CODEWITHSUNDEEP
phpregexpcre
Desmond Hume
Desmond Hume

Reputation: 8607

PCRE pattern that matches the in-delimiters text of a PCRE pattern

I'm looking for a PCRE pattern that would match the text in between the delimiters of any valid PCRE pattern regardless of delimiters and modifiers used.

Upvotes: 0

Views: 141

Answers (1)

Martin Ender
Martin Ender

Reputation: 44259

There are four paired delimiters, as far as I know: (), [], {}, <>. All other allowed characters are just used twice. According to the documentation, we can use any non-alphanumeric, non-whitespace, non-backslash character. So this pattern should work:

/
^
(?=([^a-zA-Z0-9\s\\\\])) # make sure the pattern begins with a valid delimiter
                         # and capture it into group 1
(?|                      # alternation for different delimiter types
                         # each alternative captures the pattern into group 2
  \((.*)\)               # handle (...)
|
  \[(.*)\]               # handle [...]
|
  \{(.*)\}               # handle {...}
|
  <(.*)>                 # handle <...>
|
  .(.*)\1                # handle all other delimiters with a backreference
)
[imsxeADSUXu]*           # allow for modifiers
$
/xs

If you use this $pattern in

preg_match($pattern, $input, $matches);

then you'll find your desired result in $matches[2].

Of course, this will accept a bunch of invalid patterns, because it does not ensure that the delimiter does not appear somewhere sooner in the pattern.

Upvotes: 2

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