| <!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/memchr-2.5.0/src/memmem/twoway.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>twoway.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="../../../memchr/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="../../../memchr/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> |
| <span id="721">721</span> |
| <span id="722">722</span> |
| <span id="723">723</span> |
| <span id="724">724</span> |
| <span id="725">725</span> |
| <span id="726">726</span> |
| <span id="727">727</span> |
| <span id="728">728</span> |
| <span id="729">729</span> |
| <span id="730">730</span> |
| <span id="731">731</span> |
| <span id="732">732</span> |
| <span id="733">733</span> |
| <span id="734">734</span> |
| <span id="735">735</span> |
| <span id="736">736</span> |
| <span id="737">737</span> |
| <span id="738">738</span> |
| <span id="739">739</span> |
| <span id="740">740</span> |
| <span id="741">741</span> |
| <span id="742">742</span> |
| <span id="743">743</span> |
| <span id="744">744</span> |
| <span id="745">745</span> |
| <span id="746">746</span> |
| <span id="747">747</span> |
| <span id="748">748</span> |
| <span id="749">749</span> |
| <span id="750">750</span> |
| <span id="751">751</span> |
| <span id="752">752</span> |
| <span id="753">753</span> |
| <span id="754">754</span> |
| <span id="755">755</span> |
| <span id="756">756</span> |
| <span id="757">757</span> |
| <span id="758">758</span> |
| <span id="759">759</span> |
| <span id="760">760</span> |
| <span id="761">761</span> |
| <span id="762">762</span> |
| <span id="763">763</span> |
| <span id="764">764</span> |
| <span id="765">765</span> |
| <span id="766">766</span> |
| <span id="767">767</span> |
| <span id="768">768</span> |
| <span id="769">769</span> |
| <span id="770">770</span> |
| <span id="771">771</span> |
| <span id="772">772</span> |
| <span id="773">773</span> |
| <span id="774">774</span> |
| <span id="775">775</span> |
| <span id="776">776</span> |
| <span id="777">777</span> |
| <span id="778">778</span> |
| <span id="779">779</span> |
| <span id="780">780</span> |
| <span id="781">781</span> |
| <span id="782">782</span> |
| <span id="783">783</span> |
| <span id="784">784</span> |
| <span id="785">785</span> |
| <span id="786">786</span> |
| <span id="787">787</span> |
| <span id="788">788</span> |
| <span id="789">789</span> |
| <span id="790">790</span> |
| <span id="791">791</span> |
| <span id="792">792</span> |
| <span id="793">793</span> |
| <span id="794">794</span> |
| <span id="795">795</span> |
| <span id="796">796</span> |
| <span id="797">797</span> |
| <span id="798">798</span> |
| <span id="799">799</span> |
| <span id="800">800</span> |
| <span id="801">801</span> |
| <span id="802">802</span> |
| <span id="803">803</span> |
| <span id="804">804</span> |
| <span id="805">805</span> |
| <span id="806">806</span> |
| <span id="807">807</span> |
| <span id="808">808</span> |
| <span id="809">809</span> |
| <span id="810">810</span> |
| <span id="811">811</span> |
| <span id="812">812</span> |
| <span id="813">813</span> |
| <span id="814">814</span> |
| <span id="815">815</span> |
| <span id="816">816</span> |
| <span id="817">817</span> |
| <span id="818">818</span> |
| <span id="819">819</span> |
| <span id="820">820</span> |
| <span id="821">821</span> |
| <span id="822">822</span> |
| <span id="823">823</span> |
| <span id="824">824</span> |
| <span id="825">825</span> |
| <span id="826">826</span> |
| <span id="827">827</span> |
| <span id="828">828</span> |
| <span id="829">829</span> |
| <span id="830">830</span> |
| <span id="831">831</span> |
| <span id="832">832</span> |
| <span id="833">833</span> |
| <span id="834">834</span> |
| <span id="835">835</span> |
| <span id="836">836</span> |
| <span id="837">837</span> |
| <span id="838">838</span> |
| <span id="839">839</span> |
| <span id="840">840</span> |
| <span id="841">841</span> |
| <span id="842">842</span> |
| <span id="843">843</span> |
| <span id="844">844</span> |
| <span id="845">845</span> |
| <span id="846">846</span> |
| <span id="847">847</span> |
| <span id="848">848</span> |
| <span id="849">849</span> |
| <span id="850">850</span> |
| <span id="851">851</span> |
| <span id="852">852</span> |
| <span id="853">853</span> |
| <span id="854">854</span> |
| <span id="855">855</span> |
| <span id="856">856</span> |
| <span id="857">857</span> |
| <span id="858">858</span> |
| <span id="859">859</span> |
| <span id="860">860</span> |
| <span id="861">861</span> |
| <span id="862">862</span> |
| <span id="863">863</span> |
| <span id="864">864</span> |
| <span id="865">865</span> |
| <span id="866">866</span> |
| <span id="867">867</span> |
| <span id="868">868</span> |
| <span id="869">869</span> |
| <span id="870">870</span> |
| <span id="871">871</span> |
| <span id="872">872</span> |
| <span id="873">873</span> |
| <span id="874">874</span> |
| <span id="875">875</span> |
| <span id="876">876</span> |
| <span id="877">877</span> |
| <span id="878">878</span> |
| </pre><pre class="rust"><code><span class="kw">use </span>core::cmp; |
| |
| <span class="kw">use </span><span class="kw">crate</span>::memmem::{prefilter::Pre, util}; |
| |
| <span class="doccomment">/// Two-Way search in the forward direction. |
| </span><span class="attribute">#[derive(Clone, Copy, Debug)] |
| </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">struct </span>Forward(TwoWay); |
| |
| <span class="doccomment">/// Two-Way search in the reverse direction. |
| </span><span class="attribute">#[derive(Clone, Copy, Debug)] |
| </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">struct </span>Reverse(TwoWay); |
| |
| <span class="doccomment">/// An implementation of the TwoWay substring search algorithm, with heuristics |
| /// for accelerating search based on frequency analysis. |
| /// |
| /// This searcher supports forward and reverse search, although not |
| /// simultaneously. It runs in O(n + m) time and O(1) space, where |
| /// `n ~ len(needle)` and `m ~ len(haystack)`. |
| /// |
| /// The implementation here roughly matches that which was developed by |
| /// Crochemore and Perrin in their 1991 paper "Two-way string-matching." The |
| /// changes in this implementation are 1) the use of zero-based indices, 2) a |
| /// heuristic skip table based on the last byte (borrowed from Rust's standard |
| /// library) and 3) the addition of heuristics for a fast skip loop. That is, |
| /// (3) this will detect bytes that are believed to be rare in the needle and |
| /// use fast vectorized instructions to find their occurrences quickly. The |
| /// Two-Way algorithm is then used to confirm whether a match at that location |
| /// occurred. |
| /// |
| /// The heuristic for fast skipping is automatically shut off if it's |
| /// detected to be ineffective at search time. Generally, this only occurs in |
| /// pathological cases. But this is generally necessary in order to preserve |
| /// a `O(n + m)` time bound. |
| /// |
| /// The code below is fairly complex and not obviously correct at all. It's |
| /// likely necessary to read the Two-Way paper cited above in order to fully |
| /// grok this code. The essence of it is: |
| /// |
| /// 1) Do something to detect a "critical" position in the needle. |
| /// 2) For the current position in the haystack, look if needle[critical..] |
| /// matches at that position. |
| /// 3) If so, look if needle[..critical] matches. |
| /// 4) If a mismatch occurs, shift the search by some amount based on the |
| /// critical position and a pre-computed shift. |
| /// |
| /// This type is wrapped in Forward and Reverse types that expose consistent |
| /// forward or reverse APIs. |
| </span><span class="attribute">#[derive(Clone, Copy, Debug)] |
| </span><span class="kw">struct </span>TwoWay { |
| <span class="doccomment">/// A small bitset used as a quick prefilter (in addition to the faster |
| /// SIMD based prefilter). Namely, a bit 'i' is set if and only if b%64==i |
| /// for any b in the needle. |
| /// |
| /// When used as a prefilter, if the last byte at the current candidate |
| /// position is NOT in this set, then we can skip that entire candidate |
| /// position (the length of the needle). This is essentially the shift |
| /// trick found in Boyer-Moore, but only applied to bytes that don't appear |
| /// in the needle. |
| /// |
| /// N.B. This trick was inspired by something similar in std's |
| /// implementation of Two-Way. |
| </span>byteset: ApproximateByteSet, |
| <span class="doccomment">/// A critical position in needle. Specifically, this position corresponds |
| /// to beginning of either the minimal or maximal suffix in needle. (N.B. |
| /// See SuffixType below for why "minimal" isn't quite the correct word |
| /// here.) |
| /// |
| /// This is the position at which every search begins. Namely, search |
| /// starts by scanning text to the right of this position, and only if |
| /// there's a match does the text to the left of this position get scanned. |
| </span>critical_pos: usize, |
| <span class="doccomment">/// The amount we shift by in the Two-Way search algorithm. This |
| /// corresponds to the "small period" and "large period" cases. |
| </span>shift: Shift, |
| } |
| |
| <span class="kw">impl </span>Forward { |
| <span class="doccomment">/// Create a searcher that uses the Two-Way algorithm by searching forwards |
| /// through any haystack. |
| </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>new(needle: <span class="kw-2">&</span>[u8]) -> Forward { |
| <span class="kw">if </span>needle.is_empty() { |
| <span class="kw">return </span>Forward(TwoWay::empty()); |
| } |
| |
| <span class="kw">let </span>byteset = ApproximateByteSet::new(needle); |
| <span class="kw">let </span>min_suffix = Suffix::forward(needle, SuffixKind::Minimal); |
| <span class="kw">let </span>max_suffix = Suffix::forward(needle, SuffixKind::Maximal); |
| <span class="kw">let </span>(period_lower_bound, critical_pos) = |
| <span class="kw">if </span>min_suffix.pos > max_suffix.pos { |
| (min_suffix.period, min_suffix.pos) |
| } <span class="kw">else </span>{ |
| (max_suffix.period, max_suffix.pos) |
| }; |
| <span class="kw">let </span>shift = Shift::forward(needle, period_lower_bound, critical_pos); |
| Forward(TwoWay { byteset, critical_pos, shift }) |
| } |
| |
| <span class="doccomment">/// Find the position of the first occurrence of this searcher's needle in |
| /// the given haystack. If one does not exist, then return None. |
| /// |
| /// This accepts prefilter state that is useful when using the same |
| /// searcher multiple times, such as in an iterator. |
| /// |
| /// Callers must guarantee that the needle is non-empty and its length is |
| /// <= the haystack's length. |
| </span><span class="attribute">#[inline(always)] |
| </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>find( |
| <span class="kw-2">&</span><span class="self">self</span>, |
| pre: <span class="prelude-ty">Option</span><<span class="kw-2">&mut </span>Pre<<span class="lifetime">'_</span>>>, |
| haystack: <span class="kw-2">&</span>[u8], |
| needle: <span class="kw-2">&</span>[u8], |
| ) -> <span class="prelude-ty">Option</span><usize> { |
| <span class="macro">debug_assert!</span>(!needle.is_empty(), <span class="string">"needle should not be empty"</span>); |
| <span class="macro">debug_assert!</span>(needle.len() <= haystack.len(), <span class="string">"haystack too short"</span>); |
| |
| <span class="kw">match </span><span class="self">self</span>.<span class="number">0</span>.shift { |
| Shift::Small { period } => { |
| <span class="self">self</span>.find_small_imp(pre, haystack, needle, period) |
| } |
| Shift::Large { shift } => { |
| <span class="self">self</span>.find_large_imp(pre, haystack, needle, shift) |
| } |
| } |
| } |
| |
| <span class="doccomment">/// Like find, but handles the degenerate substring test cases. This is |
| /// only useful for conveniently testing this substring implementation in |
| /// isolation. |
| </span><span class="attribute">#[cfg(test)] |
| </span><span class="kw">fn </span>find_general( |
| <span class="kw-2">&</span><span class="self">self</span>, |
| pre: <span class="prelude-ty">Option</span><<span class="kw-2">&mut </span>Pre<<span class="lifetime">'_</span>>>, |
| haystack: <span class="kw-2">&</span>[u8], |
| needle: <span class="kw-2">&</span>[u8], |
| ) -> <span class="prelude-ty">Option</span><usize> { |
| <span class="kw">if </span>needle.is_empty() { |
| <span class="prelude-val">Some</span>(<span class="number">0</span>) |
| } <span class="kw">else if </span>haystack.len() < needle.len() { |
| <span class="prelude-val">None |
| </span>} <span class="kw">else </span>{ |
| <span class="self">self</span>.find(pre, haystack, needle) |
| } |
| } |
| |
| <span class="comment">// Each of the two search implementations below can be accelerated by a |
| // prefilter, but it is not always enabled. To avoid its overhead when |
| // its disabled, we explicitly inline each search implementation based on |
| // whether a prefilter will be used or not. The decision on which to use |
| // is made in the parent meta searcher. |
| |
| </span><span class="attribute">#[inline(always)] |
| </span><span class="kw">fn </span>find_small_imp( |
| <span class="kw-2">&</span><span class="self">self</span>, |
| <span class="kw-2">mut </span>pre: <span class="prelude-ty">Option</span><<span class="kw-2">&mut </span>Pre<<span class="lifetime">'_</span>>>, |
| haystack: <span class="kw-2">&</span>[u8], |
| needle: <span class="kw-2">&</span>[u8], |
| period: usize, |
| ) -> <span class="prelude-ty">Option</span><usize> { |
| <span class="kw">let </span>last_byte = needle.len() - <span class="number">1</span>; |
| <span class="kw">let </span><span class="kw-2">mut </span>pos = <span class="number">0</span>; |
| <span class="kw">let </span><span class="kw-2">mut </span>shift = <span class="number">0</span>; |
| <span class="kw">while </span>pos + needle.len() <= haystack.len() { |
| <span class="kw">let </span><span class="kw-2">mut </span>i = cmp::max(<span class="self">self</span>.<span class="number">0</span>.critical_pos, shift); |
| <span class="kw">if let </span><span class="prelude-val">Some</span>(pre) = pre.as_mut() { |
| <span class="kw">if </span>pre.should_call() { |
| pos += pre.call(<span class="kw-2">&</span>haystack[pos..], needle)<span class="question-mark">?</span>; |
| shift = <span class="number">0</span>; |
| i = <span class="self">self</span>.<span class="number">0</span>.critical_pos; |
| <span class="kw">if </span>pos + needle.len() > haystack.len() { |
| <span class="kw">return </span><span class="prelude-val">None</span>; |
| } |
| } |
| } |
| <span class="kw">if </span>!<span class="self">self</span>.<span class="number">0</span>.byteset.contains(haystack[pos + last_byte]) { |
| pos += needle.len(); |
| shift = <span class="number">0</span>; |
| <span class="kw">continue</span>; |
| } |
| <span class="kw">while </span>i < needle.len() && needle[i] == haystack[pos + i] { |
| i += <span class="number">1</span>; |
| } |
| <span class="kw">if </span>i < needle.len() { |
| pos += i - <span class="self">self</span>.<span class="number">0</span>.critical_pos + <span class="number">1</span>; |
| shift = <span class="number">0</span>; |
| } <span class="kw">else </span>{ |
| <span class="kw">let </span><span class="kw-2">mut </span>j = <span class="self">self</span>.<span class="number">0</span>.critical_pos; |
| <span class="kw">while </span>j > shift && needle[j] == haystack[pos + j] { |
| j -= <span class="number">1</span>; |
| } |
| <span class="kw">if </span>j <= shift && needle[shift] == haystack[pos + shift] { |
| <span class="kw">return </span><span class="prelude-val">Some</span>(pos); |
| } |
| pos += period; |
| shift = needle.len() - period; |
| } |
| } |
| <span class="prelude-val">None |
| </span>} |
| |
| <span class="attribute">#[inline(always)] |
| </span><span class="kw">fn </span>find_large_imp( |
| <span class="kw-2">&</span><span class="self">self</span>, |
| <span class="kw-2">mut </span>pre: <span class="prelude-ty">Option</span><<span class="kw-2">&mut </span>Pre<<span class="lifetime">'_</span>>>, |
| haystack: <span class="kw-2">&</span>[u8], |
| needle: <span class="kw-2">&</span>[u8], |
| shift: usize, |
| ) -> <span class="prelude-ty">Option</span><usize> { |
| <span class="kw">let </span>last_byte = needle.len() - <span class="number">1</span>; |
| <span class="kw">let </span><span class="kw-2">mut </span>pos = <span class="number">0</span>; |
| <span class="lifetime">'outer</span>: <span class="kw">while </span>pos + needle.len() <= haystack.len() { |
| <span class="kw">if let </span><span class="prelude-val">Some</span>(pre) = pre.as_mut() { |
| <span class="kw">if </span>pre.should_call() { |
| pos += pre.call(<span class="kw-2">&</span>haystack[pos..], needle)<span class="question-mark">?</span>; |
| <span class="kw">if </span>pos + needle.len() > haystack.len() { |
| <span class="kw">return </span><span class="prelude-val">None</span>; |
| } |
| } |
| } |
| |
| <span class="kw">if </span>!<span class="self">self</span>.<span class="number">0</span>.byteset.contains(haystack[pos + last_byte]) { |
| pos += needle.len(); |
| <span class="kw">continue</span>; |
| } |
| <span class="kw">let </span><span class="kw-2">mut </span>i = <span class="self">self</span>.<span class="number">0</span>.critical_pos; |
| <span class="kw">while </span>i < needle.len() && needle[i] == haystack[pos + i] { |
| i += <span class="number">1</span>; |
| } |
| <span class="kw">if </span>i < needle.len() { |
| pos += i - <span class="self">self</span>.<span class="number">0</span>.critical_pos + <span class="number">1</span>; |
| } <span class="kw">else </span>{ |
| <span class="kw">for </span>j <span class="kw">in </span>(<span class="number">0</span>..<span class="self">self</span>.<span class="number">0</span>.critical_pos).rev() { |
| <span class="kw">if </span>needle[j] != haystack[pos + j] { |
| pos += shift; |
| <span class="kw">continue </span><span class="lifetime">'outer</span>; |
| } |
| } |
| <span class="kw">return </span><span class="prelude-val">Some</span>(pos); |
| } |
| } |
| <span class="prelude-val">None |
| </span>} |
| } |
| |
| <span class="kw">impl </span>Reverse { |
| <span class="doccomment">/// Create a searcher that uses the Two-Way algorithm by searching in |
| /// reverse through any haystack. |
| </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>new(needle: <span class="kw-2">&</span>[u8]) -> Reverse { |
| <span class="kw">if </span>needle.is_empty() { |
| <span class="kw">return </span>Reverse(TwoWay::empty()); |
| } |
| |
| <span class="kw">let </span>byteset = ApproximateByteSet::new(needle); |
| <span class="kw">let </span>min_suffix = Suffix::reverse(needle, SuffixKind::Minimal); |
| <span class="kw">let </span>max_suffix = Suffix::reverse(needle, SuffixKind::Maximal); |
| <span class="kw">let </span>(period_lower_bound, critical_pos) = |
| <span class="kw">if </span>min_suffix.pos < max_suffix.pos { |
| (min_suffix.period, min_suffix.pos) |
| } <span class="kw">else </span>{ |
| (max_suffix.period, max_suffix.pos) |
| }; |
| <span class="comment">// let critical_pos = needle.len() - critical_pos; |
| </span><span class="kw">let </span>shift = Shift::reverse(needle, period_lower_bound, critical_pos); |
| Reverse(TwoWay { byteset, critical_pos, shift }) |
| } |
| |
| <span class="doccomment">/// Find the position of the last occurrence of this searcher's needle |
| /// in the given haystack. If one does not exist, then return None. |
| /// |
| /// This will automatically initialize prefilter state. This should only |
| /// be used for one-off searches. |
| /// |
| /// Callers must guarantee that the needle is non-empty and its length is |
| /// <= the haystack's length. |
| </span><span class="attribute">#[inline(always)] |
| </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>rfind( |
| <span class="kw-2">&</span><span class="self">self</span>, |
| haystack: <span class="kw-2">&</span>[u8], |
| needle: <span class="kw-2">&</span>[u8], |
| ) -> <span class="prelude-ty">Option</span><usize> { |
| <span class="macro">debug_assert!</span>(!needle.is_empty(), <span class="string">"needle should not be empty"</span>); |
| <span class="macro">debug_assert!</span>(needle.len() <= haystack.len(), <span class="string">"haystack too short"</span>); |
| <span class="comment">// For the reverse case, we don't use a prefilter. It's plausible that |
| // perhaps we should, but it's a lot of additional code to do it, and |
| // it's not clear that it's actually worth it. If you have a really |
| // compelling use case for this, please file an issue. |
| </span><span class="kw">match </span><span class="self">self</span>.<span class="number">0</span>.shift { |
| Shift::Small { period } => { |
| <span class="self">self</span>.rfind_small_imp(haystack, needle, period) |
| } |
| Shift::Large { shift } => { |
| <span class="self">self</span>.rfind_large_imp(haystack, needle, shift) |
| } |
| } |
| } |
| |
| <span class="doccomment">/// Like rfind, but handles the degenerate substring test cases. This is |
| /// only useful for conveniently testing this substring implementation in |
| /// isolation. |
| </span><span class="attribute">#[cfg(test)] |
| </span><span class="kw">fn </span>rfind_general(<span class="kw-2">&</span><span class="self">self</span>, haystack: <span class="kw-2">&</span>[u8], needle: <span class="kw-2">&</span>[u8]) -> <span class="prelude-ty">Option</span><usize> { |
| <span class="kw">if </span>needle.is_empty() { |
| <span class="prelude-val">Some</span>(haystack.len()) |
| } <span class="kw">else if </span>haystack.len() < needle.len() { |
| <span class="prelude-val">None |
| </span>} <span class="kw">else </span>{ |
| <span class="self">self</span>.rfind(haystack, needle) |
| } |
| } |
| |
| <span class="attribute">#[inline(always)] |
| </span><span class="kw">fn </span>rfind_small_imp( |
| <span class="kw-2">&</span><span class="self">self</span>, |
| haystack: <span class="kw-2">&</span>[u8], |
| needle: <span class="kw-2">&</span>[u8], |
| period: usize, |
| ) -> <span class="prelude-ty">Option</span><usize> { |
| <span class="kw">let </span>nlen = needle.len(); |
| <span class="kw">let </span><span class="kw-2">mut </span>pos = haystack.len(); |
| <span class="kw">let </span><span class="kw-2">mut </span>shift = nlen; |
| <span class="kw">while </span>pos >= nlen { |
| <span class="kw">if </span>!<span class="self">self</span>.<span class="number">0</span>.byteset.contains(haystack[pos - nlen]) { |
| pos -= nlen; |
| shift = nlen; |
| <span class="kw">continue</span>; |
| } |
| <span class="kw">let </span><span class="kw-2">mut </span>i = cmp::min(<span class="self">self</span>.<span class="number">0</span>.critical_pos, shift); |
| <span class="kw">while </span>i > <span class="number">0 </span>&& needle[i - <span class="number">1</span>] == haystack[pos - nlen + i - <span class="number">1</span>] { |
| i -= <span class="number">1</span>; |
| } |
| <span class="kw">if </span>i > <span class="number">0 </span>|| needle[<span class="number">0</span>] != haystack[pos - nlen] { |
| pos -= <span class="self">self</span>.<span class="number">0</span>.critical_pos - i + <span class="number">1</span>; |
| shift = nlen; |
| } <span class="kw">else </span>{ |
| <span class="kw">let </span><span class="kw-2">mut </span>j = <span class="self">self</span>.<span class="number">0</span>.critical_pos; |
| <span class="kw">while </span>j < shift && needle[j] == haystack[pos - nlen + j] { |
| j += <span class="number">1</span>; |
| } |
| <span class="kw">if </span>j >= shift { |
| <span class="kw">return </span><span class="prelude-val">Some</span>(pos - nlen); |
| } |
| pos -= period; |
| shift = period; |
| } |
| } |
| <span class="prelude-val">None |
| </span>} |
| |
| <span class="attribute">#[inline(always)] |
| </span><span class="kw">fn </span>rfind_large_imp( |
| <span class="kw-2">&</span><span class="self">self</span>, |
| haystack: <span class="kw-2">&</span>[u8], |
| needle: <span class="kw-2">&</span>[u8], |
| shift: usize, |
| ) -> <span class="prelude-ty">Option</span><usize> { |
| <span class="kw">let </span>nlen = needle.len(); |
| <span class="kw">let </span><span class="kw-2">mut </span>pos = haystack.len(); |
| <span class="kw">while </span>pos >= nlen { |
| <span class="kw">if </span>!<span class="self">self</span>.<span class="number">0</span>.byteset.contains(haystack[pos - nlen]) { |
| pos -= nlen; |
| <span class="kw">continue</span>; |
| } |
| <span class="kw">let </span><span class="kw-2">mut </span>i = <span class="self">self</span>.<span class="number">0</span>.critical_pos; |
| <span class="kw">while </span>i > <span class="number">0 </span>&& needle[i - <span class="number">1</span>] == haystack[pos - nlen + i - <span class="number">1</span>] { |
| i -= <span class="number">1</span>; |
| } |
| <span class="kw">if </span>i > <span class="number">0 </span>|| needle[<span class="number">0</span>] != haystack[pos - nlen] { |
| pos -= <span class="self">self</span>.<span class="number">0</span>.critical_pos - i + <span class="number">1</span>; |
| } <span class="kw">else </span>{ |
| <span class="kw">let </span><span class="kw-2">mut </span>j = <span class="self">self</span>.<span class="number">0</span>.critical_pos; |
| <span class="kw">while </span>j < nlen && needle[j] == haystack[pos - nlen + j] { |
| j += <span class="number">1</span>; |
| } |
| <span class="kw">if </span>j == nlen { |
| <span class="kw">return </span><span class="prelude-val">Some</span>(pos - nlen); |
| } |
| pos -= shift; |
| } |
| } |
| <span class="prelude-val">None |
| </span>} |
| } |
| |
| <span class="kw">impl </span>TwoWay { |
| <span class="kw">fn </span>empty() -> TwoWay { |
| TwoWay { |
| byteset: ApproximateByteSet::new(<span class="string">b""</span>), |
| critical_pos: <span class="number">0</span>, |
| shift: Shift::Large { shift: <span class="number">0 </span>}, |
| } |
| } |
| } |
| |
| <span class="doccomment">/// A representation of the amount we're allowed to shift by during Two-Way |
| /// search. |
| /// |
| /// When computing a critical factorization of the needle, we find the position |
| /// of the critical factorization by finding the needle's maximal (or minimal) |
| /// suffix, along with the period of that suffix. It turns out that the period |
| /// of that suffix is a lower bound on the period of the needle itself. |
| /// |
| /// This lower bound is equivalent to the actual period of the needle in |
| /// some cases. To describe that case, we denote the needle as `x` where |
| /// `x = uv` and `v` is the lexicographic maximal suffix of `v`. The lower |
| /// bound given here is always the period of `v`, which is `<= period(x)`. The |
| /// case where `period(v) == period(x)` occurs when `len(u) < (len(x) / 2)` and |
| /// where `u` is a suffix of `v[0..period(v)]`. |
| /// |
| /// This case is important because the search algorithm for when the |
| /// periods are equivalent is slightly different than the search algorithm |
| /// for when the periods are not equivalent. In particular, when they aren't |
| /// equivalent, we know that the period of the needle is no less than half its |
| /// length. In this case, we shift by an amount less than or equal to the |
| /// period of the needle (determined by the maximum length of the components |
| /// of the critical factorization of `x`, i.e., `max(len(u), len(v))`).. |
| /// |
| /// The above two cases are represented by the variants below. Each entails |
| /// a different instantiation of the Two-Way search algorithm. |
| /// |
| /// N.B. If we could find a way to compute the exact period in all cases, |
| /// then we could collapse this case analysis and simplify the algorithm. The |
| /// Two-Way paper suggests this is possible, but more reading is required to |
| /// grok why the authors didn't pursue that path. |
| </span><span class="attribute">#[derive(Clone, Copy, Debug)] |
| </span><span class="kw">enum </span>Shift { |
| Small { period: usize }, |
| Large { shift: usize }, |
| } |
| |
| <span class="kw">impl </span>Shift { |
| <span class="doccomment">/// Compute the shift for a given needle in the forward direction. |
| /// |
| /// This requires a lower bound on the period and a critical position. |
| /// These can be computed by extracting both the minimal and maximal |
| /// lexicographic suffixes, and choosing the right-most starting position. |
| /// The lower bound on the period is then the period of the chosen suffix. |
| </span><span class="kw">fn </span>forward( |
| needle: <span class="kw-2">&</span>[u8], |
| period_lower_bound: usize, |
| critical_pos: usize, |
| ) -> Shift { |
| <span class="kw">let </span>large = cmp::max(critical_pos, needle.len() - critical_pos); |
| <span class="kw">if </span>critical_pos * <span class="number">2 </span>>= needle.len() { |
| <span class="kw">return </span>Shift::Large { shift: large }; |
| } |
| |
| <span class="kw">let </span>(u, v) = needle.split_at(critical_pos); |
| <span class="kw">if </span>!util::is_suffix(<span class="kw-2">&</span>v[..period_lower_bound], u) { |
| <span class="kw">return </span>Shift::Large { shift: large }; |
| } |
| Shift::Small { period: period_lower_bound } |
| } |
| |
| <span class="doccomment">/// Compute the shift for a given needle in the reverse direction. |
| /// |
| /// This requires a lower bound on the period and a critical position. |
| /// These can be computed by extracting both the minimal and maximal |
| /// lexicographic suffixes, and choosing the left-most starting position. |
| /// The lower bound on the period is then the period of the chosen suffix. |
| </span><span class="kw">fn </span>reverse( |
| needle: <span class="kw-2">&</span>[u8], |
| period_lower_bound: usize, |
| critical_pos: usize, |
| ) -> Shift { |
| <span class="kw">let </span>large = cmp::max(critical_pos, needle.len() - critical_pos); |
| <span class="kw">if </span>(needle.len() - critical_pos) * <span class="number">2 </span>>= needle.len() { |
| <span class="kw">return </span>Shift::Large { shift: large }; |
| } |
| |
| <span class="kw">let </span>(v, u) = needle.split_at(critical_pos); |
| <span class="kw">if </span>!util::is_prefix(<span class="kw-2">&</span>v[v.len() - period_lower_bound..], u) { |
| <span class="kw">return </span>Shift::Large { shift: large }; |
| } |
| Shift::Small { period: period_lower_bound } |
| } |
| } |
| |
| <span class="doccomment">/// A suffix extracted from a needle along with its period. |
| </span><span class="attribute">#[derive(Debug)] |
| </span><span class="kw">struct </span>Suffix { |
| <span class="doccomment">/// The starting position of this suffix. |
| /// |
| /// If this is a forward suffix, then `&bytes[pos..]` can be used. If this |
| /// is a reverse suffix, then `&bytes[..pos]` can be used. That is, for |
| /// forward suffixes, this is an inclusive starting position, where as for |
| /// reverse suffixes, this is an exclusive ending position. |
| </span>pos: usize, |
| <span class="doccomment">/// The period of this suffix. |
| /// |
| /// Note that this is NOT necessarily the period of the string from which |
| /// this suffix comes from. (It is always less than or equal to the period |
| /// of the original string.) |
| </span>period: usize, |
| } |
| |
| <span class="kw">impl </span>Suffix { |
| <span class="kw">fn </span>forward(needle: <span class="kw-2">&</span>[u8], kind: SuffixKind) -> Suffix { |
| <span class="macro">debug_assert!</span>(!needle.is_empty()); |
| |
| <span class="comment">// suffix represents our maximal (or minimal) suffix, along with |
| // its period. |
| </span><span class="kw">let </span><span class="kw-2">mut </span>suffix = Suffix { pos: <span class="number">0</span>, period: <span class="number">1 </span>}; |
| <span class="comment">// The start of a suffix in `needle` that we are considering as a |
| // more maximal (or minimal) suffix than what's in `suffix`. |
| </span><span class="kw">let </span><span class="kw-2">mut </span>candidate_start = <span class="number">1</span>; |
| <span class="comment">// The current offset of our suffixes that we're comparing. |
| // |
| // When the characters at this offset are the same, then we mush on |
| // to the next position since no decision is possible. When the |
| // candidate's character is greater (or lesser) than the corresponding |
| // character than our current maximal (or minimal) suffix, then the |
| // current suffix is changed over to the candidate and we restart our |
| // search. Otherwise, the candidate suffix is no good and we restart |
| // our search on the next candidate. |
| // |
| // The three cases above correspond to the three cases in the loop |
| // below. |
| </span><span class="kw">let </span><span class="kw-2">mut </span>offset = <span class="number">0</span>; |
| |
| <span class="kw">while </span>candidate_start + offset < needle.len() { |
| <span class="kw">let </span>current = needle[suffix.pos + offset]; |
| <span class="kw">let </span>candidate = needle[candidate_start + offset]; |
| <span class="kw">match </span>kind.cmp(current, candidate) { |
| SuffixOrdering::Accept => { |
| suffix = Suffix { pos: candidate_start, period: <span class="number">1 </span>}; |
| candidate_start += <span class="number">1</span>; |
| offset = <span class="number">0</span>; |
| } |
| SuffixOrdering::Skip => { |
| candidate_start += offset + <span class="number">1</span>; |
| offset = <span class="number">0</span>; |
| suffix.period = candidate_start - suffix.pos; |
| } |
| SuffixOrdering::Push => { |
| <span class="kw">if </span>offset + <span class="number">1 </span>== suffix.period { |
| candidate_start += suffix.period; |
| offset = <span class="number">0</span>; |
| } <span class="kw">else </span>{ |
| offset += <span class="number">1</span>; |
| } |
| } |
| } |
| } |
| suffix |
| } |
| |
| <span class="kw">fn </span>reverse(needle: <span class="kw-2">&</span>[u8], kind: SuffixKind) -> Suffix { |
| <span class="macro">debug_assert!</span>(!needle.is_empty()); |
| |
| <span class="comment">// See the comments in `forward` for how this works. |
| </span><span class="kw">let </span><span class="kw-2">mut </span>suffix = Suffix { pos: needle.len(), period: <span class="number">1 </span>}; |
| <span class="kw">if </span>needle.len() == <span class="number">1 </span>{ |
| <span class="kw">return </span>suffix; |
| } |
| <span class="kw">let </span><span class="kw-2">mut </span>candidate_start = needle.len() - <span class="number">1</span>; |
| <span class="kw">let </span><span class="kw-2">mut </span>offset = <span class="number">0</span>; |
| |
| <span class="kw">while </span>offset < candidate_start { |
| <span class="kw">let </span>current = needle[suffix.pos - offset - <span class="number">1</span>]; |
| <span class="kw">let </span>candidate = needle[candidate_start - offset - <span class="number">1</span>]; |
| <span class="kw">match </span>kind.cmp(current, candidate) { |
| SuffixOrdering::Accept => { |
| suffix = Suffix { pos: candidate_start, period: <span class="number">1 </span>}; |
| candidate_start -= <span class="number">1</span>; |
| offset = <span class="number">0</span>; |
| } |
| SuffixOrdering::Skip => { |
| candidate_start -= offset + <span class="number">1</span>; |
| offset = <span class="number">0</span>; |
| suffix.period = suffix.pos - candidate_start; |
| } |
| SuffixOrdering::Push => { |
| <span class="kw">if </span>offset + <span class="number">1 </span>== suffix.period { |
| candidate_start -= suffix.period; |
| offset = <span class="number">0</span>; |
| } <span class="kw">else </span>{ |
| offset += <span class="number">1</span>; |
| } |
| } |
| } |
| } |
| suffix |
| } |
| } |
| |
| <span class="doccomment">/// The kind of suffix to extract. |
| </span><span class="attribute">#[derive(Clone, Copy, Debug)] |
| </span><span class="kw">enum </span>SuffixKind { |
| <span class="doccomment">/// Extract the smallest lexicographic suffix from a string. |
| /// |
| /// Technically, this doesn't actually pick the smallest lexicographic |
| /// suffix. e.g., Given the choice between `a` and `aa`, this will choose |
| /// the latter over the former, even though `a < aa`. The reasoning for |
| /// this isn't clear from the paper, but it still smells like a minimal |
| /// suffix. |
| </span>Minimal, |
| <span class="doccomment">/// Extract the largest lexicographic suffix from a string. |
| /// |
| /// Unlike `Minimal`, this really does pick the maximum suffix. e.g., Given |
| /// the choice between `z` and `zz`, this will choose the latter over the |
| /// former. |
| </span>Maximal, |
| } |
| |
| <span class="doccomment">/// The result of comparing corresponding bytes between two suffixes. |
| </span><span class="attribute">#[derive(Clone, Copy, Debug)] |
| </span><span class="kw">enum </span>SuffixOrdering { |
| <span class="doccomment">/// This occurs when the given candidate byte indicates that the candidate |
| /// suffix is better than the current maximal (or minimal) suffix. That is, |
| /// the current candidate suffix should supplant the current maximal (or |
| /// minimal) suffix. |
| </span>Accept, |
| <span class="doccomment">/// This occurs when the given candidate byte excludes the candidate suffix |
| /// from being better than the current maximal (or minimal) suffix. That |
| /// is, the current candidate suffix should be dropped and the next one |
| /// should be considered. |
| </span>Skip, |
| <span class="doccomment">/// This occurs when no decision to accept or skip the candidate suffix |
| /// can be made, e.g., when corresponding bytes are equivalent. In this |
| /// case, the next corresponding bytes should be compared. |
| </span>Push, |
| } |
| |
| <span class="kw">impl </span>SuffixKind { |
| <span class="doccomment">/// Returns true if and only if the given candidate byte indicates that |
| /// it should replace the current suffix as the maximal (or minimal) |
| /// suffix. |
| </span><span class="kw">fn </span>cmp(<span class="self">self</span>, current: u8, candidate: u8) -> SuffixOrdering { |
| <span class="kw">use </span><span class="self">self</span>::SuffixOrdering::<span class="kw-2">*</span>; |
| |
| <span class="kw">match </span><span class="self">self </span>{ |
| SuffixKind::Minimal <span class="kw">if </span>candidate < current => Accept, |
| SuffixKind::Minimal <span class="kw">if </span>candidate > current => Skip, |
| SuffixKind::Minimal => Push, |
| SuffixKind::Maximal <span class="kw">if </span>candidate > current => Accept, |
| SuffixKind::Maximal <span class="kw">if </span>candidate < current => Skip, |
| SuffixKind::Maximal => Push, |
| } |
| } |
| } |
| |
| <span class="doccomment">/// A bitset used to track whether a particular byte exists in a needle or not. |
| /// |
| /// Namely, bit 'i' is set if and only if byte%64==i for any byte in the |
| /// needle. If a particular byte in the haystack is NOT in this set, then one |
| /// can conclude that it is also not in the needle, and thus, one can advance |
| /// in the haystack by needle.len() bytes. |
| </span><span class="attribute">#[derive(Clone, Copy, Debug)] |
| </span><span class="kw">struct </span>ApproximateByteSet(u64); |
| |
| <span class="kw">impl </span>ApproximateByteSet { |
| <span class="doccomment">/// Create a new set from the given needle. |
| </span><span class="kw">fn </span>new(needle: <span class="kw-2">&</span>[u8]) -> ApproximateByteSet { |
| <span class="kw">let </span><span class="kw-2">mut </span>bits = <span class="number">0</span>; |
| <span class="kw">for </span><span class="kw-2">&</span>b <span class="kw">in </span>needle { |
| bits |= <span class="number">1 </span><< (b % <span class="number">64</span>); |
| } |
| ApproximateByteSet(bits) |
| } |
| |
| <span class="doccomment">/// Return true if and only if the given byte might be in this set. This |
| /// may return a false positive, but will never return a false negative. |
| </span><span class="attribute">#[inline(always)] |
| </span><span class="kw">fn </span>contains(<span class="kw-2">&</span><span class="self">self</span>, byte: u8) -> bool { |
| <span class="self">self</span>.<span class="number">0 </span>& (<span class="number">1 </span><< (byte % <span class="number">64</span>)) != <span class="number">0 |
| </span>} |
| } |
| |
| <span class="attribute">#[cfg(all(test, feature = <span class="string">"std"</span>, not(miri)))] |
| </span><span class="kw">mod </span>tests { |
| <span class="kw">use </span>quickcheck::quickcheck; |
| |
| <span class="kw">use super</span>::<span class="kw-2">*</span>; |
| |
| <span class="macro">define_memmem_quickcheck_tests!</span>( |
| <span class="kw">super</span>::simpletests::twoway_find, |
| <span class="kw">super</span>::simpletests::twoway_rfind |
| ); |
| |
| <span class="doccomment">/// Convenience wrapper for computing the suffix as a byte string. |
| </span><span class="kw">fn </span>get_suffix_forward(needle: <span class="kw-2">&</span>[u8], kind: SuffixKind) -> (<span class="kw-2">&</span>[u8], usize) { |
| <span class="kw">let </span>s = Suffix::forward(needle, kind); |
| (<span class="kw-2">&</span>needle[s.pos..], s.period) |
| } |
| |
| <span class="doccomment">/// Convenience wrapper for computing the reverse suffix as a byte string. |
| </span><span class="kw">fn </span>get_suffix_reverse(needle: <span class="kw-2">&</span>[u8], kind: SuffixKind) -> (<span class="kw-2">&</span>[u8], usize) { |
| <span class="kw">let </span>s = Suffix::reverse(needle, kind); |
| (<span class="kw-2">&</span>needle[..s.pos], s.period) |
| } |
| |
| <span class="doccomment">/// Return all of the non-empty suffixes in the given byte string. |
| </span><span class="kw">fn </span>suffixes(bytes: <span class="kw-2">&</span>[u8]) -> Vec<<span class="kw-2">&</span>[u8]> { |
| (<span class="number">0</span>..bytes.len()).map(|i| <span class="kw-2">&</span>bytes[i..]).collect() |
| } |
| |
| <span class="doccomment">/// Return the lexicographically maximal suffix of the given byte string. |
| </span><span class="kw">fn </span>naive_maximal_suffix_forward(needle: <span class="kw-2">&</span>[u8]) -> <span class="kw-2">&</span>[u8] { |
| <span class="kw">let </span><span class="kw-2">mut </span>sufs = suffixes(needle); |
| sufs.sort(); |
| sufs.pop().unwrap() |
| } |
| |
| <span class="doccomment">/// Return the lexicographically maximal suffix of the reverse of the given |
| /// byte string. |
| </span><span class="kw">fn </span>naive_maximal_suffix_reverse(needle: <span class="kw-2">&</span>[u8]) -> Vec<u8> { |
| <span class="kw">let </span><span class="kw-2">mut </span>reversed = needle.to_vec(); |
| reversed.reverse(); |
| <span class="kw">let </span><span class="kw-2">mut </span>got = naive_maximal_suffix_forward(<span class="kw-2">&</span>reversed).to_vec(); |
| got.reverse(); |
| got |
| } |
| |
| <span class="attribute">#[test] |
| </span><span class="kw">fn </span>suffix_forward() { |
| <span class="macro">macro_rules! </span>assert_suffix_min { |
| (<span class="macro-nonterminal">$given</span>:expr, <span class="macro-nonterminal">$expected</span>:expr, <span class="macro-nonterminal">$period</span>:expr) => { |
| <span class="kw">let </span>(got_suffix, got_period) = |
| get_suffix_forward(<span class="macro-nonterminal">$given</span>.as_bytes(), SuffixKind::Minimal); |
| <span class="kw">let </span>got_suffix = std::str::from_utf8(got_suffix).unwrap(); |
| <span class="macro">assert_eq!</span>((<span class="macro-nonterminal">$expected</span>, <span class="macro-nonterminal">$period</span>), (got_suffix, got_period)); |
| }; |
| } |
| |
| <span class="macro">macro_rules! </span>assert_suffix_max { |
| (<span class="macro-nonterminal">$given</span>:expr, <span class="macro-nonterminal">$expected</span>:expr, <span class="macro-nonterminal">$period</span>:expr) => { |
| <span class="kw">let </span>(got_suffix, got_period) = |
| get_suffix_forward(<span class="macro-nonterminal">$given</span>.as_bytes(), SuffixKind::Maximal); |
| <span class="kw">let </span>got_suffix = std::str::from_utf8(got_suffix).unwrap(); |
| <span class="macro">assert_eq!</span>((<span class="macro-nonterminal">$expected</span>, <span class="macro-nonterminal">$period</span>), (got_suffix, got_period)); |
| }; |
| } |
| |
| <span class="macro">assert_suffix_min!</span>(<span class="string">"a"</span>, <span class="string">"a"</span>, <span class="number">1</span>); |
| <span class="macro">assert_suffix_max!</span>(<span class="string">"a"</span>, <span class="string">"a"</span>, <span class="number">1</span>); |
| |
| <span class="macro">assert_suffix_min!</span>(<span class="string">"ab"</span>, <span class="string">"ab"</span>, <span class="number">2</span>); |
| <span class="macro">assert_suffix_max!</span>(<span class="string">"ab"</span>, <span class="string">"b"</span>, <span class="number">1</span>); |
| |
| <span class="macro">assert_suffix_min!</span>(<span class="string">"ba"</span>, <span class="string">"a"</span>, <span class="number">1</span>); |
| <span class="macro">assert_suffix_max!</span>(<span class="string">"ba"</span>, <span class="string">"ba"</span>, <span class="number">2</span>); |
| |
| <span class="macro">assert_suffix_min!</span>(<span class="string">"abc"</span>, <span class="string">"abc"</span>, <span class="number">3</span>); |
| <span class="macro">assert_suffix_max!</span>(<span class="string">"abc"</span>, <span class="string">"c"</span>, <span class="number">1</span>); |
| |
| <span class="macro">assert_suffix_min!</span>(<span class="string">"acb"</span>, <span class="string">"acb"</span>, <span class="number">3</span>); |
| <span class="macro">assert_suffix_max!</span>(<span class="string">"acb"</span>, <span class="string">"cb"</span>, <span class="number">2</span>); |
| |
| <span class="macro">assert_suffix_min!</span>(<span class="string">"cba"</span>, <span class="string">"a"</span>, <span class="number">1</span>); |
| <span class="macro">assert_suffix_max!</span>(<span class="string">"cba"</span>, <span class="string">"cba"</span>, <span class="number">3</span>); |
| |
| <span class="macro">assert_suffix_min!</span>(<span class="string">"abcabc"</span>, <span class="string">"abcabc"</span>, <span class="number">3</span>); |
| <span class="macro">assert_suffix_max!</span>(<span class="string">"abcabc"</span>, <span class="string">"cabc"</span>, <span class="number">3</span>); |
| |
| <span class="macro">assert_suffix_min!</span>(<span class="string">"abcabcabc"</span>, <span class="string">"abcabcabc"</span>, <span class="number">3</span>); |
| <span class="macro">assert_suffix_max!</span>(<span class="string">"abcabcabc"</span>, <span class="string">"cabcabc"</span>, <span class="number">3</span>); |
| |
| <span class="macro">assert_suffix_min!</span>(<span class="string">"abczz"</span>, <span class="string">"abczz"</span>, <span class="number">5</span>); |
| <span class="macro">assert_suffix_max!</span>(<span class="string">"abczz"</span>, <span class="string">"zz"</span>, <span class="number">1</span>); |
| |
| <span class="macro">assert_suffix_min!</span>(<span class="string">"zzabc"</span>, <span class="string">"abc"</span>, <span class="number">3</span>); |
| <span class="macro">assert_suffix_max!</span>(<span class="string">"zzabc"</span>, <span class="string">"zzabc"</span>, <span class="number">5</span>); |
| |
| <span class="macro">assert_suffix_min!</span>(<span class="string">"aaa"</span>, <span class="string">"aaa"</span>, <span class="number">1</span>); |
| <span class="macro">assert_suffix_max!</span>(<span class="string">"aaa"</span>, <span class="string">"aaa"</span>, <span class="number">1</span>); |
| |
| <span class="macro">assert_suffix_min!</span>(<span class="string">"foobar"</span>, <span class="string">"ar"</span>, <span class="number">2</span>); |
| <span class="macro">assert_suffix_max!</span>(<span class="string">"foobar"</span>, <span class="string">"r"</span>, <span class="number">1</span>); |
| } |
| |
| <span class="attribute">#[test] |
| </span><span class="kw">fn </span>suffix_reverse() { |
| <span class="macro">macro_rules! </span>assert_suffix_min { |
| (<span class="macro-nonterminal">$given</span>:expr, <span class="macro-nonterminal">$expected</span>:expr, <span class="macro-nonterminal">$period</span>:expr) => { |
| <span class="kw">let </span>(got_suffix, got_period) = |
| get_suffix_reverse(<span class="macro-nonterminal">$given</span>.as_bytes(), SuffixKind::Minimal); |
| <span class="kw">let </span>got_suffix = std::str::from_utf8(got_suffix).unwrap(); |
| <span class="macro">assert_eq!</span>((<span class="macro-nonterminal">$expected</span>, <span class="macro-nonterminal">$period</span>), (got_suffix, got_period)); |
| }; |
| } |
| |
| <span class="macro">macro_rules! </span>assert_suffix_max { |
| (<span class="macro-nonterminal">$given</span>:expr, <span class="macro-nonterminal">$expected</span>:expr, <span class="macro-nonterminal">$period</span>:expr) => { |
| <span class="kw">let </span>(got_suffix, got_period) = |
| get_suffix_reverse(<span class="macro-nonterminal">$given</span>.as_bytes(), SuffixKind::Maximal); |
| <span class="kw">let </span>got_suffix = std::str::from_utf8(got_suffix).unwrap(); |
| <span class="macro">assert_eq!</span>((<span class="macro-nonterminal">$expected</span>, <span class="macro-nonterminal">$period</span>), (got_suffix, got_period)); |
| }; |
| } |
| |
| <span class="macro">assert_suffix_min!</span>(<span class="string">"a"</span>, <span class="string">"a"</span>, <span class="number">1</span>); |
| <span class="macro">assert_suffix_max!</span>(<span class="string">"a"</span>, <span class="string">"a"</span>, <span class="number">1</span>); |
| |
| <span class="macro">assert_suffix_min!</span>(<span class="string">"ab"</span>, <span class="string">"a"</span>, <span class="number">1</span>); |
| <span class="macro">assert_suffix_max!</span>(<span class="string">"ab"</span>, <span class="string">"ab"</span>, <span class="number">2</span>); |
| |
| <span class="macro">assert_suffix_min!</span>(<span class="string">"ba"</span>, <span class="string">"ba"</span>, <span class="number">2</span>); |
| <span class="macro">assert_suffix_max!</span>(<span class="string">"ba"</span>, <span class="string">"b"</span>, <span class="number">1</span>); |
| |
| <span class="macro">assert_suffix_min!</span>(<span class="string">"abc"</span>, <span class="string">"a"</span>, <span class="number">1</span>); |
| <span class="macro">assert_suffix_max!</span>(<span class="string">"abc"</span>, <span class="string">"abc"</span>, <span class="number">3</span>); |
| |
| <span class="macro">assert_suffix_min!</span>(<span class="string">"acb"</span>, <span class="string">"a"</span>, <span class="number">1</span>); |
| <span class="macro">assert_suffix_max!</span>(<span class="string">"acb"</span>, <span class="string">"ac"</span>, <span class="number">2</span>); |
| |
| <span class="macro">assert_suffix_min!</span>(<span class="string">"cba"</span>, <span class="string">"cba"</span>, <span class="number">3</span>); |
| <span class="macro">assert_suffix_max!</span>(<span class="string">"cba"</span>, <span class="string">"c"</span>, <span class="number">1</span>); |
| |
| <span class="macro">assert_suffix_min!</span>(<span class="string">"abcabc"</span>, <span class="string">"abca"</span>, <span class="number">3</span>); |
| <span class="macro">assert_suffix_max!</span>(<span class="string">"abcabc"</span>, <span class="string">"abcabc"</span>, <span class="number">3</span>); |
| |
| <span class="macro">assert_suffix_min!</span>(<span class="string">"abcabcabc"</span>, <span class="string">"abcabca"</span>, <span class="number">3</span>); |
| <span class="macro">assert_suffix_max!</span>(<span class="string">"abcabcabc"</span>, <span class="string">"abcabcabc"</span>, <span class="number">3</span>); |
| |
| <span class="macro">assert_suffix_min!</span>(<span class="string">"abczz"</span>, <span class="string">"a"</span>, <span class="number">1</span>); |
| <span class="macro">assert_suffix_max!</span>(<span class="string">"abczz"</span>, <span class="string">"abczz"</span>, <span class="number">5</span>); |
| |
| <span class="macro">assert_suffix_min!</span>(<span class="string">"zzabc"</span>, <span class="string">"zza"</span>, <span class="number">3</span>); |
| <span class="macro">assert_suffix_max!</span>(<span class="string">"zzabc"</span>, <span class="string">"zz"</span>, <span class="number">1</span>); |
| |
| <span class="macro">assert_suffix_min!</span>(<span class="string">"aaa"</span>, <span class="string">"aaa"</span>, <span class="number">1</span>); |
| <span class="macro">assert_suffix_max!</span>(<span class="string">"aaa"</span>, <span class="string">"aaa"</span>, <span class="number">1</span>); |
| } |
| |
| <span class="macro">quickcheck! </span>{ |
| <span class="kw">fn </span>qc_suffix_forward_maximal(bytes: Vec<u8>) -> bool { |
| <span class="kw">if </span>bytes.is_empty() { |
| <span class="kw">return </span><span class="bool-val">true</span>; |
| } |
| |
| <span class="kw">let </span>(got, <span class="kw">_</span>) = get_suffix_forward(<span class="kw-2">&</span>bytes, SuffixKind::Maximal); |
| <span class="kw">let </span>expected = naive_maximal_suffix_forward(<span class="kw-2">&</span>bytes); |
| got == expected |
| } |
| |
| <span class="kw">fn </span>qc_suffix_reverse_maximal(bytes: Vec<u8>) -> bool { |
| <span class="kw">if </span>bytes.is_empty() { |
| <span class="kw">return </span><span class="bool-val">true</span>; |
| } |
| |
| <span class="kw">let </span>(got, <span class="kw">_</span>) = get_suffix_reverse(<span class="kw-2">&</span>bytes, SuffixKind::Maximal); |
| <span class="kw">let </span>expected = naive_maximal_suffix_reverse(<span class="kw-2">&</span>bytes); |
| expected == got |
| } |
| } |
| } |
| |
| <span class="attribute">#[cfg(test)] |
| </span><span class="kw">mod </span>simpletests { |
| <span class="kw">use super</span>::<span class="kw-2">*</span>; |
| |
| <span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>twoway_find( |
| haystack: <span class="kw-2">&</span>[u8], |
| needle: <span class="kw-2">&</span>[u8], |
| ) -> <span class="prelude-ty">Option</span><usize> { |
| Forward::new(needle).find_general(<span class="prelude-val">None</span>, haystack, needle) |
| } |
| |
| <span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>twoway_rfind( |
| haystack: <span class="kw-2">&</span>[u8], |
| needle: <span class="kw-2">&</span>[u8], |
| ) -> <span class="prelude-ty">Option</span><usize> { |
| Reverse::new(needle).rfind_general(haystack, needle) |
| } |
| |
| <span class="macro">define_memmem_simple_tests!</span>(twoway_find, twoway_rfind); |
| |
| <span class="comment">// This is a regression test caught by quickcheck that exercised a bug in |
| // the reverse small period handling. The bug was that we were using 'if j |
| // == shift' to determine if a match occurred, but the correct guard is 'if |
| // j >= shift', which matches the corresponding guard in the forward impl. |
| </span><span class="attribute">#[test] |
| </span><span class="kw">fn </span>regression_rev_small_period() { |
| <span class="kw">let </span>rfind = <span class="kw">super</span>::simpletests::twoway_rfind; |
| <span class="kw">let </span>haystack = <span class="string">"ababaz"</span>; |
| <span class="kw">let </span>needle = <span class="string">"abab"</span>; |
| <span class="macro">assert_eq!</span>(<span class="prelude-val">Some</span>(<span class="number">0</span>), rfind(haystack.as_bytes(), needle.as_bytes())); |
| } |
| } |
| </code></pre></div> |
| </section></div></main><div id="rustdoc-vars" data-root-path="../../../" data-current-crate="memchr" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |
