Question

I have the following formatted sample string:

== header == information about things ==headeragain== info can have characters like.*?{=

etc on just one line.

I want to parse this in to a hash such that the keys are the “==.+?==” and the values are the info after the keys. I’ve tried a couple of regular expressions to globally match these pairs:

%hash = $string =~ /(==.+?==)(.+)/g

and

%hash = $string =~ /(==.+?==)(.+?)/g

Will match the first key and then everything else as its value, and match just the keys respectively.

%hash = $string =~ /(==.+?==)(.+(?===.+?==))/g

is supposed to look ahead for the next key, but not “eat it up” as I understand it. However, it will only match the first pair and go no further.

I think this problem has come from a misunderstanding of how the global modifier acts. Do I need to tweak something in one of my expressions? Or do I need to be doing something completely different?

Answer 1

Even though you’re using non-greedy modifier, there’s no limitation for 2nd subgroup in you 2nd example.

Add positive look-ahead: (?=$|==) after value. Here (?= is a declaration of look-ahead block and $ or == is a substring, you’re searching for.

I.e. the solution is: /(==.+?==)(.+?)(?=$|==)/g