| <!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/crossbeam-channel-0.5.8/src/select_macro.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>select_macro.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="../../crossbeam_channel/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="../../crossbeam_channel/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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| <span id="1076">1076</span> |
| <span id="1077">1077</span> |
| <span id="1078">1078</span> |
| <span id="1079">1079</span> |
| <span id="1080">1080</span> |
| <span id="1081">1081</span> |
| <span id="1082">1082</span> |
| <span id="1083">1083</span> |
| <span id="1084">1084</span> |
| <span id="1085">1085</span> |
| <span id="1086">1086</span> |
| <span id="1087">1087</span> |
| <span id="1088">1088</span> |
| <span id="1089">1089</span> |
| <span id="1090">1090</span> |
| <span id="1091">1091</span> |
| <span id="1092">1092</span> |
| <span id="1093">1093</span> |
| <span id="1094">1094</span> |
| <span id="1095">1095</span> |
| <span id="1096">1096</span> |
| <span id="1097">1097</span> |
| <span id="1098">1098</span> |
| <span id="1099">1099</span> |
| <span id="1100">1100</span> |
| <span id="1101">1101</span> |
| <span id="1102">1102</span> |
| <span id="1103">1103</span> |
| <span id="1104">1104</span> |
| <span id="1105">1105</span> |
| <span id="1106">1106</span> |
| <span id="1107">1107</span> |
| <span id="1108">1108</span> |
| <span id="1109">1109</span> |
| <span id="1110">1110</span> |
| <span id="1111">1111</span> |
| <span id="1112">1112</span> |
| <span id="1113">1113</span> |
| <span id="1114">1114</span> |
| <span id="1115">1115</span> |
| <span id="1116">1116</span> |
| </pre><pre class="rust"><code><span class="doccomment">//! The `select!` macro. |
| |
| /// A helper macro for `select!` to hide the long list of macro patterns from the documentation. |
| /// |
| /// The macro consists of two stages: |
| /// 1. Parsing |
| /// 2. Code generation |
| /// |
| /// The parsing stage consists of these subparts: |
| /// 1. `@list`: Turns a list of tokens into a list of cases. |
| /// 2. `@list_errorN`: Diagnoses the syntax error. |
| /// 3. `@case`: Parses a single case and verifies its argument list. |
| /// |
| /// The codegen stage consists of these subparts: |
| /// 1. `@init`: Attempts to optimize `select!` away and initializes the list of handles. |
| /// 1. `@count`: Counts the listed cases. |
| /// 3. `@add`: Adds send/receive operations to the list of handles and starts selection. |
| /// 4. `@complete`: Completes the selected send/receive operation. |
| /// |
| /// If the parsing stage encounters a syntax error or the codegen stage ends up with too many |
| /// cases to process, the macro fails with a compile-time error. |
| </span><span class="attribute">#[doc(hidden)] |
| #[macro_export] |
| </span><span class="macro">macro_rules! </span>crossbeam_channel_internal { |
| <span class="comment">// The list is empty. Now check the arguments of each processed case. |
| </span>(@list |
| () |
| ($(<span class="macro-nonterminal">$head</span>:tt)<span class="kw-2">*</span>) |
| ) => { |
| <span class="macro-nonterminal">$</span><span class="macro">crate::crossbeam_channel_internal!</span>( |
| @<span class="macro-nonterminal">case |
| </span>($(<span class="macro-nonterminal">$head</span>)<span class="kw-2">*</span>) |
| () |
| () |
| ) |
| }; |
| <span class="comment">// If necessary, insert an empty argument list after `default`. |
| </span>(@list |
| (default => $(<span class="macro-nonterminal">$tail</span>:tt)<span class="kw-2">*</span>) |
| ($(<span class="macro-nonterminal">$head</span>:tt)<span class="kw-2">*</span>) |
| ) => { |
| <span class="macro-nonterminal">$</span><span class="macro">crate::crossbeam_channel_internal!</span>( |
| @<span class="macro-nonterminal">list |
| </span>(default() => $(<span class="macro-nonterminal">$tail</span>)<span class="kw-2">*</span>) |
| ($(<span class="macro-nonterminal">$head</span>)<span class="kw-2">*</span>) |
| ) |
| }; |
| <span class="comment">// But print an error if `default` is followed by a `->`. |
| </span>(@list |
| (default -> $(<span class="macro-nonterminal">$tail</span>:tt)<span class="kw-2">*</span>) |
| ($(<span class="macro-nonterminal">$head</span>:tt)<span class="kw-2">*</span>) |
| ) => { |
| <span class="macro">compile_error!</span>( |
| <span class="string">"expected `=>` after `default` case, found `->`" |
| </span>) |
| }; |
| <span class="comment">// Print an error if there's an `->` after the argument list in the default case. |
| </span>(@list |
| (default <span class="macro-nonterminal">$args</span>:tt -> $(<span class="macro-nonterminal">$tail</span>:tt)<span class="kw-2">*</span>) |
| ($(<span class="macro-nonterminal">$head</span>:tt)<span class="kw-2">*</span>) |
| ) => { |
| <span class="macro">compile_error!</span>( |
| <span class="string">"expected `=>` after `default` case, found `->`" |
| </span>) |
| }; |
| <span class="comment">// Print an error if there is a missing result in a recv case. |
| </span>(@list |
| (recv($(<span class="macro-nonterminal">$args</span>:tt)<span class="kw-2">*</span>) => $(<span class="macro-nonterminal">$tail</span>:tt)<span class="kw-2">*</span>) |
| ($(<span class="macro-nonterminal">$head</span>:tt)<span class="kw-2">*</span>) |
| ) => { |
| <span class="macro">compile_error!</span>( |
| <span class="string">"expected `->` after `recv` case, found `=>`" |
| </span>) |
| }; |
| <span class="comment">// Print an error if there is a missing result in a send case. |
| </span>(@list |
| (send($(<span class="macro-nonterminal">$args</span>:tt)<span class="kw-2">*</span>) => $(<span class="macro-nonterminal">$tail</span>:tt)<span class="kw-2">*</span>) |
| ($(<span class="macro-nonterminal">$head</span>:tt)<span class="kw-2">*</span>) |
| ) => { |
| <span class="macro">compile_error!</span>( |
| <span class="string">"expected `->` after `send` operation, found `=>`" |
| </span>) |
| }; |
| <span class="comment">// Make sure the arrow and the result are not repeated. |
| </span>(@list |
| (<span class="macro-nonterminal">$case</span>:ident <span class="macro-nonterminal">$args</span>:tt -> <span class="macro-nonterminal">$res</span>:tt -> $(<span class="macro-nonterminal">$tail</span>:tt)<span class="kw-2">*</span>) |
| ($(<span class="macro-nonterminal">$head</span>:tt)<span class="kw-2">*</span>) |
| ) => { |
| <span class="macro">compile_error!</span>(<span class="string">"expected `=>`, found `->`"</span>) |
| }; |
| <span class="comment">// Print an error if there is a semicolon after the block. |
| </span>(@list |
| (<span class="macro-nonterminal">$case</span>:ident <span class="macro-nonterminal">$args</span>:tt $(-> <span class="macro-nonterminal">$res</span>:pat)* => <span class="macro-nonterminal">$body</span>:block; $(<span class="macro-nonterminal">$tail</span>:tt)<span class="kw-2">*</span>) |
| ($(<span class="macro-nonterminal">$head</span>:tt)<span class="kw-2">*</span>) |
| ) => { |
| <span class="macro">compile_error!</span>( |
| <span class="string">"did you mean to put a comma instead of the semicolon after `}`?" |
| </span>) |
| }; |
| <span class="comment">// The first case is separated by a comma. |
| </span>(@list |
| (<span class="macro-nonterminal">$case</span>:ident ($(<span class="macro-nonterminal">$args</span>:tt)<span class="kw-2">*</span>) $(-> <span class="macro-nonterminal">$res</span>:pat)* => <span class="macro-nonterminal">$body</span>:expr, $(<span class="macro-nonterminal">$tail</span>:tt)<span class="kw-2">*</span>) |
| ($(<span class="macro-nonterminal">$head</span>:tt)<span class="kw-2">*</span>) |
| ) => { |
| <span class="macro-nonterminal">$</span><span class="macro">crate::crossbeam_channel_internal!</span>( |
| @<span class="macro-nonterminal">list |
| </span>($(<span class="macro-nonterminal">$tail</span>)<span class="kw-2">*</span>) |
| ($(<span class="macro-nonterminal">$head</span>)* <span class="macro-nonterminal">$case </span>($(<span class="macro-nonterminal">$args</span>)<span class="kw-2">*</span>) $(-> <span class="macro-nonterminal">$res</span>)* => { <span class="macro-nonterminal">$body </span>},) |
| ) |
| }; |
| <span class="comment">// Don't require a comma after the case if it has a proper block. |
| </span>(@list |
| (<span class="macro-nonterminal">$case</span>:ident ($(<span class="macro-nonterminal">$args</span>:tt)<span class="kw-2">*</span>) $(-> <span class="macro-nonterminal">$res</span>:pat)* => <span class="macro-nonterminal">$body</span>:block $(<span class="macro-nonterminal">$tail</span>:tt)<span class="kw-2">*</span>) |
| ($(<span class="macro-nonterminal">$head</span>:tt)<span class="kw-2">*</span>) |
| ) => { |
| <span class="macro-nonterminal">$</span><span class="macro">crate::crossbeam_channel_internal!</span>( |
| @<span class="macro-nonterminal">list |
| </span>($(<span class="macro-nonterminal">$tail</span>)<span class="kw-2">*</span>) |
| ($(<span class="macro-nonterminal">$head</span>)* <span class="macro-nonterminal">$case </span>($(<span class="macro-nonterminal">$args</span>)<span class="kw-2">*</span>) $(-> <span class="macro-nonterminal">$res</span>)* => { <span class="macro-nonterminal">$body </span>},) |
| ) |
| }; |
| <span class="comment">// Only one case remains. |
| </span>(@list |
| (<span class="macro-nonterminal">$case</span>:ident ($(<span class="macro-nonterminal">$args</span>:tt)<span class="kw-2">*</span>) $(-> <span class="macro-nonterminal">$res</span>:pat)* => <span class="macro-nonterminal">$body</span>:expr $(,)<span class="question-mark">?</span>) |
| ($(<span class="macro-nonterminal">$head</span>:tt)<span class="kw-2">*</span>) |
| ) => { |
| <span class="macro-nonterminal">$</span><span class="macro">crate::crossbeam_channel_internal!</span>( |
| @<span class="macro-nonterminal">list |
| </span>() |
| ($(<span class="macro-nonterminal">$head</span>)* <span class="macro-nonterminal">$case </span>($(<span class="macro-nonterminal">$args</span>)<span class="kw-2">*</span>) $(-> <span class="macro-nonterminal">$res</span>)* => { <span class="macro-nonterminal">$body </span>},) |
| ) |
| }; |
| <span class="comment">// Diagnose and print an error. |
| </span>(@list |
| ($(<span class="macro-nonterminal">$tail</span>:tt)<span class="kw-2">*</span>) |
| ($(<span class="macro-nonterminal">$head</span>:tt)<span class="kw-2">*</span>) |
| ) => { |
| <span class="macro-nonterminal">$</span><span class="macro">crate::crossbeam_channel_internal!</span>(@<span class="macro-nonterminal">list_error1 </span>$(<span class="macro-nonterminal">$tail</span>)<span class="kw-2">*</span>) |
| }; |
| <span class="comment">// Stage 1: check the case type. |
| </span>(@list_error1 recv $(<span class="macro-nonterminal">$tail</span>:tt)<span class="kw-2">*</span>) => { |
| <span class="macro-nonterminal">$</span><span class="macro">crate::crossbeam_channel_internal!</span>(@<span class="macro-nonterminal">list_error2 </span>recv $(<span class="macro-nonterminal">$tail</span>)<span class="kw-2">*</span>) |
| }; |
| (@list_error1 send $(<span class="macro-nonterminal">$tail</span>:tt)<span class="kw-2">*</span>) => { |
| <span class="macro-nonterminal">$</span><span class="macro">crate::crossbeam_channel_internal!</span>(@<span class="macro-nonterminal">list_error2 </span>send $(<span class="macro-nonterminal">$tail</span>)<span class="kw-2">*</span>) |
| }; |
| (@list_error1 default $(<span class="macro-nonterminal">$tail</span>:tt)<span class="kw-2">*</span>) => { |
| <span class="macro-nonterminal">$</span><span class="macro">crate::crossbeam_channel_internal!</span>(@<span class="macro-nonterminal">list_error2 </span>default $(<span class="macro-nonterminal">$tail</span>)<span class="kw-2">*</span>) |
| }; |
| (@list_error1 <span class="macro-nonterminal">$t</span>:tt $(<span class="macro-nonterminal">$tail</span>:tt)<span class="kw-2">*</span>) => { |
| <span class="macro">compile_error!</span>( |
| <span class="macro">concat!</span>( |
| <span class="string">"expected one of `recv`, `send`, or `default`, found `"</span>, |
| <span class="macro">stringify!</span>(<span class="macro-nonterminal">$t</span>), |
| <span class="string">"`"</span>, |
| ) |
| ) |
| }; |
| (@list_error1 $(<span class="macro-nonterminal">$tail</span>:tt)<span class="kw-2">*</span>) => { |
| <span class="macro-nonterminal">$</span><span class="macro">crate::crossbeam_channel_internal!</span>(@<span class="macro-nonterminal">list_error2 </span>$(<span class="macro-nonterminal">$tail</span>)<span class="kw-2">*</span>); |
| }; |
| <span class="comment">// Stage 2: check the argument list. |
| </span>(@list_error2 <span class="macro-nonterminal">$case</span>:ident) => { |
| <span class="macro">compile_error!</span>( |
| <span class="macro">concat!</span>( |
| <span class="string">"missing argument list after `"</span>, |
| <span class="macro">stringify!</span>(<span class="macro-nonterminal">$case</span>), |
| <span class="string">"`"</span>, |
| ) |
| ) |
| }; |
| (@list_error2 <span class="macro-nonterminal">$case</span>:ident => $(<span class="macro-nonterminal">$tail</span>:tt)<span class="kw-2">*</span>) => { |
| <span class="macro">compile_error!</span>( |
| <span class="macro">concat!</span>( |
| <span class="string">"missing argument list after `"</span>, |
| <span class="macro">stringify!</span>(<span class="macro-nonterminal">$case</span>), |
| <span class="string">"`"</span>, |
| ) |
| ) |
| }; |
| (@list_error2 $(<span class="macro-nonterminal">$tail</span>:tt)<span class="kw-2">*</span>) => { |
| <span class="macro-nonterminal">$</span><span class="macro">crate::crossbeam_channel_internal!</span>(@<span class="macro-nonterminal">list_error3 </span>$(<span class="macro-nonterminal">$tail</span>)<span class="kw-2">*</span>) |
| }; |
| <span class="comment">// Stage 3: check the `=>` and what comes after it. |
| </span>(@list_error3 <span class="macro-nonterminal">$case</span>:ident($(<span class="macro-nonterminal">$args</span>:tt)<span class="kw-2">*</span>) $(-> <span class="macro-nonterminal">$r</span>:pat)<span class="kw-2">*</span>) => { |
| <span class="macro">compile_error!</span>( |
| <span class="macro">concat!</span>( |
| <span class="string">"missing `=>` after `"</span>, |
| <span class="macro">stringify!</span>(<span class="macro-nonterminal">$case</span>), |
| <span class="string">"` case"</span>, |
| ) |
| ) |
| }; |
| (@list_error3 <span class="macro-nonterminal">$case</span>:ident($(<span class="macro-nonterminal">$args</span>:tt)<span class="kw-2">*</span>) $(-> <span class="macro-nonterminal">$r</span>:pat)* =>) => { |
| <span class="macro">compile_error!</span>( |
| <span class="string">"expected expression after `=>`" |
| </span>) |
| }; |
| (@list_error3 <span class="macro-nonterminal">$case</span>:ident($(<span class="macro-nonterminal">$args</span>:tt)<span class="kw-2">*</span>) $(-> <span class="macro-nonterminal">$r</span>:pat)* => <span class="macro-nonterminal">$body</span>:expr; $(<span class="macro-nonterminal">$tail</span>:tt)<span class="kw-2">*</span>) => { |
| <span class="macro">compile_error!</span>( |
| <span class="macro">concat!</span>( |
| <span class="string">"did you mean to put a comma instead of the semicolon after `"</span>, |
| <span class="macro">stringify!</span>(<span class="macro-nonterminal">$body</span>), |
| <span class="string">"`?"</span>, |
| ) |
| ) |
| }; |
| (@list_error3 <span class="macro-nonterminal">$case</span>:ident($(<span class="macro-nonterminal">$args</span>:tt)<span class="kw-2">*</span>) $(-> <span class="macro-nonterminal">$r</span>:pat)* => recv($(<span class="macro-nonterminal">$a</span>:tt)<span class="kw-2">*</span>) $(<span class="macro-nonterminal">$tail</span>:tt)<span class="kw-2">*</span>) => { |
| <span class="macro">compile_error!</span>( |
| <span class="string">"expected an expression after `=>`" |
| </span>) |
| }; |
| (@list_error3 <span class="macro-nonterminal">$case</span>:ident($(<span class="macro-nonterminal">$args</span>:tt)<span class="kw-2">*</span>) $(-> <span class="macro-nonterminal">$r</span>:pat)* => send($(<span class="macro-nonterminal">$a</span>:tt)<span class="kw-2">*</span>) $(<span class="macro-nonterminal">$tail</span>:tt)<span class="kw-2">*</span>) => { |
| <span class="macro">compile_error!</span>( |
| <span class="string">"expected an expression after `=>`" |
| </span>) |
| }; |
| (@list_error3 <span class="macro-nonterminal">$case</span>:ident($(<span class="macro-nonterminal">$args</span>:tt)<span class="kw-2">*</span>) $(-> <span class="macro-nonterminal">$r</span>:pat)* => default($(<span class="macro-nonterminal">$a</span>:tt)<span class="kw-2">*</span>) $(<span class="macro-nonterminal">$tail</span>:tt)<span class="kw-2">*</span>) => { |
| <span class="macro">compile_error!</span>( |
| <span class="string">"expected an expression after `=>`" |
| </span>) |
| }; |
| (@list_error3 <span class="macro-nonterminal">$case</span>:ident($(<span class="macro-nonterminal">$args</span>:tt)<span class="kw-2">*</span>) $(-> <span class="macro-nonterminal">$r</span>:pat)* => <span class="macro-nonterminal">$f</span>:ident($(<span class="macro-nonterminal">$a</span>:tt)<span class="kw-2">*</span>) $(<span class="macro-nonterminal">$tail</span>:tt)<span class="kw-2">*</span>) => { |
| <span class="macro">compile_error!</span>( |
| <span class="macro">concat!</span>( |
| <span class="string">"did you mean to put a comma after `"</span>, |
| <span class="macro">stringify!</span>(<span class="macro-nonterminal">$f</span>), |
| <span class="string">"("</span>, |
| <span class="macro">stringify!</span>($(<span class="macro-nonterminal">$a</span>)<span class="kw-2">*</span>), |
| <span class="string">")`?"</span>, |
| ) |
| ) |
| }; |
| (@list_error3 <span class="macro-nonterminal">$case</span>:ident($(<span class="macro-nonterminal">$args</span>:tt)<span class="kw-2">*</span>) $(-> <span class="macro-nonterminal">$r</span>:pat)* => <span class="macro-nonterminal">$f</span>:<span class="macro">ident!</span>($(<span class="macro-nonterminal">$a</span>:tt)<span class="kw-2">*</span>) $(<span class="macro-nonterminal">$tail</span>:tt)<span class="kw-2">*</span>) => { |
| <span class="macro">compile_error!</span>( |
| <span class="macro">concat!</span>( |
| <span class="string">"did you mean to put a comma after `"</span>, |
| <span class="macro">stringify!</span>(<span class="macro-nonterminal">$f</span>), |
| <span class="string">"!("</span>, |
| <span class="macro">stringify!</span>($(<span class="macro-nonterminal">$a</span>)<span class="kw-2">*</span>), |
| <span class="string">")`?"</span>, |
| ) |
| ) |
| }; |
| (@list_error3 <span class="macro-nonterminal">$case</span>:ident($(<span class="macro-nonterminal">$args</span>:tt)<span class="kw-2">*</span>) $(-> <span class="macro-nonterminal">$r</span>:pat)* => <span class="macro-nonterminal">$f</span>:<span class="macro">ident!</span>[$(<span class="macro-nonterminal">$a</span>:tt)<span class="kw-2">*</span>] $(<span class="macro-nonterminal">$tail</span>:tt)<span class="kw-2">*</span>) => { |
| <span class="macro">compile_error!</span>( |
| <span class="macro">concat!</span>( |
| <span class="string">"did you mean to put a comma after `"</span>, |
| <span class="macro">stringify!</span>(<span class="macro-nonterminal">$f</span>), |
| <span class="string">"!["</span>, |
| <span class="macro">stringify!</span>($(<span class="macro-nonterminal">$a</span>)<span class="kw-2">*</span>), |
| <span class="string">"]`?"</span>, |
| ) |
| ) |
| }; |
| (@list_error3 <span class="macro-nonterminal">$case</span>:ident($(<span class="macro-nonterminal">$args</span>:tt)<span class="kw-2">*</span>) $(-> <span class="macro-nonterminal">$r</span>:pat)* => <span class="macro-nonterminal">$f</span>:<span class="macro">ident!</span>{$(<span class="macro-nonterminal">$a</span>:tt)<span class="kw-2">*</span>} $(<span class="macro-nonterminal">$tail</span>:tt)<span class="kw-2">*</span>) => { |
| <span class="macro">compile_error!</span>( |
| <span class="macro">concat!</span>( |
| <span class="string">"did you mean to put a comma after `"</span>, |
| <span class="macro">stringify!</span>(<span class="macro-nonterminal">$f</span>), |
| <span class="string">"!{"</span>, |
| <span class="macro">stringify!</span>($(<span class="macro-nonterminal">$a</span>)<span class="kw-2">*</span>), |
| <span class="string">"}`?"</span>, |
| ) |
| ) |
| }; |
| (@list_error3 <span class="macro-nonterminal">$case</span>:ident($(<span class="macro-nonterminal">$args</span>:tt)<span class="kw-2">*</span>) $(-> <span class="macro-nonterminal">$r</span>:pat)* => <span class="macro-nonterminal">$body</span>:tt $(<span class="macro-nonterminal">$tail</span>:tt)<span class="kw-2">*</span>) => { |
| <span class="macro">compile_error!</span>( |
| <span class="macro">concat!</span>( |
| <span class="string">"did you mean to put a comma after `"</span>, |
| <span class="macro">stringify!</span>(<span class="macro-nonterminal">$body</span>), |
| <span class="string">"`?"</span>, |
| ) |
| ) |
| }; |
| (@list_error3 <span class="macro-nonterminal">$case</span>:ident($(<span class="macro-nonterminal">$args</span>:tt)<span class="kw-2">*</span>) -> => $(<span class="macro-nonterminal">$tail</span>:tt)<span class="kw-2">*</span>) => { |
| <span class="macro">compile_error!</span>(<span class="string">"missing pattern after `->`"</span>) |
| }; |
| (@list_error3 <span class="macro-nonterminal">$case</span>:ident($(<span class="macro-nonterminal">$args</span>:tt)<span class="kw-2">*</span>) <span class="macro-nonterminal">$t</span>:tt $(-> <span class="macro-nonterminal">$r</span>:pat)* => $(<span class="macro-nonterminal">$tail</span>:tt)<span class="kw-2">*</span>) => { |
| <span class="macro">compile_error!</span>( |
| <span class="macro">concat!</span>( |
| <span class="string">"expected `->`, found `"</span>, |
| <span class="macro">stringify!</span>(<span class="macro-nonterminal">$t</span>), |
| <span class="string">"`"</span>, |
| ) |
| ) |
| }; |
| (@list_error3 <span class="macro-nonterminal">$case</span>:ident($(<span class="macro-nonterminal">$args</span>:tt)<span class="kw-2">*</span>) -> <span class="macro-nonterminal">$t</span>:tt $(<span class="macro-nonterminal">$tail</span>:tt)<span class="kw-2">*</span>) => { |
| <span class="macro">compile_error!</span>( |
| <span class="macro">concat!</span>( |
| <span class="string">"expected a pattern, found `"</span>, |
| <span class="macro">stringify!</span>(<span class="macro-nonterminal">$t</span>), |
| <span class="string">"`"</span>, |
| ) |
| ) |
| }; |
| (@list_error3 recv($(<span class="macro-nonterminal">$args</span>:tt)<span class="kw-2">*</span>) <span class="macro-nonterminal">$t</span>:tt $(<span class="macro-nonterminal">$tail</span>:tt)<span class="kw-2">*</span>) => { |
| <span class="macro">compile_error!</span>( |
| <span class="macro">concat!</span>( |
| <span class="string">"expected `->`, found `"</span>, |
| <span class="macro">stringify!</span>(<span class="macro-nonterminal">$t</span>), |
| <span class="string">"`"</span>, |
| ) |
| ) |
| }; |
| (@list_error3 send($(<span class="macro-nonterminal">$args</span>:tt)<span class="kw-2">*</span>) <span class="macro-nonterminal">$t</span>:tt $(<span class="macro-nonterminal">$tail</span>:tt)<span class="kw-2">*</span>) => { |
| <span class="macro">compile_error!</span>( |
| <span class="macro">concat!</span>( |
| <span class="string">"expected `->`, found `"</span>, |
| <span class="macro">stringify!</span>(<span class="macro-nonterminal">$t</span>), |
| <span class="string">"`"</span>, |
| ) |
| ) |
| }; |
| (@list_error3 recv <span class="macro-nonterminal">$args</span>:tt $(<span class="macro-nonterminal">$tail</span>:tt)<span class="kw-2">*</span>) => { |
| <span class="macro">compile_error!</span>( |
| <span class="macro">concat!</span>( |
| <span class="string">"expected an argument list after `recv`, found `"</span>, |
| <span class="macro">stringify!</span>(<span class="macro-nonterminal">$args</span>), |
| <span class="string">"`"</span>, |
| ) |
| ) |
| }; |
| (@list_error3 send <span class="macro-nonterminal">$args</span>:tt $(<span class="macro-nonterminal">$tail</span>:tt)<span class="kw-2">*</span>) => { |
| <span class="macro">compile_error!</span>( |
| <span class="macro">concat!</span>( |
| <span class="string">"expected an argument list after `send`, found `"</span>, |
| <span class="macro">stringify!</span>(<span class="macro-nonterminal">$args</span>), |
| <span class="string">"`"</span>, |
| ) |
| ) |
| }; |
| (@list_error3 default <span class="macro-nonterminal">$args</span>:tt $(<span class="macro-nonterminal">$tail</span>:tt)<span class="kw-2">*</span>) => { |
| <span class="macro">compile_error!</span>( |
| <span class="macro">concat!</span>( |
| <span class="string">"expected an argument list or `=>` after `default`, found `"</span>, |
| <span class="macro">stringify!</span>(<span class="macro-nonterminal">$args</span>), |
| <span class="string">"`"</span>, |
| ) |
| ) |
| }; |
| (@list_error3 $(<span class="macro-nonterminal">$tail</span>:tt)<span class="kw-2">*</span>) => { |
| <span class="macro-nonterminal">$</span><span class="macro">crate::crossbeam_channel_internal!</span>(@<span class="macro-nonterminal">list_error4 </span>$(<span class="macro-nonterminal">$tail</span>)<span class="kw-2">*</span>) |
| }; |
| <span class="comment">// Stage 4: fail with a generic error message. |
| </span>(@list_error4 $(<span class="macro-nonterminal">$tail</span>:tt)<span class="kw-2">*</span>) => { |
| <span class="macro">compile_error!</span>(<span class="string">"invalid syntax"</span>) |
| }; |
| |
| <span class="comment">// Success! All cases were parsed. |
| </span>(@case |
| () |
| <span class="macro-nonterminal">$cases</span>:tt |
| <span class="macro-nonterminal">$default</span>:tt |
| ) => { |
| <span class="macro-nonterminal">$</span><span class="macro">crate::crossbeam_channel_internal!</span>( |
| @<span class="macro-nonterminal">init |
| $cases |
| $default |
| </span>) |
| }; |
| |
| <span class="comment">// Check the format of a recv case. |
| </span>(@case |
| (recv(<span class="macro-nonterminal">$r</span>:expr $(,)<span class="question-mark">?</span>) -> <span class="macro-nonterminal">$res</span>:pat => <span class="macro-nonterminal">$body</span>:tt, $(<span class="macro-nonterminal">$tail</span>:tt)<span class="kw-2">*</span>) |
| ($(<span class="macro-nonterminal">$cases</span>:tt)<span class="kw-2">*</span>) |
| <span class="macro-nonterminal">$default</span>:tt |
| ) => { |
| <span class="macro-nonterminal">$</span><span class="macro">crate::crossbeam_channel_internal!</span>( |
| @<span class="macro-nonterminal">case |
| </span>($(<span class="macro-nonterminal">$tail</span>)<span class="kw-2">*</span>) |
| ($(<span class="macro-nonterminal">$cases</span>)* recv(<span class="macro-nonterminal">$r</span>) -> <span class="macro-nonterminal">$res </span>=> <span class="macro-nonterminal">$body</span>,) |
| <span class="macro-nonterminal">$default |
| </span>) |
| }; |
| <span class="comment">// Print an error if the argument list is invalid. |
| </span>(@case |
| (recv($(<span class="macro-nonterminal">$args</span>:tt)<span class="kw-2">*</span>) -> <span class="macro-nonterminal">$res</span>:pat => <span class="macro-nonterminal">$body</span>:tt, $(<span class="macro-nonterminal">$tail</span>:tt)<span class="kw-2">*</span>) |
| ($(<span class="macro-nonterminal">$cases</span>:tt)<span class="kw-2">*</span>) |
| <span class="macro-nonterminal">$default</span>:tt |
| ) => { |
| <span class="macro">compile_error!</span>( |
| <span class="macro">concat!</span>( |
| <span class="string">"invalid argument list in `recv("</span>, |
| <span class="macro">stringify!</span>($(<span class="macro-nonterminal">$args</span>)<span class="kw-2">*</span>), |
| <span class="string">")`"</span>, |
| ) |
| ) |
| }; |
| <span class="comment">// Print an error if there is no argument list. |
| </span>(@case |
| (recv <span class="macro-nonterminal">$t</span>:tt $(<span class="macro-nonterminal">$tail</span>:tt)<span class="kw-2">*</span>) |
| ($(<span class="macro-nonterminal">$cases</span>:tt)<span class="kw-2">*</span>) |
| <span class="macro-nonterminal">$default</span>:tt |
| ) => { |
| <span class="macro">compile_error!</span>( |
| <span class="macro">concat!</span>( |
| <span class="string">"expected an argument list after `recv`, found `"</span>, |
| <span class="macro">stringify!</span>(<span class="macro-nonterminal">$t</span>), |
| <span class="string">"`"</span>, |
| ) |
| ) |
| }; |
| |
| <span class="comment">// Check the format of a send case. |
| </span>(@case |
| (send(<span class="macro-nonterminal">$s</span>:expr, <span class="macro-nonterminal">$m</span>:expr $(,)<span class="question-mark">?</span>) -> <span class="macro-nonterminal">$res</span>:pat => <span class="macro-nonterminal">$body</span>:tt, $(<span class="macro-nonterminal">$tail</span>:tt)<span class="kw-2">*</span>) |
| ($(<span class="macro-nonterminal">$cases</span>:tt)<span class="kw-2">*</span>) |
| <span class="macro-nonterminal">$default</span>:tt |
| ) => { |
| <span class="macro-nonterminal">$</span><span class="macro">crate::crossbeam_channel_internal!</span>( |
| @<span class="macro-nonterminal">case |
| </span>($(<span class="macro-nonterminal">$tail</span>)<span class="kw-2">*</span>) |
| ($(<span class="macro-nonterminal">$cases</span>)* send(<span class="macro-nonterminal">$s</span>, <span class="macro-nonterminal">$m</span>) -> <span class="macro-nonterminal">$res </span>=> <span class="macro-nonterminal">$body</span>,) |
| <span class="macro-nonterminal">$default |
| </span>) |
| }; |
| <span class="comment">// Print an error if the argument list is invalid. |
| </span>(@case |
| (send($(<span class="macro-nonterminal">$args</span>:tt)<span class="kw-2">*</span>) -> <span class="macro-nonterminal">$res</span>:pat => <span class="macro-nonterminal">$body</span>:tt, $(<span class="macro-nonterminal">$tail</span>:tt)<span class="kw-2">*</span>) |
| ($(<span class="macro-nonterminal">$cases</span>:tt)<span class="kw-2">*</span>) |
| <span class="macro-nonterminal">$default</span>:tt |
| ) => { |
| <span class="macro">compile_error!</span>( |
| <span class="macro">concat!</span>( |
| <span class="string">"invalid argument list in `send("</span>, |
| <span class="macro">stringify!</span>($(<span class="macro-nonterminal">$args</span>)<span class="kw-2">*</span>), |
| <span class="string">")`"</span>, |
| ) |
| ) |
| }; |
| <span class="comment">// Print an error if there is no argument list. |
| </span>(@case |
| (send <span class="macro-nonterminal">$t</span>:tt $(<span class="macro-nonterminal">$tail</span>:tt)<span class="kw-2">*</span>) |
| ($(<span class="macro-nonterminal">$cases</span>:tt)<span class="kw-2">*</span>) |
| <span class="macro-nonterminal">$default</span>:tt |
| ) => { |
| <span class="macro">compile_error!</span>( |
| <span class="macro">concat!</span>( |
| <span class="string">"expected an argument list after `send`, found `"</span>, |
| <span class="macro">stringify!</span>(<span class="macro-nonterminal">$t</span>), |
| <span class="string">"`"</span>, |
| ) |
| ) |
| }; |
| |
| <span class="comment">// Check the format of a default case. |
| </span>(@case |
| (default() => <span class="macro-nonterminal">$body</span>:tt, $(<span class="macro-nonterminal">$tail</span>:tt)<span class="kw-2">*</span>) |
| <span class="macro-nonterminal">$cases</span>:tt |
| () |
| ) => { |
| <span class="macro-nonterminal">$</span><span class="macro">crate::crossbeam_channel_internal!</span>( |
| @<span class="macro-nonterminal">case |
| </span>($(<span class="macro-nonterminal">$tail</span>)<span class="kw-2">*</span>) |
| <span class="macro-nonterminal">$cases |
| </span>(default() => <span class="macro-nonterminal">$body</span>,) |
| ) |
| }; |
| <span class="comment">// Check the format of a default case with timeout. |
| </span>(@case |
| (default(<span class="macro-nonterminal">$timeout</span>:expr $(,)<span class="question-mark">?</span>) => <span class="macro-nonterminal">$body</span>:tt, $(<span class="macro-nonterminal">$tail</span>:tt)<span class="kw-2">*</span>) |
| <span class="macro-nonterminal">$cases</span>:tt |
| () |
| ) => { |
| <span class="macro-nonterminal">$</span><span class="macro">crate::crossbeam_channel_internal!</span>( |
| @<span class="macro-nonterminal">case |
| </span>($(<span class="macro-nonterminal">$tail</span>)<span class="kw-2">*</span>) |
| <span class="macro-nonterminal">$cases |
| </span>(default(<span class="macro-nonterminal">$timeout</span>) => <span class="macro-nonterminal">$body</span>,) |
| ) |
| }; |
| <span class="comment">// Check for duplicate default cases... |
| </span>(@case |
| (default $(<span class="macro-nonterminal">$tail</span>:tt)<span class="kw-2">*</span>) |
| <span class="macro-nonterminal">$cases</span>:tt |
| ($(<span class="macro-nonterminal">$def</span>:tt)+) |
| ) => { |
| <span class="macro">compile_error!</span>( |
| <span class="string">"there can be only one `default` case in a `select!` block" |
| </span>) |
| }; |
| <span class="comment">// Print an error if the argument list is invalid. |
| </span>(@case |
| (default($(<span class="macro-nonterminal">$args</span>:tt)<span class="kw-2">*</span>) => <span class="macro-nonterminal">$body</span>:tt, $(<span class="macro-nonterminal">$tail</span>:tt)<span class="kw-2">*</span>) |
| <span class="macro-nonterminal">$cases</span>:tt |
| <span class="macro-nonterminal">$default</span>:tt |
| ) => { |
| <span class="macro">compile_error!</span>( |
| <span class="macro">concat!</span>( |
| <span class="string">"invalid argument list in `default("</span>, |
| <span class="macro">stringify!</span>($(<span class="macro-nonterminal">$args</span>)<span class="kw-2">*</span>), |
| <span class="string">")`"</span>, |
| ) |
| ) |
| }; |
| <span class="comment">// Print an error if there is an unexpected token after `default`. |
| </span>(@case |
| (default <span class="macro-nonterminal">$t</span>:tt $(<span class="macro-nonterminal">$tail</span>:tt)<span class="kw-2">*</span>) |
| <span class="macro-nonterminal">$cases</span>:tt |
| <span class="macro-nonterminal">$default</span>:tt |
| ) => { |
| <span class="macro">compile_error!</span>( |
| <span class="macro">concat!</span>( |
| <span class="string">"expected an argument list or `=>` after `default`, found `"</span>, |
| <span class="macro">stringify!</span>(<span class="macro-nonterminal">$t</span>), |
| <span class="string">"`"</span>, |
| ) |
| ) |
| }; |
| |
| <span class="comment">// The case was not consumed, therefore it must be invalid. |
| </span>(@case |
| (<span class="macro-nonterminal">$case</span>:ident $(<span class="macro-nonterminal">$tail</span>:tt)<span class="kw-2">*</span>) |
| <span class="macro-nonterminal">$cases</span>:tt |
| <span class="macro-nonterminal">$default</span>:tt |
| ) => { |
| <span class="macro">compile_error!</span>( |
| <span class="macro">concat!</span>( |
| <span class="string">"expected one of `recv`, `send`, or `default`, found `"</span>, |
| <span class="macro">stringify!</span>(<span class="macro-nonterminal">$case</span>), |
| <span class="string">"`"</span>, |
| ) |
| ) |
| }; |
| |
| <span class="comment">// Optimize `select!` into `try_recv()`. |
| </span>(@init |
| (recv(<span class="macro-nonterminal">$r</span>:expr) -> <span class="macro-nonterminal">$res</span>:pat => <span class="macro-nonterminal">$recv_body</span>:tt,) |
| (default() => <span class="macro-nonterminal">$default_body</span>:tt,) |
| ) => {{ |
| <span class="kw">match </span><span class="macro-nonterminal">$r </span>{ |
| <span class="kw-2">ref </span>_r => { |
| <span class="kw">let </span>_r: <span class="kw-2">&</span><span class="macro-nonterminal">$crate::Receiver</span><<span class="kw">_</span>> = _r; |
| <span class="kw">match </span>_r.try_recv() { |
| ::std::result::Result::Err(<span class="macro-nonterminal">$crate::TryRecvError::Empty</span>) => { |
| <span class="macro-nonterminal">$default_body |
| </span>} |
| _res => { |
| <span class="kw">let </span>_res = _res.map_err(|<span class="kw">_</span>| <span class="macro-nonterminal">$crate::RecvError</span>); |
| <span class="kw">let </span><span class="macro-nonterminal">$res </span>= _res; |
| <span class="macro-nonterminal">$recv_body |
| </span>} |
| } |
| } |
| } |
| }}; |
| <span class="comment">// Optimize `select!` into `recv()`. |
| </span>(@init |
| (recv(<span class="macro-nonterminal">$r</span>:expr) -> <span class="macro-nonterminal">$res</span>:pat => <span class="macro-nonterminal">$body</span>:tt,) |
| () |
| ) => {{ |
| <span class="kw">match </span><span class="macro-nonterminal">$r </span>{ |
| <span class="kw-2">ref </span>_r => { |
| <span class="kw">let </span>_r: <span class="kw-2">&</span><span class="macro-nonterminal">$crate::Receiver</span><<span class="kw">_</span>> = _r; |
| <span class="kw">let </span>_res = _r.recv(); |
| <span class="kw">let </span><span class="macro-nonterminal">$res </span>= _res; |
| <span class="macro-nonterminal">$body |
| </span>} |
| } |
| }}; |
| <span class="comment">// Optimize `select!` into `recv_timeout()`. |
| </span>(@init |
| (recv(<span class="macro-nonterminal">$r</span>:expr) -> <span class="macro-nonterminal">$res</span>:pat => <span class="macro-nonterminal">$recv_body</span>:tt,) |
| (default(<span class="macro-nonterminal">$timeout</span>:expr) => <span class="macro-nonterminal">$default_body</span>:tt,) |
| ) => {{ |
| <span class="kw">match </span><span class="macro-nonterminal">$r </span>{ |
| <span class="kw-2">ref </span>_r => { |
| <span class="kw">let </span>_r: <span class="kw-2">&</span><span class="macro-nonterminal">$crate::Receiver</span><<span class="kw">_</span>> = _r; |
| <span class="kw">match </span>_r.recv_timeout(<span class="macro-nonterminal">$timeout</span>) { |
| ::std::result::Result::Err(<span class="macro-nonterminal">$crate::RecvTimeoutError::Timeout</span>) => { |
| <span class="macro-nonterminal">$default_body |
| </span>} |
| _res => { |
| <span class="kw">let </span>_res = _res.map_err(|<span class="kw">_</span>| <span class="macro-nonterminal">$crate::RecvError</span>); |
| <span class="kw">let </span><span class="macro-nonterminal">$res </span>= _res; |
| <span class="macro-nonterminal">$recv_body |
| </span>} |
| } |
| } |
| } |
| }}; |
| |
| <span class="comment">// // Optimize the non-blocking case with two receive operations. |
| // (@init |
| // (recv($r1:expr) -> $res1:pat => $recv_body1:tt,) |
| // (recv($r2:expr) -> $res2:pat => $recv_body2:tt,) |
| // (default() => $default_body:tt,) |
| // ) => {{ |
| // match $r1 { |
| // ref _r1 => { |
| // let _r1: &$crate::Receiver<_> = _r1; |
| // |
| // match $r2 { |
| // ref _r2 => { |
| // let _r2: &$crate::Receiver<_> = _r2; |
| // |
| // // TODO(stjepang): Implement this optimization. |
| // } |
| // } |
| // } |
| // } |
| // }}; |
| // // Optimize the blocking case with two receive operations. |
| // (@init |
| // (recv($r1:expr) -> $res1:pat => $body1:tt,) |
| // (recv($r2:expr) -> $res2:pat => $body2:tt,) |
| // () |
| // ) => {{ |
| // match $r1 { |
| // ref _r1 => { |
| // let _r1: &$crate::Receiver<_> = _r1; |
| // |
| // match $r2 { |
| // ref _r2 => { |
| // let _r2: &$crate::Receiver<_> = _r2; |
| // |
| // // TODO(stjepang): Implement this optimization. |
| // } |
| // } |
| // } |
| // } |
| // }}; |
| // // Optimize the case with two receive operations and a timeout. |
| // (@init |
| // (recv($r1:expr) -> $res1:pat => $recv_body1:tt,) |
| // (recv($r2:expr) -> $res2:pat => $recv_body2:tt,) |
| // (default($timeout:expr) => $default_body:tt,) |
| // ) => {{ |
| // match $r1 { |
| // ref _r1 => { |
| // let _r1: &$crate::Receiver<_> = _r1; |
| // |
| // match $r2 { |
| // ref _r2 => { |
| // let _r2: &$crate::Receiver<_> = _r2; |
| // |
| // // TODO(stjepang): Implement this optimization. |
| // } |
| // } |
| // } |
| // } |
| // }}; |
| |
| // // Optimize `select!` into `try_send()`. |
| // (@init |
| // (send($s:expr, $m:expr) -> $res:pat => $send_body:tt,) |
| // (default() => $default_body:tt,) |
| // ) => {{ |
| // match $s { |
| // ref _s => { |
| // let _s: &$crate::Sender<_> = _s; |
| // // TODO(stjepang): Implement this optimization. |
| // } |
| // } |
| // }}; |
| // // Optimize `select!` into `send()`. |
| // (@init |
| // (send($s:expr, $m:expr) -> $res:pat => $body:tt,) |
| // () |
| // ) => {{ |
| // match $s { |
| // ref _s => { |
| // let _s: &$crate::Sender<_> = _s; |
| // // TODO(stjepang): Implement this optimization. |
| // } |
| // } |
| // }}; |
| // // Optimize `select!` into `send_timeout()`. |
| // (@init |
| // (send($s:expr, $m:expr) -> $res:pat => $body:tt,) |
| // (default($timeout:expr) => $body:tt,) |
| // ) => {{ |
| // match $s { |
| // ref _s => { |
| // let _s: &$crate::Sender<_> = _s; |
| // // TODO(stjepang): Implement this optimization. |
| // } |
| // } |
| // }}; |
| |
| // Create the list of handles and add operations to it. |
| </span>(@init |
| ($(<span class="macro-nonterminal">$cases</span>:tt)<span class="kw-2">*</span>) |
| <span class="macro-nonterminal">$default</span>:tt |
| ) => {{ |
| <span class="kw">const </span>_LEN: usize = <span class="macro-nonterminal">$</span><span class="macro">crate::crossbeam_channel_internal!</span>(@<span class="macro-nonterminal">count </span>($(<span class="macro-nonterminal">$cases</span>)<span class="kw-2">*</span>)); |
| <span class="kw">let </span>_handle: <span class="kw-2">&</span><span class="macro-nonterminal">$crate::internal::SelectHandle </span>= <span class="kw-2">&</span><span class="macro-nonterminal">$crate::never</span>::<()>(); |
| |
| <span class="attribute">#[allow(unused_mut)] |
| </span><span class="kw">let </span><span class="kw-2">mut </span>_sel = [(_handle, <span class="number">0</span>, ::std::ptr::null()); _LEN]; |
| |
| <span class="macro-nonterminal">$</span><span class="macro">crate::crossbeam_channel_internal!</span>( |
| @<span class="macro-nonterminal">add |
| </span>_sel |
| ($(<span class="macro-nonterminal">$cases</span>)<span class="kw-2">*</span>) |
| <span class="macro-nonterminal">$default |
| </span>( |
| (<span class="number">0usize </span>_oper0) |
| (<span class="number">1usize </span>_oper1) |
| (<span class="number">2usize </span>_oper2) |
| (<span class="number">3usize </span>_oper3) |
| (<span class="number">4usize </span>_oper4) |
| (<span class="number">5usize </span>_oper5) |
| (<span class="number">6usize </span>_oper6) |
| (<span class="number">7usize </span>_oper7) |
| (<span class="number">8usize </span>_oper8) |
| (<span class="number">9usize </span>_oper9) |
| (<span class="number">10usize </span>_oper10) |
| (<span class="number">11usize </span>_oper11) |
| (<span class="number">12usize </span>_oper12) |
| (<span class="number">13usize </span>_oper13) |
| (<span class="number">14usize </span>_oper14) |
| (<span class="number">15usize </span>_oper15) |
| (<span class="number">16usize </span>_oper16) |
| (<span class="number">17usize </span>_oper17) |
| (<span class="number">18usize </span>_oper18) |
| (<span class="number">19usize </span>_oper19) |
| (<span class="number">20usize </span>_oper20) |
| (<span class="number">21usize </span>_oper21) |
| (<span class="number">22usize </span>_oper22) |
| (<span class="number">23usize </span>_oper23) |
| (<span class="number">24usize </span>_oper24) |
| (<span class="number">25usize </span>_oper25) |
| (<span class="number">26usize </span>_oper26) |
| (<span class="number">27usize </span>_oper27) |
| (<span class="number">28usize </span>_oper28) |
| (<span class="number">29usize </span>_oper29) |
| (<span class="number">30usize </span>_oper30) |
| (<span class="number">31usize </span>_oper31) |
| ) |
| () |
| ) |
| }}; |
| |
| <span class="comment">// Count the listed cases. |
| </span>(@count ()) => { |
| <span class="number">0 |
| </span>}; |
| (@count (<span class="macro-nonterminal">$oper</span>:ident <span class="macro-nonterminal">$args</span>:tt -> <span class="macro-nonterminal">$res</span>:pat => <span class="macro-nonterminal">$body</span>:tt, $(<span class="macro-nonterminal">$cases</span>:tt)<span class="kw-2">*</span>)) => { |
| <span class="number">1 </span>+ <span class="macro-nonterminal">$</span><span class="macro">crate::crossbeam_channel_internal!</span>(@<span class="macro-nonterminal">count </span>($(<span class="macro-nonterminal">$cases</span>)<span class="kw-2">*</span>)) |
| }; |
| |
| <span class="comment">// Run blocking selection. |
| </span>(@add |
| <span class="macro-nonterminal">$sel</span>:ident |
| () |
| () |
| <span class="macro-nonterminal">$labels</span>:tt |
| <span class="macro-nonterminal">$cases</span>:tt |
| ) => {{ |
| <span class="kw">let </span>_oper: <span class="macro-nonterminal">$crate::SelectedOperation</span><<span class="lifetime">'_</span>> = { |
| <span class="kw">let </span>_oper = <span class="macro-nonterminal">$crate::internal::select</span>(<span class="kw-2">&mut </span><span class="macro-nonterminal">$sel</span>); |
| |
| <span class="comment">// Erase the lifetime so that `sel` can be dropped early even without NLL. |
| </span><span class="kw">unsafe </span>{ ::std::mem::transmute(_oper) } |
| }; |
| |
| <span class="macro-nonterminal">$</span><span class="macro">crate::crossbeam_channel_internal! </span>{ |
| @<span class="macro-nonterminal">complete |
| $sel |
| </span>_oper |
| <span class="macro-nonterminal">$cases |
| </span>} |
| }}; |
| <span class="comment">// Run non-blocking selection. |
| </span>(@add |
| <span class="macro-nonterminal">$sel</span>:ident |
| () |
| (default() => <span class="macro-nonterminal">$body</span>:tt,) |
| <span class="macro-nonterminal">$labels</span>:tt |
| <span class="macro-nonterminal">$cases</span>:tt |
| ) => {{ |
| <span class="kw">let </span>_oper: ::std::option::Option<<span class="macro-nonterminal">$crate::SelectedOperation</span><<span class="lifetime">'_</span>>> = { |
| <span class="kw">let </span>_oper = <span class="macro-nonterminal">$crate::internal::try_select</span>(<span class="kw-2">&mut </span><span class="macro-nonterminal">$sel</span>); |
| |
| <span class="comment">// Erase the lifetime so that `sel` can be dropped early even without NLL. |
| </span><span class="kw">unsafe </span>{ ::std::mem::transmute(_oper) } |
| }; |
| |
| <span class="kw">match </span>_oper { |
| <span class="prelude-val">None </span>=> { |
| { <span class="macro-nonterminal">$sel </span>}; |
| <span class="macro-nonterminal">$body |
| </span>} |
| <span class="prelude-val">Some</span>(_oper) => { |
| <span class="macro-nonterminal">$</span><span class="macro">crate::crossbeam_channel_internal! </span>{ |
| @<span class="macro-nonterminal">complete |
| $sel |
| </span>_oper |
| <span class="macro-nonterminal">$cases |
| </span>} |
| } |
| } |
| }}; |
| <span class="comment">// Run selection with a timeout. |
| </span>(@add |
| <span class="macro-nonterminal">$sel</span>:ident |
| () |
| (default(<span class="macro-nonterminal">$timeout</span>:expr) => <span class="macro-nonterminal">$body</span>:tt,) |
| <span class="macro-nonterminal">$labels</span>:tt |
| <span class="macro-nonterminal">$cases</span>:tt |
| ) => {{ |
| <span class="kw">let </span>_oper: ::std::option::Option<<span class="macro-nonterminal">$crate::SelectedOperation</span><<span class="lifetime">'_</span>>> = { |
| <span class="kw">let </span>_oper = <span class="macro-nonterminal">$crate::internal::select_timeout</span>(<span class="kw-2">&mut </span><span class="macro-nonterminal">$sel</span>, <span class="macro-nonterminal">$timeout</span>); |
| |
| <span class="comment">// Erase the lifetime so that `sel` can be dropped early even without NLL. |
| </span><span class="kw">unsafe </span>{ ::std::mem::transmute(_oper) } |
| }; |
| |
| <span class="kw">match </span>_oper { |
| ::std::option::Option::None => { |
| { <span class="macro-nonterminal">$sel </span>}; |
| <span class="macro-nonterminal">$body |
| </span>} |
| ::std::option::Option::Some(_oper) => { |
| <span class="macro-nonterminal">$</span><span class="macro">crate::crossbeam_channel_internal! </span>{ |
| @<span class="macro-nonterminal">complete |
| $sel |
| </span>_oper |
| <span class="macro-nonterminal">$cases |
| </span>} |
| } |
| } |
| }}; |
| <span class="comment">// Have we used up all labels? |
| </span>(@add |
| <span class="macro-nonterminal">$sel</span>:ident |
| <span class="macro-nonterminal">$input</span>:tt |
| <span class="macro-nonterminal">$default</span>:tt |
| () |
| <span class="macro-nonterminal">$cases</span>:tt |
| ) => { |
| <span class="macro">compile_error!</span>(<span class="string">"too many operations in a `select!` block"</span>) |
| }; |
| <span class="comment">// Add a receive operation to `sel`. |
| </span>(@add |
| <span class="macro-nonterminal">$sel</span>:ident |
| (recv(<span class="macro-nonterminal">$r</span>:expr) -> <span class="macro-nonterminal">$res</span>:pat => <span class="macro-nonterminal">$body</span>:tt, $(<span class="macro-nonterminal">$tail</span>:tt)<span class="kw-2">*</span>) |
| <span class="macro-nonterminal">$default</span>:tt |
| ((<span class="macro-nonterminal">$i</span>:tt <span class="macro-nonterminal">$var</span>:ident) $(<span class="macro-nonterminal">$labels</span>:tt)<span class="kw-2">*</span>) |
| ($(<span class="macro-nonterminal">$cases</span>:tt)<span class="kw-2">*</span>) |
| ) => {{ |
| <span class="kw">match </span><span class="macro-nonterminal">$r </span>{ |
| <span class="kw-2">ref </span>_r => { |
| <span class="kw">let </span><span class="macro-nonterminal">$var</span>: <span class="kw-2">&</span><span class="macro-nonterminal">$crate::Receiver</span><<span class="kw">_</span>> = <span class="kw">unsafe </span>{ |
| <span class="kw">let </span>_r: <span class="kw-2">&</span><span class="macro-nonterminal">$crate::Receiver</span><<span class="kw">_</span>> = _r; |
| |
| <span class="comment">// Erase the lifetime so that `sel` can be dropped early even without NLL. |
| </span><span class="kw">unsafe fn </span>unbind<<span class="lifetime">'a</span>, T>(x: <span class="kw-2">&</span>T) -> <span class="kw-2">&</span><span class="lifetime">'a </span>T { |
| ::std::mem::transmute(x) |
| } |
| unbind(_r) |
| }; |
| <span class="macro-nonterminal">$sel</span>[<span class="macro-nonterminal">$i</span>] = (<span class="macro-nonterminal">$var</span>, <span class="macro-nonterminal">$i</span>, <span class="macro-nonterminal">$var </span><span class="kw">as </span><span class="kw-2">*const </span><span class="macro-nonterminal">$crate::Receiver</span><<span class="kw">_</span>> <span class="kw">as </span><span class="kw-2">*const </span>u8); |
| |
| <span class="macro-nonterminal">$</span><span class="macro">crate::crossbeam_channel_internal!</span>( |
| @<span class="macro-nonterminal">add |
| $sel |
| </span>($(<span class="macro-nonterminal">$tail</span>)<span class="kw-2">*</span>) |
| <span class="macro-nonterminal">$default |
| </span>($(<span class="macro-nonterminal">$labels</span>)<span class="kw-2">*</span>) |
| ($(<span class="macro-nonterminal">$cases</span>)* [<span class="macro-nonterminal">$i</span>] recv(<span class="macro-nonterminal">$var</span>) -> <span class="macro-nonterminal">$res </span>=> <span class="macro-nonterminal">$body</span>,) |
| ) |
| } |
| } |
| }}; |
| <span class="comment">// Add a send operation to `sel`. |
| </span>(@add |
| <span class="macro-nonterminal">$sel</span>:ident |
| (send(<span class="macro-nonterminal">$s</span>:expr, <span class="macro-nonterminal">$m</span>:expr) -> <span class="macro-nonterminal">$res</span>:pat => <span class="macro-nonterminal">$body</span>:tt, $(<span class="macro-nonterminal">$tail</span>:tt)<span class="kw-2">*</span>) |
| <span class="macro-nonterminal">$default</span>:tt |
| ((<span class="macro-nonterminal">$i</span>:tt <span class="macro-nonterminal">$var</span>:ident) $(<span class="macro-nonterminal">$labels</span>:tt)<span class="kw-2">*</span>) |
| ($(<span class="macro-nonterminal">$cases</span>:tt)<span class="kw-2">*</span>) |
| ) => {{ |
| <span class="kw">match </span><span class="macro-nonterminal">$s </span>{ |
| <span class="kw-2">ref </span>_s => { |
| <span class="kw">let </span><span class="macro-nonterminal">$var</span>: <span class="kw-2">&</span><span class="macro-nonterminal">$crate::Sender</span><<span class="kw">_</span>> = <span class="kw">unsafe </span>{ |
| <span class="kw">let </span>_s: <span class="kw-2">&</span><span class="macro-nonterminal">$crate::Sender</span><<span class="kw">_</span>> = _s; |
| |
| <span class="comment">// Erase the lifetime so that `sel` can be dropped early even without NLL. |
| </span><span class="kw">unsafe fn </span>unbind<<span class="lifetime">'a</span>, T>(x: <span class="kw-2">&</span>T) -> <span class="kw-2">&</span><span class="lifetime">'a </span>T { |
| ::std::mem::transmute(x) |
| } |
| unbind(_s) |
| }; |
| <span class="macro-nonterminal">$sel</span>[<span class="macro-nonterminal">$i</span>] = (<span class="macro-nonterminal">$var</span>, <span class="macro-nonterminal">$i</span>, <span class="macro-nonterminal">$var </span><span class="kw">as </span><span class="kw-2">*const </span><span class="macro-nonterminal">$crate::Sender</span><<span class="kw">_</span>> <span class="kw">as </span><span class="kw-2">*const </span>u8); |
| |
| <span class="macro-nonterminal">$</span><span class="macro">crate::crossbeam_channel_internal!</span>( |
| @<span class="macro-nonterminal">add |
| $sel |
| </span>($(<span class="macro-nonterminal">$tail</span>)<span class="kw-2">*</span>) |
| <span class="macro-nonterminal">$default |
| </span>($(<span class="macro-nonterminal">$labels</span>)<span class="kw-2">*</span>) |
| ($(<span class="macro-nonterminal">$cases</span>)* [<span class="macro-nonterminal">$i</span>] send(<span class="macro-nonterminal">$var</span>, <span class="macro-nonterminal">$m</span>) -> <span class="macro-nonterminal">$res </span>=> <span class="macro-nonterminal">$body</span>,) |
| ) |
| } |
| } |
| }}; |
| |
| <span class="comment">// Complete a receive operation. |
| </span>(@complete |
| <span class="macro-nonterminal">$sel</span>:ident |
| <span class="macro-nonterminal">$oper</span>:ident |
| ([<span class="macro-nonterminal">$i</span>:tt] recv(<span class="macro-nonterminal">$r</span>:ident) -> <span class="macro-nonterminal">$res</span>:pat => <span class="macro-nonterminal">$body</span>:tt, $(<span class="macro-nonterminal">$tail</span>:tt)<span class="kw-2">*</span>) |
| ) => {{ |
| <span class="kw">if </span><span class="macro-nonterminal">$oper</span>.index() == <span class="macro-nonterminal">$i </span>{ |
| <span class="kw">let </span>_res = <span class="macro-nonterminal">$oper</span>.recv(<span class="macro-nonterminal">$r</span>); |
| { <span class="macro-nonterminal">$sel </span>}; |
| |
| <span class="kw">let </span><span class="macro-nonterminal">$res </span>= _res; |
| <span class="macro-nonterminal">$body |
| </span>} <span class="kw">else </span>{ |
| <span class="macro-nonterminal">$</span><span class="macro">crate::crossbeam_channel_internal! </span>{ |
| @<span class="macro-nonterminal">complete |
| $sel |
| $oper |
| </span>($(<span class="macro-nonterminal">$tail</span>)<span class="kw-2">*</span>) |
| } |
| } |
| }}; |
| <span class="comment">// Complete a send operation. |
| </span>(@complete |
| <span class="macro-nonterminal">$sel</span>:ident |
| <span class="macro-nonterminal">$oper</span>:ident |
| ([<span class="macro-nonterminal">$i</span>:tt] send(<span class="macro-nonterminal">$s</span>:ident, <span class="macro-nonterminal">$m</span>:expr) -> <span class="macro-nonterminal">$res</span>:pat => <span class="macro-nonterminal">$body</span>:tt, $(<span class="macro-nonterminal">$tail</span>:tt)<span class="kw-2">*</span>) |
| ) => {{ |
| <span class="kw">if </span><span class="macro-nonterminal">$oper</span>.index() == <span class="macro-nonterminal">$i </span>{ |
| <span class="kw">let </span>_res = <span class="macro-nonterminal">$oper</span>.send(<span class="macro-nonterminal">$s</span>, <span class="macro-nonterminal">$m</span>); |
| { <span class="macro-nonterminal">$sel </span>}; |
| |
| <span class="kw">let </span><span class="macro-nonterminal">$res </span>= _res; |
| <span class="macro-nonterminal">$body |
| </span>} <span class="kw">else </span>{ |
| <span class="macro-nonterminal">$</span><span class="macro">crate::crossbeam_channel_internal! </span>{ |
| @<span class="macro-nonterminal">complete |
| $sel |
| $oper |
| </span>($(<span class="macro-nonterminal">$tail</span>)<span class="kw-2">*</span>) |
| } |
| } |
| }}; |
| <span class="comment">// Panic if we don't identify the selected case, but this should never happen. |
| </span>(@complete |
| <span class="macro-nonterminal">$sel</span>:ident |
| <span class="macro-nonterminal">$oper</span>:ident |
| () |
| ) => {{ |
| <span class="macro">unreachable!</span>( |
| <span class="string">"internal error in crossbeam-channel: invalid case" |
| </span>) |
| }}; |
| |
| <span class="comment">// Catches a bug within this macro (should not happen). |
| </span>(@$(<span class="macro-nonterminal">$tokens</span>:tt)<span class="kw-2">*</span>) => { |
| <span class="macro">compile_error!</span>( |
| <span class="macro">concat!</span>( |
| <span class="string">"internal error in crossbeam-channel: "</span>, |
| <span class="macro">stringify!</span>(@$(<span class="macro-nonterminal">$tokens</span>)<span class="kw-2">*</span>), |
| ) |
| ) |
| }; |
| |
| <span class="comment">// The entry points. |
| </span>() => { |
| <span class="macro">compile_error!</span>(<span class="string">"empty `select!` block"</span>) |
| }; |
| ($(<span class="macro-nonterminal">$case</span>:ident $(($(<span class="macro-nonterminal">$args</span>:tt)<span class="kw-2">*</span>))* => <span class="macro-nonterminal">$body</span>:expr $(,)<span class="kw-2">*</span>)<span class="kw-2">*</span>) => { |
| <span class="macro-nonterminal">$</span><span class="macro">crate::crossbeam_channel_internal!</span>( |
| @<span class="macro-nonterminal">list |
| </span>($(<span class="macro-nonterminal">$case </span>$(($(<span class="macro-nonterminal">$args</span>)<span class="kw-2">*</span>))* => { <span class="macro-nonterminal">$body </span>},)<span class="kw-2">*</span>) |
| () |
| ) |
| }; |
| ($(<span class="macro-nonterminal">$tokens</span>:tt)<span class="kw-2">*</span>) => { |
| <span class="macro-nonterminal">$</span><span class="macro">crate::crossbeam_channel_internal!</span>( |
| @<span class="macro-nonterminal">list |
| </span>($(<span class="macro-nonterminal">$tokens</span>)<span class="kw-2">*</span>) |
| () |
| ) |
| }; |
| } |
| |
| <span class="doccomment">/// Selects from a set of channel operations. |
| /// |
| /// This macro allows you to define a set of channel operations, wait until any one of them becomes |
| /// ready, and finally execute it. If multiple operations are ready at the same time, a random one |
| /// among them is selected. |
| /// |
| /// It is also possible to define a `default` case that gets executed if none of the operations are |
| /// ready, either right away or for a certain duration of time. |
| /// |
| /// An operation is considered to be ready if it doesn't have to block. Note that it is ready even |
| /// when it will simply return an error because the channel is disconnected. |
| /// |
| /// The `select!` macro is a convenience wrapper around [`Select`]. However, it cannot select over a |
| /// dynamically created list of channel operations. |
| /// |
| /// [`Select`]: super::Select |
| /// |
| /// # Examples |
| /// |
| /// Block until a send or a receive operation is selected: |
| /// |
| /// ``` |
| /// use crossbeam_channel::{select, unbounded}; |
| /// |
| /// let (s1, r1) = unbounded(); |
| /// let (s2, r2) = unbounded(); |
| /// s1.send(10).unwrap(); |
| /// |
| /// // Since both operations are initially ready, a random one will be executed. |
| /// select! { |
| /// recv(r1) -> msg => assert_eq!(msg, Ok(10)), |
| /// send(s2, 20) -> res => { |
| /// assert_eq!(res, Ok(())); |
| /// assert_eq!(r2.recv(), Ok(20)); |
| /// } |
| /// } |
| /// ``` |
| /// |
| /// Select from a set of operations without blocking: |
| /// |
| /// ``` |
| /// use std::thread; |
| /// use std::time::Duration; |
| /// use crossbeam_channel::{select, unbounded}; |
| /// |
| /// let (s1, r1) = unbounded(); |
| /// let (s2, r2) = unbounded(); |
| /// |
| /// thread::spawn(move || { |
| /// thread::sleep(Duration::from_secs(1)); |
| /// s1.send(10).unwrap(); |
| /// }); |
| /// thread::spawn(move || { |
| /// thread::sleep(Duration::from_millis(500)); |
| /// s2.send(20).unwrap(); |
| /// }); |
| /// |
| /// // None of the operations are initially ready. |
| /// select! { |
| /// recv(r1) -> msg => panic!(), |
| /// recv(r2) -> msg => panic!(), |
| /// default => println!("not ready"), |
| /// } |
| /// ``` |
| /// |
| /// Select over a set of operations with a timeout: |
| /// |
| /// ``` |
| /// use std::thread; |
| /// use std::time::Duration; |
| /// use crossbeam_channel::{select, unbounded}; |
| /// |
| /// let (s1, r1) = unbounded(); |
| /// let (s2, r2) = unbounded(); |
| /// |
| /// thread::spawn(move || { |
| /// thread::sleep(Duration::from_secs(1)); |
| /// s1.send(10).unwrap(); |
| /// }); |
| /// thread::spawn(move || { |
| /// thread::sleep(Duration::from_millis(500)); |
| /// s2.send(20).unwrap(); |
| /// }); |
| /// |
| /// // None of the two operations will become ready within 100 milliseconds. |
| /// select! { |
| /// recv(r1) -> msg => panic!(), |
| /// recv(r2) -> msg => panic!(), |
| /// default(Duration::from_millis(100)) => println!("timed out"), |
| /// } |
| /// ``` |
| /// |
| /// Optionally add a receive operation to `select!` using [`never`]: |
| /// |
| /// ``` |
| /// use std::thread; |
| /// use std::time::Duration; |
| /// use crossbeam_channel::{select, never, unbounded}; |
| /// |
| /// let (s1, r1) = unbounded(); |
| /// let (s2, r2) = unbounded(); |
| /// |
| /// thread::spawn(move || { |
| /// thread::sleep(Duration::from_secs(1)); |
| /// s1.send(10).unwrap(); |
| /// }); |
| /// thread::spawn(move || { |
| /// thread::sleep(Duration::from_millis(500)); |
| /// s2.send(20).unwrap(); |
| /// }); |
| /// |
| /// // This receiver can be a `Some` or a `None`. |
| /// let r2 = Some(&r2); |
| /// |
| /// // None of the two operations will become ready within 100 milliseconds. |
| /// select! { |
| /// recv(r1) -> msg => panic!(), |
| /// recv(r2.unwrap_or(&never())) -> msg => assert_eq!(msg, Ok(20)), |
| /// } |
| /// ``` |
| /// |
| /// To optionally add a timeout to `select!`, see the [example] for [`never`]. |
| /// |
| /// [`never`]: super::never |
| /// [example]: super::never#examples |
| </span><span class="attribute">#[macro_export] |
| </span><span class="macro">macro_rules! </span>select { |
| ($(<span class="macro-nonterminal">$tokens</span>:tt)<span class="kw-2">*</span>) => { |
| <span class="macro-nonterminal">$</span><span class="macro">crate::crossbeam_channel_internal!</span>( |
| $(<span class="macro-nonterminal">$tokens</span>)* |
| ) |
| }; |
| } |
| </code></pre></div> |
| </section></div></main><div id="rustdoc-vars" data-root-path="../../" data-current-crate="crossbeam_channel" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |
