From: Joel VanderWerf <vjoel@...>
Date: 2009-08-29T06:08:29+09:00
Subject: Re: I need a string#all_indices method--is there such a thing?

Bertram Scharpf wrote:
> Hi,
> 
> Am Freitag, 28. Aug 2009, 17:40:05 +0900 schrieb timr:
>> Scan gives you the matches, not the indices (which is what I need).
>>
>>>> "this is a test for scan".scan(/t/)
>> => ["t", "t", "t"]
> 
> There's a trick to do it with String#scan:
> 
>   a = []
>   "this is a test for scan".scan( /t/) { a.push $`.length }
>   a
> 
> This does not work when the matches overlap.
> 
>   "banana".scan /ana/       #=> ["ana"]
> 
> Bertram
> 
> 

Same difficulty with overlap, but for variety:

class String
   def all_indexes re
     a=[];scan(re) {a<<$~.begin(0)};a
   end
end

p "foo bar baz".all_indexes(/.../)
p "banana".all_indexes(/ana/)

__END__

Output:

[0, 3, 6]
[1]

-- 
       vjoel : Joel VanderWerf : path berkeley edu : 510 665 3407