hash.rb

############################################################################
# Copyright 2009,2010 Benjamin Kellermann                                  #
#                                                                          #
# This file is part of dudle.                                              #
#                                                                          #
# Dudle is free software: you can redistribute it and/or modify it under   #
# the terms of the GNU Affero General Public License as published by       #
# the Free Software Foundation, either version 3 of the License, or        #
# (at your option) any later version.                                      #
#                                                                          #
# Dudle is distributed in the hope that it will be useful, but WITHOUT ANY #
# WARRANTY; without even the implied warranty of MERCHANTABILITY or        #
# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Affero General Public     #
# License for more details.                                                #
#                                                                          #
# You should have received a copy of the GNU Affero General Public License #
# along with dudle.  If not, see <http://www.gnu.org/licenses/>.           #
############################################################################

class Hash
	####################################################
	# compare self with other hash                     #
	# in the order of fieldarray                       #
	# {1=>a,2=>b}.compare_by_values({1=>c,2=>d},[2,1]) #
	#  -> compares b,d and afterwards a,c              #
	####################################################
	def compare_by_values(other, fieldarray)
		return  0 if fieldarray.size == 0
		return  1 if  self[fieldarray[0]].nil?
		return -1 if other[fieldarray[0]].nil?

		if self[fieldarray[0]] == other[fieldarray[0]]
			if fieldarray.size == 1
				return 0
			else
				return self.compare_by_values(other, fieldarray[1,fieldarray.size-1])
			end
		else
			self[fieldarray[0]] <=> other[fieldarray[0]]
		end
	end
end

if __FILE__ == $0
require "test/unit"
  class Hash_test < Test::Unit::TestCase
    def test_compare_by_values
			a = {1 =>1, 2=>2, 3=>3}
			b = {1 =>1, 2=>2, 3=>2}
			c = {1 =>1, 2=>3, 3=>3}
			d = {1 =>1, 2=>3}

      assert_equal( 0,a.compare_by_values(a,[1,2,3]))
      assert_equal( 1,a.compare_by_values(b,[1,2,3]))
      assert_equal(-1,a.compare_by_values(c,[1,2,3]))
      assert_equal(-1,c.compare_by_values(d,[1,2,3]))
      assert_equal( 1,d.compare_by_values(c,[1,2,3]))
      assert_equal( 0,d.compare_by_values(c,[]))
    end
  end
end