modern-ahocorasick

modern-ahocorasick

Forked from https://github.com/BrunoRB/ahocorasick and make it modern! Thanks to the author(BrunoRB) of ahocorasick

Implementation of the Aho-Corasick string searching algorithm, as described in the paper "Efficient string matching: an aid to bibliographic search".

this pkg has cjs and esm format, and have .d.ts file.

Install

npm i modern-ahocorasick
yarn add modern-ahocorasick
pnpm i modern-ahocorasick

Usage

// esm
import AhoCorasick from 'modern-ahocorasick'
// cjs
const AhoCorasick = require('modern-ahocorasick')

const ac = new AhoCorasick(['keyword1', 'keyword2', 'etc'])
const results = ac.search('should find keyword1 at position 19 and keyword2 at position 47.')

// [ [ 19, [ 'keyword1' ] ], [ 47, [ 'keyword2' ] ] ]

Visualization

See https://brunorb.github.io/ahocorasick/visualization.html for an interactive visualization of the algorithm.

API

Constructor

constructor(keywords: string[])

Initializes the Aho-Corasick state machine with the provided keywords.

Parameters:

• keywords: An array of strings representing the keywords to search for.

Example:

const keywords = ['he', 'she', 'his', 'hers']
const ac = new AhoCorasick(keywords)

---

Methods

search(str: string): [number, string[]][]

Searches the input string str for occurrences of any of the keywords and returns a list of matches.

Parameters:

• str: The input string to search.

Returns:

• An array of tuples. Each tuple contains:
  • The ending index of the match in the input string.
  • An array of matched keywords at that position.

Example:

const ac = new AhoCorasick(['keyword1', 'keyword2', 'etc'])
const results = ac.search('should find keyword1 at position 19 and keyword2 at position 47.')

// [ [ 19, [ 'keyword1' ] ], [ 47, [ 'keyword2' ] ] ]

---

match(str: string): boolean

Checks if any keyword exists in the input string str.

Parameters:

• str: The input string to search.

Returns:

• true if any keyword is found.
• false otherwise.

Example:

const ac = new AhoCorasick(['he', 'she', 'his', 'hers'])
console.log(ac.match('ushers')) // Output: true
console.log(ac.match('xyz')) // Output: false

---

Internal Functionality

While the _buildTables method is not part of the public API, it is responsible for building the transition (gotoFn), output, and failure functions used by the Aho-Corasick algorithm.

---

Examples

Example 1: Basic Search

const keywords = ['cat', 'bat', 'rat']
const ac = new AhoCorasick(keywords)

const text = 'the cat chased the rat while a bat flew by'
const matches = ac.search(text)

Example 2: Check Match Presence

const ac = new AhoCorasick(['abc', '123'])

console.log(ac.match('hello abc world')) // Output: true
console.log(ac.match('hello world')) // Output: false

---

Example: Case-Insensitive Search

const keywords = ['hello', 'world']
const ac = new AhoCorasick(keywords.map(k => k.toLowerCase()))

const text = 'Hello World'
const matches = ac.search(text.toLowerCase())
console.log(matches)
// Output: [
//   [4, ["hello"]],
//   [10, ["world"]]
// ]

This document serves as a complete guide for using the AhoCorasick class for multi-pattern string matching.

License

The MIT License