| <!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/join.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>join.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="doccomment">//! The futures-rs `join! macro implementation. |
| |
| </span><span class="kw">use </span>proc_macro::TokenStream; |
| <span class="kw">use </span>proc_macro2::{Span, TokenStream <span class="kw">as </span>TokenStream2}; |
| <span class="kw">use </span>quote::{format_ident, quote}; |
| <span class="kw">use </span>syn::parse::{Parse, ParseStream}; |
| <span class="kw">use </span>syn::{Expr, Ident, Token}; |
| |
| <span class="attribute">#[derive(Default)] |
| </span><span class="kw">struct </span>Join { |
| fut_exprs: Vec<Expr>, |
| } |
| |
| <span class="kw">impl </span>Parse <span class="kw">for </span>Join { |
| <span class="kw">fn </span>parse(input: ParseStream<<span class="lifetime">'_</span>>) -> syn::Result<<span class="self">Self</span>> { |
| <span class="kw">let </span><span class="kw-2">mut </span>join = <span class="self">Self</span>::default(); |
| |
| <span class="kw">while </span>!input.is_empty() { |
| join.fut_exprs.push(input.parse::<Expr>()<span class="question-mark">?</span>); |
| |
| <span class="kw">if </span>!input.is_empty() { |
| input.parse::<<span class="macro">Token!</span>[,]>()<span class="question-mark">?</span>; |
| } |
| } |
| |
| <span class="prelude-val">Ok</span>(join) |
| } |
| } |
| |
| <span class="kw">fn </span>bind_futures(fut_exprs: Vec<Expr>, span: Span) -> (Vec<TokenStream2>, Vec<Ident>) { |
| <span class="kw">let </span><span class="kw-2">mut </span>future_let_bindings = Vec::with_capacity(fut_exprs.len()); |
| <span class="kw">let </span>future_names: Vec<<span class="kw">_</span>> = fut_exprs |
| .into_iter() |
| .enumerate() |
| .map(|(i, expr)| { |
| <span class="kw">let </span>name = <span class="macro">format_ident!</span>(<span class="string">"_fut{}"</span>, i, span = span); |
| future_let_bindings.push(<span class="macro">quote! </span>{ |
| <span class="comment">// Move future into a local so that it is pinned in one place and |
| // is no longer accessible by the end user. |
| </span><span class="kw">let </span><span class="kw-2">mut </span>#name = __futures_crate::future::maybe_done(#expr); |
| <span class="kw">let </span><span class="kw-2">mut </span>#name = <span class="kw">unsafe </span>{ __futures_crate::Pin::new_unchecked(<span class="kw-2">&mut </span>#name) }; |
| }); |
| name |
| }) |
| .collect(); |
| |
| (future_let_bindings, future_names) |
| } |
| |
| <span class="doccomment">/// The `join!` macro. |
| </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>join(input: TokenStream) -> TokenStream { |
| <span class="kw">let </span>parsed = <span class="macro">syn::parse_macro_input!</span>(input <span class="kw">as </span>Join); |
| |
| <span class="comment">// should be def_site, but that's unstable |
| </span><span class="kw">let </span>span = Span::call_site(); |
| |
| <span class="kw">let </span>(future_let_bindings, future_names) = bind_futures(parsed.fut_exprs, span); |
| |
| <span class="kw">let </span>poll_futures = future_names.iter().map(|fut| { |
| <span class="macro">quote! </span>{ |
| __all_done &= __futures_crate::future::Future::poll( |
| #fut.as_mut(), __cx).is_ready(); |
| } |
| }); |
| <span class="kw">let </span>take_outputs = future_names.iter().map(|fut| { |
| <span class="macro">quote! </span>{ |
| #fut.as_mut().take_output().unwrap(), |
| } |
| }); |
| |
| TokenStream::from(<span class="macro">quote! </span>{ { |
| #( #future_let_bindings )* |
| |
| __futures_crate::future::poll_fn(<span class="kw">move </span>|__cx: <span class="kw-2">&mut </span>__futures_crate::task::Context<<span class="lifetime">'_</span>>| { |
| <span class="kw">let </span><span class="kw-2">mut </span>__all_done = <span class="bool-val">true</span>; |
| #( #poll_futures )* |
| <span class="kw">if </span>__all_done { |
| __futures_crate::task::Poll::Ready(( |
| #( #take_outputs )* |
| )) |
| } <span class="kw">else </span>{ |
| __futures_crate::task::Poll::Pending |
| } |
| }).<span class="kw">await |
| </span>} }) |
| } |
| |
| <span class="doccomment">/// The `try_join!` macro. |
| </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>try_join(input: TokenStream) -> TokenStream { |
| <span class="kw">let </span>parsed = <span class="macro">syn::parse_macro_input!</span>(input <span class="kw">as </span>Join); |
| |
| <span class="comment">// should be def_site, but that's unstable |
| </span><span class="kw">let </span>span = Span::call_site(); |
| |
| <span class="kw">let </span>(future_let_bindings, future_names) = bind_futures(parsed.fut_exprs, span); |
| |
| <span class="kw">let </span>poll_futures = future_names.iter().map(|fut| { |
| <span class="macro">quote! </span>{ |
| <span class="kw">if </span>__futures_crate::future::Future::poll( |
| #fut.as_mut(), __cx).is_pending() |
| { |
| __all_done = <span class="bool-val">false</span>; |
| } <span class="kw">else if </span>#fut.as_mut().output_mut().unwrap().is_err() { |
| <span class="comment">// `.err().unwrap()` rather than `.unwrap_err()` so that we don't introduce |
| // a `T: Debug` bound. |
| // Also, for an error type of ! any code after `err().unwrap()` is unreachable. |
| </span><span class="attribute">#[allow(unreachable_code)] |
| </span><span class="kw">return </span>__futures_crate::task::Poll::Ready( |
| __futures_crate::Err( |
| #fut.as_mut().take_output().unwrap().err().unwrap() |
| ) |
| ); |
| } |
| } |
| }); |
| <span class="kw">let </span>take_outputs = future_names.iter().map(|fut| { |
| <span class="macro">quote! </span>{ |
| <span class="comment">// `.ok().unwrap()` rather than `.unwrap()` so that we don't introduce |
| // an `E: Debug` bound. |
| // Also, for an ok type of ! any code after `ok().unwrap()` is unreachable. |
| </span><span class="attribute">#[allow(unreachable_code)] |
| </span>#fut.as_mut().take_output().unwrap().ok().unwrap(), |
| } |
| }); |
| |
| TokenStream::from(<span class="macro">quote! </span>{ { |
| #( #future_let_bindings )* |
| |
| <span class="attribute">#[allow(clippy::diverging_sub_expression)] |
| </span>__futures_crate::future::poll_fn(<span class="kw">move </span>|__cx: <span class="kw-2">&mut </span>__futures_crate::task::Context<<span class="lifetime">'_</span>>| { |
| <span class="kw">let </span><span class="kw-2">mut </span>__all_done = <span class="bool-val">true</span>; |
| #( #poll_futures )* |
| <span class="kw">if </span>__all_done { |
| __futures_crate::task::Poll::Ready( |
| __futures_crate::Ok(( |
| #( #take_outputs )* |
| )) |
| ) |
| } <span class="kw">else </span>{ |
| __futures_crate::task::Poll::Pending |
| } |
| }).<span class="kw">await |
| </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> |
