| <!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/executor.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>executor.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_macro::TokenStream; |
| <span class="kw">use </span>proc_macro2::Span; |
| <span class="kw">use </span>quote::{quote, quote_spanned, ToTokens}; |
| |
| <span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>test(args: TokenStream, item: TokenStream) -> TokenStream { |
| <span class="kw">if </span>!args.is_empty() { |
| <span class="kw">return </span>syn::Error::new_spanned(proc_macro2::TokenStream::from(args), <span class="string">"invalid argument"</span>) |
| .to_compile_error() |
| .into(); |
| } |
| |
| <span class="kw">let </span><span class="kw-2">mut </span>input = <span class="macro">syn::parse_macro_input!</span>(item <span class="kw">as </span>syn::ItemFn); |
| |
| <span class="kw">if </span>input.sig.asyncness.take().is_none() { |
| <span class="kw">return </span>syn::Error::new_spanned(input.sig.fn_token, <span class="string">"Only async functions are supported"</span>) |
| .to_compile_error() |
| .into(); |
| } |
| |
| <span class="comment">// If type mismatch occurs, the current rustc points to the last statement. |
| </span><span class="kw">let </span>(last_stmt_start_span, last_stmt_end_span) = { |
| <span class="kw">let </span><span class="kw-2">mut </span>last_stmt = input |
| .block |
| .stmts |
| .last() |
| .map(ToTokens::into_token_stream) |
| .unwrap_or_default() |
| .into_iter(); |
| <span class="comment">// `Span` on stable Rust has a limitation that only points to the first |
| // token, not the whole tokens. We can work around this limitation by |
| // using the first/last span of the tokens like |
| // `syn::Error::new_spanned` does. |
| </span><span class="kw">let </span>start = last_stmt.next().map_or_else(Span::call_site, |t| t.span()); |
| <span class="kw">let </span>end = last_stmt.last().map_or(start, |t| t.span()); |
| (start, end) |
| }; |
| |
| <span class="kw">let </span>path = <span class="macro">quote_spanned! </span>{last_stmt_start_span=> |
| ::futures_test::__private |
| }; |
| <span class="kw">let </span>body = <span class="kw-2">&</span>input.block; |
| input.block.stmts = <span class="macro">vec!</span>[syn::Stmt::Expr( |
| syn::parse2(<span class="macro">quote_spanned! </span>{last_stmt_end_span=> |
| #path::block_on(<span class="kw">async </span>#body) |
| }) |
| .unwrap(), |
| <span class="prelude-val">None</span>, |
| )]; |
| |
| <span class="kw">let </span>gen = <span class="macro">quote! </span>{ |
| <span class="attribute">#[::core::prelude::v1::test] |
| </span>#input |
| }; |
| |
| gen.into() |
| } |
| </code></pre></div> |
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