CODEWITHSUNDEEP
regexperlawksed
Tohiko
Tohiko

Reputation: 1982

Replace string with matched expression

I have the following text in multiple files Hello{Some Text}, and I want to replace it with Some Text. Where Some Text might include balanced braces { }. For example: Hello{Some { other} Text} should be replaced by Some { other} Text.

Is there an easy way to achieve this in sed, awk, perl or some other tool?

Upvotes: 1

Views: 76

Answers (1)

revo
revo

Reputation: 48751

You have to choose perl since it supports sub-routine calls. A recursive match on {[^{}]*} should occur continuously and should fail if an unbalanced brace is found. Below regex does the job:

Hello({((?:[^{}]*+|(?1))*)})

See live demo here

Note: it fails on facing with escaped braces.

Perl:

$ echo 'Hello{Some { other} Text}' | perl -pe 's~Hello({((?:[^{}]*+|(?1))*)})~$2~g'
Some { other} Text

Regex breakdown:

Hello # Match `Hello`
( # Start of 1st capturing group
    { # Match `{`
    ( # Start of 2nd capturing group
        (?: # Start of non-capturing group
            [^{}]*+ # Match anything but `{` or `}` possessively
            | # Or
            (?1) # Recurs first group
        )* # End of NCG, repeat as much as possible
    ) # End of 2nd CP
    } # Match `}`
) # End of 1st CP

Upvotes: 3

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