# Author::    Marc Rene Arns  (Base64.decode64('bGludXhAbWFyY3JlbmVhcm5zLmRl\n'))
# Copyright:: Copyright (c) 2011 Marc Rene Arns 
# License::   Distributes under the same terms as Ruby

# This module has two methods to convert between @under_scored_instance_variables
# and recursive Hashes, see README and the unit tests for examples

module InstanceVariableHash
  # get all instance variables that begin with 'key' as a recursive Hash (separated by _) 
  def instance_variables_get_as_hash(key)
    response = {} # we need a hash to have an object (id) to attach to
    self.instance_variables.each do |var|
      if var =~ /^@#{Regexp.escape(key.to_s)}(.*)$/ # we take the exact match and the subkeys
        keys, hsh, pre = $1.split('_'), response, []
        keys[0] = key # put the key itself into the result to have it in the loop
        stop = keys.size 
        keys.each do |k|
          pre << k
          if pre.size == stop # last element
            hsh[k] = self.instance_variable_get("@#{pre.join('_')}")
          else
            hsh[k] ||= {} 
            hsh = hsh[k]            
          end
        end
      end
    end
    return response[key]
  end

  # set instance variables by a Hash, so that they will end up with underscored names
  def instance_variables_set_with_hash(hsh)    
    meth = proc do |pre,h|
      h.each do |k,v|
        keys = (pre.dup << k)
        v.is_a?(Hash) ? meth.call(keys,v) : self.instance_variable_set("@#{keys.join('_')}", v)
      end
    end

    meth.call [], hsh
  end
end