<!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 `map_model&#x2F;src&#x2F;objects&#x2F;block.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>block.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" type="text/css" href="../../../normalize.css"><link rel="stylesheet" type="text/css" href="../../../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" type="text/css" href="../../../ayu.css" disabled><link rel="stylesheet" type="text/css" href="../../../dark.css" disabled><link rel="stylesheet" type="text/css" href="../../../light.css" id="themeStyle"><script id="default-settings" ></script><script src="../../../storage.js"></script><script src="../../../crates.js"></script><script defer src="../../../main.js"></script><script defer src="../../../source-script.js"></script><script defer src="../../../source-files.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"><div class="sidebar-menu" role="button">&#9776;</div><a class="sidebar-logo" href="../../../map_model/index.html"><div class="logo-container"><img class="rust-logo" src="../../../rust-logo.png" alt="logo"></div>
        </a></nav><main><div class="width-limiter"><div class="sub-container"><a class="sub-logo-container" href="../../../map_model/index.html"><img class="rust-logo" src="../../../rust-logo.png" alt="logo"></a><nav class="sub"><div class="theme-picker"><button id="theme-picker" aria-label="Pick another theme!" aria-haspopup="menu" title="themes"><img width="18" height="18" alt="Pick another theme!" src="../../../brush.svg"></button><div id="theme-choices" role="menu"></div></div><form class="search-form"><div class="search-container"><div><select id="crate-search"><option value="All crates">All crates</option></select><input class="search-input" name="search" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"></div><button type="button" id="help-button" title="help">?</button><a id="settings-menu" href="../../../settings.html" title="settings"><img width="18" height="18" alt="Change settings" src="../../../wheel.svg"></a></div></form></nav></div><section id="main-content" class="content"><div class="example-wrap"><pre class="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>
</pre><pre class="rust"><code><span class="kw">use</span> <span class="ident">std::collections</span>::{<span class="ident">BTreeSet</span>, <span class="ident">HashMap</span>, <span class="ident">HashSet</span>};
<span class="kw">use</span> <span class="ident">std::fmt</span>;

<span class="kw">use</span> <span class="ident">anyhow::Result</span>;
<span class="kw">use</span> <span class="ident">serde</span>::{<span class="ident">Deserialize</span>, <span class="ident">Serialize</span>};

<span class="kw">use</span> <span class="ident">abstutil::wraparound_get</span>;
<span class="kw">use</span> <span class="ident">geom</span>::{<span class="ident">Polygon</span>, <span class="ident">Pt2D</span>, <span class="ident">Ring</span>};

<span class="kw">use</span> <span class="kw">crate</span>::{<span class="ident">CommonEndpoint</span>, <span class="ident">Direction</span>, <span class="ident">LaneID</span>, <span class="ident">Map</span>, <span class="ident">RoadID</span>, <span class="ident">RoadSideID</span>, <span class="ident">SideOfRoad</span>};

<span class="doccomment">/// A block is defined by a perimeter that traces along the sides of roads. Inside the perimeter,</span>
<span class="doccomment">/// the block may contain buildings and interior roads. In the simple case, a block represents a</span>
<span class="doccomment">/// single &quot;city block&quot;, with no interior roads. It may also cover a &quot;neighborhood&quot;, where the</span>
<span class="doccomment">/// perimeter contains some &quot;major&quot; and the interior consists only of &quot;minor&quot; roads.</span>
<span class="comment">// TODO Maybe &quot;block&quot; is a misleading term. &quot;Contiguous road trace area&quot;?</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Clone</span>, <span class="ident">Serialize</span>, <span class="ident">Deserialize</span>)]</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">Block</span> {
    <span class="kw">pub</span> <span class="ident">perimeter</span>: <span class="ident">Perimeter</span>,
    <span class="doccomment">/// The polygon covers the interior of the block.</span>
    <span class="kw">pub</span> <span class="ident">polygon</span>: <span class="ident">Polygon</span>,
}

<span class="doccomment">/// A sequence of roads in order, beginning and ending at the same place. No &quot;crossings&quot; -- tracing</span>
<span class="doccomment">/// along this sequence should geometrically yield a simple polygon.</span>
<span class="comment">// TODO Handle the map boundary. Sometimes this perimeter should be broken up by border</span>
<span class="comment">// intersections or possibly by water/park areas.</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Clone</span>, <span class="ident">Serialize</span>, <span class="ident">Deserialize</span>)]</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">Perimeter</span> {
    <span class="kw">pub</span> <span class="ident">roads</span>: <span class="ident">Vec</span><span class="op">&lt;</span><span class="ident">RoadSideID</span><span class="op">&gt;</span>,
    <span class="doccomment">/// These roads exist entirely within the perimeter</span>
    <span class="kw">pub</span> <span class="ident">interior</span>: <span class="ident">BTreeSet</span><span class="op">&lt;</span><span class="ident">RoadID</span><span class="op">&gt;</span>,
}

<span class="kw">impl</span> <span class="ident">Perimeter</span> {
    <span class="doccomment">/// Starting at any lane, snap to the nearest side of that road, then begin tracing a single</span>
    <span class="doccomment">/// block, with no interior roads. This will fail if a map boundary is reached. The results are</span>
    <span class="doccomment">/// unusual when crossing the entrance to a tunnel or bridge, and so `skip` is used to avoid</span>
    <span class="doccomment">/// tracing there.</span>
    <span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">single_block</span>(<span class="ident">map</span>: <span class="kw-2">&amp;</span><span class="ident">Map</span>, <span class="ident">start</span>: <span class="ident">LaneID</span>, <span class="ident">skip</span>: <span class="kw-2">&amp;</span><span class="ident">HashSet</span><span class="op">&lt;</span><span class="ident">RoadID</span><span class="op">&gt;</span>) -&gt; <span class="prelude-ty">Result</span><span class="op">&lt;</span><span class="ident">Perimeter</span><span class="op">&gt;</span> {
        <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">roads</span> <span class="op">=</span> <span class="ident">Vec::new</span>();
        <span class="kw">let</span> <span class="ident">start_road_side</span> <span class="op">=</span> <span class="ident">map</span>.<span class="ident">get_l</span>(<span class="ident">start</span>).<span class="ident">get_nearest_side_of_road</span>(<span class="ident">map</span>);

        <span class="kw">if</span> <span class="ident">skip</span>.<span class="ident">contains</span>(<span class="kw-2">&amp;</span><span class="ident">start_road_side</span>.<span class="ident">road</span>) {
            <span class="macro">bail!</span>(<span class="string">&quot;Started on a road we shouldn&#39;t trace&quot;</span>);
        }

        <span class="comment">// We need to track which side of the road we&#39;re at, but also which direction we&#39;re facing</span>
        <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">current_road_side</span> <span class="op">=</span> <span class="ident">start_road_side</span>;
        <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">current_intersection</span> <span class="op">=</span> <span class="ident">map</span>.<span class="ident">get_l</span>(<span class="ident">start</span>).<span class="ident">dst_i</span>;
        <span class="kw">loop</span> {
            <span class="kw">let</span> <span class="ident">i</span> <span class="op">=</span> <span class="ident">map</span>.<span class="ident">get_i</span>(<span class="ident">current_intersection</span>);
            <span class="kw">if</span> <span class="ident">i</span>.<span class="ident">is_border</span>() {
                <span class="macro">bail!</span>(<span class="string">&quot;hit the map boundary&quot;</span>);
            }
            <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">sorted_roads</span> <span class="op">=</span> <span class="ident">i</span>.<span class="ident">get_road_sides_sorted_by_incoming_angle</span>(<span class="ident">map</span>);
            <span class="ident">sorted_roads</span>.<span class="ident">retain</span>(<span class="op">|</span><span class="ident">id</span><span class="op">|</span> <span class="op">!</span><span class="ident">skip</span>.<span class="ident">contains</span>(<span class="kw-2">&amp;</span><span class="ident">id</span>.<span class="ident">road</span>));
            <span class="kw">let</span> <span class="ident">idx</span> <span class="op">=</span> <span class="ident">sorted_roads</span>
                .<span class="ident">iter</span>()
                .<span class="ident">position</span>(<span class="op">|</span><span class="ident">x</span><span class="op">|</span> <span class="kw-2">*</span><span class="ident">x</span> <span class="op">==</span> <span class="ident">current_road_side</span>)
                .<span class="ident">unwrap</span>() <span class="kw">as</span> <span class="ident">isize</span>;
            <span class="comment">// Do we go clockwise or counter-clockwise around the intersection? Well, unless we&#39;re</span>
            <span class="comment">// at a dead-end, we want to avoid the other side of the same road.</span>
            <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">next</span> <span class="op">=</span> <span class="kw-2">*</span><span class="ident">wraparound_get</span>(<span class="kw-2">&amp;</span><span class="ident">sorted_roads</span>, <span class="ident">idx</span> <span class="op">+</span> <span class="number">1</span>);
            <span class="macro">assert_ne!</span>(<span class="ident">next</span>, <span class="ident">current_road_side</span>);
            <span class="kw">if</span> <span class="ident">next</span>.<span class="ident">road</span> <span class="op">==</span> <span class="ident">current_road_side</span>.<span class="ident">road</span> {
                <span class="ident">next</span> <span class="op">=</span> <span class="kw-2">*</span><span class="ident">wraparound_get</span>(<span class="kw-2">&amp;</span><span class="ident">sorted_roads</span>, <span class="ident">idx</span> <span class="op">-</span> <span class="number">1</span>);
                <span class="macro">assert_ne!</span>(<span class="ident">next</span>, <span class="ident">current_road_side</span>);
                <span class="kw">if</span> <span class="ident">next</span>.<span class="ident">road</span> <span class="op">==</span> <span class="ident">current_road_side</span>.<span class="ident">road</span> {
                    <span class="comment">// We must be at a dead-end</span>
                    <span class="macro">assert_eq!</span>(<span class="number">2</span>, <span class="ident">sorted_roads</span>.<span class="ident">len</span>());
                }
            }
            <span class="ident">roads</span>.<span class="ident">push</span>(<span class="ident">current_road_side</span>);
            <span class="ident">current_road_side</span> <span class="op">=</span> <span class="ident">next</span>;
            <span class="ident">current_intersection</span> <span class="op">=</span> <span class="ident">map</span>
                .<span class="ident">get_r</span>(<span class="ident">current_road_side</span>.<span class="ident">road</span>)
                .<span class="ident">other_endpt</span>(<span class="ident">current_intersection</span>);

            <span class="kw">if</span> <span class="ident">current_road_side</span> <span class="op">==</span> <span class="ident">start_road_side</span> {
                <span class="ident">roads</span>.<span class="ident">push</span>(<span class="ident">start_road_side</span>);
                <span class="kw">break</span>;
            }
        }
        <span class="macro">assert_eq!</span>(<span class="ident">roads</span>[<span class="number">0</span>], <span class="kw-2">*</span><span class="ident">roads</span>.<span class="ident">last</span>().<span class="ident">unwrap</span>());
        <span class="prelude-val">Ok</span>(<span class="ident">Perimeter</span> {
            <span class="ident">roads</span>,
            <span class="ident">interior</span>: <span class="ident">BTreeSet::new</span>(),
        })
    }

    <span class="doccomment">/// This calculates all single block perimeters for the entire map. The resulting list does not</span>
    <span class="doccomment">/// cover roads near the map boundary.</span>
    <span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">find_all_single_blocks</span>(<span class="ident">map</span>: <span class="kw-2">&amp;</span><span class="ident">Map</span>) -&gt; <span class="ident">Vec</span><span class="op">&lt;</span><span class="ident">Perimeter</span><span class="op">&gt;</span> {
        <span class="kw">let</span> <span class="ident">skip</span> <span class="op">=</span> <span class="ident">Perimeter::find_roads_to_skip_tracing</span>(<span class="ident">map</span>);

        <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">seen</span> <span class="op">=</span> <span class="ident">HashSet::new</span>();
        <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">perimeters</span> <span class="op">=</span> <span class="ident">Vec::new</span>();
        <span class="kw">for</span> <span class="ident">lane</span> <span class="kw">in</span> <span class="ident">map</span>.<span class="ident">all_lanes</span>() {
            <span class="kw">let</span> <span class="ident">side</span> <span class="op">=</span> <span class="ident">lane</span>.<span class="ident">get_nearest_side_of_road</span>(<span class="ident">map</span>);
            <span class="kw">if</span> <span class="ident">seen</span>.<span class="ident">contains</span>(<span class="kw-2">&amp;</span><span class="ident">side</span>) {
                <span class="kw">continue</span>;
            }
            <span class="kw">match</span> <span class="ident">Perimeter::single_block</span>(<span class="ident">map</span>, <span class="ident">lane</span>.<span class="ident">id</span>, <span class="kw-2">&amp;</span><span class="ident">skip</span>) {
                <span class="prelude-val">Ok</span>(<span class="ident">perimeter</span>) =&gt; {
                    <span class="ident">seen</span>.<span class="ident">extend</span>(<span class="ident">perimeter</span>.<span class="ident">roads</span>.<span class="ident">clone</span>());
                    <span class="ident">perimeters</span>.<span class="ident">push</span>(<span class="ident">perimeter</span>);
                }
                <span class="prelude-val">Err</span>(<span class="ident">err</span>) =&gt; {
                    <span class="comment">// The logs are quite spammy and not helpful yet, since they&#39;re all expected</span>
                    <span class="comment">// cases near the map boundary</span>
                    <span class="kw">if</span> <span class="bool-val">false</span> {
                        <span class="macro">warn!</span>(<span class="string">&quot;Failed from {}: {}&quot;</span>, <span class="ident">lane</span>.<span class="ident">id</span>, <span class="ident">err</span>);
                    }
                    <span class="comment">// Don&#39;t try again</span>
                    <span class="ident">seen</span>.<span class="ident">insert</span>(<span class="ident">side</span>);
                }
            }
        }
        <span class="ident">perimeters</span>
    }

    <span class="doccomment">/// Trying to form blocks near railways or cycleways that involve bridges/tunnels often causes</span>
    <span class="doccomment">/// overlapping geometry or blocks that&#39;re way too large. These are extremely imperfect</span>
    <span class="doccomment">/// heuristics to avoid the worst problems.</span>
    <span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">find_roads_to_skip_tracing</span>(<span class="ident">map</span>: <span class="kw-2">&amp;</span><span class="ident">Map</span>) -&gt; <span class="ident">HashSet</span><span class="op">&lt;</span><span class="ident">RoadID</span><span class="op">&gt;</span> {
        <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">skip</span> <span class="op">=</span> <span class="ident">HashSet::new</span>();
        <span class="kw">for</span> <span class="ident">r</span> <span class="kw">in</span> <span class="ident">map</span>.<span class="ident">all_roads</span>() {
            <span class="kw">if</span> <span class="ident">r</span>.<span class="ident">is_light_rail</span>() {
                <span class="ident">skip</span>.<span class="ident">insert</span>(<span class="ident">r</span>.<span class="ident">id</span>);
            } <span class="kw">else</span> <span class="kw">if</span> <span class="ident">r</span>.<span class="ident">is_cycleway</span>() <span class="op">&amp;&amp;</span> <span class="ident">r</span>.<span class="ident">zorder</span> <span class="op">!</span><span class="op">=</span> <span class="number">0</span> {
                <span class="ident">skip</span>.<span class="ident">insert</span>(<span class="ident">r</span>.<span class="ident">id</span>);
            }
        }
        <span class="ident">skip</span>
    }

    <span class="doccomment">/// A perimeter has the first and last road matching up, but that&#39;s confusing to</span>
    <span class="doccomment">/// work with. Temporarily undo that.</span>
    <span class="kw">fn</span> <span class="ident">undo_invariant</span>(<span class="kw-2">&amp;mut</span> <span class="self">self</span>) {
        <span class="macro">assert_eq!</span>(<span class="prelude-val">Some</span>(<span class="self">self</span>.<span class="ident">roads</span>[<span class="number">0</span>]), <span class="self">self</span>.<span class="ident">roads</span>.<span class="ident">pop</span>());
    }

    <span class="doccomment">/// Restore the first=last invariant. Methods may temporarily break this, but must restore it</span>
    <span class="doccomment">/// before returning.</span>
    <span class="kw">fn</span> <span class="ident">restore_invariant</span>(<span class="kw-2">&amp;mut</span> <span class="self">self</span>) {
        <span class="self">self</span>.<span class="ident">roads</span>.<span class="ident">push</span>(<span class="self">self</span>.<span class="ident">roads</span>[<span class="number">0</span>]);
    }

    <span class="doccomment">/// Try to merge two blocks. Returns true if this is successful, which will only be when the</span>
    <span class="doccomment">/// blocks are adjacent, but the merge wouldn&#39;t create an interior &quot;hole&quot;.</span>
    <span class="doccomment">///</span>
    <span class="doccomment">/// Note this may modify both perimeters and still return `false`. The modification is just to</span>
    <span class="doccomment">/// rotate the order of the road loop; this doesn&#39;t logically change the perimeter.</span>
    <span class="doccomment">///</span>
    <span class="doccomment">/// TODO Due to https://github.com/a-b-street/abstreet/issues/841, it seems like rotation</span>
    <span class="doccomment">/// sometimes breaks `to_block`, so for now, always revert to the original upon failure.</span>
    <span class="comment">// TODO Would it be cleaner to return a Result here and always restore the invariant?</span>
    <span class="kw">fn</span> <span class="ident">try_to_merge</span>(
        <span class="kw-2">&amp;mut</span> <span class="self">self</span>,
        <span class="ident">map</span>: <span class="kw-2">&amp;</span><span class="ident">Map</span>,
        <span class="ident">other</span>: <span class="kw-2">&amp;mut</span> <span class="ident">Perimeter</span>,
        <span class="ident">debug_failures</span>: <span class="ident">bool</span>,
        <span class="ident">use_expensive_blockfinding</span>: <span class="ident">bool</span>,
    ) -&gt; <span class="ident">bool</span> {
        <span class="kw">let</span> <span class="ident">orig_self</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">clone</span>();
        <span class="kw">let</span> <span class="ident">orig_other</span> <span class="op">=</span> <span class="ident">other</span>.<span class="ident">clone</span>();

        <span class="self">self</span>.<span class="ident">undo_invariant</span>();
        <span class="ident">other</span>.<span class="ident">undo_invariant</span>();

        <span class="comment">// Calculate common roads</span>
        <span class="kw">let</span> <span class="ident">roads1</span>: <span class="ident">HashSet</span><span class="op">&lt;</span><span class="ident">RoadID</span><span class="op">&gt;</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">roads</span>.<span class="ident">iter</span>().<span class="ident">map</span>(<span class="op">|</span><span class="ident">id</span><span class="op">|</span> <span class="ident">id</span>.<span class="ident">road</span>).<span class="ident">collect</span>();
        <span class="kw">let</span> <span class="ident">roads2</span>: <span class="ident">HashSet</span><span class="op">&lt;</span><span class="ident">RoadID</span><span class="op">&gt;</span> <span class="op">=</span> <span class="ident">other</span>.<span class="ident">roads</span>.<span class="ident">iter</span>().<span class="ident">map</span>(<span class="op">|</span><span class="ident">id</span><span class="op">|</span> <span class="ident">id</span>.<span class="ident">road</span>).<span class="ident">collect</span>();
        <span class="kw">let</span> <span class="ident">common</span>: <span class="ident">HashSet</span><span class="op">&lt;</span><span class="ident">RoadID</span><span class="op">&gt;</span> <span class="op">=</span> <span class="ident">roads1</span>.<span class="ident">intersection</span>(<span class="kw-2">&amp;</span><span class="ident">roads2</span>).<span class="ident">cloned</span>().<span class="ident">collect</span>();
        <span class="kw">if</span> <span class="ident">common</span>.<span class="ident">is_empty</span>() {
            <span class="kw">if</span> <span class="ident">debug_failures</span> {
                <span class="macro">warn!</span>(<span class="string">&quot;No common roads&quot;</span>);
            }
            <span class="kw-2">*</span><span class="self">self</span> <span class="op">=</span> <span class="ident">orig_self</span>;
            <span class="kw-2">*</span><span class="ident">other</span> <span class="op">=</span> <span class="ident">orig_other</span>;
            <span class="kw">return</span> <span class="bool-val">false</span>;
        }

        <span class="comment">// &quot;Rotate&quot; the order of roads, so that all of the overlapping roads are at the end of the</span>
        <span class="comment">// list. If the entire perimeter is surrounded by the other, then no rotation needed.</span>
        <span class="kw">if</span> <span class="self">self</span>.<span class="ident">roads</span>.<span class="ident">len</span>() <span class="op">!</span><span class="op">=</span> <span class="ident">common</span>.<span class="ident">len</span>() {
            <span class="kw">while</span> <span class="ident">common</span>.<span class="ident">contains</span>(<span class="kw-2">&amp;</span><span class="self">self</span>.<span class="ident">roads</span>[<span class="number">0</span>].<span class="ident">road</span>)
                <span class="op">|</span><span class="op">|</span> <span class="op">!</span><span class="ident">common</span>.<span class="ident">contains</span>(<span class="kw-2">&amp;</span><span class="self">self</span>.<span class="ident">roads</span>.<span class="ident">last</span>().<span class="ident">unwrap</span>().<span class="ident">road</span>)
            {
                <span class="self">self</span>.<span class="ident">roads</span>.<span class="ident">rotate_left</span>(<span class="number">1</span>);
            }
        }
        <span class="comment">// Same thing with the other</span>
        <span class="kw">if</span> <span class="ident">other</span>.<span class="ident">roads</span>.<span class="ident">len</span>() <span class="op">!</span><span class="op">=</span> <span class="ident">common</span>.<span class="ident">len</span>() {
            <span class="kw">while</span> <span class="ident">common</span>.<span class="ident">contains</span>(<span class="kw-2">&amp;</span><span class="ident">other</span>.<span class="ident">roads</span>[<span class="number">0</span>].<span class="ident">road</span>)
                <span class="op">|</span><span class="op">|</span> <span class="op">!</span><span class="ident">common</span>.<span class="ident">contains</span>(<span class="kw-2">&amp;</span><span class="ident">other</span>.<span class="ident">roads</span>.<span class="ident">last</span>().<span class="ident">unwrap</span>().<span class="ident">road</span>)
            {
                <span class="ident">other</span>.<span class="ident">roads</span>.<span class="ident">rotate_left</span>(<span class="number">1</span>);
            }
        }

        <span class="kw">if</span> <span class="ident">debug_failures</span> {
            <span class="macro">println!</span>(<span class="string">&quot;\nCommon: {:?}\n{:?}\n{:?}&quot;</span>, <span class="ident">common</span>, <span class="self">self</span>, <span class="ident">other</span>);
        }

        <span class="comment">// Check if all of the common roads are at the end of each perimeter,</span>
        <span class="comment">// so we can &quot;blindly&quot; do this snipping. If this isn&#39;t true, then the overlapping portions</span>
        <span class="comment">// are split by non-overlapping roads. This happens when merging the two blocks would</span>
        <span class="comment">// result in a &quot;hole.&quot;</span>
        <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">ok</span> <span class="op">=</span> <span class="bool-val">true</span>;
        <span class="kw">for</span> <span class="ident">id</span> <span class="kw">in</span> <span class="self">self</span>.<span class="ident">roads</span>.<span class="ident">iter</span>().<span class="ident">rev</span>().<span class="ident">take</span>(<span class="ident">common</span>.<span class="ident">len</span>()) {
            <span class="kw">if</span> <span class="op">!</span><span class="ident">common</span>.<span class="ident">contains</span>(<span class="kw-2">&amp;</span><span class="ident">id</span>.<span class="ident">road</span>) {
                <span class="kw">if</span> <span class="ident">debug_failures</span> {
                    <span class="macro">warn!</span>(
                        <span class="string">&quot;The common roads on the first aren&#39;t consecutive, near {:?}&quot;</span>,
                        <span class="ident">id</span>
                    );
                }
                <span class="ident">ok</span> <span class="op">=</span> <span class="bool-val">false</span>;
                <span class="kw">break</span>;
            }
        }
        <span class="kw">for</span> <span class="ident">id</span> <span class="kw">in</span> <span class="ident">other</span>.<span class="ident">roads</span>.<span class="ident">iter</span>().<span class="ident">rev</span>().<span class="ident">take</span>(<span class="ident">common</span>.<span class="ident">len</span>()) {
            <span class="kw">if</span> <span class="op">!</span><span class="ident">common</span>.<span class="ident">contains</span>(<span class="kw-2">&amp;</span><span class="ident">id</span>.<span class="ident">road</span>) {
                <span class="kw">if</span> <span class="ident">debug_failures</span> {
                    <span class="macro">warn!</span>(
                        <span class="string">&quot;The common roads on the second aren&#39;t consecutive, near {:?}&quot;</span>,
                        <span class="ident">id</span>
                    );
                }
                <span class="ident">ok</span> <span class="op">=</span> <span class="bool-val">false</span>;
                <span class="kw">break</span>;
            }
        }
        <span class="kw">if</span> <span class="op">!</span><span class="ident">ok</span> {
            <span class="kw-2">*</span><span class="self">self</span> <span class="op">=</span> <span class="ident">orig_self</span>;
            <span class="kw-2">*</span><span class="ident">other</span> <span class="op">=</span> <span class="ident">orig_other</span>;
            <span class="kw">return</span> <span class="bool-val">false</span>;
        }

        <span class="comment">// Very straightforward snipping now</span>
        <span class="kw">for</span> <span class="kw">_</span> <span class="kw">in</span> <span class="number">0</span>..<span class="ident">common</span>.<span class="ident">len</span>() {
            <span class="self">self</span>.<span class="ident">roads</span>.<span class="ident">pop</span>().<span class="ident">unwrap</span>();
            <span class="ident">other</span>.<span class="ident">roads</span>.<span class="ident">pop</span>().<span class="ident">unwrap</span>();
        }

        <span class="comment">// This order assumes everything is clockwise to start with.</span>
        <span class="self">self</span>.<span class="ident">roads</span>.<span class="ident">append</span>(<span class="kw-2">&amp;mut</span> <span class="ident">other</span>.<span class="ident">roads</span>);

        <span class="comment">// TODO This case was introduced with find_roads_to_skip_tracing. Not sure why.</span>
        <span class="kw">if</span> <span class="self">self</span>.<span class="ident">roads</span>.<span class="ident">is_empty</span>() {
            <span class="kw">if</span> <span class="ident">debug_failures</span> {
                <span class="macro">warn!</span>(<span class="string">&quot;Two perimeters had every road in common: {:?}&quot;</span>, <span class="ident">common</span>);
            }
            <span class="kw-2">*</span><span class="self">self</span> <span class="op">=</span> <span class="ident">orig_self</span>;
            <span class="kw-2">*</span><span class="ident">other</span> <span class="op">=</span> <span class="ident">orig_other</span>;
            <span class="kw">return</span> <span class="bool-val">false</span>;
        }

        <span class="self">self</span>.<span class="ident">interior</span>.<span class="ident">extend</span>(<span class="ident">common</span>);
        <span class="self">self</span>.<span class="ident">interior</span>.<span class="ident">append</span>(<span class="kw-2">&amp;mut</span> <span class="ident">other</span>.<span class="ident">interior</span>);

        <span class="comment">// Restore the first=last invariant</span>
        <span class="self">self</span>.<span class="ident">restore_invariant</span>();

        <span class="comment">// Make sure we didn&#39;t wind up with any internal dead-ends</span>
        <span class="self">self</span>.<span class="ident">collapse_deadends</span>();

        <span class="comment">// TODO Something in this method is buggy and produces invalid merges.</span>
        <span class="comment">// https://github.com/a-b-street/abstreet/issues/841</span>
        <span class="comment">// First try a lightweight detection for problems. If the caller detects the net result is</span>
        <span class="comment">// invalid, they&#39;ll override this flag and try again.</span>
        <span class="kw">let</span> <span class="ident">err</span> <span class="op">=</span> <span class="kw">if</span> <span class="ident">use_expensive_blockfinding</span> {
            <span class="self">self</span>.<span class="ident">clone</span>().<span class="ident">to_block</span>(<span class="ident">map</span>).<span class="ident">err</span>()
        } <span class="kw">else</span> {
            <span class="self">self</span>.<span class="ident">check_continuity</span>(<span class="ident">map</span>).<span class="ident">err</span>()
        };
        <span class="kw">if</span> <span class="kw">let</span> <span class="prelude-val">Some</span>(<span class="ident">err</span>) <span class="op">=</span> <span class="ident">err</span> {
            <span class="macro">debug!</span>(
                <span class="string">&quot;A merged perimeter couldn&#39;t be blockified: {}. {:?}&quot;</span>,
                <span class="ident">err</span>, <span class="self">self</span>
            );
            <span class="kw-2">*</span><span class="self">self</span> <span class="op">=</span> <span class="ident">orig_self</span>;
            <span class="kw-2">*</span><span class="ident">other</span> <span class="op">=</span> <span class="ident">orig_other</span>;
            <span class="kw">return</span> <span class="bool-val">false</span>;
        }

        <span class="bool-val">true</span>
    }

    <span class="kw">fn</span> <span class="ident">check_continuity</span>(<span class="kw-2">&amp;</span><span class="self">self</span>, <span class="ident">map</span>: <span class="kw-2">&amp;</span><span class="ident">Map</span>) -&gt; <span class="prelude-ty">Result</span><span class="op">&lt;</span>()<span class="op">&gt;</span> {
        <span class="kw">for</span> <span class="ident">pair</span> <span class="kw">in</span> <span class="self">self</span>.<span class="ident">roads</span>.<span class="ident">windows</span>(<span class="number">2</span>) {
            <span class="kw">let</span> <span class="ident">r1</span> <span class="op">=</span> <span class="ident">map</span>.<span class="ident">get_r</span>(<span class="ident">pair</span>[<span class="number">0</span>].<span class="ident">road</span>);
            <span class="kw">let</span> <span class="ident">r2</span> <span class="op">=</span> <span class="ident">map</span>.<span class="ident">get_r</span>(<span class="ident">pair</span>[<span class="number">1</span>].<span class="ident">road</span>);
            <span class="kw">if</span> <span class="ident">r1</span>.<span class="ident">common_endpoint</span>(<span class="ident">r2</span>) <span class="op">==</span> <span class="ident">CommonEndpoint::None</span> {
                <span class="macro">bail!</span>(<span class="string">&quot;Part of the perimeter goes from {:?} to {:?}, but they don&#39;t share a common endpoint&quot;</span>, <span class="ident">pair</span>[<span class="number">0</span>], <span class="ident">pair</span>[<span class="number">1</span>]);
            }
        }
        <span class="prelude-val">Ok</span>(())
    }

    <span class="doccomment">/// Try to merge all given perimeters. If successful, only one perimeter will be returned.</span>
    <span class="doccomment">/// Perimeters are never &quot;destroyed&quot; -- if not merged, they&#39;ll appear in the results. If</span>
    <span class="doccomment">/// `stepwise_debug` is true, returns after performing just one merge.</span>
    <span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">merge_all</span>(
        <span class="ident">map</span>: <span class="kw-2">&amp;</span><span class="ident">Map</span>,
        <span class="kw-2">mut</span> <span class="ident">input</span>: <span class="ident">Vec</span><span class="op">&lt;</span><span class="ident">Perimeter</span><span class="op">&gt;</span>,
        <span class="ident">stepwise_debug</span>: <span class="ident">bool</span>,
        <span class="ident">use_expensive_blockfinding</span>: <span class="ident">bool</span>,
    ) -&gt; <span class="ident">Vec</span><span class="op">&lt;</span><span class="ident">Perimeter</span><span class="op">&gt;</span> {
        <span class="comment">// Internal dead-ends break merging, so first collapse of those. Do this before even</span>
        <span class="comment">// looking for neighbors, since find_common_roads doesn&#39;t understand dead-ends.</span>
        <span class="kw">for</span> <span class="ident">p</span> <span class="kw">in</span> <span class="kw-2">&amp;mut</span> <span class="ident">input</span> {
            <span class="ident">p</span>.<span class="ident">collapse_deadends</span>();
        }

        <span class="kw">loop</span> {
            <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">debug</span> <span class="op">=</span> <span class="bool-val">false</span>;
            <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">results</span>: <span class="ident">Vec</span><span class="op">&lt;</span><span class="ident">Perimeter</span><span class="op">&gt;</span> <span class="op">=</span> <span class="ident">Vec::new</span>();
            <span class="kw">let</span> <span class="ident">num_input</span> <span class="op">=</span> <span class="ident">input</span>.<span class="ident">len</span>();
            <span class="lifetime">&#39;INPUT</span>: <span class="kw">for</span> <span class="kw-2">mut</span> <span class="ident">perimeter</span> <span class="kw">in</span> <span class="ident">input</span> {
                <span class="kw">if</span> <span class="ident">debug</span> {
                    <span class="ident">results</span>.<span class="ident">push</span>(<span class="ident">perimeter</span>);
                    <span class="kw">continue</span>;
                }

                <span class="kw">for</span> <span class="ident">other</span> <span class="kw">in</span> <span class="kw-2">&amp;mut</span> <span class="ident">results</span> {
                    <span class="kw">if</span> <span class="ident">other</span>.<span class="ident">try_to_merge</span>(
                        <span class="ident">map</span>,
                        <span class="kw-2">&amp;mut</span> <span class="ident">perimeter</span>,
                        <span class="ident">stepwise_debug</span>,
                        <span class="ident">use_expensive_blockfinding</span>,
                    ) {
                        <span class="comment">// To debug, return after any single change</span>
                        <span class="ident">debug</span> <span class="op">=</span> <span class="ident">stepwise_debug</span>;
                        <span class="kw">continue</span> <span class="lifetime">&#39;INPUT</span>;
                    }
                }

                <span class="comment">// No match</span>
                <span class="ident">results</span>.<span class="ident">push</span>(<span class="ident">perimeter</span>);
            }

            <span class="comment">// Should we try merging again?</span>
            <span class="kw">if</span> <span class="ident">results</span>.<span class="ident">len</span>() <span class="op">&gt;</span> <span class="number">1</span> <span class="op">&amp;&amp;</span> <span class="ident">results</span>.<span class="ident">len</span>() <span class="op">&lt;</span> <span class="ident">num_input</span> <span class="op">&amp;&amp;</span> <span class="op">!</span><span class="ident">stepwise_debug</span> {
                <span class="ident">input</span> <span class="op">=</span> <span class="ident">results</span>;
                <span class="kw">continue</span>;
            }
            <span class="kw">return</span> <span class="ident">results</span>;
        }
    }

    <span class="doccomment">/// If the perimeter follows any dead-end roads, &quot;collapse&quot; them and instead make the perimeter</span>
    <span class="doccomment">/// contain the dead-end.</span>
    <span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">collapse_deadends</span>(<span class="kw-2">&amp;mut</span> <span class="self">self</span>) {
        <span class="kw">let</span> <span class="ident">orig</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">clone</span>();
        <span class="self">self</span>.<span class="ident">undo_invariant</span>();

        <span class="comment">// TODO Workaround https://github.com/a-b-street/abstreet/issues/834. If this is a loop</span>
        <span class="comment">// around a disconnected fragment of road, don&#39;t touch it</span>
        <span class="kw">if</span> <span class="self">self</span>.<span class="ident">roads</span>.<span class="ident">len</span>() <span class="op">==</span> <span class="number">2</span> <span class="op">&amp;&amp;</span> <span class="self">self</span>.<span class="ident">roads</span>[<span class="number">0</span>].<span class="ident">road</span> <span class="op">==</span> <span class="self">self</span>.<span class="ident">roads</span>[<span class="number">1</span>].<span class="ident">road</span> {
            <span class="self">self</span>.<span class="ident">restore_invariant</span>();
            <span class="kw">return</span>;
        }

        <span class="comment">// If the dead-end straddles the loop, it&#39;s confusing. Just rotate until that&#39;s not true.</span>
        <span class="kw">while</span> <span class="self">self</span>.<span class="ident">roads</span>[<span class="number">0</span>].<span class="ident">road</span> <span class="op">==</span> <span class="self">self</span>.<span class="ident">roads</span>.<span class="ident">last</span>().<span class="ident">unwrap</span>().<span class="ident">road</span> {
            <span class="self">self</span>.<span class="ident">roads</span>.<span class="ident">rotate_left</span>(<span class="number">1</span>);
        }

        <span class="comment">// TODO This won&#39;t handle a deadend that&#39;s more than 1 segment long</span>
        <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">roads</span>: <span class="ident">Vec</span><span class="op">&lt;</span><span class="ident">RoadSideID</span><span class="op">&gt;</span> <span class="op">=</span> <span class="ident">Vec::new</span>();
        <span class="kw">for</span> <span class="ident">id</span> <span class="kw">in</span> <span class="self">self</span>.<span class="ident">roads</span>.<span class="ident">drain</span>(..) {
            <span class="kw">if</span> <span class="prelude-val">Some</span>(<span class="ident">id</span>.<span class="ident">road</span>) <span class="op">==</span> <span class="ident">roads</span>.<span class="ident">last</span>().<span class="ident">map</span>(<span class="op">|</span><span class="ident">id</span><span class="op">|</span> <span class="ident">id</span>.<span class="ident">road</span>) {
                <span class="ident">roads</span>.<span class="ident">pop</span>();
                <span class="self">self</span>.<span class="ident">interior</span>.<span class="ident">insert</span>(<span class="ident">id</span>.<span class="ident">road</span>);
            } <span class="kw">else</span> {
                <span class="ident">roads</span>.<span class="ident">push</span>(<span class="ident">id</span>);
            }
        }

        <span class="self">self</span>.<span class="ident">roads</span> <span class="op">=</span> <span class="ident">roads</span>;
        <span class="kw">if</span> <span class="self">self</span>.<span class="ident">roads</span>.<span class="ident">is_empty</span>() {
            <span class="comment">// TODO This case was introduced with find_roads_to_skip_tracing. Not sure why.</span>
            <span class="kw-2">*</span><span class="self">self</span> <span class="op">=</span> <span class="ident">orig</span>;
            <span class="kw">return</span>;
        }
        <span class="self">self</span>.<span class="ident">restore_invariant</span>();
    }

    <span class="doccomment">/// Consider the perimeters as a graph, with adjacency determined by sharing any road in common.</span>
    <span class="doccomment">/// Partition adjacent perimeters, subject to the predicate. Each partition should produce a</span>
    <span class="doccomment">/// single result with `merge_all`.</span>
    <span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">partition_by_predicate</span><span class="op">&lt;</span><span class="ident">F</span>: <span class="ident">Fn</span>(<span class="ident">RoadID</span>) -&gt; <span class="ident">bool</span><span class="op">&gt;</span>(
        <span class="ident">input</span>: <span class="ident">Vec</span><span class="op">&lt;</span><span class="ident">Perimeter</span><span class="op">&gt;</span>,
        <span class="ident">predicate</span>: <span class="ident">F</span>,
    ) -&gt; <span class="ident">Vec</span><span class="op">&lt;</span><span class="ident">Vec</span><span class="op">&lt;</span><span class="ident">Perimeter</span><span class="op">&gt;</span><span class="op">&gt;</span> {
        <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">road_to_perimeters</span>: <span class="ident">HashMap</span><span class="op">&lt;</span><span class="ident">RoadID</span>, <span class="ident">Vec</span><span class="op">&lt;</span><span class="ident">usize</span><span class="op">&gt;</span><span class="op">&gt;</span> <span class="op">=</span> <span class="ident">HashMap::new</span>();
        <span class="kw">for</span> (<span class="ident">idx</span>, <span class="ident">perimeter</span>) <span class="kw">in</span> <span class="ident">input</span>.<span class="ident">iter</span>().<span class="ident">enumerate</span>() {
            <span class="kw">for</span> <span class="ident">id</span> <span class="kw">in</span> <span class="kw-2">&amp;</span><span class="ident">perimeter</span>.<span class="ident">roads</span> {
                <span class="ident">road_to_perimeters</span>
                    .<span class="ident">entry</span>(<span class="ident">id</span>.<span class="ident">road</span>)
                    .<span class="ident">or_insert_with</span>(<span class="ident">Vec::new</span>)
                    .<span class="ident">push</span>(<span class="ident">idx</span>);
            }
        }

        <span class="comment">// Start at one perimeter, floodfill to adjacent perimeters, subject to the predicate.</span>
        <span class="comment">// Returns the indices of everything in that component.</span>
        <span class="kw">let</span> <span class="ident">floodfill</span> <span class="op">=</span> <span class="op">|</span><span class="ident">start</span>: <span class="ident">usize</span><span class="op">|</span> -&gt; <span class="ident">BTreeSet</span><span class="op">&lt;</span><span class="ident">usize</span><span class="op">&gt;</span> {
            <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">visited</span> <span class="op">=</span> <span class="ident">BTreeSet::new</span>();
            <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">queue</span> <span class="op">=</span> <span class="macro">vec!</span>[<span class="ident">start</span>];
            <span class="kw">while</span> <span class="op">!</span><span class="ident">queue</span>.<span class="ident">is_empty</span>() {
                <span class="kw">let</span> <span class="ident">current</span> <span class="op">=</span> <span class="ident">queue</span>.<span class="ident">pop</span>().<span class="ident">unwrap</span>();
                <span class="kw">if</span> <span class="ident">visited</span>.<span class="ident">contains</span>(<span class="kw-2">&amp;</span><span class="ident">current</span>) {
                    <span class="kw">continue</span>;
                }
                <span class="ident">visited</span>.<span class="ident">insert</span>(<span class="ident">current</span>);
                <span class="kw">for</span> <span class="ident">id</span> <span class="kw">in</span> <span class="kw-2">&amp;</span><span class="ident">input</span>[<span class="ident">current</span>].<span class="ident">roads</span> {
                    <span class="kw">if</span> <span class="ident">predicate</span>(<span class="ident">id</span>.<span class="ident">road</span>) {
                        <span class="ident">queue</span>.<span class="ident">extend</span>(<span class="ident">road_to_perimeters</span>[<span class="kw-2">&amp;</span><span class="ident">id</span>.<span class="ident">road</span>].<span class="ident">clone</span>());
                    }
                }
            }
            <span class="ident">visited</span>
        };

        <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">partitions</span>: <span class="ident">Vec</span><span class="op">&lt;</span><span class="ident">BTreeSet</span><span class="op">&lt;</span><span class="ident">usize</span><span class="op">&gt;</span><span class="op">&gt;</span> <span class="op">=</span> <span class="ident">Vec::new</span>();
        <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">finished</span>: <span class="ident">HashSet</span><span class="op">&lt;</span><span class="ident">usize</span><span class="op">&gt;</span> <span class="op">=</span> <span class="ident">HashSet::new</span>();
        <span class="kw">for</span> <span class="ident">start</span> <span class="kw">in</span> <span class="number">0</span>..<span class="ident">input</span>.<span class="ident">len</span>() {
            <span class="kw">if</span> <span class="ident">finished</span>.<span class="ident">contains</span>(<span class="kw-2">&amp;</span><span class="ident">start</span>) {
                <span class="kw">continue</span>;
            }
            <span class="kw">let</span> <span class="ident">partition</span> <span class="op">=</span> <span class="ident">floodfill</span>(<span class="ident">start</span>);
            <span class="ident">finished</span>.<span class="ident">extend</span>(<span class="ident">partition</span>.<span class="ident">clone</span>());
            <span class="ident">partitions</span>.<span class="ident">push</span>(<span class="ident">partition</span>);
        }

        <span class="comment">// Map the indices back to the actual perimeters.</span>
        <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">perimeters</span>: <span class="ident">Vec</span><span class="op">&lt;</span><span class="prelude-ty">Option</span><span class="op">&lt;</span><span class="ident">Perimeter</span><span class="op">&gt;</span><span class="op">&gt;</span> <span class="op">=</span> <span class="ident">input</span>.<span class="ident">into_iter</span>().<span class="ident">map</span>(<span class="prelude-val">Some</span>).<span class="ident">collect</span>();
        <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">results</span> <span class="op">=</span> <span class="ident">Vec::new</span>();
        <span class="kw">for</span> <span class="ident">indices</span> <span class="kw">in</span> <span class="ident">partitions</span> {
            <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">partition</span> <span class="op">=</span> <span class="ident">Vec::new</span>();
            <span class="kw">for</span> <span class="ident">idx</span> <span class="kw">in</span> <span class="ident">indices</span> {
                <span class="ident">partition</span>.<span class="ident">push</span>(<span class="ident">perimeters</span>[<span class="ident">idx</span>].<span class="ident">take</span>().<span class="ident">unwrap</span>());
            }
            <span class="ident">results</span>.<span class="ident">push</span>(<span class="ident">partition</span>);
        }
        <span class="comment">// Sanity check</span>
        <span class="kw">for</span> <span class="ident">maybe_perimeter</span> <span class="kw">in</span> <span class="ident">perimeters</span> {
            <span class="macro">assert!</span>(<span class="ident">maybe_perimeter</span>.<span class="ident">is_none</span>());
        }
        <span class="ident">results</span>
    }

    <span class="doccomment">/// Assign each perimeter one of `num_colors`, such that no two adjacent perimeters share the</span>
    <span class="doccomment">/// same color. May fail. The resulting colors are expressed as `[0, num_colors)`.</span>
    <span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">calculate_coloring</span>(<span class="ident">input</span>: <span class="kw-2">&amp;</span>[<span class="ident">Perimeter</span>], <span class="ident">num_colors</span>: <span class="ident">usize</span>) -&gt; <span class="prelude-ty">Option</span><span class="op">&lt;</span><span class="ident">Vec</span><span class="op">&lt;</span><span class="ident">usize</span><span class="op">&gt;</span><span class="op">&gt;</span> {
        <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">road_to_perimeters</span>: <span class="ident">HashMap</span><span class="op">&lt;</span><span class="ident">RoadID</span>, <span class="ident">Vec</span><span class="op">&lt;</span><span class="ident">usize</span><span class="op">&gt;</span><span class="op">&gt;</span> <span class="op">=</span> <span class="ident">HashMap::new</span>();
        <span class="kw">for</span> (<span class="ident">idx</span>, <span class="ident">perimeter</span>) <span class="kw">in</span> <span class="ident">input</span>.<span class="ident">iter</span>().<span class="ident">enumerate</span>() {
            <span class="kw">for</span> <span class="ident">id</span> <span class="kw">in</span> <span class="kw-2">&amp;</span><span class="ident">perimeter</span>.<span class="ident">roads</span> {
                <span class="ident">road_to_perimeters</span>
                    .<span class="ident">entry</span>(<span class="ident">id</span>.<span class="ident">road</span>)
                    .<span class="ident">or_insert_with</span>(<span class="ident">Vec::new</span>)
                    .<span class="ident">push</span>(<span class="ident">idx</span>);
            }
        }

        <span class="comment">// Greedily fill out a color for each perimeter, in the same order as the input</span>
        <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">assigned_colors</span> <span class="op">=</span> <span class="ident">Vec::new</span>();
        <span class="kw">for</span> (<span class="ident">this_idx</span>, <span class="ident">perimeter</span>) <span class="kw">in</span> <span class="ident">input</span>.<span class="ident">iter</span>().<span class="ident">enumerate</span>() {
            <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">available_colors</span>: <span class="ident">Vec</span><span class="op">&lt;</span><span class="ident">bool</span><span class="op">&gt;</span> <span class="op">=</span>
                <span class="ident">std::iter::repeat</span>(<span class="bool-val">true</span>).<span class="ident">take</span>(<span class="ident">num_colors</span>).<span class="ident">collect</span>();
            <span class="comment">// Find all neighbors</span>
            <span class="kw">for</span> <span class="ident">id</span> <span class="kw">in</span> <span class="kw-2">&amp;</span><span class="ident">perimeter</span>.<span class="ident">roads</span> {
                <span class="kw">for</span> <span class="ident">other_idx</span> <span class="kw">in</span> <span class="kw-2">&amp;</span><span class="ident">road_to_perimeters</span>[<span class="kw-2">&amp;</span><span class="ident">id</span>.<span class="ident">road</span>] {
                    <span class="comment">// We assign colors in order, so any neighbor index smaller than us has been</span>
                    <span class="comment">// chosen</span>
                    <span class="kw">if</span> <span class="kw-2">*</span><span class="ident">other_idx</span> <span class="op">&lt;</span> <span class="ident">this_idx</span> {
                        <span class="ident">available_colors</span>[<span class="ident">assigned_colors</span>[<span class="kw-2">*</span><span class="ident">other_idx</span>]] <span class="op">=</span> <span class="bool-val">false</span>;
                    }
                }
            }
            <span class="kw">if</span> <span class="kw">let</span> <span class="prelude-val">Some</span>(<span class="ident">color</span>) <span class="op">=</span> <span class="ident">available_colors</span>.<span class="ident">iter</span>().<span class="ident">position</span>(<span class="op">|</span><span class="ident">x</span><span class="op">|</span> <span class="kw-2">*</span><span class="ident">x</span>) {
                <span class="ident">assigned_colors</span>.<span class="ident">push</span>(<span class="ident">color</span>);
            } <span class="kw">else</span> {
                <span class="comment">// Too few colors?</span>
                <span class="kw">return</span> <span class="prelude-val">None</span>;
            }
        }
        <span class="prelude-val">Some</span>(<span class="ident">assigned_colors</span>)
    }

    <span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">to_block</span>(<span class="self">self</span>, <span class="ident">map</span>: <span class="kw-2">&amp;</span><span class="ident">Map</span>) -&gt; <span class="prelude-ty">Result</span><span class="op">&lt;</span><span class="ident">Block</span><span class="op">&gt;</span> {
        <span class="comment">// Trace along the perimeter and build the polygon</span>
        <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">pts</span>: <span class="ident">Vec</span><span class="op">&lt;</span><span class="ident">Pt2D</span><span class="op">&gt;</span> <span class="op">=</span> <span class="ident">Vec::new</span>();
        <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">first_intersection</span> <span class="op">=</span> <span class="prelude-val">None</span>;
        <span class="kw">for</span> <span class="ident">pair</span> <span class="kw">in</span> <span class="self">self</span>.<span class="ident">roads</span>.<span class="ident">windows</span>(<span class="number">2</span>) {
            <span class="kw">let</span> <span class="ident">lane1</span> <span class="op">=</span> <span class="ident">pair</span>[<span class="number">0</span>].<span class="ident">get_outermost_lane</span>(<span class="ident">map</span>);
            <span class="kw">let</span> <span class="ident">road1</span> <span class="op">=</span> <span class="ident">map</span>.<span class="ident">get_parent</span>(<span class="ident">lane1</span>.<span class="ident">id</span>);
            <span class="kw">let</span> <span class="ident">lane2</span> <span class="op">=</span> <span class="ident">pair</span>[<span class="number">1</span>].<span class="ident">get_outermost_lane</span>(<span class="ident">map</span>);
            <span class="comment">// If lane1 and lane2 are the same, then it just means we found a dead-end road with</span>
            <span class="comment">// exactly one lane, which is usually a footway or cycleway that legitimately is a</span>
            <span class="comment">// dead-end, or connects to some other road we didn&#39;t import. We&#39;ll just trace around</span>
            <span class="comment">// it like a normal dead-end road.</span>
            <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">pl</span> <span class="op">=</span> <span class="kw">match</span> <span class="ident">pair</span>[<span class="number">0</span>].<span class="ident">side</span> {
                <span class="ident">SideOfRoad::Right</span> =&gt; <span class="ident">road1</span>.<span class="ident">center_pts</span>.<span class="ident">must_shift_right</span>(<span class="ident">road1</span>.<span class="ident">get_half_width</span>()),
                <span class="ident">SideOfRoad::Left</span> =&gt; <span class="ident">road1</span>.<span class="ident">center_pts</span>.<span class="ident">must_shift_left</span>(<span class="ident">road1</span>.<span class="ident">get_half_width</span>()),
            };
            <span class="kw">if</span> <span class="ident">lane1</span>.<span class="ident">dir</span> <span class="op">==</span> <span class="ident">Direction::Back</span> {
                <span class="ident">pl</span> <span class="op">=</span> <span class="ident">pl</span>.<span class="ident">reversed</span>();
            }
            <span class="kw">let</span> <span class="ident">keep_lane_orientation</span> <span class="op">=</span> <span class="kw">if</span> <span class="ident">pair</span>[<span class="number">0</span>].<span class="ident">road</span> <span class="op">==</span> <span class="ident">pair</span>[<span class="number">1</span>].<span class="ident">road</span> {
                <span class="comment">// We&#39;re doubling back at a dead-end. Always follow the orientation of the lane.</span>
                <span class="bool-val">true</span>
            } <span class="kw">else</span> {
                <span class="kw">match</span> <span class="ident">lane1</span>.<span class="ident">common_endpoint</span>(<span class="ident">lane2</span>) {
                    <span class="ident">CommonEndpoint::One</span>(<span class="ident">i</span>) =&gt; <span class="ident">i</span> <span class="op">==</span> <span class="ident">lane1</span>.<span class="ident">dst_i</span>,
                    <span class="ident">CommonEndpoint::Both</span> =&gt; {
                        <span class="comment">// Two different roads link the same two intersections. I don&#39;t think we</span>
                        <span class="comment">// can decide the order of points other than seeing which endpoint is</span>
                        <span class="comment">// closest to our last point.</span>
                        <span class="kw">if</span> <span class="kw">let</span> <span class="prelude-val">Some</span>(<span class="ident">last</span>) <span class="op">=</span> <span class="ident">pts</span>.<span class="ident">last</span>() {
                            <span class="ident">last</span>.<span class="ident">dist_to</span>(<span class="ident">pl</span>.<span class="ident">first_pt</span>()) <span class="op">&lt;</span> <span class="ident">last</span>.<span class="ident">dist_to</span>(<span class="ident">pl</span>.<span class="ident">last_pt</span>())
                        } <span class="kw">else</span> {
                            <span class="comment">// The orientation doesn&#39;t matter</span>
                            <span class="bool-val">true</span>
                        }
                    }
                    <span class="ident">CommonEndpoint::None</span> =&gt; <span class="macro">bail!</span>(
                        <span class="string">&quot;{} and {} don&#39;t share a common endpoint&quot;</span>,
                        <span class="ident">lane1</span>.<span class="ident">id</span>,
                        <span class="ident">lane2</span>.<span class="ident">id</span>
                    ),
                }
            };
            <span class="kw">if</span> <span class="op">!</span><span class="ident">keep_lane_orientation</span> {
                <span class="ident">pl</span> <span class="op">=</span> <span class="ident">pl</span>.<span class="ident">reversed</span>();
            }

            <span class="comment">// Before we add this road&#39;s points, try to trace along the polygon&#39;s boundary. Usually</span>
            <span class="comment">// this has no effect (we&#39;ll dedupe points), but sometimes there&#39;s an extra curve.</span>
            <span class="comment">//</span>
            <span class="comment">// Note this logic is similar to how we find SharedSidewalkCorners. Don&#39;t rely on that</span>
            <span class="comment">// existing, since the outermost lane mightn&#39;t be a sidewalk.</span>
            <span class="comment">//</span>
            <span class="comment">// If the ring.doubles_back(), don&#39;t bother. If we tried to trace the boundary, it</span>
            <span class="comment">// usually breaks the final Ring we produce. Better to skip bad intersection polygons</span>
            <span class="comment">// and still produce a reasonable looking block.</span>
            <span class="kw">let</span> <span class="ident">prev_i</span> <span class="op">=</span> <span class="kw">if</span> <span class="ident">keep_lane_orientation</span> {
                <span class="ident">lane1</span>.<span class="ident">src_i</span>
            } <span class="kw">else</span> {
                <span class="ident">lane1</span>.<span class="ident">dst_i</span>
            };
            <span class="kw">if</span> <span class="ident">first_intersection</span>.<span class="ident">is_none</span>() {
                <span class="ident">first_intersection</span> <span class="op">=</span> <span class="prelude-val">Some</span>(<span class="ident">prev_i</span>);
            }
            <span class="kw">if</span> <span class="kw">let</span> <span class="prelude-val">Some</span>(<span class="ident">last_pt</span>) <span class="op">=</span> <span class="ident">pts</span>.<span class="ident">last</span>() {
                <span class="kw">let</span> <span class="ident">prev_i</span> <span class="op">=</span> <span class="ident">map</span>.<span class="ident">get_i</span>(<span class="ident">prev_i</span>);
                <span class="kw">if</span> <span class="kw">let</span> <span class="prelude-val">Some</span>(<span class="ident">ring</span>) <span class="op">=</span> <span class="ident">prev_i</span>.<span class="ident">polygon</span>.<span class="ident">get_outer_ring</span>() {
                    <span class="kw">if</span> <span class="op">!</span><span class="ident">ring</span>.<span class="ident">doubles_back</span>() {
                        <span class="comment">// At dead-ends, trace around the intersection on the longer side</span>
                        <span class="kw">let</span> <span class="ident">longer</span> <span class="op">=</span> <span class="ident">prev_i</span>.<span class="ident">is_deadend</span>();
                        <span class="kw">if</span> <span class="kw">let</span> <span class="prelude-val">Some</span>(<span class="ident">slice</span>) <span class="op">=</span> <span class="ident">ring</span>.<span class="ident">get_slice_between</span>(<span class="kw-2">*</span><span class="ident">last_pt</span>, <span class="ident">pl</span>.<span class="ident">first_pt</span>(), <span class="ident">longer</span>)
                        {
                            <span class="ident">pts</span>.<span class="ident">extend</span>(<span class="ident">slice</span>.<span class="ident">into_points</span>());
                        }
                    }
                }
            }

            <span class="ident">pts</span>.<span class="ident">extend</span>(<span class="ident">pl</span>.<span class="ident">into_points</span>());
        }
        <span class="comment">// Do the intersection boundary tracing for the last piece. We didn&#39;t know enough to do it</span>
        <span class="comment">// the first time.</span>
        <span class="kw">let</span> <span class="ident">first_intersection</span> <span class="op">=</span> <span class="ident">map</span>.<span class="ident">get_i</span>(<span class="ident">first_intersection</span>.<span class="ident">unwrap</span>());
        <span class="kw">if</span> <span class="kw">let</span> <span class="prelude-val">Some</span>(<span class="ident">ring</span>) <span class="op">=</span> <span class="ident">first_intersection</span>.<span class="ident">polygon</span>.<span class="ident">get_outer_ring</span>() {
            <span class="kw">if</span> <span class="op">!</span><span class="ident">ring</span>.<span class="ident">doubles_back</span>() {
                <span class="kw">let</span> <span class="ident">longer</span> <span class="op">=</span> <span class="ident">first_intersection</span>.<span class="ident">is_deadend</span>();
                <span class="kw">if</span> <span class="kw">let</span> <span class="prelude-val">Some</span>(<span class="ident">slice</span>) <span class="op">=</span> <span class="ident">ring</span>.<span class="ident">get_slice_between</span>(<span class="kw-2">*</span><span class="ident">pts</span>.<span class="ident">last</span>().<span class="ident">unwrap</span>(), <span class="ident">pts</span>[<span class="number">0</span>], <span class="ident">longer</span>) {
                    <span class="ident">pts</span>.<span class="ident">extend</span>(<span class="ident">slice</span>.<span class="ident">into_points</span>());
                }
            }
        }
        <span class="ident">pts</span>.<span class="ident">push</span>(<span class="ident">pts</span>[<span class="number">0</span>]);
        <span class="ident">pts</span>.<span class="ident">dedup</span>();
        <span class="kw">let</span> <span class="ident">polygon</span> <span class="op">=</span> <span class="ident">Ring::new</span>(<span class="ident">pts</span>)<span class="question-mark">?</span>.<span class="ident">into_polygon</span>();
        <span class="comment">// TODO To debug anyway, can use buggy_new, but there&#39;s pretty much always a root problem</span>
        <span class="comment">// in the map geometry that should be properly fixed.</span>
        <span class="comment">//let polygon = Polygon::buggy_new(pts);</span>

        <span class="prelude-val">Ok</span>(<span class="ident">Block</span> {
            <span class="ident">perimeter</span>: <span class="self">self</span>,
            <span class="ident">polygon</span>,
        })
    }

    <span class="doccomment">/// Does this perimeter completely enclose the other?</span>
    <span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">contains</span>(<span class="kw-2">&amp;</span><span class="self">self</span>, <span class="ident">other</span>: <span class="kw-2">&amp;</span><span class="ident">Perimeter</span>) -&gt; <span class="ident">bool</span> {
        <span class="ident">other</span>
            .<span class="ident">roads</span>
            .<span class="ident">iter</span>()
            .<span class="ident">all</span>(<span class="op">|</span><span class="ident">id</span><span class="op">|</span> <span class="self">self</span>.<span class="ident">interior</span>.<span class="ident">contains</span>(<span class="kw-2">&amp;</span><span class="ident">id</span>.<span class="ident">road</span>) <span class="op">|</span><span class="op">|</span> <span class="self">self</span>.<span class="ident">roads</span>.<span class="ident">contains</span>(<span class="ident">id</span>))
    }
}

<span class="kw">impl</span> <span class="ident">fmt::Debug</span> <span class="kw">for</span> <span class="ident">Perimeter</span> {
    <span class="kw">fn</span> <span class="ident">fmt</span>(<span class="kw-2">&amp;</span><span class="self">self</span>, <span class="ident">f</span>: <span class="kw-2">&amp;mut</span> <span class="ident">fmt::Formatter</span><span class="op">&lt;</span><span class="lifetime">&#39;_</span><span class="op">&gt;</span>) -&gt; <span class="ident">fmt::Result</span> {
        <span class="macro">writeln!</span>(<span class="ident">f</span>, <span class="string">&quot;Perimeter:&quot;</span>)<span class="question-mark">?</span>;
        <span class="kw">for</span> <span class="ident">id</span> <span class="kw">in</span> <span class="kw-2">&amp;</span><span class="self">self</span>.<span class="ident">roads</span> {
            <span class="macro">writeln!</span>(<span class="ident">f</span>, <span class="string">&quot;- {:?} of {}&quot;</span>, <span class="ident">id</span>.<span class="ident">side</span>, <span class="ident">id</span>.<span class="ident">road</span>)<span class="question-mark">?</span>;
        }
        <span class="prelude-val">Ok</span>(())
    }
}
</code></pre></div>
</section><section id="search" class="content hidden"></section></div></main><div id="rustdoc-vars" data-root-path="../../../" data-current-crate="map_model" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.59.0 (9d1b2106e 2022-02-23)" ></div>
</body></html>