Ruby regex key search

Question

http://ruby-doc.org/core-1.9.3/Hash.html#method-i-include-3F

It is possible to convert hash.has_key?(String) to have a regex search capabilities?

Answer 1

I think that using any? is a good solution as stated by qqbenq, but I would prefer using it with grep since it's more succinct.

hash.keys.grep(/regexp/).any?

Answer 2

I am not aware of an absolute answer for this question but if I were to write a hacky method for this, I would do this

!!hash.keys.detect{ |k| k.to_s =~ /Your_Regex_here/ }

This will return true when any key matches regex and false otherwise.

Answer 3

If you are only interested in a yes/no answer, then any? might be a good option:

hash.keys.any? { |key| key.to_s.match(regexp)}

where regexp is a regular expression.

Answer 4

I would advise extending Hash with a new method instead of replacing has_key?.

class Hash
  def has_rkey?(search)
    search = Regexp.new(search.to_s) unless search.is_a?(Regexp)
    !!keys.detect{ |key| key =~ search }
  end
end

This will work with strings, symbols or a regexp as arguments.

irb> h = {:test => 1}
 => {:test=>1}  
irb> h.has_rkey?(:te)
 => true 
irb> h.has_rkey?("te")
 => true 
irb> h.has_rkey?(/te/)
 => true 
irb> h.has_rkey?("foo")
 => false 
irb> h.has_rkey?(:foo)
 => false 
irb> h.has_rkey?(/foo/)
 => false