| <!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/tokio-stream-0.1.14/src/stream_map.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>stream_map.rs - source</title><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceSerif4-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../FiraSans-Regular.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../FiraSans-Medium.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceCodePro-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceSerif4-Bold.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceCodePro-Semibold.ttf.woff2"><link rel="stylesheet" href="../../normalize.css"><link rel="stylesheet" href="../../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" href="../../ayu.css" disabled><link rel="stylesheet" href="../../dark.css" disabled><link rel="stylesheet" href="../../light.css" id="themeStyle"><script id="default-settings" ></script><script src="../../storage.js"></script><script defer src="../../source-script.js"></script><script defer src="../../source-files.js"></script><script defer src="../../main.js"></script><noscript><link rel="stylesheet" href="../../noscript.css"></noscript><link rel="alternate icon" type="image/png" href="../../favicon-16x16.png"><link rel="alternate icon" type="image/png" href="../../favicon-32x32.png"><link rel="icon" type="image/svg+xml" href="../../favicon.svg"></head><body class="rustdoc source"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><a class="sidebar-logo" href="../../tokio_stream/index.html"><div class="logo-container"><img class="rust-logo" src="../../rust-logo.svg" alt="logo"></div></a></nav><main><div class="width-limiter"><nav class="sub"><a class="sub-logo-container" href="../../tokio_stream/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> |
| <span id="331">331</span> |
| <span id="332">332</span> |
| <span id="333">333</span> |
| <span id="334">334</span> |
| <span id="335">335</span> |
| <span id="336">336</span> |
| <span id="337">337</span> |
| <span id="338">338</span> |
| <span id="339">339</span> |
| <span id="340">340</span> |
| <span id="341">341</span> |
| <span id="342">342</span> |
| <span id="343">343</span> |
| <span id="344">344</span> |
| <span id="345">345</span> |
| <span id="346">346</span> |
| <span id="347">347</span> |
| <span id="348">348</span> |
| <span id="349">349</span> |
| <span id="350">350</span> |
| <span id="351">351</span> |
| <span id="352">352</span> |
| <span id="353">353</span> |
| <span id="354">354</span> |
| <span id="355">355</span> |
| <span id="356">356</span> |
| <span id="357">357</span> |
| <span id="358">358</span> |
| <span id="359">359</span> |
| <span id="360">360</span> |
| <span id="361">361</span> |
| <span id="362">362</span> |
| <span id="363">363</span> |
| <span id="364">364</span> |
| <span id="365">365</span> |
| <span id="366">366</span> |
| <span id="367">367</span> |
| <span id="368">368</span> |
| <span id="369">369</span> |
| <span id="370">370</span> |
| <span id="371">371</span> |
| <span id="372">372</span> |
| <span id="373">373</span> |
| <span id="374">374</span> |
| <span id="375">375</span> |
| <span id="376">376</span> |
| <span id="377">377</span> |
| <span id="378">378</span> |
| <span id="379">379</span> |
| <span id="380">380</span> |
| <span id="381">381</span> |
| <span id="382">382</span> |
| <span id="383">383</span> |
| <span id="384">384</span> |
| <span id="385">385</span> |
| <span id="386">386</span> |
| <span id="387">387</span> |
| <span id="388">388</span> |
| <span id="389">389</span> |
| <span id="390">390</span> |
| <span id="391">391</span> |
| <span id="392">392</span> |
| <span id="393">393</span> |
| <span id="394">394</span> |
| <span id="395">395</span> |
| <span id="396">396</span> |
| <span id="397">397</span> |
| <span id="398">398</span> |
| <span id="399">399</span> |
| <span id="400">400</span> |
| <span id="401">401</span> |
| <span id="402">402</span> |
| <span id="403">403</span> |
| <span id="404">404</span> |
| <span id="405">405</span> |
| <span id="406">406</span> |
| <span id="407">407</span> |
| <span id="408">408</span> |
| <span id="409">409</span> |
| <span id="410">410</span> |
| <span id="411">411</span> |
| <span id="412">412</span> |
| <span id="413">413</span> |
| <span id="414">414</span> |
| <span id="415">415</span> |
| <span id="416">416</span> |
| <span id="417">417</span> |
| <span id="418">418</span> |
| <span id="419">419</span> |
| <span id="420">420</span> |
| <span id="421">421</span> |
| <span id="422">422</span> |
| <span id="423">423</span> |
| <span id="424">424</span> |
| <span id="425">425</span> |
| <span id="426">426</span> |
| <span id="427">427</span> |
| <span id="428">428</span> |
| <span id="429">429</span> |
| <span id="430">430</span> |
| <span id="431">431</span> |
| <span id="432">432</span> |
| <span id="433">433</span> |
| <span id="434">434</span> |
| <span id="435">435</span> |
| <span id="436">436</span> |
| <span id="437">437</span> |
| <span id="438">438</span> |
| <span id="439">439</span> |
| <span id="440">440</span> |
| <span id="441">441</span> |
| <span id="442">442</span> |
| <span id="443">443</span> |
| <span id="444">444</span> |
| <span id="445">445</span> |
| <span id="446">446</span> |
| <span id="447">447</span> |
| <span id="448">448</span> |
| <span id="449">449</span> |
| <span id="450">450</span> |
| <span id="451">451</span> |
| <span id="452">452</span> |
| <span id="453">453</span> |
| <span id="454">454</span> |
| <span id="455">455</span> |
| <span id="456">456</span> |
| <span id="457">457</span> |
| <span id="458">458</span> |
| <span id="459">459</span> |
| <span id="460">460</span> |
| <span id="461">461</span> |
| <span id="462">462</span> |
| <span id="463">463</span> |
| <span id="464">464</span> |
| <span id="465">465</span> |
| <span id="466">466</span> |
| <span id="467">467</span> |
| <span id="468">468</span> |
| <span id="469">469</span> |
| <span id="470">470</span> |
| <span id="471">471</span> |
| <span id="472">472</span> |
| <span id="473">473</span> |
| <span id="474">474</span> |
| <span id="475">475</span> |
| <span id="476">476</span> |
| <span id="477">477</span> |
| <span id="478">478</span> |
| <span id="479">479</span> |
| <span id="480">480</span> |
| <span id="481">481</span> |
| <span id="482">482</span> |
| <span id="483">483</span> |
| <span id="484">484</span> |
| <span id="485">485</span> |
| <span id="486">486</span> |
| <span id="487">487</span> |
| <span id="488">488</span> |
| <span id="489">489</span> |
| <span id="490">490</span> |
| <span id="491">491</span> |
| <span id="492">492</span> |
| <span id="493">493</span> |
| <span id="494">494</span> |
| <span id="495">495</span> |
| <span id="496">496</span> |
| <span id="497">497</span> |
| <span id="498">498</span> |
| <span id="499">499</span> |
| <span id="500">500</span> |
| <span id="501">501</span> |
| <span id="502">502</span> |
| <span id="503">503</span> |
| <span id="504">504</span> |
| <span id="505">505</span> |
| <span id="506">506</span> |
| <span id="507">507</span> |
| <span id="508">508</span> |
| <span id="509">509</span> |
| <span id="510">510</span> |
| <span id="511">511</span> |
| <span id="512">512</span> |
| <span id="513">513</span> |
| <span id="514">514</span> |
| <span id="515">515</span> |
| <span id="516">516</span> |
| <span id="517">517</span> |
| <span id="518">518</span> |
| <span id="519">519</span> |
| <span id="520">520</span> |
| <span id="521">521</span> |
| <span id="522">522</span> |
| <span id="523">523</span> |
| <span id="524">524</span> |
| <span id="525">525</span> |
| <span id="526">526</span> |
| <span id="527">527</span> |
| <span id="528">528</span> |
| <span id="529">529</span> |
| <span id="530">530</span> |
| <span id="531">531</span> |
| <span id="532">532</span> |
| <span id="533">533</span> |
| <span id="534">534</span> |
| <span id="535">535</span> |
| <span id="536">536</span> |
| <span id="537">537</span> |
| <span id="538">538</span> |
| <span id="539">539</span> |
| <span id="540">540</span> |
| <span id="541">541</span> |
| <span id="542">542</span> |
| <span id="543">543</span> |
| <span id="544">544</span> |
| <span id="545">545</span> |
| <span id="546">546</span> |
| <span id="547">547</span> |
| <span id="548">548</span> |
| <span id="549">549</span> |
| <span id="550">550</span> |
| <span id="551">551</span> |
| <span id="552">552</span> |
| <span id="553">553</span> |
| <span id="554">554</span> |
| <span id="555">555</span> |
| <span id="556">556</span> |
| <span id="557">557</span> |
| <span id="558">558</span> |
| <span id="559">559</span> |
| <span id="560">560</span> |
| <span id="561">561</span> |
| <span id="562">562</span> |
| <span id="563">563</span> |
| <span id="564">564</span> |
| <span id="565">565</span> |
| <span id="566">566</span> |
| <span id="567">567</span> |
| <span id="568">568</span> |
| <span id="569">569</span> |
| <span id="570">570</span> |
| <span id="571">571</span> |
| <span id="572">572</span> |
| <span id="573">573</span> |
| <span id="574">574</span> |
| <span id="575">575</span> |
| <span id="576">576</span> |
| <span id="577">577</span> |
| <span id="578">578</span> |
| <span id="579">579</span> |
| <span id="580">580</span> |
| <span id="581">581</span> |
| <span id="582">582</span> |
| <span id="583">583</span> |
| <span id="584">584</span> |
| <span id="585">585</span> |
| <span id="586">586</span> |
| <span id="587">587</span> |
| <span id="588">588</span> |
| <span id="589">589</span> |
| <span id="590">590</span> |
| <span id="591">591</span> |
| <span id="592">592</span> |
| <span id="593">593</span> |
| <span id="594">594</span> |
| <span id="595">595</span> |
| <span id="596">596</span> |
| <span id="597">597</span> |
| <span id="598">598</span> |
| <span id="599">599</span> |
| <span id="600">600</span> |
| <span id="601">601</span> |
| <span id="602">602</span> |
| <span id="603">603</span> |
| <span id="604">604</span> |
| <span id="605">605</span> |
| <span id="606">606</span> |
| <span id="607">607</span> |
| <span id="608">608</span> |
| <span id="609">609</span> |
| <span id="610">610</span> |
| <span id="611">611</span> |
| <span id="612">612</span> |
| <span id="613">613</span> |
| <span id="614">614</span> |
| <span id="615">615</span> |
| <span id="616">616</span> |
| <span id="617">617</span> |
| <span id="618">618</span> |
| <span id="619">619</span> |
| <span id="620">620</span> |
| <span id="621">621</span> |
| <span id="622">622</span> |
| <span id="623">623</span> |
| <span id="624">624</span> |
| <span id="625">625</span> |
| <span id="626">626</span> |
| <span id="627">627</span> |
| <span id="628">628</span> |
| <span id="629">629</span> |
| <span id="630">630</span> |
| <span id="631">631</span> |
| <span id="632">632</span> |
| <span id="633">633</span> |
| <span id="634">634</span> |
| <span id="635">635</span> |
| <span id="636">636</span> |
| <span id="637">637</span> |
| <span id="638">638</span> |
| <span id="639">639</span> |
| <span id="640">640</span> |
| <span id="641">641</span> |
| <span id="642">642</span> |
| <span id="643">643</span> |
| <span id="644">644</span> |
| <span id="645">645</span> |
| <span id="646">646</span> |
| <span id="647">647</span> |
| <span id="648">648</span> |
| <span id="649">649</span> |
| <span id="650">650</span> |
| <span id="651">651</span> |
| <span id="652">652</span> |
| <span id="653">653</span> |
| <span id="654">654</span> |
| <span id="655">655</span> |
| <span id="656">656</span> |
| <span id="657">657</span> |
| <span id="658">658</span> |
| <span id="659">659</span> |
| <span id="660">660</span> |
| <span id="661">661</span> |
| <span id="662">662</span> |
| <span id="663">663</span> |
| <span id="664">664</span> |
| <span id="665">665</span> |
| <span id="666">666</span> |
| <span id="667">667</span> |
| <span id="668">668</span> |
| <span id="669">669</span> |
| <span id="670">670</span> |
| <span id="671">671</span> |
| <span id="672">672</span> |
| <span id="673">673</span> |
| <span id="674">674</span> |
| <span id="675">675</span> |
| <span id="676">676</span> |
| <span id="677">677</span> |
| <span id="678">678</span> |
| <span id="679">679</span> |
| <span id="680">680</span> |
| <span id="681">681</span> |
| <span id="682">682</span> |
| <span id="683">683</span> |
| <span id="684">684</span> |
| <span id="685">685</span> |
| <span id="686">686</span> |
| <span id="687">687</span> |
| <span id="688">688</span> |
| <span id="689">689</span> |
| <span id="690">690</span> |
| <span id="691">691</span> |
| <span id="692">692</span> |
| <span id="693">693</span> |
| <span id="694">694</span> |
| <span id="695">695</span> |
| <span id="696">696</span> |
| <span id="697">697</span> |
| <span id="698">698</span> |
| <span id="699">699</span> |
| <span id="700">700</span> |
| <span id="701">701</span> |
| <span id="702">702</span> |
| <span id="703">703</span> |
| <span id="704">704</span> |
| <span id="705">705</span> |
| <span id="706">706</span> |
| <span id="707">707</span> |
| <span id="708">708</span> |
| <span id="709">709</span> |
| <span id="710">710</span> |
| <span id="711">711</span> |
| <span id="712">712</span> |
| <span id="713">713</span> |
| <span id="714">714</span> |
| <span id="715">715</span> |
| <span id="716">716</span> |
| <span id="717">717</span> |
| <span id="718">718</span> |
| <span id="719">719</span> |
| <span id="720">720</span> |
| </pre><pre class="rust"><code><span class="kw">use </span><span class="kw">crate</span>::Stream; |
| |
| <span class="kw">use </span>std::borrow::Borrow; |
| <span class="kw">use </span>std::hash::Hash; |
| <span class="kw">use </span>std::pin::Pin; |
| <span class="kw">use </span>std::task::{Context, Poll}; |
| |
| <span class="doccomment">/// Combine many streams into one, indexing each source stream with a unique |
| /// key. |
| /// |
| /// `StreamMap` is similar to [`StreamExt::merge`] in that it combines source |
| /// streams into a single merged stream that yields values in the order that |
| /// they arrive from the source streams. However, `StreamMap` has a lot more |
| /// flexibility in usage patterns. |
| /// |
| /// `StreamMap` can: |
| /// |
| /// * Merge an arbitrary number of streams. |
| /// * Track which source stream the value was received from. |
| /// * Handle inserting and removing streams from the set of managed streams at |
| /// any point during iteration. |
| /// |
| /// All source streams held by `StreamMap` are indexed using a key. This key is |
| /// included with the value when a source stream yields a value. The key is also |
| /// used to remove the stream from the `StreamMap` before the stream has |
| /// completed streaming. |
| /// |
| /// # `Unpin` |
| /// |
| /// Because the `StreamMap` API moves streams during runtime, both streams and |
| /// keys must be `Unpin`. In order to insert a `!Unpin` stream into a |
| /// `StreamMap`, use [`pin!`] to pin the stream to the stack or [`Box::pin`] to |
| /// pin the stream in the heap. |
| /// |
| /// # Implementation |
| /// |
| /// `StreamMap` is backed by a `Vec<(K, V)>`. There is no guarantee that this |
| /// internal implementation detail will persist in future versions, but it is |
| /// important to know the runtime implications. In general, `StreamMap` works |
| /// best with a "smallish" number of streams as all entries are scanned on |
| /// insert, remove, and polling. In cases where a large number of streams need |
| /// to be merged, it may be advisable to use tasks sending values on a shared |
| /// [`mpsc`] channel. |
| /// |
| /// # Notes |
| /// |
| /// `StreamMap` removes finished streams automatically, without alerting the user. |
| /// In some scenarios, the caller would want to know on closed streams. |
| /// To do this, use [`StreamNotifyClose`] as a wrapper to your stream. |
| /// It will return None when the stream is closed. |
| /// |
| /// [`StreamExt::merge`]: crate::StreamExt::merge |
| /// [`mpsc`]: https://docs.rs/tokio/1.0/tokio/sync/mpsc/index.html |
| /// [`pin!`]: https://docs.rs/tokio/1.0/tokio/macro.pin.html |
| /// [`Box::pin`]: std::boxed::Box::pin |
| /// [`StreamNotifyClose`]: crate::StreamNotifyClose |
| /// |
| /// # Examples |
| /// |
| /// Merging two streams, then remove them after receiving the first value |
| /// |
| /// ``` |
| /// use tokio_stream::{StreamExt, StreamMap, Stream}; |
| /// use tokio::sync::mpsc; |
| /// use std::pin::Pin; |
| /// |
| /// #[tokio::main] |
| /// async fn main() { |
| /// let (tx1, mut rx1) = mpsc::channel::<usize>(10); |
| /// let (tx2, mut rx2) = mpsc::channel::<usize>(10); |
| /// |
| /// // Convert the channels to a `Stream`. |
| /// let rx1 = Box::pin(async_stream::stream! { |
| /// while let Some(item) = rx1.recv().await { |
| /// yield item; |
| /// } |
| /// }) as Pin<Box<dyn Stream<Item = usize> + Send>>; |
| /// |
| /// let rx2 = Box::pin(async_stream::stream! { |
| /// while let Some(item) = rx2.recv().await { |
| /// yield item; |
| /// } |
| /// }) as Pin<Box<dyn Stream<Item = usize> + Send>>; |
| /// |
| /// tokio::spawn(async move { |
| /// tx1.send(1).await.unwrap(); |
| /// |
| /// // This value will never be received. The send may or may not return |
| /// // `Err` depending on if the remote end closed first or not. |
| /// let _ = tx1.send(2).await; |
| /// }); |
| /// |
| /// tokio::spawn(async move { |
| /// tx2.send(3).await.unwrap(); |
| /// let _ = tx2.send(4).await; |
| /// }); |
| /// |
| /// let mut map = StreamMap::new(); |
| /// |
| /// // Insert both streams |
| /// map.insert("one", rx1); |
| /// map.insert("two", rx2); |
| /// |
| /// // Read twice |
| /// for _ in 0..2 { |
| /// let (key, val) = map.next().await.unwrap(); |
| /// |
| /// if key == "one" { |
| /// assert_eq!(val, 1); |
| /// } else { |
| /// assert_eq!(val, 3); |
| /// } |
| /// |
| /// // Remove the stream to prevent reading the next value |
| /// map.remove(key); |
| /// } |
| /// } |
| /// ``` |
| /// |
| /// This example models a read-only client to a chat system with channels. The |
| /// client sends commands to join and leave channels. `StreamMap` is used to |
| /// manage active channel subscriptions. |
| /// |
| /// For simplicity, messages are displayed with `println!`, but they could be |
| /// sent to the client over a socket. |
| /// |
| /// ```no_run |
| /// use tokio_stream::{Stream, StreamExt, StreamMap}; |
| /// |
| /// enum Command { |
| /// Join(String), |
| /// Leave(String), |
| /// } |
| /// |
| /// fn commands() -> impl Stream<Item = Command> { |
| /// // Streams in user commands by parsing `stdin`. |
| /// # tokio_stream::pending() |
| /// } |
| /// |
| /// // Join a channel, returns a stream of messages received on the channel. |
| /// fn join(channel: &str) -> impl Stream<Item = String> + Unpin { |
| /// // left as an exercise to the reader |
| /// # tokio_stream::pending() |
| /// } |
| /// |
| /// #[tokio::main] |
| /// async fn main() { |
| /// let mut channels = StreamMap::new(); |
| /// |
| /// // Input commands (join / leave channels). |
| /// let cmds = commands(); |
| /// tokio::pin!(cmds); |
| /// |
| /// loop { |
| /// tokio::select! { |
| /// Some(cmd) = cmds.next() => { |
| /// match cmd { |
| /// Command::Join(chan) => { |
| /// // Join the channel and add it to the `channels` |
| /// // stream map |
| /// let msgs = join(&chan); |
| /// channels.insert(chan, msgs); |
| /// } |
| /// Command::Leave(chan) => { |
| /// channels.remove(&chan); |
| /// } |
| /// } |
| /// } |
| /// Some((chan, msg)) = channels.next() => { |
| /// // Received a message, display it on stdout with the channel |
| /// // it originated from. |
| /// println!("{}: {}", chan, msg); |
| /// } |
| /// // Both the `commands` stream and the `channels` stream are |
| /// // complete. There is no more work to do, so leave the loop. |
| /// else => break, |
| /// } |
| /// } |
| /// } |
| /// ``` |
| /// |
| /// Using `StreamNotifyClose` to handle closed streams with `StreamMap`. |
| /// |
| /// ``` |
| /// use tokio_stream::{StreamExt, StreamMap, StreamNotifyClose}; |
| /// |
| /// #[tokio::main] |
| /// async fn main() { |
| /// let mut map = StreamMap::new(); |
| /// let stream = StreamNotifyClose::new(tokio_stream::iter(vec![0, 1])); |
| /// let stream2 = StreamNotifyClose::new(tokio_stream::iter(vec![0, 1])); |
| /// map.insert(0, stream); |
| /// map.insert(1, stream2); |
| /// while let Some((key, val)) = map.next().await { |
| /// match val { |
| /// Some(val) => println!("got {val:?} from stream {key:?}"), |
| /// None => println!("stream {key:?} closed"), |
| /// } |
| /// } |
| /// } |
| /// ``` |
| |
| </span><span class="attribute">#[derive(Debug)] |
| </span><span class="kw">pub struct </span>StreamMap<K, V> { |
| <span class="doccomment">/// Streams stored in the map |
| </span>entries: Vec<(K, V)>, |
| } |
| |
| <span class="kw">impl</span><K, V> StreamMap<K, V> { |
| <span class="doccomment">/// An iterator visiting all key-value pairs in arbitrary order. |
| /// |
| /// The iterator element type is &'a (K, V). |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use tokio_stream::{StreamMap, pending}; |
| /// |
| /// let mut map = StreamMap::new(); |
| /// |
| /// map.insert("a", pending::<i32>()); |
| /// map.insert("b", pending()); |
| /// map.insert("c", pending()); |
| /// |
| /// for (key, stream) in map.iter() { |
| /// println!("({}, {:?})", key, stream); |
| /// } |
| /// ``` |
| </span><span class="kw">pub fn </span>iter(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="kw">impl </span>Iterator<Item = <span class="kw-2">&</span>(K, V)> { |
| <span class="self">self</span>.entries.iter() |
| } |
| |
| <span class="doccomment">/// An iterator visiting all key-value pairs mutably in arbitrary order. |
| /// |
| /// The iterator element type is &'a mut (K, V). |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use tokio_stream::{StreamMap, pending}; |
| /// |
| /// let mut map = StreamMap::new(); |
| /// |
| /// map.insert("a", pending::<i32>()); |
| /// map.insert("b", pending()); |
| /// map.insert("c", pending()); |
| /// |
| /// for (key, stream) in map.iter_mut() { |
| /// println!("({}, {:?})", key, stream); |
| /// } |
| /// ``` |
| </span><span class="kw">pub fn </span>iter_mut(<span class="kw-2">&mut </span><span class="self">self</span>) -> <span class="kw">impl </span>Iterator<Item = <span class="kw-2">&mut </span>(K, V)> { |
| <span class="self">self</span>.entries.iter_mut() |
| } |
| |
| <span class="doccomment">/// Creates an empty `StreamMap`. |
| /// |
| /// The stream map is initially created with a capacity of `0`, so it will |
| /// not allocate until it is first inserted into. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use tokio_stream::{StreamMap, Pending}; |
| /// |
| /// let map: StreamMap<&str, Pending<()>> = StreamMap::new(); |
| /// ``` |
| </span><span class="kw">pub fn </span>new() -> StreamMap<K, V> { |
| StreamMap { entries: <span class="macro">vec!</span>[] } |
| } |
| |
| <span class="doccomment">/// Creates an empty `StreamMap` with the specified capacity. |
| /// |
| /// The stream map will be able to hold at least `capacity` elements without |
| /// reallocating. If `capacity` is 0, the stream map will not allocate. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use tokio_stream::{StreamMap, Pending}; |
| /// |
| /// let map: StreamMap<&str, Pending<()>> = StreamMap::with_capacity(10); |
| /// ``` |
| </span><span class="kw">pub fn </span>with_capacity(capacity: usize) -> StreamMap<K, V> { |
| StreamMap { |
| entries: Vec::with_capacity(capacity), |
| } |
| } |
| |
| <span class="doccomment">/// Returns an iterator visiting all keys in arbitrary order. |
| /// |
| /// The iterator element type is &'a K. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use tokio_stream::{StreamMap, pending}; |
| /// |
| /// let mut map = StreamMap::new(); |
| /// |
| /// map.insert("a", pending::<i32>()); |
| /// map.insert("b", pending()); |
| /// map.insert("c", pending()); |
| /// |
| /// for key in map.keys() { |
| /// println!("{}", key); |
| /// } |
| /// ``` |
| </span><span class="kw">pub fn </span>keys(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="kw">impl </span>Iterator<Item = <span class="kw-2">&</span>K> { |
| <span class="self">self</span>.iter().map(|(k, <span class="kw">_</span>)| k) |
| } |
| |
| <span class="doccomment">/// An iterator visiting all values in arbitrary order. |
| /// |
| /// The iterator element type is &'a V. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use tokio_stream::{StreamMap, pending}; |
| /// |
| /// let mut map = StreamMap::new(); |
| /// |
| /// map.insert("a", pending::<i32>()); |
| /// map.insert("b", pending()); |
| /// map.insert("c", pending()); |
| /// |
| /// for stream in map.values() { |
| /// println!("{:?}", stream); |
| /// } |
| /// ``` |
| </span><span class="kw">pub fn </span>values(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="kw">impl </span>Iterator<Item = <span class="kw-2">&</span>V> { |
| <span class="self">self</span>.iter().map(|(<span class="kw">_</span>, v)| v) |
| } |
| |
| <span class="doccomment">/// An iterator visiting all values mutably in arbitrary order. |
| /// |
| /// The iterator element type is &'a mut V. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use tokio_stream::{StreamMap, pending}; |
| /// |
| /// let mut map = StreamMap::new(); |
| /// |
| /// map.insert("a", pending::<i32>()); |
| /// map.insert("b", pending()); |
| /// map.insert("c", pending()); |
| /// |
| /// for stream in map.values_mut() { |
| /// println!("{:?}", stream); |
| /// } |
| /// ``` |
| </span><span class="kw">pub fn </span>values_mut(<span class="kw-2">&mut </span><span class="self">self</span>) -> <span class="kw">impl </span>Iterator<Item = <span class="kw-2">&mut </span>V> { |
| <span class="self">self</span>.iter_mut().map(|(<span class="kw">_</span>, v)| v) |
| } |
| |
| <span class="doccomment">/// Returns the number of streams the map can hold without reallocating. |
| /// |
| /// This number is a lower bound; the `StreamMap` might be able to hold |
| /// more, but is guaranteed to be able to hold at least this many. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use tokio_stream::{StreamMap, Pending}; |
| /// |
| /// let map: StreamMap<i32, Pending<()>> = StreamMap::with_capacity(100); |
| /// assert!(map.capacity() >= 100); |
| /// ``` |
| </span><span class="kw">pub fn </span>capacity(<span class="kw-2">&</span><span class="self">self</span>) -> usize { |
| <span class="self">self</span>.entries.capacity() |
| } |
| |
| <span class="doccomment">/// Returns the number of streams in the map. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use tokio_stream::{StreamMap, pending}; |
| /// |
| /// let mut a = StreamMap::new(); |
| /// assert_eq!(a.len(), 0); |
| /// a.insert(1, pending::<i32>()); |
| /// assert_eq!(a.len(), 1); |
| /// ``` |
| </span><span class="kw">pub fn </span>len(<span class="kw-2">&</span><span class="self">self</span>) -> usize { |
| <span class="self">self</span>.entries.len() |
| } |
| |
| <span class="doccomment">/// Returns `true` if the map contains no elements. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use tokio_stream::{StreamMap, pending}; |
| /// |
| /// let mut a = StreamMap::new(); |
| /// assert!(a.is_empty()); |
| /// a.insert(1, pending::<i32>()); |
| /// assert!(!a.is_empty()); |
| /// ``` |
| </span><span class="kw">pub fn </span>is_empty(<span class="kw-2">&</span><span class="self">self</span>) -> bool { |
| <span class="self">self</span>.entries.is_empty() |
| } |
| |
| <span class="doccomment">/// Clears the map, removing all key-stream pairs. Keeps the allocated |
| /// memory for reuse. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use tokio_stream::{StreamMap, pending}; |
| /// |
| /// let mut a = StreamMap::new(); |
| /// a.insert(1, pending::<i32>()); |
| /// a.clear(); |
| /// assert!(a.is_empty()); |
| /// ``` |
| </span><span class="kw">pub fn </span>clear(<span class="kw-2">&mut </span><span class="self">self</span>) { |
| <span class="self">self</span>.entries.clear(); |
| } |
| |
| <span class="doccomment">/// Insert a key-stream pair into the map. |
| /// |
| /// If the map did not have this key present, `None` is returned. |
| /// |
| /// If the map did have this key present, the new `stream` replaces the old |
| /// one and the old stream is returned. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use tokio_stream::{StreamMap, pending}; |
| /// |
| /// let mut map = StreamMap::new(); |
| /// |
| /// assert!(map.insert(37, pending::<i32>()).is_none()); |
| /// assert!(!map.is_empty()); |
| /// |
| /// map.insert(37, pending()); |
| /// assert!(map.insert(37, pending()).is_some()); |
| /// ``` |
| </span><span class="kw">pub fn </span>insert(<span class="kw-2">&mut </span><span class="self">self</span>, k: K, stream: V) -> <span class="prelude-ty">Option</span><V> |
| <span class="kw">where |
| </span>K: Hash + Eq, |
| { |
| <span class="kw">let </span>ret = <span class="self">self</span>.remove(<span class="kw-2">&</span>k); |
| <span class="self">self</span>.entries.push((k, stream)); |
| |
| ret |
| } |
| |
| <span class="doccomment">/// Removes a key from the map, returning the stream at the key if the key was previously in the map. |
| /// |
| /// The key may be any borrowed form of the map's key type, but `Hash` and |
| /// `Eq` on the borrowed form must match those for the key type. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use tokio_stream::{StreamMap, pending}; |
| /// |
| /// let mut map = StreamMap::new(); |
| /// map.insert(1, pending::<i32>()); |
| /// assert!(map.remove(&1).is_some()); |
| /// assert!(map.remove(&1).is_none()); |
| /// ``` |
| </span><span class="kw">pub fn </span>remove<Q: <span class="question-mark">?</span>Sized>(<span class="kw-2">&mut </span><span class="self">self</span>, k: <span class="kw-2">&</span>Q) -> <span class="prelude-ty">Option</span><V> |
| <span class="kw">where |
| </span>K: Borrow<Q>, |
| Q: Hash + Eq, |
| { |
| <span class="kw">for </span>i <span class="kw">in </span><span class="number">0</span>..<span class="self">self</span>.entries.len() { |
| <span class="kw">if </span><span class="self">self</span>.entries[i].<span class="number">0</span>.borrow() == k { |
| <span class="kw">return </span><span class="prelude-val">Some</span>(<span class="self">self</span>.entries.swap_remove(i).<span class="number">1</span>); |
| } |
| } |
| |
| <span class="prelude-val">None |
| </span>} |
| |
| <span class="doccomment">/// Returns `true` if the map contains a stream for the specified key. |
| /// |
| /// The key may be any borrowed form of the map's key type, but `Hash` and |
| /// `Eq` on the borrowed form must match those for the key type. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use tokio_stream::{StreamMap, pending}; |
| /// |
| /// let mut map = StreamMap::new(); |
| /// map.insert(1, pending::<i32>()); |
| /// assert_eq!(map.contains_key(&1), true); |
| /// assert_eq!(map.contains_key(&2), false); |
| /// ``` |
| </span><span class="kw">pub fn </span>contains_key<Q: <span class="question-mark">?</span>Sized>(<span class="kw-2">&</span><span class="self">self</span>, k: <span class="kw-2">&</span>Q) -> bool |
| <span class="kw">where |
| </span>K: Borrow<Q>, |
| Q: Hash + Eq, |
| { |
| <span class="kw">for </span>i <span class="kw">in </span><span class="number">0</span>..<span class="self">self</span>.entries.len() { |
| <span class="kw">if </span><span class="self">self</span>.entries[i].<span class="number">0</span>.borrow() == k { |
| <span class="kw">return </span><span class="bool-val">true</span>; |
| } |
| } |
| |
| <span class="bool-val">false |
| </span>} |
| } |
| |
| <span class="kw">impl</span><K, V> StreamMap<K, V> |
| <span class="kw">where |
| </span>K: Unpin, |
| V: Stream + Unpin, |
| { |
| <span class="doccomment">/// Polls the next value, includes the vec entry index |
| </span><span class="kw">fn </span>poll_next_entry(<span class="kw-2">&mut </span><span class="self">self</span>, cx: <span class="kw-2">&mut </span>Context<<span class="lifetime">'_</span>>) -> Poll<<span class="prelude-ty">Option</span><(usize, V::Item)>> { |
| <span class="kw">use </span>Poll::<span class="kw-2">*</span>; |
| |
| <span class="kw">let </span>start = <span class="self">self</span>::rand::thread_rng_n(<span class="self">self</span>.entries.len() <span class="kw">as </span>u32) <span class="kw">as </span>usize; |
| <span class="kw">let </span><span class="kw-2">mut </span>idx = start; |
| |
| <span class="kw">for _ in </span><span class="number">0</span>..<span class="self">self</span>.entries.len() { |
| <span class="kw">let </span>(<span class="kw">_</span>, stream) = <span class="kw-2">&mut </span><span class="self">self</span>.entries[idx]; |
| |
| <span class="kw">match </span>Pin::new(stream).poll_next(cx) { |
| Ready(<span class="prelude-val">Some</span>(val)) => <span class="kw">return </span>Ready(<span class="prelude-val">Some</span>((idx, val))), |
| Ready(<span class="prelude-val">None</span>) => { |
| <span class="comment">// Remove the entry |
| </span><span class="self">self</span>.entries.swap_remove(idx); |
| |
| <span class="comment">// Check if this was the last entry, if so the cursor needs |
| // to wrap |
| </span><span class="kw">if </span>idx == <span class="self">self</span>.entries.len() { |
| idx = <span class="number">0</span>; |
| } <span class="kw">else if </span>idx < start && start <= <span class="self">self</span>.entries.len() { |
| <span class="comment">// The stream being swapped into the current index has |
| // already been polled, so skip it. |
| </span>idx = idx.wrapping_add(<span class="number">1</span>) % <span class="self">self</span>.entries.len(); |
| } |
| } |
| Pending => { |
| idx = idx.wrapping_add(<span class="number">1</span>) % <span class="self">self</span>.entries.len(); |
| } |
| } |
| } |
| |
| <span class="comment">// If the map is empty, then the stream is complete. |
| </span><span class="kw">if </span><span class="self">self</span>.entries.is_empty() { |
| Ready(<span class="prelude-val">None</span>) |
| } <span class="kw">else </span>{ |
| Pending |
| } |
| } |
| } |
| |
| <span class="kw">impl</span><K, V> Default <span class="kw">for </span>StreamMap<K, V> { |
| <span class="kw">fn </span>default() -> <span class="self">Self </span>{ |
| <span class="self">Self</span>::new() |
| } |
| } |
| |
| <span class="kw">impl</span><K, V> Stream <span class="kw">for </span>StreamMap<K, V> |
| <span class="kw">where |
| </span>K: Clone + Unpin, |
| V: Stream + Unpin, |
| { |
| <span class="kw">type </span>Item = (K, V::Item); |
| |
| <span class="kw">fn </span>poll_next(<span class="kw-2">mut </span><span class="self">self</span>: Pin<<span class="kw-2">&mut </span><span class="self">Self</span>>, cx: <span class="kw-2">&mut </span>Context<<span class="lifetime">'_</span>>) -> Poll<<span class="prelude-ty">Option</span><<span class="self">Self</span>::Item>> { |
| <span class="kw">if let </span><span class="prelude-val">Some</span>((idx, val)) = <span class="macro">ready!</span>(<span class="self">self</span>.poll_next_entry(cx)) { |
| <span class="kw">let </span>key = <span class="self">self</span>.entries[idx].<span class="number">0</span>.clone(); |
| Poll::Ready(<span class="prelude-val">Some</span>((key, val))) |
| } <span class="kw">else </span>{ |
| Poll::Ready(<span class="prelude-val">None</span>) |
| } |
| } |
| |
| <span class="kw">fn </span>size_hint(<span class="kw-2">&</span><span class="self">self</span>) -> (usize, <span class="prelude-ty">Option</span><usize>) { |
| <span class="kw">let </span><span class="kw-2">mut </span>ret = (<span class="number">0</span>, <span class="prelude-val">Some</span>(<span class="number">0</span>)); |
| |
| <span class="kw">for </span>(<span class="kw">_</span>, stream) <span class="kw">in </span><span class="kw-2">&</span><span class="self">self</span>.entries { |
| <span class="kw">let </span>hint = stream.size_hint(); |
| |
| ret.<span class="number">0 </span>+= hint.<span class="number">0</span>; |
| |
| <span class="kw">match </span>(ret.<span class="number">1</span>, hint.<span class="number">1</span>) { |
| (<span class="prelude-val">Some</span>(a), <span class="prelude-val">Some</span>(b)) => ret.<span class="number">1 </span>= <span class="prelude-val">Some</span>(a + b), |
| (<span class="prelude-val">Some</span>(<span class="kw">_</span>), <span class="prelude-val">None</span>) => ret.<span class="number">1 </span>= <span class="prelude-val">None</span>, |
| <span class="kw">_ </span>=> {} |
| } |
| } |
| |
| ret |
| } |
| } |
| |
| <span class="kw">impl</span><K, V> FromIterator<(K, V)> <span class="kw">for </span>StreamMap<K, V> |
| <span class="kw">where |
| </span>K: Hash + Eq, |
| { |
| <span class="kw">fn </span>from_iter<T: IntoIterator<Item = (K, V)>>(iter: T) -> <span class="self">Self </span>{ |
| <span class="kw">let </span>iterator = iter.into_iter(); |
| <span class="kw">let </span>(lower_bound, <span class="kw">_</span>) = iterator.size_hint(); |
| <span class="kw">let </span><span class="kw-2">mut </span>stream_map = <span class="self">Self</span>::with_capacity(lower_bound); |
| |
| <span class="kw">for </span>(key, value) <span class="kw">in </span>iterator { |
| stream_map.insert(key, value); |
| } |
| |
| stream_map |
| } |
| } |
| |
| <span class="kw">impl</span><K, V> Extend<(K, V)> <span class="kw">for </span>StreamMap<K, V> { |
| <span class="kw">fn </span>extend<T>(<span class="kw-2">&mut </span><span class="self">self</span>, iter: T) |
| <span class="kw">where |
| </span>T: IntoIterator<Item = (K, V)>, |
| { |
| <span class="self">self</span>.entries.extend(iter); |
| } |
| } |
| |
| <span class="kw">mod </span>rand { |
| <span class="kw">use </span>std::cell::Cell; |
| |
| <span class="kw">mod </span>loom { |
| <span class="attribute">#[cfg(not(loom))] |
| </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">mod </span>rand { |
| <span class="kw">use </span>std::collections::hash_map::RandomState; |
| <span class="kw">use </span>std::hash::{BuildHasher, Hash, Hasher}; |
| <span class="kw">use </span>std::sync::atomic::AtomicU32; |
| <span class="kw">use </span>std::sync::atomic::Ordering::Relaxed; |
| |
| <span class="kw">static </span>COUNTER: AtomicU32 = AtomicU32::new(<span class="number">1</span>); |
| |
| <span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>seed() -> u64 { |
| <span class="kw">let </span>rand_state = RandomState::new(); |
| |
| <span class="kw">let </span><span class="kw-2">mut </span>hasher = rand_state.build_hasher(); |
| |
| <span class="comment">// Hash some unique-ish data to generate some new state |
| </span>COUNTER.fetch_add(<span class="number">1</span>, Relaxed).hash(<span class="kw-2">&mut </span>hasher); |
| |
| <span class="comment">// Get the seed |
| </span>hasher.finish() |
| } |
| } |
| |
| <span class="attribute">#[cfg(loom)] |
| </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">mod </span>rand { |
| <span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>seed() -> u64 { |
| <span class="number">1 |
| </span>} |
| } |
| } |
| |
| <span class="doccomment">/// Fast random number generate |
| /// |
| /// Implement xorshift64+: 2 32-bit xorshift sequences added together. |
| /// Shift triplet `[17,7,16]` was calculated as indicated in Marsaglia's |
| /// Xorshift paper: <https://www.jstatsoft.org/article/view/v008i14/xorshift.pdf> |
| /// This generator passes the SmallCrush suite, part of TestU01 framework: |
| /// <http://simul.iro.umontreal.ca/testu01/tu01.html> |
| </span><span class="attribute">#[derive(Debug)] |
| </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">struct </span>FastRand { |
| one: Cell<u32>, |
| two: Cell<u32>, |
| } |
| |
| <span class="kw">impl </span>FastRand { |
| <span class="doccomment">/// Initialize a new, thread-local, fast random number generator. |
| </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>new(seed: u64) -> FastRand { |
| <span class="kw">let </span>one = (seed >> <span class="number">32</span>) <span class="kw">as </span>u32; |
| <span class="kw">let </span><span class="kw-2">mut </span>two = seed <span class="kw">as </span>u32; |
| |
| <span class="kw">if </span>two == <span class="number">0 </span>{ |
| <span class="comment">// This value cannot be zero |
| </span>two = <span class="number">1</span>; |
| } |
| |
| FastRand { |
| one: Cell::new(one), |
| two: Cell::new(two), |
| } |
| } |
| |
| <span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>fastrand_n(<span class="kw-2">&</span><span class="self">self</span>, n: u32) -> u32 { |
| <span class="comment">// This is similar to fastrand() % n, but faster. |
| // See https://lemire.me/blog/2016/06/27/a-fast-alternative-to-the-modulo-reduction/ |
| </span><span class="kw">let </span>mul = (<span class="self">self</span>.fastrand() <span class="kw">as </span>u64).wrapping_mul(n <span class="kw">as </span>u64); |
| (mul >> <span class="number">32</span>) <span class="kw">as </span>u32 |
| } |
| |
| <span class="kw">fn </span>fastrand(<span class="kw-2">&</span><span class="self">self</span>) -> u32 { |
| <span class="kw">let </span><span class="kw-2">mut </span>s1 = <span class="self">self</span>.one.get(); |
| <span class="kw">let </span>s0 = <span class="self">self</span>.two.get(); |
| |
| s1 ^= s1 << <span class="number">17</span>; |
| s1 = s1 ^ s0 ^ s1 >> <span class="number">7 </span>^ s0 >> <span class="number">16</span>; |
| |
| <span class="self">self</span>.one.set(s0); |
| <span class="self">self</span>.two.set(s1); |
| |
| s0.wrapping_add(s1) |
| } |
| } |
| |
| <span class="comment">// Used by `StreamMap` |
| </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>thread_rng_n(n: u32) -> u32 { |
| <span class="macro">thread_local! </span>{ |
| <span class="kw">static </span>THREAD_RNG: FastRand = FastRand::new(loom::rand::seed()); |
| } |
| |
| THREAD_RNG.with(|rng| rng.fastrand_n(n)) |
| } |
| } |
| </code></pre></div> |
| </section></div></main><div id="rustdoc-vars" data-root-path="../../" data-current-crate="tokio_stream" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |