| <!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/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="../../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> |
| <span id="2">2</span> |
| <span id="3">3</span> |
| <span id="4">4</span> |
| <span id="5">5</span> |
| <span id="6">6</span> |
| <span id="7">7</span> |
| <span id="8">8</span> |
| <span id="9">9</span> |
| <span id="10">10</span> |
| <span id="11">11</span> |
| <span id="12">12</span> |
| <span id="13">13</span> |
| <span id="14">14</span> |
| <span id="15">15</span> |
| <span id="16">16</span> |
| <span id="17">17</span> |
| <span id="18">18</span> |
| <span id="19">19</span> |
| <span id="20">20</span> |
| <span id="21">21</span> |
| <span id="22">22</span> |
| <span id="23">23</span> |
| <span id="24">24</span> |
| <span id="25">25</span> |
| <span id="26">26</span> |
| <span id="27">27</span> |
| <span id="28">28</span> |
| <span id="29">29</span> |
| <span id="30">30</span> |
| <span id="31">31</span> |
| <span id="32">32</span> |
| <span id="33">33</span> |
| <span id="34">34</span> |
| <span id="35">35</span> |
| <span id="36">36</span> |
| <span id="37">37</span> |
| <span id="38">38</span> |
| <span id="39">39</span> |
| <span id="40">40</span> |
| <span id="41">41</span> |
| <span id="42">42</span> |
| <span id="43">43</span> |
| <span id="44">44</span> |
| <span id="45">45</span> |
| <span id="46">46</span> |
| <span id="47">47</span> |
| <span id="48">48</span> |
| <span id="49">49</span> |
| <span id="50">50</span> |
| <span id="51">51</span> |
| <span id="52">52</span> |
| <span id="53">53</span> |
| <span id="54">54</span> |
| <span id="55">55</span> |
| <span id="56">56</span> |
| <span id="57">57</span> |
| <span id="58">58</span> |
| <span id="59">59</span> |
| <span id="60">60</span> |
| <span id="61">61</span> |
| <span id="62">62</span> |
| <span id="63">63</span> |
| <span id="64">64</span> |
| <span id="65">65</span> |
| <span id="66">66</span> |
| <span id="67">67</span> |
| <span id="68">68</span> |
| <span id="69">69</span> |
| <span id="70">70</span> |
| <span id="71">71</span> |
| <span id="72">72</span> |
| <span id="73">73</span> |
| <span id="74">74</span> |
| <span id="75">75</span> |
| <span id="76">76</span> |
| <span id="77">77</span> |
| <span id="78">78</span> |
| <span id="79">79</span> |
| <span id="80">80</span> |
| <span id="81">81</span> |
| <span id="82">82</span> |
| <span id="83">83</span> |
| <span id="84">84</span> |
| <span id="85">85</span> |
| <span id="86">86</span> |
| <span id="87">87</span> |
| <span id="88">88</span> |
| <span id="89">89</span> |
| <span id="90">90</span> |
| <span id="91">91</span> |
| <span id="92">92</span> |
| <span id="93">93</span> |
| <span id="94">94</span> |
| <span id="95">95</span> |
| <span id="96">96</span> |
| <span id="97">97</span> |
| <span id="98">98</span> |
| <span id="99">99</span> |
| <span id="100">100</span> |
| <span id="101">101</span> |
| <span id="102">102</span> |
| <span id="103">103</span> |
| <span id="104">104</span> |
| <span id="105">105</span> |
| <span id="106">106</span> |
| <span id="107">107</span> |
| <span id="108">108</span> |
| <span id="109">109</span> |
| <span id="110">110</span> |
| <span id="111">111</span> |
| <span id="112">112</span> |
| <span id="113">113</span> |
| <span id="114">114</span> |
| <span id="115">115</span> |
| <span id="116">116</span> |
| <span id="117">117</span> |
| <span id="118">118</span> |
| <span id="119">119</span> |
| <span id="120">120</span> |
| <span id="121">121</span> |
| <span id="122">122</span> |
| <span id="123">123</span> |
| <span id="124">124</span> |
| <span id="125">125</span> |
| <span id="126">126</span> |
| <span id="127">127</span> |
| <span id="128">128</span> |
| <span id="129">129</span> |
| <span id="130">130</span> |
| <span id="131">131</span> |
| <span id="132">132</span> |
| <span id="133">133</span> |
| <span id="134">134</span> |
| <span id="135">135</span> |
| <span id="136">136</span> |
| <span id="137">137</span> |
| <span id="138">138</span> |
| <span id="139">139</span> |
| <span id="140">140</span> |
| <span id="141">141</span> |
| <span id="142">142</span> |
| <span id="143">143</span> |
| <span id="144">144</span> |
| <span id="145">145</span> |
| <span id="146">146</span> |
| <span id="147">147</span> |
| <span id="148">148</span> |
| <span id="149">149</span> |
| <span id="150">150</span> |
| <span id="151">151</span> |
| <span id="152">152</span> |
| <span id="153">153</span> |
| <span id="154">154</span> |
| <span id="155">155</span> |
| <span id="156">156</span> |
| <span id="157">157</span> |
| <span id="158">158</span> |
| <span id="159">159</span> |
| <span id="160">160</span> |
| <span id="161">161</span> |
| <span id="162">162</span> |
| <span id="163">163</span> |
| <span id="164">164</span> |
| <span id="165">165</span> |
| <span id="166">166</span> |
| <span id="167">167</span> |
| <span id="168">168</span> |
| <span id="169">169</span> |
| <span id="170">170</span> |
| <span id="171">171</span> |
| <span id="172">172</span> |
| <span id="173">173</span> |
| <span id="174">174</span> |
| <span id="175">175</span> |
| <span id="176">176</span> |
| <span id="177">177</span> |
| <span id="178">178</span> |
| <span id="179">179</span> |
| <span id="180">180</span> |
| <span id="181">181</span> |
| <span id="182">182</span> |
| <span id="183">183</span> |
| <span id="184">184</span> |
| <span id="185">185</span> |
| <span id="186">186</span> |
| <span id="187">187</span> |
| <span id="188">188</span> |
| <span id="189">189</span> |
| <span id="190">190</span> |
| <span id="191">191</span> |
| <span id="192">192</span> |
| <span id="193">193</span> |
| <span id="194">194</span> |
| <span id="195">195</span> |
| <span id="196">196</span> |
| <span id="197">197</span> |
| <span id="198">198</span> |
| <span id="199">199</span> |
| <span id="200">200</span> |
| <span id="201">201</span> |
| <span id="202">202</span> |
| <span id="203">203</span> |
| <span id="204">204</span> |
| <span id="205">205</span> |
| <span id="206">206</span> |
| <span id="207">207</span> |
| <span id="208">208</span> |
| <span id="209">209</span> |
| <span id="210">210</span> |
| <span id="211">211</span> |
| <span id="212">212</span> |
| <span id="213">213</span> |
| <span id="214">214</span> |
| <span id="215">215</span> |
| <span id="216">216</span> |
| <span id="217">217</span> |
| <span id="218">218</span> |
| <span id="219">219</span> |
| <span id="220">220</span> |
| <span id="221">221</span> |
| <span id="222">222</span> |
| <span id="223">223</span> |
| <span id="224">224</span> |
| <span id="225">225</span> |
| <span id="226">226</span> |
| <span id="227">227</span> |
| <span id="228">228</span> |
| <span id="229">229</span> |
| <span id="230">230</span> |
| <span id="231">231</span> |
| <span id="232">232</span> |
| <span id="233">233</span> |
| <span id="234">234</span> |
| <span id="235">235</span> |
| <span id="236">236</span> |
| <span id="237">237</span> |
| <span id="238">238</span> |
| <span id="239">239</span> |
| <span id="240">240</span> |
| <span id="241">241</span> |
| <span id="242">242</span> |
| <span id="243">243</span> |
| <span id="244">244</span> |
| <span id="245">245</span> |
| <span id="246">246</span> |
| <span id="247">247</span> |
| <span id="248">248</span> |
| <span id="249">249</span> |
| <span id="250">250</span> |
| <span id="251">251</span> |
| <span id="252">252</span> |
| <span id="253">253</span> |
| <span id="254">254</span> |
| <span id="255">255</span> |
| <span id="256">256</span> |
| <span id="257">257</span> |
| <span id="258">258</span> |
| <span id="259">259</span> |
| <span id="260">260</span> |
| <span id="261">261</span> |
| <span id="262">262</span> |
| <span id="263">263</span> |
| <span id="264">264</span> |
| <span id="265">265</span> |
| <span id="266">266</span> |
| <span id="267">267</span> |
| <span id="268">268</span> |
| <span id="269">269</span> |
| <span id="270">270</span> |
| <span id="271">271</span> |
| <span id="272">272</span> |
| <span id="273">273</span> |
| <span id="274">274</span> |
| <span id="275">275</span> |
| <span id="276">276</span> |
| <span id="277">277</span> |
| <span id="278">278</span> |
| <span id="279">279</span> |
| <span id="280">280</span> |
| <span id="281">281</span> |
| <span id="282">282</span> |
| <span id="283">283</span> |
| <span id="284">284</span> |
| <span id="285">285</span> |
| <span id="286">286</span> |
| <span id="287">287</span> |
| <span id="288">288</span> |
| <span id="289">289</span> |
| <span id="290">290</span> |
| <span id="291">291</span> |
| <span id="292">292</span> |
| <span id="293">293</span> |
| <span id="294">294</span> |
| <span id="295">295</span> |
| <span id="296">296</span> |
| <span id="297">297</span> |
| <span id="298">298</span> |
| <span id="299">299</span> |
| <span id="300">300</span> |
| <span id="301">301</span> |
| <span id="302">302</span> |
| <span id="303">303</span> |
| <span id="304">304</span> |
| <span id="305">305</span> |
| <span id="306">306</span> |
| <span id="307">307</span> |
| <span id="308">308</span> |
| <span id="309">309</span> |
| <span id="310">310</span> |
| <span id="311">311</span> |
| <span id="312">312</span> |
| <span id="313">313</span> |
| <span id="314">314</span> |
| <span id="315">315</span> |
| <span id="316">316</span> |
| <span id="317">317</span> |
| <span id="318">318</span> |
| <span id="319">319</span> |
| <span id="320">320</span> |
| <span id="321">321</span> |
| <span id="322">322</span> |
| <span id="323">323</span> |
| <span id="324">324</span> |
| <span id="325">325</span> |
| <span id="326">326</span> |
| <span id="327">327</span> |
| <span id="328">328</span> |
| <span id="329">329</span> |
| <span id="330">330</span> |
| </pre><pre class="rust"><code><span class="doccomment">//! The futures-rs `select! macro implementation. |
| |
| </span><span class="kw">use </span>proc_macro::TokenStream; |
| <span class="kw">use </span>proc_macro2::Span; |
| <span class="kw">use </span>quote::{format_ident, quote}; |
| <span class="kw">use </span>syn::parse::{Parse, ParseStream}; |
| <span class="kw">use </span>syn::{parse_quote, Expr, Ident, Pat, Token}; |
| |
| <span class="kw">mod </span>kw { |
| <span class="macro">syn::custom_keyword!</span>(complete); |
| } |
| |
| <span class="kw">struct </span>Select { |
| <span class="comment">// span of `complete`, then expression after `=> ...` |
| </span>complete: <span class="prelude-ty">Option</span><Expr>, |
| default: <span class="prelude-ty">Option</span><Expr>, |
| normal_fut_exprs: Vec<Expr>, |
| normal_fut_handlers: Vec<(Pat, Expr)>, |
| } |
| |
| <span class="attribute">#[allow(clippy::large_enum_variant)] |
| </span><span class="kw">enum </span>CaseKind { |
| Complete, |
| Default, |
| Normal(Pat, Expr), |
| } |
| |
| <span class="kw">impl </span>Parse <span class="kw">for </span>Select { |
| <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>select = <span class="self">Self </span>{ |
| complete: <span class="prelude-val">None</span>, |
| default: <span class="prelude-val">None</span>, |
| normal_fut_exprs: <span class="macro">vec!</span>[], |
| normal_fut_handlers: <span class="macro">vec!</span>[], |
| }; |
| |
| <span class="kw">while </span>!input.is_empty() { |
| <span class="kw">let </span>case_kind = <span class="kw">if </span>input.peek(kw::complete) { |
| <span class="comment">// `complete` |
| </span><span class="kw">if </span>select.complete.is_some() { |
| <span class="kw">return </span><span class="prelude-val">Err</span>(input.error(<span class="string">"multiple `complete` cases found, only one allowed"</span>)); |
| } |
| input.parse::<kw::complete>()<span class="question-mark">?</span>; |
| CaseKind::Complete |
| } <span class="kw">else if </span>input.peek(<span class="macro">Token!</span>[default]) { |
| <span class="comment">// `default` |
| </span><span class="kw">if </span>select.default.is_some() { |
| <span class="kw">return </span><span class="prelude-val">Err</span>(input.error(<span class="string">"multiple `default` cases found, only one allowed"</span>)); |
| } |
| input.parse::<Ident>()<span class="question-mark">?</span>; |
| CaseKind::Default |
| } <span class="kw">else </span>{ |
| <span class="comment">// `<pat> = <expr>` |
| </span><span class="kw">let </span>pat = Pat::parse_multi_with_leading_vert(input)<span class="question-mark">?</span>; |
| input.parse::<<span class="macro">Token!</span>[=]>()<span class="question-mark">?</span>; |
| <span class="kw">let </span>expr = input.parse()<span class="question-mark">?</span>; |
| CaseKind::Normal(pat, expr) |
| }; |
| |
| <span class="comment">// `=> <expr>` |
| </span>input.parse::<<span class="macro">Token!</span>[=>]>()<span class="question-mark">?</span>; |
| <span class="kw">let </span>expr = input.parse::<Expr>()<span class="question-mark">?</span>; |
| |
| <span class="comment">// Commas after the expression are only optional if it's a `Block` |
| // or it is the last branch in the `match`. |
| </span><span class="kw">let </span>is_block = <span class="kw">match </span>expr { |
| Expr::Block(<span class="kw">_</span>) => <span class="bool-val">true</span>, |
| <span class="kw">_ </span>=> <span class="bool-val">false</span>, |
| }; |
| <span class="kw">if </span>is_block || input.is_empty() { |
| input.parse::<<span class="prelude-ty">Option</span><<span class="macro">Token!</span>[,]>>()<span class="question-mark">?</span>; |
| } <span class="kw">else </span>{ |
| input.parse::<<span class="macro">Token!</span>[,]>()<span class="question-mark">?</span>; |
| } |
| |
| <span class="kw">match </span>case_kind { |
| CaseKind::Complete => select.complete = <span class="prelude-val">Some</span>(expr), |
| CaseKind::Default => select.default = <span class="prelude-val">Some</span>(expr), |
| CaseKind::Normal(pat, fut_expr) => { |
| select.normal_fut_exprs.push(fut_expr); |
| select.normal_fut_handlers.push((pat, expr)); |
| } |
| } |
| } |
| |
| <span class="prelude-val">Ok</span>(select) |
| } |
| } |
| |
| <span class="comment">// Enum over all the cases in which the `select!` waiting has completed and the result |
| // can be processed. |
| // |
| // `enum __PrivResult<_1, _2, ...> { _1(_1), _2(_2), ..., Complete }` |
| </span><span class="kw">fn </span>declare_result_enum( |
| result_ident: Ident, |
| variants: usize, |
| complete: bool, |
| span: Span, |
| ) -> (Vec<Ident>, syn::ItemEnum) { |
| <span class="comment">// "_0", "_1", "_2" |
| </span><span class="kw">let </span>variant_names: Vec<Ident> = |
| (<span class="number">0</span>..variants).map(|num| <span class="macro">format_ident!</span>(<span class="string">"_{}"</span>, num, span = span)).collect(); |
| |
| <span class="kw">let </span>type_parameters = <span class="kw-2">&</span>variant_names; |
| <span class="kw">let </span>variants = <span class="kw-2">&</span>variant_names; |
| |
| <span class="kw">let </span>complete_variant = <span class="kw">if </span>complete { <span class="prelude-val">Some</span>(<span class="macro">quote!</span>(Complete)) } <span class="kw">else </span>{ <span class="prelude-val">None </span>}; |
| |
| <span class="kw">let </span>enum_item = <span class="macro">parse_quote! </span>{ |
| <span class="kw">enum </span>#result_ident<#(#type_parameters,)<span class="kw-2">*</span>> { |
| #( |
| #variants(#type_parameters), |
| )* |
| #complete_variant |
| } |
| }; |
| |
| (variant_names, enum_item) |
| } |
| |
| <span class="doccomment">/// The `select!` macro. |
| </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>select(input: TokenStream) -> TokenStream { |
| select_inner(input, <span class="bool-val">true</span>) |
| } |
| |
| <span class="doccomment">/// The `select_biased!` macro. |
| </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>select_biased(input: TokenStream) -> TokenStream { |
| select_inner(input, <span class="bool-val">false</span>) |
| } |
| |
| <span class="kw">fn </span>select_inner(input: TokenStream, random: bool) -> TokenStream { |
| <span class="kw">let </span>parsed = <span class="macro">syn::parse_macro_input!</span>(input <span class="kw">as </span>Select); |
| |
| <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>enum_ident = Ident::new(<span class="string">"__PrivResult"</span>, span); |
| |
| <span class="kw">let </span>(variant_names, enum_item) = declare_result_enum( |
| enum_ident.clone(), |
| parsed.normal_fut_exprs.len(), |
| parsed.complete.is_some(), |
| span, |
| ); |
| |
| <span class="comment">// bind non-`Ident` future exprs w/ `let` |
| </span><span class="kw">let </span><span class="kw-2">mut </span>future_let_bindings = Vec::with_capacity(parsed.normal_fut_exprs.len()); |
| <span class="kw">let </span>bound_future_names: Vec<<span class="kw">_</span>> = parsed |
| .normal_fut_exprs |
| .into_iter() |
| .zip(variant_names.iter()) |
| .map(|(expr, variant_name)| { |
| <span class="kw">match </span>expr { |
| syn::Expr::Path(path) => { |
| <span class="comment">// Don't bind futures that are already a path. |
| // This prevents creating redundant stack space |
| // for them. |
| // Passing Futures by path requires those Futures to implement Unpin. |
| // We check for this condition here in order to be able to |
| // safely use Pin::new_unchecked(&mut #path) later on. |
| </span>future_let_bindings.push(<span class="macro">quote! </span>{ |
| __futures_crate::async_await::assert_fused_future(<span class="kw-2">&</span>#path); |
| __futures_crate::async_await::assert_unpin(<span class="kw-2">&</span>#path); |
| }); |
| path |
| } |
| <span class="kw">_ </span>=> { |
| <span class="comment">// Bind and pin the resulting Future on the stack. This is |
| // necessary to support direct select! calls on !Unpin |
| // Futures. The Future is not explicitly pinned here with |
| // a Pin call, but assumed as pinned. The actual Pin is |
| // created inside the poll() function below to defer the |
| // creation of the temporary pointer, which would otherwise |
| // increase the size of the generated Future. |
| // Safety: This is safe since the lifetime of the Future |
| // is totally constraint to the lifetime of the select! |
| // expression, and the Future can't get moved inside it |
| // (it is shadowed). |
| </span>future_let_bindings.push(<span class="macro">quote! </span>{ |
| <span class="kw">let </span><span class="kw-2">mut </span>#variant_name = #expr; |
| }); |
| <span class="macro">parse_quote! </span>{ #variant_name } |
| } |
| } |
| }) |
| .collect(); |
| |
| <span class="comment">// For each future, make an `&mut dyn FnMut(&mut Context<'_>) -> Option<Poll<__PrivResult<...>>` |
| // to use for polling that individual future. These will then be put in an array. |
| </span><span class="kw">let </span>poll_functions = bound_future_names.iter().zip(variant_names.iter()).map( |
| |(bound_future_name, variant_name)| { |
| <span class="comment">// Below we lazily create the Pin on the Future below. |
| // This is done in order to avoid allocating memory in the generator |
| // for the Pin variable. |
| // Safety: This is safe because one of the following condition applies: |
| // 1. The Future is passed by the caller by name, and we assert that |
| // it implements Unpin. |
| // 2. The Future is created in scope of the select! function and will |
| // not be moved for the duration of it. It is thereby stack-pinned |
| </span><span class="macro">quote! </span>{ |
| <span class="kw">let </span><span class="kw-2">mut </span>#variant_name = |__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>#bound_future_name = <span class="kw">unsafe </span>{ |
| __futures_crate::Pin::new_unchecked(<span class="kw-2">&mut </span>#bound_future_name) |
| }; |
| <span class="kw">if </span>__futures_crate::future::FusedFuture::is_terminated(<span class="kw-2">&</span>#bound_future_name) { |
| __futures_crate::None |
| } <span class="kw">else </span>{ |
| __futures_crate::Some(__futures_crate::future::FutureExt::poll_unpin( |
| <span class="kw-2">&mut </span>#bound_future_name, |
| __cx, |
| ).map(#enum_ident::#variant_name)) |
| } |
| }; |
| <span class="kw">let </span>#variant_name: <span class="kw-2">&mut </span><span class="kw">dyn </span>FnMut( |
| <span class="kw-2">&mut </span>__futures_crate::task::Context<<span class="lifetime">'_</span>> |
| ) -> __futures_crate::Option<__futures_crate::task::Poll<<span class="kw">_</span>>> = <span class="kw-2">&mut </span>#variant_name; |
| } |
| }, |
| ); |
| |
| <span class="kw">let </span>none_polled = <span class="kw">if </span>parsed.complete.is_some() { |
| <span class="macro">quote! </span>{ |
| __futures_crate::task::Poll::Ready(#enum_ident::Complete) |
| } |
| } <span class="kw">else </span>{ |
| <span class="macro">quote! </span>{ |
| <span class="macro">panic!</span>(<span class="string">"all futures in select! were completed,\ |
| but no `complete =>` handler was provided"</span>) |
| } |
| }; |
| |
| <span class="kw">let </span>branches = parsed.normal_fut_handlers.into_iter().zip(variant_names.iter()).map( |
| |((pat, expr), variant_name)| { |
| <span class="macro">quote! </span>{ |
| #enum_ident::#variant_name(#pat) => { #expr }, |
| } |
| }, |
| ); |
| <span class="kw">let </span>branches = <span class="macro">quote! </span>{ #( #branches )* }; |
| |
| <span class="kw">let </span>complete_branch = parsed.complete.map(|complete_expr| { |
| <span class="macro">quote! </span>{ |
| #enum_ident::Complete => { #complete_expr }, |
| } |
| }); |
| |
| <span class="kw">let </span>branches = <span class="macro">quote! </span>{ |
| #branches |
| #complete_branch |
| }; |
| |
| <span class="kw">let </span>await_select_fut = <span class="kw">if </span>parsed.default.is_some() { |
| <span class="comment">// For select! with default this returns the Poll result |
| </span><span class="macro">quote! </span>{ |
| __poll_fn(<span class="kw-2">&mut </span>__futures_crate::task::Context::from_waker( |
| __futures_crate::task::noop_waker_ref() |
| )) |
| } |
| } <span class="kw">else </span>{ |
| <span class="macro">quote! </span>{ |
| __futures_crate::future::poll_fn(__poll_fn).<span class="kw">await |
| </span>} |
| }; |
| |
| <span class="kw">let </span>execute_result_expr = <span class="kw">if let </span><span class="prelude-val">Some</span>(default_expr) = <span class="kw-2">&</span>parsed.default { |
| <span class="comment">// For select! with default __select_result is a Poll, otherwise not |
| </span><span class="macro">quote! </span>{ |
| <span class="kw">match </span>__select_result { |
| __futures_crate::task::Poll::Ready(result) => <span class="kw">match </span>result { |
| #branches |
| }, |
| <span class="kw">_ </span>=> #default_expr |
| } |
| } |
| } <span class="kw">else </span>{ |
| <span class="macro">quote! </span>{ |
| <span class="kw">match </span>__select_result { |
| #branches |
| } |
| } |
| }; |
| |
| <span class="kw">let </span>shuffle = <span class="kw">if </span>random { |
| <span class="macro">quote! </span>{ |
| __futures_crate::async_await::shuffle(<span class="kw-2">&mut </span>__select_arr); |
| } |
| } <span class="kw">else </span>{ |
| <span class="macro">quote!</span>() |
| }; |
| |
| TokenStream::from(<span class="macro">quote! </span>{ { |
| #enum_item |
| |
| <span class="kw">let </span>__select_result = { |
| #( #future_let_bindings )* |
| |
| <span class="kw">let </span><span class="kw-2">mut </span>__poll_fn = |__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>__any_polled = <span class="bool-val">false</span>; |
| |
| #( #poll_functions )* |
| |
| <span class="kw">let </span><span class="kw-2">mut </span>__select_arr = [#( #variant_names ),<span class="kw-2">*</span>]; |
| #shuffle |
| <span class="kw">for </span>poller <span class="kw">in </span><span class="kw-2">&mut </span>__select_arr { |
| <span class="kw">let </span>poller: <span class="kw-2">&mut &mut </span><span class="kw">dyn </span>FnMut( |
| <span class="kw-2">&mut </span>__futures_crate::task::Context<<span class="lifetime">'_</span>> |
| ) -> __futures_crate::Option<__futures_crate::task::Poll<<span class="kw">_</span>>> = poller; |
| <span class="kw">match </span>poller(__cx) { |
| __futures_crate::Some(x @ __futures_crate::task::Poll::Ready(<span class="kw">_</span>)) => |
| <span class="kw">return </span>x, |
| __futures_crate::Some(__futures_crate::task::Poll::Pending) => { |
| __any_polled = <span class="bool-val">true</span>; |
| } |
| __futures_crate::None => {} |
| } |
| } |
| |
| <span class="kw">if </span>!__any_polled { |
| #none_polled |
| } <span class="kw">else </span>{ |
| __futures_crate::task::Poll::Pending |
| } |
| }; |
| |
| #await_select_fut |
| }; |
| |
| #execute_result_expr |
| } }) |
| } |
| </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> |