Regexp Capture Access

Ruby
1

Given that:

%r{(\w,)+}.match(‘a,b,c’)[0] #=> “a,b,”

and

%r{(\w,)+}.match(‘a,b,c’)[1] #=> “b,”

How do I access the capture that contains “a,”?

2

Try:

%r{(\w,)+}.match(‘a,b,c’).to_s[0…1] #=> “a,”

2008/4/2, Oliver S. [email protected]:

3

On Wed, Apr 2, 2008 at 3:20 PM, Oliver S.
[email protected] wrote:

Posted via http://www.ruby-forum.com/.

Use scan

“a,b,c”.scan(/\w+,/) → [‘a,’, ‘b,’]
and in order to have the whole match you have to join the result of scan
again.

HTH
Robert

–
http://ruby-smalltalk.blogspot.com/

Whereof one cannot speak, thereof one must be silent.
Ludwig Wittgenstein

4

The reason why it’s acting like this is because Regexes try to find the
largest possible match from your expression. Hence, your expression

%r{(\w,)+}.match(‘a,b,c’)[0]

will return the first match (and largest) “a,b,”

Im sure you’re asking this for a bigger reason, so you have to refine
your
regular expression for that specific purpose. if you just want to split
based on a “,” then simply do ‘a,b,c’.split(’,’) which returns an array
[“a”, “b”, “c”]

If any other, please post the actual problem.

HTH
Mutahhir.

5

On Wed, Apr 2, 2008 at 8:20 AM, Oliver S.
[email protected] wrote:

Given that:

%r{(\w,)+}.match(‘a,b,c’)[0] #=> “a,b,”

and

%r{(\w,)+}.match(‘a,b,c’)[1] #=> “b,”

How do I access the capture that contains “a,”?

Maybe leave the plus symbol (+) out?

r = /(\w,)/
r.match(‘hi,a,b,c’)[1]
=> “i,”

I’d probably use #scan, or even #split, instead.

Todd

6

Nevermind. I was trying to parse CSV. I thought pre-written tools
weren’t capable of understanding quoted values with commas inside but I
was wrong so I can use them.

I do find it amazing that you can’t access multiple matches for a single
sub-pattern though. That’s a serious limitation IMO.

7

On Wed, Apr 2, 2008 at 9:27 AM, Robert D. [email protected]
wrote:

Use scan

“a,b,c”.scan(/\w+,/) → [‘a,’, ‘b,’]
and in order to have the whole match you have to join the result of scan again.

HTH
Robert

Yeah, I was thinking of that regexp also, but I assumed the OP wanted
the last word letter before a comma.

Oliver, what is it that you’re looking for?

Todd

8

On Wed, Apr 2, 2008 at 10:28 AM, Oliver S.
[email protected] wrote:

Nevermind. I was trying to parse CSV. I thought pre-written tools
weren’t capable of understanding quoted values with commas inside but I
was wrong so I can use them.

I do find it amazing that you can’t access multiple matches for a single
sub-pattern though. That’s a serious limitation IMO.

I’m not sure I understand this correctly, because I think your pattern
was wrong.

Todd