<!DOCTYPE html><htmllang="en"><head><metacharset="utf-8"><metaname="viewport"content="width=device-width, initial-scale=1.0"><metaname="generator"content="rustdoc"><metaname="description"content="An implementation of the Rabin-Karp substring search algorithm."><title>memchr::arch::all::rabinkarp - Rust</title><linkrel="preload"as="font"type="font/woff2"crossoriginhref="../../../../static.files/SourceSerif4-Regular-46f98efaafac5295.ttf.woff2"><linkrel="preload"as="font"type="font/woff2"crossoriginhref="../../../../static.files/FiraSans-Regular-018c141bf0843ffd.woff2"><linkrel="preload"as="font"type="font/woff2"crossoriginhref="../../../../static.files/FiraSans-Medium-8f9a781e4970d388.woff2"><linkrel="preload"as="font"type="font/woff2"crossoriginhref="../../../../static.files/SourceCodePro-Regular-562dcc5011b6de7d.ttf.woff2"><linkrel="preload"as="font"type="font/woff2"crossoriginhref="../../../../static.files/SourceCodePro-Semibold-d899c5a5c4aeb14a.ttf.woff2"><linkrel="stylesheet"href="../../../../static.files/normalize-76eba96aa4d2e634.css"><linkrel="stylesheet"href="../../../../static.files/rustdoc-5bc39a1768837dd0.css"><metaname="rustdoc-vars"data-root-path="../../../../"data-static-root-path="../../../../static.files/"data-current-crate="memchr"data-themes=""data-resource-suffix=""data-rustdoc-version="1.77.1 (7cf61ebde 2024-03-27)"data-channel="1.77.1"data-search-js="search-dd67cee4cfa65049.js"data-settings-js="settings-4313503d2e1961c2.js"><scriptsrc="../../../../static.files/storage-4c98445ec4002617.js"></script><scriptdefersrc="../sidebar-items.js"></script><scriptdefersrc="../../../../static.files/main-48f368f3872407c8.js"></script><noscript><linkrel="stylesheet"href="../../../../static.files/noscript-04d5337699b92874.css"></noscript><linkrel="alternate icon"type="image/png"href="../../../../static.files/favicon-16x16-8b506e7a72182f1c.png"><linkrel="alternate icon"type="image/png"href="../../../../static.files/favicon-32x32-422f7d1d52889060.png"><linkrel="icon"type="image/svg+xml"href="../../../../static.files/favicon-2c020d218678b618.svg"></head><bodyclass="rustdoc mod"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><navclass="mobile-topbar"><buttonclass="sidebar-menu-toggle"title="show sidebar"></button></nav><navclass="sidebar"><divclass="sidebar-crate"><h2><ahref="../../../../memchr/index.html">memchr</a><spanclass="version">2.7.2</span></h2></div><h2class="location"><ahref="#">Module rabinkarp</a></h2><divclass="sidebar-elems"><section><ulclass="block"><li><ahref="#structs">Structs</a></li></ul></section><h2><ahref="../index.html">In memchr::arch::all</a></h2></div></nav><divclass="sidebar-resizer"></div>
<main><divclass="width-limiter"><navclass="sub"><formclass="search-form"><span></span><divid="sidebar-button"tabindex="-1"><ahref="../../../../memchr/all.html"title="show sidebar"></a></div><inputclass="search-input"name="search"aria-label="Run search in the documentation"autocomplete="off"spellcheck="false"placeholder="Click or press ‘S’ to search, ‘?’ for more options…"type="search"><divid="help-button"tabindex="-1"><ahref="../../../../help.html"title="help">?</a></div><divid="settings-menu"tabindex="-1"><ahref="../../../../settings.html"title="settings"><imgwidth="22"height="22"alt="Change settings"src="../../../../static.files/wheel-7b819b6101059cd0.svg"></a></div></form></nav><sectionid="main-content"class="content"><divclass="main-heading"><h1>Module <ahref="../../../index.html">memchr</a>::<wbr><ahref="../../index.html">arch</a>::<wbr><ahref="../index.html">all</a>::<wbr><aclass="mod"href="#">rabinkarp</a><buttonid="copy-path"title="Copy item path to clipboard"><imgsrc="../../../../static.files/clipboard-7571035ce49a181d.svg"width="19"height="18"alt="Copy item path"></button></h1><spanclass="out-of-band"><aclass="src"href="../../../../src/memchr/arch/all/rabinkarp.rs.html#1-390">source</a> · <buttonid="toggle-all-docs"title="collapse all docs">[<span>−</span>]</button></span></div><detailsclass="toggle top-doc"open><summaryclass="hideme"><span>Expand description</span></summary><divclass="docblock"><p>An implementation of the <ahref="https://en.wikipedia.org/wiki/Rabin%E2%80%93Karp_algorithm">Rabin-Karp substring search algorithm</a>.</p>
<p>Rabin-Karp works by creating a hash of the needle provided and then computing
a rolling hash for each needle sized window in the haystack. When the rolling
hash matches the hash of the needle, a byte-wise comparison is done to check
if a match exists. The worst case time complexity of Rabin-Karp is <code>O(m * n)</code> where <code>m ~ len(needle)</code> and <code>n ~ len(haystack)</code>. Its worst case space
complexity is constant.</p>
<p>The main utility of Rabin-Karp is that the searcher can be constructed very
quickly with very little memory. This makes it especially useful when searching
for small needles in small haystacks, as it might finish its search before a
</div></details><h2id="structs"class="section-header">Structs<ahref="#structs"class="anchor">§</a></h2><ulclass="item-table"><li><divclass="item-name"><aclass="struct"href="struct.Finder.html"title="struct memchr::arch::all::rabinkarp::Finder">Finder</a></div><divclass="desc docblock-short">A forward substring searcher using the Rabin-Karp algorithm.</div></li><li><divclass="item-name"><aclass="struct"href="struct.FinderRev.html"title="struct memchr::arch::all::rabinkarp::FinderRev">FinderRev</a></div><divclass="desc docblock-short">A reverse substring searcher using the Rabin-Karp algorithm.</div></li></ul></section></div></main></body></html>
