Mixing named and unnamed captures

[hetsch]

Hi slevithan,

first thanks for your great library. Really, really appreciating your work!

Don't know if I'm doing something wrong, but consider the following:

var url = 'page/edit/en/4f55fbbab51bda0df1000001/unnamed'
var re = XRegExp('^page/edit/(?<language>[a-z]{2})/(?<entityId>[a-z0-9]{24})/(?:.*)$');
var match = XRegExp.exec(url, re);
console.log(match);
/**
output:

0: "page/edit/en/4f55fbbab51bda0df1000001/unnamed",
1: "en",
2:"4f55fbbab51bda0df1000001",
entityId:"4f55fbbab51bda0df1000001",    
index:0,
input:"page/edit/en/4f55fbbab51bda0df1000001/unnamed",
language:"en"
*/

My problem is that i have to capture the "unnamed" part of the url (?:.*). The match object doesn't hold me the value of "unnamed"...

Is XRegExp not able to mix named and unnamed captures, or am I am missing something?

Thanks!

[slevithan]

Thanks...I'm glad XRegExp is useful to you!

Unless I'm missing something, though...

(?: ) is not an "unnamed capture"; it is explicitly a noncapturing group. That's the whole point of using the (?: ) syntax instead of simply ( ).

XRegExp supports mixing named and unnamed captures just fine. ;-) Unnamed capturing groups of the form ( ) must be referred to by number. Noncapturing groups of the form (?: ) do not produce backreferences at all. This is standard behavior with nearly all regex flavors, including the native JavaScript RegExp syntax.

[hetsch]

Mindblowing - I'm a complete idiot :-)
Think I got a little bit too exited about named captures in javascript and forgott all other basics, hehe..

Thank's for your tutorial and help! :-)

[hetsch]

Once again,

i know this shouldn't be a mailing list but i'm not quite sure how to contact you otherwise. My problem is that i need to capture some parts of an url. It works fine, except if i have two or more parameters that have the same value. I would need to know that the "language" parameter has the index 3 and not index 2 in the result object so that i can extract all named parameters and check what's left in the result (unnamed)...

var re = new XRegExp('page/edit/(.*)/(.*)/(?<language>[a-z]{2})/(?<entityId>[a-z0-9]{24})/(.*)');
var url = 'http://localhost:5000/admin/page/edit/unnamed1/sameValue/sameValue/4f55fbbab51bda0df1000001/unnamed2'
console.log(XRegExp.exec(url, re));

/**
0 "page/edit/unnamed1/en/e...1bda0df1000001/unnamed2"   
1 "unnamed1"    
2 "en"
3 "en"  
4 "4f55fbbab51bda0df1000001"    
5 "unnamed2"
entityId "4f55fbbab51bda0df1000001"
index 28
input "http://localhost:5000/a...1bda0df1000001/unnamed2"
language "en"
*/

Is there some trick for that kind of problem? Sorry for my poor english, and again - thanks

maybe this gist would explain it a little bit more: https://gist.github.com/2035325

[slevithan]

Backreference numbers are assigned from left to right. Your language capturing group is the third from the left, so result.language and result[3] are equivalent.

Even though mixing named and unnamed capturing groups works fine, I do not recommend doing so because it can be confusing.