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safe-regex

detect potentially catastrophic exponential-time regular expressions by limiting the star height to 1

WARNING: This module merely seems to work given all the catastrophic regular expressions I could find scouring the internet, but I don't have enough of a background in automata to be absolutely sure that this module will catch all exponential-time cases.

# example

var safe = require('safe-regex');
var regex = process.argv.slice(2).join(' ');
console.log(safe(regex));
$ node safe.js '(x+x+)+y'
false
$ node safe.js '(beep|boop)*'
true
$ node safe.js '(a+){10}'
false
$ node safe.js '\blocation\s*:[^:\n]+\b(Oakland|San Francisco)\b'
true

# methods

var safe = require('safe-regex')

## var ok = safe(re, opts={})

Return a boolean `ok` whether or not the regex `re` is safe and not possibly catastrophic.

`re` can be a `RegExp` object or just a string.

If the `re` is a string and is an invalid regex, returns `false`.

- `opts.limit` - maximum number of allowed repetitions in the entire regex. Default: `25`.

# install

With npm do:

npm install safe-regex

# license

MIT