📦 @eklabdev/regexid

A deterministic, lexicographic regex match generator for fixed-length patterns. Supports literal + ranged character sets like [a-z]{2}, [0-9]{1,3}, and embedded string prefixes/suffixes.

✨ Features

Deterministic traversal of regex matches (not random like randexp)
Lexicographic next() string matching
Supports:
- [a-z]{n} and [abc]{n}
- [a-z]{n,m} range repetitions (unrolled)
- Literal strings before/after/within regex blocks
Generates the first match, next match, and total possible combinations
Written in modern TypeScript with full ESM support

🚀 Installation

npm install @eklabdev/regexid

Or if you're using Bun:

bash

bun add @eklabdev/regexid

🛠️ Usage

import {
  nextRegexGenerator,
  getFirstValidMatch,
  parseRegex,
  getNextMatch,
  countRegexCombinations,
} from '@eklabdev/regexid'

const pattern = 'ex[a-b]{2}yz[0-2]{1}'

const first = getFirstValidMatch(pattern)
console.log(first) // "exaayz0"

const gen = nextRegexGenerator(pattern, first)

console.log(gen.next().value) // "exaayz1"
console.log(gen.next().value) // "exabyz0"

const total = countRegexCombinations(pattern)
console.log(`Total combinations: ${total}`) // 12

📚 API

parseRegex(regexStr: string): RegexToken[]

Parses a simplified regex string into tokenized parts:

[
{ type: 'literal', value: 'ex' },
{ type: 'range', ranges: [['a','z']], repeat: 1 },
...
]

getFirstValidMatch(regexStr: string): string

Returns the lexicographically first valid string that matches the regex pattern.

getNextMatch(tokens: RegexToken[], current: string): string | null

Given parsed tokens and a current string, returns the next valid match or null if exhausted.

nextRegexGenerator(regexStr: string, current: string): Generator

Yields a lexicographically sorted sequence of valid regex matches from the current string onward.

countRegexCombinations(regexStr: string): number

Returns the total number of deterministic combinations for a supported regex pattern.

Ignores literal characters
Unrolls {n,m} as full range

🔧 Limitations

For now, this package does not support:

Regex alternation: (a|b)
Optional modifiers: ?, *, +
Grouping and backreferences
Negative classes: [^a-z]

🧪 Testing

This project uses Mocha + Chai for unit tests.

npm test

🤝 Contributing

Pull requests are welcome! If you’d like to contribute:

Fork this repo

Run tests (npm test)

Follow project style (.prettierrc included)