| <!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta name="generator" content="rustdoc"><meta name="description" content="Source of the Rust file `/root/.cargo/registry/src/github.com-1ecc6299db9ec823/aho-corasick-1.0.2/src/nfa/mod.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>mod.rs - source</title><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../SourceSerif4-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../FiraSans-Regular.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../FiraSans-Medium.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../SourceCodePro-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../SourceSerif4-Bold.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../SourceCodePro-Semibold.ttf.woff2"><link rel="stylesheet" href="../../../normalize.css"><link rel="stylesheet" href="../../../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" href="../../../ayu.css" disabled><link rel="stylesheet" href="../../../dark.css" disabled><link rel="stylesheet" href="../../../light.css" id="themeStyle"><script id="default-settings" ></script><script src="../../../storage.js"></script><script defer src="../../../source-script.js"></script><script defer src="../../../source-files.js"></script><script defer src="../../../main.js"></script><noscript><link rel="stylesheet" href="../../../noscript.css"></noscript><link rel="alternate icon" type="image/png" href="../../../favicon-16x16.png"><link rel="alternate icon" type="image/png" href="../../../favicon-32x32.png"><link rel="icon" type="image/svg+xml" href="../../../favicon.svg"></head><body class="rustdoc source"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><a class="sidebar-logo" href="../../../aho_corasick/index.html"><div class="logo-container"><img class="rust-logo" src="../../../rust-logo.svg" alt="logo"></div></a></nav><main><div class="width-limiter"><nav class="sub"><a class="sub-logo-container" href="../../../aho_corasick/index.html"><img class="rust-logo" src="../../../rust-logo.svg" alt="logo"></a><form class="search-form"><div class="search-container"><span></span><input class="search-input" name="search" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><div id="help-button" title="help" tabindex="-1"><a href="../../../help.html">?</a></div><div id="settings-menu" tabindex="-1"><a href="../../../settings.html" title="settings"><img width="22" height="22" alt="Change settings" src="../../../wheel.svg"></a></div></div></form></nav><section id="main-content" class="content"><div class="example-wrap"><pre class="src-line-numbers"><span id="1">1</span> |
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| </pre><pre class="rust"><code><span class="doccomment">/*! |
| Provides direct access to NFA implementations of Aho-Corasick. |
| |
| The principle characteristic of an NFA in this crate is that it may |
| transition through multiple states per byte of haystack. In Aho-Corasick |
| parlance, NFAs follow failure transitions during a search. In contrast, |
| a [`DFA`](crate::dfa::DFA) pre-computes all failure transitions during |
| compilation at the expense of a much bigger memory footprint. |
| |
| Currently, there are two NFA implementations provided: noncontiguous and |
| contiguous. The names reflect their internal representation, and consequently, |
| the trade offs associated with them: |
| |
| * A [`noncontiguous::NFA`] uses a separate allocation for every NFA state to |
| represent its transitions in a sparse format. This is ideal for building an |
| NFA, since it cheaply permits different states to have a different number of |
| transitions. A noncontiguous NFA is where the main Aho-Corasick construction |
| algorithm is implemented. All other Aho-Corasick implementations are built by |
| first constructing a noncontiguous NFA. |
| * A [`contiguous::NFA`] is uses a single allocation to represent all states, |
| while still encoding most states as sparse states but permitting states near |
| the starting state to have a dense representation. The dense representation |
| uses more memory, but permits computing transitions during a search more |
| quickly. By only making the most active states dense (the states near the |
| starting state), a contiguous NFA better balances memory usage with search |
| speed. The single contiguous allocation also uses less overhead per state and |
| enables compression tricks where most states only use 8 bytes of heap memory. |
| |
| When given the choice between these two, you almost always want to pick a |
| contiguous NFA. It takes only a little longer to build, but both its memory |
| usage and search speed are typically much better than a noncontiguous NFA. A |
| noncontiguous NFA is useful when prioritizing build times, or when there are |
| so many patterns that a contiguous NFA could not be built. (Currently, because |
| of both memory and search speed improvements, a contiguous NFA has a smaller |
| internal limit on the total number of NFA states it can represent. But you |
| would likely need to have hundreds of thousands or even millions of patterns |
| before you hit this limit.) |
| */ |
| </span><span class="kw">pub mod </span>contiguous; |
| <span class="kw">pub mod </span>noncontiguous; |
| </code></pre></div> |
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