exreg

A module to generate strings to match regular expressions

Creating Strings for regular expressions

While it's easy to create a regular expression to match a string, doing the opposite can be quite challenging.

This module will take a regular expression and generate a string that is guaranteed to be matched by that regular expression. In version 1.x.x, a regular expression will always result in the same string and it will be the simplest string that will match it. \d will always result in a 0; \b will always result in an a. In version 2.x.x, I'll add support for more varied matching strings.

What regex features are supported?

The latest support can be found by running npm test in this project. The specs will be listed as the tests pass.

However, for convenience, I'll list what's currently supported here:

• The . character
• Normal characters
• The | character
• Standard character classes
• Inclusive character classes of the form [...]
• Quantifiers
• Groups (capturing and non-capturing)
• Special characters

Not currently supported:

• Lookaheads
• Captured Group references
• Word boundaries
• Start/end of string matchers
• Exclusive character classes of the form [^...]

Bug reporting

If you find a regex such that the generated string is not a match please open an issue and include the failing regex.

Contributing

Any code that you'd like to contribute (and I'd be very appreciative of it) should be submitted via a Pull Request. There should be tests to support your change and they should pass.

Releasing a new version

Do the following:

• Make sure you're on develop and that you're in sync with the git repo
• npm version
• git push
• Create a PR into the master branch of exreg
• Once this PR is approved and merged, the new version will be published