dfa

library1.2.0jsnpmunverified

A JavaScript library that compiles a regular-expression-like syntax into fast deterministic finite automata (DFA). Version 1.2.0 is the latest as of 2025, with no active development in recent years. It is designed for pattern matching against non-string sequences (e.g., arrays of symbols) and provides a portable state machine representation. Supports common regex operators like alternation, concatenation, repetition, and tagging. Files are written in a custom CoffeeScript-like DSL and compiled to efficient match tables.

serialization

npm install dfa

github ↗package ↗

INSTALL

IMPORT

SIG · DFA

dfa

serializationjavascriptv1.2.0

harness data pending

Install & Compatibility

Where this runs

No compatibility data collected yet for this library.

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

compile

✓ import compile from 'dfa/compile'

✗ import { compile } from 'dfa'

Default export from 'dfa/compile', not a named export from 'dfa'.

default

✓ import dfa from 'dfa'

✗ const dfa = require('dfa')

ESM only; CommonJS require may fail if the package is not properly transpiled.

compile (CJS)

✓ const compile = require('dfa/compile').default

✗ const compile = require('dfa/compile')

In CommonJS, the default export is under .default due to ESM compatibility.

dfa

✓ import dfa from 'dfa'; dfa.compile(...)

✗ import { dfa } from 'dfa'

dfa is the default export of 'dfa' package, which exposes a compile method.

Shows how to define a state machine DSL, compile it, and find matches in an array of symbols.

import compile from 'dfa/compile'; import fs from 'fs'; const machineCode = ` X = 0; L = 1; V = 2; T = 3; LV = 4; LVT = 5; M = 6; decomposed = L V T?; partial = LV T?; composed = LVT; main = (decomposed | partial | composed) M?; `; const stateMachine = compile(machineCode); // Input as array of symbols (as per your symbol mapping) const input = [0, 1, 2, 3, 0, 4, 6]; for (const [start, end] of stateMachine.match(input)) { console.log(`Match from ${start} to ${end}`); }

Debug

Known issues

gotchaThe package uses ESM-only imports. CommonJS require() will not work without additional configuration (e.g., using .default).

fix

Use import syntax or set up your environment to handle ESM packages. If you must use require(), use require('dfa/compile').default.

affects: >=1.0.0

deprecatedThe package has not been updated since 2017 and the author has not responded to issues. No security fixes or new features are expected.

fix

Consider using an alternative library or forking the repository if updates are needed.

affects: all

gotchaThe compile function expects a string containing the DSL, not a file path. Passing a file path will result in a parse error.

fix

Read the file contents using fs.readFileSync or similar, then pass the string to compile.

affects: all

gotchaThe match() method returns an iterator of [start, end] arrays, but end is exclusive. Users often expect inclusive end indices.

fix

Adjust your logic: the match covers indices from start to end-1 inclusive.

affects: all

gotchaSymbols must be integers; non-integer values (e.g., strings) are not supported and will cause unexpected behavior.

fix

Map your input values to integers before using match().

affects: all

breakingIn version 1.2.0, the package changed from CommonJS to ESM. Older versions used CJS and had different import behavior.

fix

If upgrading from <1.2.0, update import statements from require('dfa/compile') to import compile from 'dfa/compile'.

affects: 1.2.0

Errors

Common errors & fixes

SyntaxError: Unexpected token 'export'

Using require() on an ESM-only module without a transpiler.

fix

Use import syntax or set type: 'module' in package.json, or use dynamic import().

TypeError: compile is not a function

Using the default export incorrectly: e.g., import { compile } from 'dfa' instead of import compile from 'dfa/compile'.

fix

Use the correct import: import compile from 'dfa/compile'.

Error: Failed to load module: dfa/compile

The package is not recognized; possibly missing a build step or using an older bundler.

fix

Ensure your bundler (webpack, rollup, etc.) supports ESM and that the package is installed correctly.

Upgrade

Version history

1.2.0latest on npm

Audit

Dependencies

No dependency data recorded yet.

Agent activity

11 hits · last 30 days

node

Resources

githubhttps://github.com/devongovett/dfa ↗

packagehttps://www.npmjs.com/package/dfa ↗