| <!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/git/checkouts/tokio-377c595163f99a10/dfe252d/tokio-macros/src/select.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>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="../../tokio_macros/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="../../tokio_macros/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_macro::{TokenStream, TokenTree}; |
| <span class="kw">use </span>proc_macro2::Span; |
| <span class="kw">use </span>quote::quote; |
| <span class="kw">use </span>syn::Ident; |
| |
| <span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>declare_output_enum(input: TokenStream) -> TokenStream { |
| <span class="comment">// passed in is: `(_ _ _)` with one `_` per branch |
| </span><span class="kw">let </span>branches = <span class="kw">match </span>input.into_iter().next() { |
| <span class="prelude-val">Some</span>(TokenTree::Group(group)) => group.stream().into_iter().count(), |
| <span class="kw">_ </span>=> <span class="macro">panic!</span>(<span class="string">"unexpected macro input"</span>), |
| }; |
| |
| <span class="kw">let </span>variants = (<span class="number">0</span>..branches) |
| .map(|num| Ident::new(<span class="kw-2">&</span><span class="macro">format!</span>(<span class="string">"_{}"</span>, num), Span::call_site())) |
| .collect::<Vec<<span class="kw">_</span>>>(); |
| |
| <span class="comment">// Use a bitfield to track which futures completed |
| </span><span class="kw">let </span>mask = Ident::new( |
| <span class="kw">if </span>branches <= <span class="number">8 </span>{ |
| <span class="string">"u8" |
| </span>} <span class="kw">else if </span>branches <= <span class="number">16 </span>{ |
| <span class="string">"u16" |
| </span>} <span class="kw">else if </span>branches <= <span class="number">32 </span>{ |
| <span class="string">"u32" |
| </span>} <span class="kw">else if </span>branches <= <span class="number">64 </span>{ |
| <span class="string">"u64" |
| </span>} <span class="kw">else </span>{ |
| <span class="macro">panic!</span>(<span class="string">"up to 64 branches supported"</span>); |
| }, |
| Span::call_site(), |
| ); |
| |
| TokenStream::from(<span class="macro">quote! </span>{ |
| <span class="kw">pub</span>(<span class="kw">super</span>) <span class="kw">enum </span>Out<#( #variants ),<span class="kw-2">*</span>> { |
| #( #variants(#variants), )* |
| <span class="comment">// Include a `Disabled` variant signifying that all select branches |
| // failed to resolve. |
| </span>Disabled, |
| } |
| |
| <span class="kw">pub</span>(<span class="kw">super</span>) <span class="kw">type </span>Mask = #mask; |
| }) |
| } |
| |
| <span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>clean_pattern_macro(input: TokenStream) -> TokenStream { |
| <span class="comment">// If this isn't a pattern, we return the token stream as-is. The select! |
| // macro is using it in a location requiring a pattern, so an error will be |
| // emitted there. |
| </span><span class="kw">let </span><span class="kw-2">mut </span>input: syn::Pat = <span class="kw">match </span>syn::parse(input.clone()) { |
| <span class="prelude-val">Ok</span>(it) => it, |
| <span class="prelude-val">Err</span>(<span class="kw">_</span>) => <span class="kw">return </span>input, |
| }; |
| |
| clean_pattern(<span class="kw-2">&mut </span>input); |
| quote::ToTokens::into_token_stream(input).into() |
| } |
| |
| <span class="comment">// Removes any occurrences of ref or mut in the provided pattern. |
| </span><span class="kw">fn </span>clean_pattern(pat: <span class="kw-2">&mut </span>syn::Pat) { |
| <span class="kw">match </span>pat { |
| syn::Pat::Box(_box) => {} |
| syn::Pat::Lit(_literal) => {} |
| syn::Pat::Macro(_macro) => {} |
| syn::Pat::Path(_path) => {} |
| syn::Pat::Range(_range) => {} |
| syn::Pat::Rest(_rest) => {} |
| syn::Pat::Verbatim(_tokens) => {} |
| syn::Pat::Wild(_underscore) => {} |
| syn::Pat::Ident(ident) => { |
| ident.by_ref = <span class="prelude-val">None</span>; |
| ident.mutability = <span class="prelude-val">None</span>; |
| <span class="kw">if let </span><span class="prelude-val">Some</span>((_at, pat)) = <span class="kw-2">&mut </span>ident.subpat { |
| clean_pattern(<span class="kw-2">&mut *</span>pat); |
| } |
| } |
| syn::Pat::Or(or) => { |
| <span class="kw">for </span>case <span class="kw">in </span>or.cases.iter_mut() { |
| clean_pattern(case); |
| } |
| } |
| syn::Pat::Slice(slice) => { |
| <span class="kw">for </span>elem <span class="kw">in </span>slice.elems.iter_mut() { |
| clean_pattern(elem); |
| } |
| } |
| syn::Pat::Struct(struct_pat) => { |
| <span class="kw">for </span>field <span class="kw">in </span>struct_pat.fields.iter_mut() { |
| clean_pattern(<span class="kw-2">&mut </span>field.pat); |
| } |
| } |
| syn::Pat::Tuple(tuple) => { |
| <span class="kw">for </span>elem <span class="kw">in </span>tuple.elems.iter_mut() { |
| clean_pattern(elem); |
| } |
| } |
| syn::Pat::TupleStruct(tuple) => { |
| <span class="kw">for </span>elem <span class="kw">in </span>tuple.pat.elems.iter_mut() { |
| clean_pattern(elem); |
| } |
| } |
| syn::Pat::Reference(reference) => { |
| reference.mutability = <span class="prelude-val">None</span>; |
| clean_pattern(<span class="kw-2">&mut </span>reference.pat); |
| } |
| syn::Pat::Type(type_pat) => { |
| clean_pattern(<span class="kw-2">&mut </span>type_pat.pat); |
| } |
| <span class="kw">_ </span>=> {} |
| } |
| } |
| </code></pre></div> |
| </section></div></main><div id="rustdoc-vars" data-root-path="../../" data-current-crate="tokio_macros" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |
