JavaScript regex to skip sub pattern

Question

I really can't figure this one out.

I have a string where I'm trying to match the three groups marked with opening and closing braces (e.g {content}), with the custom string I have below a double brace means it is escaped.

SetValue:{1} when {OVERVIEW{{}}.Debug=1} else {0}
// Here is an actual real life example
ValidWhen: {! Matches('^\\d{{3}}\\s\\d{{3}}\\s\\d{{3}}[\\s\\S]', COLLECTION.AccountNumber)} {Account Number must not be more than 9 numbers.}

I can't figure out a regex to match the second group as {OVERVIEW{{}}.Debug=1} instead of {OVERVIEW{{ the closest I've got is using this regex as I thought I might be able to use the lookbehind to prevent it stopping on the double braces.

/{(?!\}).*?\}/

Is this even possible? Or do I need some more elaborate string parsing?

@MarcoBonelli: Not an exact duplicate. This one doesn't have nested braces. — nhahtdh
– nhahtdh, Commented Oct 13, 2014 at 9:46
@nhahtdh your regex won't work if there is anything inside {{}} .. — Avinash Raj
– Avinash Raj, Commented Oct 13, 2014 at 9:47
@AvinashRaj: I have state my assumption that the regex only works for "valid input", though I do make an assumption that {{}} never appear outside {}. — nhahtdh
– nhahtdh, Commented Oct 13, 2014 at 9:48
@AvinashRaj It's to do with the product it's used on, gets injected as a string, hence the double slash escape and the double braces indicate to escape a brace. — Ally
– Ally, Commented Oct 13, 2014 at 9:48

nhahtdh · Accepted Answer · 2014-10-13 09:57:45Z

3

The following regex works for valid input¹:

/{(?:[^{}]|{{|}})*}/

We simply disallow any {} inside braces, and allow only double {{ and }}.

¹ Here are some input that the regex above may return unexpected result:

{{0}} text

This regex will match {0}, which is most likely incorrect.

{{ OVER}

Unbalaced braces and most likely invalid code.

{ A {B } C}

Nested braces - not sure if this is valid, but the regex above will grab {B }.

Demo on regex101

edited Oct 13, 2014 at 9:57

answered Oct 13, 2014 at 9:31

nhahtdh

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Comments

vks · Accepted Answer · 2014-10-13 09:47:50Z

1

{[^}{]*}|{\S+}

Try this. See demo.

http://regex101.com/r/sK8oK9/6

edited Oct 13, 2014 at 9:47

answered Oct 13, 2014 at 9:30

vks

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2 Comments

Ally Over a year ago

Thanks but breaks down without the spaces e.g. matching SetValue:{1}when{OVERVIEW{{}}.Debug=1} else {0}

Ally Over a year ago

Appreciated but I think it still falls down, I've updated the question to add a more involved real example.

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