Custom rule using lookbehind becomes Invalid configuration

[asa08]

I want to use lookbehind in a custom rule but get Invalid configuration for 'xxx'. Falling back to default..
Is there any other way?

Example

No setClass on the line before the line containing configur.

(?<!setClass.*?\n.*?)configur

Highlighted

func setup() {
  configur()
}

Not Highlighted

func setup() {
  setClass()
  configur()
}

Thank you.

[SimplyDanny]

Lookbehind is allowed in principle, yet the documentation for NSRegularExpression states:

The length of possible strings matched by the look-behind pattern must not be unbounded (no * or + operators).

That's causing the regex to fail to be constructed. You need to look for an alternative expression.