Untitled

module Kernel
  def match_class?( class_spec )
    case class_spec
    when Class
      # A plain value
      return false unless self.is_a? class_spec
    when Hash
      # When we expect a keyed enumerator
      return false unless self.method(:each)
      # A hashlike each will return two values
      self.each do |(k,v)|
        key_type = class_spec.keys.select { |s| k.is_a? s }
        # Pass if any of the possible spec types fit the data.
        return false unless key_type.any? { |s| v.match_class?( class_spec[s] ) }
      end
    when Array
      # When we expect an enumerator
      return false unless self.method(:each)
      # Treat the array of specs as a repeatable sequence
      # Make sure the data matches each spec in turn
      spec_list = class_spec.each.cycle
      self.each do |i|
        next_spec = spec_list.next
        return false unless i.match_class?( next_spec )
      end
    end
    true
  end
end

# Examples:

# Simple, and overkill. Should have used is_a?
1.match_class? Integer

# Slightly more complex...
[ 1, 2, 3 ].match_class? [ Integer ]

# Much more complex...
[ { :foo => 1 }, { :foo => 2 } ].match_class?( [ { Symbol => Integer } ] )

# And to prove it works, this will fail:
[ { :foo => 1 }, { :foo => 2.0 } ].match_class?( [ { Symbol => Integer } ] )