From: Robert Klemme <shortcutter@...>
Date: 2008-09-01T21:25:06+09:00
Subject: Re: gsub html sanitizer

2008/9/1 Chealsea S. <marikoc@gmail.com>:
> 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 :)

As long as the number of strings is not too large you can use Regexp.union:

irb(main):004:0> replacements =
{"apple"=>"fruit","cat"=>"animal","flower"=>"plant"}
=> {"cat"=>"animal", "apple"=>"fruit", "flower"=>"plant"}
irb(main):005:0> Regexp.union replacements.keys
=> /cat|apple|flower/
irb(main):006:0> "apple cat
flower".gsub(Regexp.union(replacements.keys)) {|m| replacements[m]}
=> "fruit animal plant"

If the number increases you probably rather want something like this

irb(main):007:0> "apple cat flower".gsub(/\w+/) {|m| replacements[m] || m}
=> "fruit animal plant"

Kind regards

robert


-- 
use.inject do |as, often| as.you_can - without end