ruby regex: match and get position(s) of

Question

I'd like to match a regex and get the position in the string of the match

For example,

"AustinTexasDallasTexas".match_with_posn /(Texas)/

I'd like match_with_posn to return something like: [6, 17] where 6 and 17 are the start positions for both instances of the word Texas.

Is there anything like this?

Answer 1

Using Ruby 1.8.6+, you can do this:

require 'enumerator' #Only for 1.8.6, newer versions should not need this.

s = "AustinTexasDallasTexas"
positions = s.enum_for(:scan, /Texas/).map { Regexp.last_match.begin(0) }

This will create an array with:

=> [6, 17]

Answer 2

Sort of, see String#index

"AustinTexasDallasTexas".index /Texas/
=> 6

Now, you could extend the String API.

class String
  def indices e
    start, result = -1, []
    result << start while start = (self.index e, start + 1)
    result
  end
end
p "AustinTexasDallasTexas".indices /Texas/
=> [6, 17]

Answer 3

"AustinTexasDallasTexas".gsub(/Texas/).map { Regexp.last_match.begin(0) }
  #=> [6, 17]