I think I'm messing up Regex or do not understand ...

# getting-started

[Jonathan Kolberg]

I think I'm messing up Regex or do not understand it enought.

When I have val result = "44".toRegex().findAll("14446") why is result only of length one, in my understanding it should match 1$44$45 and 14$44$5 . Here I marked the match visually with $

[ephemient]

findAll does not return overlapping matches

[ephemient]

you can see, for example, that

".+".toRegex().findAll("abc")

only returns the single run of abc, not abc bc c

[Jonathan Kolberg]

Hm how do I find overlapping matches then, is there something in the std?

I could of cause check for every suffix, if it starts with the pattern, but that seems tedious

[ephemient]

nothing in stdlib, but you can do it yourself with a loop moving find(startIndex=) to match.range.first + 1

[ephemient]

e.g.

generateSequence(regex.find(str)) { regex.find(str, startIndex = it.range.first + 1) }

[Johann Pardanaud]

Here’s a clever regex solution based on capturing groups and lookahead assertions: https://stackoverflow.com/a/11430936/1513045

[Johann Pardanaud]

I am unable to try this in Kotlin at the moment, but it could work.