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A regular expression converter
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Automata.js

Automata.js is a regular expression converter written in JS for both Node.js and browser.

It aims to convert regular expression to finite state machine(FSM, like NFA). Besides, dot script transition is provided so that you can make diagrams with Graphiz.

Try it online!

screenshot

Development

// Install dependency modules.
npm install

// Run test.
make test

// Generate browser js.
make distribution

API Description

Currently, Automata.js supports minimal regular expressions:

  • +: One or more
  • *: Zero
  • ?: Zero or one
  • (): Capture everything enclosed
  • |: Or
  • \n: Newline
  • \r: Carriage return
  • \t: Tab
  • \w: [a-zA-Z0-9_]
  • \d: [0-9]

FSM

FSM is a object represent a finite state machine(NFA, DFA).

The json definition is below:

{
  initialState: 'id',
  acceptState: ['id', ... ] ,
  numOfStates: Integer,
  type: 'DFA' or 'NFA',
  transitions: {
    'id': { 'to_id': label, },
    ...,
  }
}

FSM.toDotScript()

Convert the fsm to Graphiz dot script.

FSM.match(text)

  • text: String

Determine whether text matches to the FSM. This methods only supports DFA.

RegParser

RegParser is a regular expression parser.

RegParser.reset(string)

Set regular expression string in parser.

RegParser.parseToNFA()

Parses the given regular expression.

Returns a FSM object, the FSM represents a Nondeterministic Finite Automata(NFA).

RegParser.parseToDFA()

Parses the given regular expression.

Returns a FSM object, the FSM represents a Deterministic Finite Automata(DFA).

Usage

Usage in Node.js

Install via npm install automata.js.

var regParser = require('automata.js');

var parser = new regParser.RegParser('a*b');
var nfa = parser.parseToNFA();

console.log(nfa.toDotScript());

Usage in Browser

Automata.js uses node-browserify to generate a browser distribution.

You can use Viz.js to render graphiz dot script in your web page.

var regParser = require('automata.js');

var parser = new regParser.RegParser('a*b');
var nfa = regParser.parseToNFA();

// render dot script to svg.
var result = Viz(nfa.toDotScript(), 'svg', 'dot');
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