| <!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-macro-0.3.28/src/stream_select.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>stream_select.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_macro/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_macro/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>proc_macro2::TokenStream; |
| <span class="kw">use </span>quote::{format_ident, quote, ToTokens}; |
| <span class="kw">use </span>syn::{parse::Parser, punctuated::Punctuated, Expr, Index, Token}; |
| |
| <span class="doccomment">/// The `stream_select!` macro. |
| </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>stream_select(input: TokenStream) -> <span class="prelude-ty">Result</span><TokenStream, syn::Error> { |
| <span class="kw">let </span>args = Punctuated::<Expr, <span class="macro">Token!</span>[,]>::parse_terminated.parse2(input)<span class="question-mark">?</span>; |
| <span class="kw">if </span>args.len() < <span class="number">2 </span>{ |
| <span class="kw">return </span><span class="prelude-val">Ok</span>(<span class="macro">quote! </span>{ |
| <span class="macro">compile_error!</span>(<span class="string">"stream select macro needs at least two arguments."</span>) |
| }); |
| } |
| <span class="kw">let </span>generic_idents = (<span class="number">0</span>..args.len()).map(|i| <span class="macro">format_ident!</span>(<span class="string">"_{}"</span>, i)).collect::<Vec<<span class="kw">_</span>>>(); |
| <span class="kw">let </span>field_idents = (<span class="number">0</span>..args.len()).map(|i| <span class="macro">format_ident!</span>(<span class="string">"__{}"</span>, i)).collect::<Vec<<span class="kw">_</span>>>(); |
| <span class="kw">let </span>field_idents_2 = (<span class="number">0</span>..args.len()).map(|i| <span class="macro">format_ident!</span>(<span class="string">"___{}"</span>, i)).collect::<Vec<<span class="kw">_</span>>>(); |
| <span class="kw">let </span>field_indices = (<span class="number">0</span>..args.len()).map(Index::from).collect::<Vec<<span class="kw">_</span>>>(); |
| <span class="kw">let </span>args = args.iter().map(|e| e.to_token_stream()); |
| |
| <span class="prelude-val">Ok</span>(<span class="macro">quote! </span>{ |
| { |
| <span class="attribute">#[derive(Debug)] |
| </span><span class="kw">struct </span>StreamSelect<#(#generic_idents),<span class="kw-2">*</span>> (#(<span class="prelude-ty">Option</span><#generic_idents>),<span class="kw-2">*</span>); |
| |
| <span class="kw">enum </span>StreamEnum<#(#generic_idents),<span class="kw-2">*</span>> { |
| #( |
| #generic_idents(#generic_idents) |
| ),<span class="kw-2">*</span>, |
| <span class="prelude-val">None</span>, |
| } |
| |
| <span class="kw">impl</span><ITEM, #(#generic_idents),<span class="kw-2">*</span>> __futures_crate::stream::Stream <span class="kw">for </span>StreamEnum<#(#generic_idents),<span class="kw-2">*</span>> |
| <span class="kw">where </span>#(#generic_idents: __futures_crate::stream::Stream<Item=ITEM> + ::std::marker::Unpin,)* |
| { |
| <span class="kw">type </span>Item = ITEM; |
| |
| <span class="kw">fn </span>poll_next(<span class="kw-2">mut </span><span class="self">self</span>: ::std::pin::Pin<<span class="kw-2">&mut </span><span class="self">Self</span>>, cx: <span class="kw-2">&mut </span>__futures_crate::task::Context<<span class="lifetime">'_</span>>) -> __futures_crate::task::Poll<<span class="prelude-ty">Option</span><<span class="self">Self</span>::Item>> { |
| <span class="kw">match </span><span class="self">self</span>.get_mut() { |
| #( |
| <span class="self">Self</span>::#generic_idents(#generic_idents) => ::std::pin::Pin::new(#generic_idents).poll_next(cx) |
| ),<span class="kw-2">*</span>, |
| <span class="self">Self</span>::None => <span class="macro">panic!</span>(<span class="string">"StreamEnum::None should never be polled!"</span>), |
| } |
| } |
| } |
| |
| <span class="kw">impl</span><ITEM, #(#generic_idents),<span class="kw-2">*</span>> __futures_crate::stream::Stream <span class="kw">for </span>StreamSelect<#(#generic_idents),<span class="kw-2">*</span>> |
| <span class="kw">where </span>#(#generic_idents: __futures_crate::stream::Stream<Item=ITEM> + ::std::marker::Unpin,)* |
| { |
| <span class="kw">type </span>Item = ITEM; |
| |
| <span class="kw">fn </span>poll_next(<span class="kw-2">mut </span><span class="self">self</span>: ::std::pin::Pin<<span class="kw-2">&mut </span><span class="self">Self</span>>, cx: <span class="kw-2">&mut </span>__futures_crate::task::Context<<span class="lifetime">'_</span>>) -> __futures_crate::task::Poll<<span class="prelude-ty">Option</span><<span class="self">Self</span>::Item>> { |
| <span class="kw">let </span><span class="self">Self</span>(#(<span class="kw-2">ref mut </span>#field_idents),<span class="kw-2">*</span>) = <span class="self">self</span>.get_mut(); |
| #( |
| <span class="kw">let </span><span class="kw-2">mut </span>#field_idents_2 = <span class="bool-val">false</span>; |
| )* |
| <span class="kw">let </span><span class="kw-2">mut </span>any_pending = <span class="bool-val">false</span>; |
| { |
| <span class="kw">let </span><span class="kw-2">mut </span>stream_array = [#(#field_idents.as_mut().map(|f| StreamEnum::#generic_idents(f)).unwrap_or(StreamEnum::None)),<span class="kw-2">*</span>]; |
| __futures_crate::async_await::shuffle(<span class="kw-2">&mut </span>stream_array); |
| |
| <span class="kw">for </span><span class="kw-2">mut </span>s <span class="kw">in </span>stream_array { |
| <span class="kw">if let </span>StreamEnum::None = s { |
| <span class="kw">continue</span>; |
| } <span class="kw">else </span>{ |
| <span class="kw">match </span>__futures_crate::stream::Stream::poll_next(::std::pin::Pin::new(<span class="kw-2">&mut </span>s), cx) { |
| r @ __futures_crate::task::Poll::Ready(<span class="prelude-val">Some</span>(<span class="kw">_</span>)) => { |
| <span class="kw">return </span>r; |
| }, |
| __futures_crate::task::Poll::Pending => { |
| any_pending = <span class="bool-val">true</span>; |
| }, |
| __futures_crate::task::Poll::Ready(<span class="prelude-val">None</span>) => { |
| <span class="kw">match </span>s { |
| #( |
| StreamEnum::#generic_idents(<span class="kw">_</span>) => { #field_idents_2 = <span class="bool-val">true</span>; } |
| ),<span class="kw-2">*</span>, |
| StreamEnum::None => <span class="macro">panic!</span>(<span class="string">"StreamEnum::None should never be polled!"</span>), |
| } |
| }, |
| } |
| } |
| } |
| } |
| #( |
| <span class="kw">if </span>#field_idents_2 { |
| <span class="kw-2">*</span>#field_idents = <span class="prelude-val">None</span>; |
| } |
| )* |
| <span class="kw">if </span>any_pending { |
| __futures_crate::task::Poll::Pending |
| } <span class="kw">else </span>{ |
| __futures_crate::task::Poll::Ready(<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><span class="kw-2">mut </span>s = (<span class="number">0</span>, <span class="prelude-val">Some</span>(<span class="number">0</span>)); |
| #( |
| <span class="kw">if let </span><span class="prelude-val">Some</span>(new_hint) = <span class="self">self</span>.#field_indices.as_ref().map(|s| s.size_hint()) { |
| s.<span class="number">0 </span>+= new_hint.<span class="number">0</span>; |
| <span class="comment">// We can change this out for `.zip` when the MSRV is 1.46.0 or higher. |
| </span>s.<span class="number">1 </span>= s.<span class="number">1</span>.and_then(|a| new_hint.<span class="number">1</span>.map(|b| a + b)); |
| } |
| )* |
| s |
| } |
| } |
| |
| StreamSelect(#(<span class="prelude-val">Some</span>(#args)),<span class="kw-2">*</span>) |
| |
| } |
| }) |
| } |
| </code></pre></div> |
| </section></div></main><div id="rustdoc-vars" data-root-path="../../" data-current-crate="futures_macro" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |
