hash.rb

############################################################################
# Copyright 2009-2019 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]]
			return 0 if fieldarray.size == 1

			compare_by_values(other, fieldarray[1, fieldarray.size - 1])

		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