Re^2: How do I avoid double substitution when replacing many patterns?

The leading $and the middle \w are common between patterns. In fact, all that's required is to require a closing ) only when there was an opening (.

Using a less well known feature

\$ # Our '$' prefix
(?:
    # Optionally *don't* find the opening paren.
  |
    (\() # Optionally find the opening paren
)
(\w+) # The middle part is captured in $2
(?(1)\)) # Require a closing paren only if $1 matched.
[download]

Merely removing the prefix

\$ # Our '$' prefix
( # Capture into $1
    (?:
        \w+ # Plain word.
      |
        \( \w+ \) # A word with parentheses around it.
    )
)
[download]

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Re^3: How do I avoid double substitution when replacing many patterns? by japhy (Canon) on Jan 20, 2007 at 18:18 UTC
You could change `(?: \| ( \( ) )` [download] to `( \( )?` [download] ... unless you get queasy when you see quantifiers placed on capturing groups. Jeff `japhy` Pinyan, P.L., P.M., P.O.D, X.S.: Perl, regex, and `perl` hacker How can we ever be the sold short or the cheated, we who for every service have long ago been overpaid? ~~ Meister Eckhart	[reply] [d/l] [select]
Re^4: How do I avoid double substitution when replacing many patterns? by diotalevi (Canon) on Jan 20, 2007 at 19:02 UTC
I thought about it but decided I wasn't sure whether that would work correctly with the later conditional. If it does, great. ⠤⠤ ⠙⠊⠕⠞⠁⠇⠑⠧⠊	[reply]