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Community Expert
Manan JoshiCommunity Expert
Community Expert
December 18, 2016
Answered

Positive lookahead not working

  • December 18, 2016
  • 1 reply
  • 3817 views

Hi All,

I am trying to use positive lookahead in my script but it does not give me the desired results, the grep expression however does work outside InDesign.

https://regex101.com/r/QbWDyJ/2​

I want to find all + that does not lie in between <>

However on using it in a script is get blank results, are there any limitations on using positive lookahead in InDesign?

-Manan

This topic has been closed for replies.
Correct answer Marc Autret

Due to the way ExtendScript RegExp unexpectedly works with the non-greedy operator, you may try this regex instead:

/\+(?=[^><+]*(?:[\+<]|$))/g

EDIT: But this won't work if you can have multiple '+' in a tag :-/

@+

Marc


In case you have patterns of this form, AA+BB+CC<DD+EE+FF>GG+HH+II<JJ+KK>LL+MM etc., I think you need both a negative and a positive lookahead to only capture '+' outside of the tags.

Then try this:

/\+(?![^<>]*>)(?=[^><+]*(?:[\+<]|$))/g

@+

Marc

1 reply

Marc Autret
Marc Autret
Legend
December 18, 2016

That should work.

Make sure your findWhat string properly escapes the leading backslash:

app.findGrepPreferences.findWhat = "\\+(?=[^>]*?<)";

@+

Marc

M
Community Expert
Manan JoshiCommunity ExpertAuthor
Community Expert
December 18, 2016

Hi Marc,

Thanks for replying

I am not using this grep expression to search within the InDesign document, i am using it to search within a string in my JSX. A sample code is as below

Running the code on Extendscript Toolkit engine or InDesign CC 2015 engine gives the same result.

var input = "<ab+c>he+ll+o<de+f>"

input.match(/\+(?=[^>]*?<)/g)

This returns null

An interesting thing is if i use the input as "<ab+c>he+ll+o+<de+f>"

it does find the + after o

Something seems to be missing.

-Manan

-Manan
Obi-wan Kenobi
Obi-wan Kenobi
Legend
December 18, 2016

Aha!

I've tried:

\+(?![^<]*?>)

And it finds the 4 "+"!

(^/)

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