Case insensitive like (ilike) in Datamapper with Postgresql

gistfile1.rb

require 'dm-core'
require 'dm-do-adapter'

module DataMapper
  class Query
    module Conditions
      class ILikeComparison < AbstractComparison
        slug :ilike

        private

        # Overloads the +expected+ method in AbstractComparison
        #
        # Return a regular expression suitable for matching against the
        # records value.
        #
        # @return [Regexp]
        #
        # @see AbtractComparison#expected
        #
        # @api semipublic
        def expected
          Regexp.new('\A' << super.gsub('%', '.*').tr('_', '.') << '\z')
        end

        # @return [String]
        #
        # @see AbstractComparison#to_s
        #
        # @api private
        def comparator_string
          'ILIKE'
        end
      end # class LikeComparison
    end
  end

  module Adapters
    class DataObjectsAdapter < AbstractAdapter
      module SQL #:nodoc:
      
        alias :old_comparison_operator :comparison_operator
  
        def comparison_operator(comparison)
          case comparison.slug
            when :ilike  then 'ILIKE'
            else old_comparison_operator(comparison)
          end
        end
      end
    end
  end
end

Know of a solution like this for PostgreSQL's SIMILAR TO condition (regex)? That'd be very much appreciated :)