12_rpn_calculator

gistfile1.rb

class RPNCalculator
	attr_accessor :calculator

	def initialize
		@calculator = []
	end

	def push (number)
		@calculator << number
	end

	def value
		@calculator.last
	end

	def plus
		if @calculator == []
			raise 'calculator is empty'
		end
		number1 = @calculator.pop
		number2 = @calculator.pop
		new_number = number1 + number2
		@calculator << new_number
		
	end

	def minus	
		if @calculator == []
			raise 'calculator is empty'
		end
		number1 = @calculator.pop
		number2 = @calculator.pop
		new_number = number1 - number2
		@calculator << new_number
		
	end

	def divide
		if @calculator == []
			raise 'calculator is empty'
		end
		number1 = @calculator.pop
		number2 = @calculator.pop
		new_number = number1.to_f / number2
		@calculator << new_number
		
	end

	def times
		if @calculator == []
			raise 'calculator is empty'
		end
		number1 = @calculator.pop
		number2 = @calculator.pop
		new_number = number1 * number2
		@calculator << new_number
	end

	def tokens (string)
		string.split(' ').each do | z |
			if z == "*"
				@calculator<<:*
			elsif z == "-"
				@calculator<<:-
			elsif z == "+"
				@calculator<<:+
			elsif z == "/"
				@calculator<<:/
			else
				@calculator<<z.to_i
			end
		end
		@calculator
	end
				
	def evaluate (string)
		string.split(' ').each do | z |
			z.to_i == 0 ? z : z = z.to_i
			if z == "*"
				@calculator << @calculator.pop * @calculator.pop
			elsif z == "-"
				@calculator << @calculator.pop - @calculator.pop
			elsif z == "+"
				@calculator << @calculator.pop + @calculator.pop
			elsif z == "/"
				@calculator << @calculator.pop.to_f / @calculator.pop
			else
				@calculator << z
			end
			
		end
		@calculator.last
	end

end