Regular Expression: Help on creating appropriate expression needed...
Hi there!
I'm now trying since hours to construct an appropriate regex that will fit my needs. Here is the starting situation:
I've got a string like
"abc F123[F456[F789]] 123"
In this string I want to find the following expressions:
- F123[F456[F789]] An expression is defined as follows:I tried this by using the following regex:
[F][0-9]+[\[]{1,}.*?[\]]{1,}|[F][0-9]+ F123[F456[F789]] ). What do I have to do to find also the other needed matches (recursicely)?Greets,
ReneMT
[974 byte] By [
renemt ] at [2008-2-19]
Overview Hey ReneMT...I know you have been patiently waiting for an answer to this and have not given up. <G> You still post to the forum and I like challanges, so I gave it a shot. The bad news is that due to the nested nature of the data, one cannot do a capture within a capture.... But that leaves two options which can be done. I wonder how you handled the situation and hope you post what you found.
Option 1 As you mentioned you were able to capture the whole thing but unable to get any submatches. This almost borders on Lexical Analysis where it is done in two phases which has a Scanner then Evaluator phase.I had to do somthing similar when I had scrape screen data (no this wasn't in the 80's but the 21st century) and I devised a system which I called Cascading Regular Expressions. I setup multiple expressions to parse out / weed the text until the final expession actually captured the target data.
Option 2 I can't speak to your data needs but I have come up with a regex that gives an inidicator that tells the consumer that the following match group is a subset of the current one. Let me show you the regex:
/// <summary>(?<=F)(?<Data> \d{1,3})(?<SubMatch> \[)? ",
Here is what happens using the Explicit capture, the regex will only capture two sections in each capture group. The first named capture, named Data , is the numeric portion of the (FXXX) pattern returning the XXX. The second named capture called SubMatch which is optional, per-se and will need to be checked for existance and if it holds data which could be a [.
This gives he consumer of the code all of the data broken out into match groups. Then has to check if SubMatch exists for each group and has data. If that is the case then the next capture group actually belongs to the current capture group as a sub match. By keeping track of the recursion, one can figure out how to present the data.
Example
F123[F456[F789]]
Results in
Group 1 Data 123 SubMatch [ Group 2 Data 456SubMatch [Data 789SubMatch
renemt wrote: