CODEWITHSUNDEEP
regexscala
Knows Not Much
Knows Not Much

Reputation: 31546

Regex should not contain a character unless

If I have a string like 

foo&bar&baz

and I want to extract tokens foo, bar, baz from it. a regex is easy to write

val regex = "([^&]+)".r
regex.findAllIn("foo&bar&baz").map(_.toString).toList

This gives me the answer I want. 

List("foo", "bar", "baz")

But the input can have the & symbol escaped with _&_

So if the input is 

foo_&_bar&baz

The output should be foo&bar, baz.

I googled and found this thread which has similar problem

RegEx disallow a character unless escaped

Based on this thread I changed my regex to 

val regex = "((?:_&_|[^&]*)+)".r

But this doesn't work the output is

List("foo_", "", "_bar", "", "baz", "")

Upvotes: 1

Views: 56

Answers (1)

Wiktor Stribiżew
Wiktor Stribiżew

Reputation: 626926

You may use

val regex = "(?:_&_|[^&])+".r
println( regex.findAllIn("foo_&_bar&baz").map(_.toString).toList )
// => List(foo_&_bar, baz)

See the regex demo and a Scala demo.

The (?:_&_|[^&])+ regex matches 1 or more repetitons of _&_ or, if not found at the current location, char other than &.

Upvotes: 2

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