From: "Jesús Gabriel y Galán" <jgabrielygalan@...>
Date: 2008-09-01T21:25:48+09:00
Subject: Re: gsub html sanitizer

On Mon, Sep 1, 2008 at 2:09 PM, Chealsea S. <marikoc@gmail.com> wrote:
> I'm new to Ruby and a bit confused about how gsub works. I've read the
> documentation, searched ruby-forum, and tried numerous google searches,
> but can't seem to figure out how to do something that should be simple.
>
> This is just an example, but say I have a string "apple cat flower". I'd
> like to replace all instances of the pattern "apple" with the string
> "fruit," "cat" with the string "animal," and "flower" with the string
> "plant." Meaning I have more than 1 pattern to replace, each with a
> specific string to replace.
>
> So I want "apple cat flower" to be converted into "fruit animal plant".
>
> I hope this isn't too confusing. Help is appreciated :)

If you don't mind a loop, you could gsub each pattern one at a time.

irb(main):002:0> patterns = {"apple" => "fruit", "cat" => "animal",
"flower" => "plant"}
=> {"cat"=>"animal", "apple"=>"fruit", "flower"=>"plant"}
irb(main):003:0> s = "apple cat flower"
=> "apple cat flower"
irb(main):004:0> patterns.each {|p,r| s.gsub!(p, r)}
=> {"cat"=>"animal", "apple"=>"fruit", "flower"=>"plant"}
irb(main):005:0> s
=> "fruit animal plant"

You could also build a big regexp and let gsub do the loop:

irb(main):008:0> s = "apple cat flower"
=> "apple cat flower"
irb(main):009:0> re = Regexp.new("(#{patterns.keys.join("|")})")
=> /(cat|apple|flower)/
irb(main):010:0> s.gsub(re) {patterns[$1]}
=> "fruit animal plant"

Hope this helps,

Jesus.