I found some interesting possibility in many regex engines:
It's possible to place backreference inside the capture group and reference this group.
For example: (\1)
My question: for what regex patterns it may be used? I can't imagine...
A:
Consider this sample:
[something] some text [something]
You can use backreferences this way:
(\[something\])(.*?)\1
Rubens Farias
2010-02-04 12:45:28
+3
A:
There is an explanation for use of nested references, which I think clearly demonstrates the marginal usefulness of this feature.
SilentGhost
2010-02-04 12:54:03
Example regex, please.
ControlFlow
2010-02-04 13:04:11
If you sloooowly read my question, you'll understand that I'm not asking about how backreferences are used normally. Take a look WHERE backreference were placed in the example regex I provide.
ControlFlow
2010-02-04 14:02:23
@ControlFlow: I don't see you posting *any* regex. I can't imagine what `(\1)` could possibly match or be useful for, or even compile. is this question limited to .net? if not, do provide us with some actual examples.
SilentGhost
2010-02-04 14:14:35
`(\1)` does compile on .NET, but I am yet to find any possible use for it.
Max Shawabkeh
2010-02-04 14:28:11
@SilentGhost The `(\1)` regex was the minimal example, not useful at all, just to demonstrate what I'm talking about. Thanks for the link, I've expecting the usefullness... Thank you!
ControlFlow
2010-02-04 15:11:17
A:
How about this (ignore the whitespace):
{ .* ( { .* \1 .* } ) .* }
to match the body of a method in C#/Java/...
d0rk
2010-02-24 19:25:47
It will not work, backreference matches with the capture group 1 matched text, not the pattern in the group 1 itself.
ControlFlow
2010-02-24 20:07:53