Ruby regex - replace dots with spaces in the middle of text

Question

I have a long text in which I'd like to replace dots with spaces but only in the middle of the text. For example:

Domain:...................google.com

I need this to be:

Domain:                   google.com

I came upon this regex that replaces the dots with a single space:

str.gsub!(/(?<=:)\.+(?=[^\.])/, ' ')

But it isn't sufficient because it produces:

Domain: google.com

I need to keep as many spaces as dots were. How would you solve it?

Answer 1

You are nearly there, your regexp is fine, just use block version of String#gsub to calculate the length of match for replacement:

▶ str = 'Domain:...................google.com'
#⇒ "Domain:...................google.com"
▶ str.gsub(/(?<=:)\.+(?=[^\.])/) { |m| ' ' * m.length }
#⇒ "Domain:                   google.com"

Answer 2

If you need to do that in the context you describe (a key/value separated with : where the value is a domain name), you can simply use:

> s='Domain:............www.google.com'
 => "Domain:............www.google.com" 
> s.gsub(/(?<=[:.])\./, ' ')
 => "Domain:            www.google.com"

Because a domain name doesn't contain a : or consecutive dots.

For a more general use, see @mudasobwa answer or you can do that too:

s.gsub(/(?:\G(?!\A)|\A[^:]*:\K)\./, ' ')

(Where the \G anchor that matches the position after the previous match, forces the next results to be contiguous).