Convert a regular expression in a string to a regexp object in ruby

I take a regular expression as an input from the user and match values against that regex. But, the problem i have is that the input i receive is a string. e.g. "/abc|def/i" And i am not able to convert it to a regex object. If it try Regexp.new(string) it escapes all the characters so i get something like /\/abc|def\/i/

I was able to capture the part between the forward slashes using another regex and build a regexp object using it. For the above example, i capture "abc|def" and when i do Regexp.new("abc|def") i g开发者_如何学编程et /abc|def/ which is what i wanted but i need a way to also add the regexp options(e.g. 'i' in the above example) in the string to the ruby regexp object.

How can i achieve this ???

Also, there must be a easier way to achieve all of this. Any help would be greatly appreciated.

Here's a quick way to do it /#{my_string_pattern}/

No magic required

You might look into using the to_regexp gem; it doesn't use eval and it will allow you to do this:

 "/(abc|def)/i".to_regexp
 # => /(abc|def)/i

Source at https://github.com/seamusabshere/to_regexp

Just for fun... enjoy:

class Regexp
  def self.parse(s)
    optmap = {
      "i" => Regexp::IGNORECASE,
      "x" => Regexp::EXTENDED,
      "m" => Regexp::MULTILINE
    }

    match = s.match(/\/(.*)\/(.*)/) or raise "Invalid regexp string"
    pat = match.captures[0]
    opt_str = match.captures[1]
    opts = opt_str.split(//).map { |c| optmap[c] }.reduce { |x, n| x | n }
    Regexp.new(pat, opts)
  end
end

# because you aren't hacking Ruby until you've added a method to String...
class String
  def to_regex
    Regexp.parse(self)
  end
end

It works, too!

As you've suggested, I think that your method might be a way to handle it. You can clean it up a little by doing something like this...

class String
  def to_regexp(case_insensitive = false)
    str = self[\/(.*)\/,1]
    Regexp.new(str, case_insensitive)
  end
end

This is just one way to clean it up and make the functionality inherent to Strings so you don't have to worry about it.