finding the sub expression index

[saktheesh p]

How can i find the sub expression indes of a matched string i.e

if i get a matcher class how do i know which sub expression of the regular expression index it belonged to ?

p.s : i want to find it form the matcher class and not by matching a particular group in that regular expression pattern pattern

[Sergey A. Samokhodkin]

Can't understand the question.
Elaborate please. Examples are welcome.

[saktheesh p]

say i concatenate 5 regular expression with "or"
i.e the regular expression is like  "re1|re2|re3|re4|re5"

and i have a string say abcabcabcacb( for example)

if i give matcher.findAll() it retuns me a match iterator

now i need to find from the matcher class/or by some means the regular expression that matched the string ( p.s: i cannot use the match group thing cause i cannot check for each group whether it matched)

[Sergey A. Samokhodkin]

There is no straightforward way to do it.
There still exists a crappy workaround: wrap each RE in a named group and check each one whether it's captured:

String[] reArray=..;
StringBuffer sb=new StringBuffer();
for(int i=0;i<reArray.length;i++){
   sb+="({g"+i+"}"+re[i]+")";
   if(i<(reArray.length-1)) sb+="|";
}
Pattern p=new Pattern(sb.toString());

Matcher m=p.matcher(target);
if(m.find()){
  for(int i=0;i<reArray.length;i++){
    if(m.isCaptured("g"+i)) return i;
  }
}

Basically, it's easy to implement the functionality you look for. But how the API may look like?

[saktheesh p]

i have a problem i doin this i need to identify it from the matcher class is there any way that i can access the sub expression index form it , ( at least by tweaking the package a little like extending the scope to public etc ..) is there any way to do this

[Sergey A. Samokhodkin]

Missed the point again. Identify what? The "the sub expression index" is too ambiguous. Give examples, please.

[saktheesh p]

thats what  detailed in my previous reply say i have n sub expression combined by r an sub expression  x may have subexpressions in it .

now i have a set of string i match the string and i get the results now i need to which subexpression matched the particular part of the string WITHOUT MAKING ANY PREOPERATIONS IN THE REGULAR EXPRESSIONS( like adding a group name)

e.g

regular exp : "((h|o)|(hi[m])|(\([^(][^)])|(r+))"

match string:  "i told him"

say i get a match "him" in the match result class is there any way for me to find the sub expression index of the part (hi[m]) i.e where in the regular expression that the string matched even the starting index of it will do e.g (hi[m]) starting index 7 from the start of the regular exprssion <or> the Nth group i.e if i get the him matched 2nd group

i hope i have given it clear

[Sergey A. Samokhodkin]

Ok, what you actually need is a kind of namespaces, am I right?
Something like we take two REs, each with groups 1..3, somehow setup a namespace for each RE, then merge them and have groups 1..3 in the NS#1 and groups 1..3 in the NS#2 inside a single RE.
And, when retrieving the groups, we supply the namespace id.

Is it close to what you need?

[saktheesh p]

yes u were almost  near

i have come up with another problem of same sort ( if i can solve this ill not have that problem )
is there any way to find out the index in the reguar expression that nmatched the text like
aabc|nngha|jjtk is the reguar expression and "nngha" is my matched text is there any way to find that nngha matched from position 5 of the regular expression

thanks in advance

[Nobody/Anonymous]

I think saktheesh means more like:

...
MatchResult match = iterator.nextMatch();
for (all groups) {
int startIdx = match.start(i);
}

which gives you the starting position on the searched text for a particular group on a particular match.

  []s Gustavo

[Nobody/Anonymous]

Or maybe saktheesh wants the opposite, which would be the position on the regex.  If that's what he/she wants, I've never heard of anything close to it...

[]s Gustavo