifetime">'a </span><span class="kw-2">mut </span>St::Item>; |
| |
| <span class="kw">fn </span>poll(<span class="self">self</span>: Pin<<span class="kw-2">&mut </span><span class="self">Self</span>>, cx: <span class="kw-2">&mut </span>Context<<span class="lifetime">'_</span>>) -> Poll<<span class="self">Self</span>::Output> { |
| <span class="kw">let </span>inner = <span class="self">self</span>.project().inner; |
| <span class="kw">if let </span><span class="prelude-val">Some</span>(peekable) = inner { |
| <span class="macro">ready!</span>(peekable.as_mut().poll_peek_mut(cx)); |
| |
| inner.take().unwrap().poll_peek_mut(cx) |
| } <span class="kw">else </span>{ |
| <span class="macro">panic!</span>(<span class="string">"PeekMut polled after completion"</span>) |
| } |
| } |
| } |
| |
| <span class="macro">pin_project! </span>{ |
| <span class="doccomment">/// Future for the [`Peekable::next_if`](self::Peekable::next_if) method. |
| </span><span class="attribute">#[must_use = <span class="string">"futures do nothing unless polled"</span>] |
| </span><span class="kw">pub struct </span>NextIf<<span class="lifetime">'a</span>, St: Stream, F> { |
| inner: <span class="prelude-ty">Option</span><(Pin<<span class="kw-2">&</span><span class="lifetime">'a </span><span class="kw-2">mut </span>Peekable<St>>, F)>, |
| } |
| } |
| |
| <span class="kw">impl</span><St, F> fmt::Debug <span class="kw">for </span>NextIf<<span class="lifetime">'_</span>, St, F> |
| <span class="kw">where |
| </span>St: Stream + fmt::Debug, |
| St::Item: fmt::Debug, |
| { |
| <span class="kw">fn </span>fmt(<span class="kw-2">&</span><span class="self">self</span>, f: <span class="kw-2">&mut </span>fmt::Formatter<<span class="lifetime">'_</span>>) -> fmt::Result { |
| f.debug_struct(<span class="string">"NextIf"</span>).field(<span class="string">"inner"</span>, <span class="kw-2">&</span><span class="self">self</span>.inner.as_ref().map(|(s, _f)| s)).finish() |
| } |
| } |
| |
| <span class="attribute">#[allow(single_use_lifetimes)] </span><span class="comment">// https://github.com/rust-lang/rust/issues/55058 |
| </span><span class="kw">impl</span><St, F> FusedFuture <span class="kw">for </span>NextIf<<span class="lifetime">'_</span>, St, F> |
| <span class="kw">where |
| </span>St: Stream, |
| F: <span class="kw">for</span><<span class="lifetime">'a</span>> FnOnce1<<span class="kw-2">&</span><span class="lifetime">'a </span>St::Item, Output = bool>, |
| { |
| <span class="kw">fn </span>is_terminated(<span class="kw-2">&</span><span class="self">self</span>) -> bool { |
| <span class="self">self</span>.inner.is_none() |
| } |
| } |
| |
| <span class="attribute">#[allow(single_use_lifetimes)] </span><span class="comment">// https://github.com/rust-lang/rust/issues/55058 |
| </span><span class="kw">impl</span><St, F> Future <span class="kw">for </span>NextIf<<span class="lifetime">'_</span>, St, F> |
| <span class="kw">where |
| </span>St: Stream, |
| F: <span class="kw">for</span><<span class="lifetime">'a</span>> FnOnce1<<span class="kw-2">&</span><span class="lifetime">'a </span>St::Item, Output = bool>, |
| { |
| <span class="kw">type </span>Output = <span class="prelude-ty">Option</span><St::Item>; |
| |
| <span class="kw">fn </span>poll(<span class="self">self</span>: Pin<<span class="kw-2">&mut </span><span class="self">Self</span>>, cx: <span class="kw-2">&mut </span>Context<<span class="lifetime">'_</span>>) -> Poll<<span class="self">Self</span>::Output> { |
| <span class="kw">let </span>inner = <span class="self">self</span>.project().inner; |
| <span class="kw">if let </span><span class="prelude-val">Some</span>((peekable, <span class="kw">_</span>)) = inner { |
| <span class="kw">let </span>res = <span class="macro">ready!</span>(peekable.as_mut().poll_next(cx)); |
| |
| <span class="kw">let </span>(peekable, func) = inner.take().unwrap(); |
| <span class="kw">match </span>res { |
| <span class="prelude-val">Some</span>(<span class="kw-2">ref </span>matched) <span class="kw">if </span>func.call_once(matched) => Poll::Ready(res), |
| other => { |
| <span class="kw">let </span>peekable = peekable.project(); |
| <span class="comment">// Since we called `self.next()`, we consumed `self.peeked`. |
| </span><span class="macro">assert!</span>(peekable.peeked.is_none()); |
| <span class="kw-2">*</span>peekable.peeked = other; |
| Poll::Ready(<span class="prelude-val">None</span>) |
| } |
| } |
| } <span class="kw">else </span>{ |
| <span class="macro">panic!</span>(<span class="string">"NextIf polled after completion"</span>) |
| } |
| } |
| } |
| |
| <span class="macro">pin_project! </span>{ |
| <span class="doccomment">/// Future for the [`Peekable::next_if_eq`](self::Peekable::next_if_eq) method. |
| </span><span class="attribute">#[must_use = <span class="string">"futures do nothing unless polled"</span>] |
| </span><span class="kw">pub struct </span>NextIfEq<<span class="lifetime">'a</span>, St: Stream, T: <span class="question-mark">?</span>Sized> { |
| <span class="attribute">#[pin] |
| </span>inner: NextIf<<span class="lifetime">'a</span>, St, NextIfEqFn<<span class="lifetime">'a</span>, T, St::Item>>, |
| } |
| } |
| |
| <span class="kw">impl</span><St, T> fmt::Debug <span class="kw">for </span>NextIfEq<<span class="lifetime">'_</span>, St, T> |
| <span class="kw">where |
| </span>St: Stream + fmt::Debug, |
| St::Item: fmt::Debug, |
| T: <span class="question-mark">?</span>Sized, |
| { |
| <span class="kw">fn </span>fmt(<span class="kw-2">&</span><span class="self">self</span>, f: <span class="kw-2">&mut </span>fmt::Formatter<<span class="lifetime">'_</span>>) -> fmt::Result { |
| f.debug_struct(<span class="string">"NextIfEq"</span>) |
| .field(<span class="string">"inner"</span>, <span class="kw-2">&</span><span class="self">self</span>.inner.inner.as_ref().map(|(s, _f)| s)) |
| .finish() |
| } |
| } |
| |
| <span class="kw">impl</span><St, T> FusedFuture <span class="kw">for </span>NextIfEq<<span class="lifetime">'_</span>, St, T> |
| <span class="kw">where |
| </span>St: Stream, |
| T: <span class="question-mark">?</span>Sized, |
| St::Item: PartialEq<T>, |
| { |
| <span class="kw">fn </span>is_terminated(<span class="kw-2">&</span><span class="self">self</span>) -> bool { |
| <span class="self">self</span>.inner.is_terminated() |
| } |
| } |
| |
| <span class="kw">impl</span><St, T> Future <span class="kw">for </span>NextIfEq<<span class="lifetime">'_</span>, St, T> |
| <span class="kw">where |
| </span>St: Stream, |
| T: <span class="question-mark">?</span>Sized, |
| St::Item: PartialEq<T>, |
| { |
| <span class="kw">type </span>Output = <span class="prelude-ty">Option</span><St::Item>; |
| |
| <span class="kw">fn </span>poll(<span class="self">self</span>: Pin<<span class="kw-2">&mut </span><span class="self">Self</span>>, cx: <span class="kw-2">&mut </span>Context<<span class="lifetime">'_</span>>) -> Poll<<span class="self">Self</span>::Output> { |
| <span class="self">self</span>.project().inner.poll(cx) |
| } |
| } |
| |
| <span class="kw">struct </span>NextIfEqFn<<span class="lifetime">'a</span>, T: <span class="question-mark">?</span>Sized, Item> { |
| expected: <span class="kw-2">&</span><span class="lifetime">'a </span>T, |
| _next: PhantomData<Item>, |
| } |
| |
| <span class="kw">impl</span><T, Item> FnOnce1<<span class="kw-2">&</span>Item> <span class="kw">for </span>NextIfEqFn<<span class="lifetime">'_</span>, T, Item> |
| <span class="kw">where |
| </span>T: <span class="question-mark">?</span>Sized, |
| Item: PartialEq<T>, |
| { |
| <span class="kw">type </span>Output = bool; |
| |
| <span class="kw">fn </span>call_once(<span class="self">self</span>, next: <span class="kw-2">&</span>Item) -> <span class="self">Self</span>::Output { |
| next == <span class="self">self</span>.expected |
| } |
| } |
| </code></pre></div> |
| </section></div></main><div id="rustdoc-vars" data-root-path="../../../../" data-current-crate="futures_util" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |
