CODEWITHSUNDEEP
phpregex
TomTom
TomTom

Reputation: 1885

How to name regexp groups?

I have a Regular Expression:

'/ abc \( (complexRegex)(,complexRegex)*? \) /Uux'

To match something like: abc(complexStructure,complexStructure,complexStructure)

How to not write complexRegex twice?

Upvotes: 0

Views: 180

Answers (4)

Amadan
Amadan

Reputation: 198324

In basic PHP, no way (except by using the variable trick as eisberg suggests, but it's still repeated in the regexp itself). In PHP5, I heard they put in Oniguruma (Ruby 1.9's extended regexp engine), but I haven't tried for myself, and can't find a decent reference except what Oniguruma's Wikipedia page says. If it's true, you can have this:

/abc:(?<complexRegex>d.f)(,\g<complexRegex>)*:ghi/

It will match "abc:def,daf,dif:ghi", for example, without repeating the pattern (d.f), by assigning a name to the pattern (complexRegex).

Upvotes: 2

eisberg
eisberg

Reputation: 3771

You are in PHP you can avoid writing your complexRegex by variables!

$complexRegex = 'your complexRegex here';

$regex = '/ abc \( (' . $complexRegex . ')(,' . $complexRegex . ')*? \) /Uux';

Also read about back references in PCRE: http://www.php.net/manual/en/regexp.reference.back-references.php

Upvotes: 1

garyh
garyh

Reputation: 2852

You can also use backreferences eg

(x[ms]l).com/\1    

# the \1 is the backreference which matches the first capture group

will match

xml.com/xml
 and 
xsl.com/xsl

Upvotes: -1

jaudette
jaudette

Reputation: 2313

You can match 0 or 1 comma with ?

'/ abc \((,?(complexRegex))* \)/

I added white space to make it clearer but you should match any number of white spaces wherever required.

Upvotes: 0

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