Monkey patch for SimpleForm to be able to override bootstrap grid classes

simple_form_wrappers_merge_classes.rb

module SimpleForm
  module Wrappers
    class Many

      private

      def wrap(input, options, content)
        return content if options[namespace] == false
        return if defaults[:unless_blank] && content.empty?

        tag = (namespace && options[:"#{namespace}_tag"]) || @defaults[:tag]
        return content unless tag

        klass = html_classes(input, options)
        opts  = html_options(options)
        merge_classes(klass, opts[:class])
        opts[:class] = klass.join(' ').strip unless klass.empty?
        input.template.content_tag(tag, content, opts)
      end

      def merge_classes(klass, klass2)
        klass << klass2 unless klass2.blank?
        ['col-xs-\d+', 'col-sm-\d+', 'col-md-\d+', 'col-lg-\d+'].each do |bc|
          matches = klass.grep(Regexp.new(bc))
          matches[0...(matches.size-1)].each do |match|
            klass.delete(match)
          end
        end
      end

    end
  end
end