Examples

Realistic patterns, worked out. See the Reference for the full syntax and the Cheatsheet for a quick lookup.

Usernames

Xeger.take("[a-z][a-z0-9_]{2,5}", 10)
#=> ["a00", "a01", "a02", ...]

Version strings

Xeger.take("v\\d{1,2}\\.\\d{1,2}", 10)
#=> ["v0.0", "v0.1", "v0.2", ...]

Simple passwords

Xeger.take("[A-Z][a-z]{3}\\d{2}", 10)
#=> ["Aaaa00", "Aaaa01", "Aaaa02", ...]

US-style phone numbers

Xeger.take("555-\\d{4}", 10)
#=> ["555-0000", "555-0001", "555-0002", ...]

Hex color codes

Xeger.take("#[0-9A-F]{6}", 10)
#=> ["#000000", "#000001", "#000002", ...]

ZIP codes (optional +4)

Xeger.take("\\d{5}(-\\d{4})?", 10)
#=> ["00000", "00001", "00002", ...]

URL-style slugs

Xeger.take("[a-z0-9]+(-[a-z0-9]+)*", 10, max_repeat: 3)
#=> ["0", "1", "2", "3", "4", "5", "6", "7", "8", "9"]

Email-ish addresses

Xeger.stream("[a-z0-9]{3,8}@(gmail|yahoo|outlook)\\.com")
|> Enum.take(5)
#=> ["000@gmail.com", "000@yahoo.com", "001@gmail.com", "001@yahoo.com", "002@gmail.com"]

An unbounded pattern, streamed lazily

Xeger.stream("[0-9a-f]+")
|> Enum.take(5)
#=> ["0", "1", "2", "3", "4"]

No :max_repeat here -- [0-9a-f]+ is genuinely infinite, but stream/2 enumerates it lazily one length at a time, so Enum.take/2 only does as much work as it needs to.

One random test fixture value

Xeger.random("[A-Z]{2}-\\d{6}")
#=> "QK-482017" -- a different match on every call

Xeger.random("[A-Z]{2}-\\d{6}", seed: 123)
#=> reproducible -- pin a seed in a test for a stable fixture value

random/2 picks one match directly instead of enumerating, so it stays cheap even for a pattern like this one where the full match set is huge.

Reusing a compiled pattern with the ~X sigil

import Xeger, only: [sigil_X: 2]

~X/[A-Z]{2}\\d{6}/s |> Enum.take(5)
#=> ["AA000000", "AA000001", "AA000002", "AA000003", "AA000004"]

A runnable demo script

examples/sigil_demo.exs in this repo walks through several of the patterns above (plus a couple more) end to end:

elixir examples/sigil_demo.exs