| <!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/then.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>then.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>core::fmt; |
| <span class="kw">use </span>core::pin::Pin; |
| <span class="kw">use </span>futures_core::future::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">/// Stream for the [`then`](super::StreamExt::then) method. |
| </span><span class="attribute">#[must_use = <span class="string">"streams do nothing unless polled"</span>] |
| </span><span class="kw">pub struct </span>Then<St, Fut, F> { |
| <span class="attribute">#[pin] |
| </span>stream: St, |
| <span class="attribute">#[pin] |
| </span>future: <span class="prelude-ty">Option</span><Fut>, |
| f: F, |
| } |
| } |
| |
| <span class="kw">impl</span><St, Fut, F> fmt::Debug <span class="kw">for </span>Then<St, Fut, F> |
| <span class="kw">where |
| </span>St: fmt::Debug, |
| Fut: 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">"Then"</span>).field(<span class="string">"stream"</span>, <span class="kw-2">&</span><span class="self">self</span>.stream).field(<span class="string">"future"</span>, <span class="kw-2">&</span><span class="self">self</span>.future).finish() |
| } |
| } |
| |
| <span class="kw">impl</span><St, Fut, F> Then<St, Fut, F> |
| <span class="kw">where |
| </span>St: Stream, |
| F: FnMut(St::Item) -> Fut, |
| { |
| <span class="kw">pub</span>(<span class="kw">super</span>) <span class="kw">fn </span>new(stream: St, f: F) -> <span class="self">Self </span>{ |
| <span class="self">Self </span>{ stream, future: <span class="prelude-val">None</span>, f } |
| } |
| |
| <span class="macro">delegate_access_inner!</span>(stream, St, ()); |
| } |
| |
| <span class="kw">impl</span><St, Fut, F> FusedStream <span class="kw">for </span>Then<St, Fut, F> |
| <span class="kw">where |
| </span>St: FusedStream, |
| F: FnMut(St::Item) -> Fut, |
| Fut: Future, |
| { |
| <span class="kw">fn </span>is_terminated(<span class="kw-2">&</span><span class="self">self</span>) -> bool { |
| <span class="self">self</span>.future.is_none() && <span class="self">self</span>.stream.is_terminated() |
| } |
| } |
| |
| <span class="kw">impl</span><St, Fut, F> Stream <span class="kw">for </span>Then<St, Fut, F> |
| <span class="kw">where |
| </span>St: Stream, |
| F: FnMut(St::Item) -> Fut, |
| Fut: Future, |
| { |
| <span class="kw">type </span>Item = Fut::Output; |
| |
| <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><span class="kw-2">mut </span>this = <span class="self">self</span>.project(); |
| |
| Poll::Ready(<span class="kw">loop </span>{ |
| <span class="kw">if let </span><span class="prelude-val">Some</span>(fut) = this.future.as_mut().as_pin_mut() { |
| <span class="kw">let </span>item = <span class="macro">ready!</span>(fut.poll(cx)); |
| this.future.set(<span class="prelude-val">None</span>); |
| <span class="kw">break </span><span class="prelude-val">Some</span>(item); |
| } <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)) { |
| this.future.set(<span class="prelude-val">Some</span>((this.f)(item))); |
| } <span class="kw">else </span>{ |
| <span class="kw">break </span><span class="prelude-val">None</span>; |
| } |
| }) |
| } |
| |
| <span class="kw">fn </span>size_hint(<span class="kw-2">&</span><span class="self">self</span>) -> (usize, <span class="prelude-ty">Option</span><usize>) { |
| <span class="kw">let </span>future_len = usize::from(<span class="self">self</span>.future.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(future_len); |
| <span class="kw">let </span>upper = <span class="kw">match </span>upper { |
| <span class="prelude-val">Some</span>(x) => x.checked_add(future_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, Fut, F, Item> Sink<Item> <span class="kw">for </span>Then<S, Fut, F> |
| <span class="kw">where |
| </span>S: Sink<Item>, |
| { |
| <span class="kw">type </span>Error = S::Error; |
| |
| <span class="macro">delegate_sink!</span>(stream, Item); |
| } |
| </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> |
