Print all permutations of a string in ruby

Ruby program for Print all permutations of a string. Here more information.

#  Ruby program for
#  Print all permutations of a string
class Permutation 
	#  Swapping two string elements by index
	def swap(text, size, a, b) 
		#  Check valid location of swap element
		if ((a >= 0 && a < size) && (b >= 0 && b < size)) 
 			# Get first character
            first = text[a]
            text[a]=text[b]
            text[b]=first
		end
		return text
	end

	#  Method which is print all permutations of given string
	def findPermutation(text, n, size) 
		if (n > size) 
			return
		end

		if (n == size) 
			print(text, "\n")
			return
		end

		i = n
		while (i < size) 
			#  Swap the element
			text = self.swap(text, size, i, n)
			self.findPermutation(text, n + 1, size)
			#  Swap the element
			text = self.swap(text, size, i, n)
			i += 1
		end

	end

end

def main() 
	task = Permutation.new()
	text = "ABC"
	size = text.length
	task.findPermutation(text, 0, size)
	print("\n")
	text = "abcd"
	size = text.length
	task.findPermutation(text, 0, size)
end

main()

Output

ABC
ACB
BAC
BCA
CBA
CAB

abcd
abdc
acbd
acdb
adcb
adbc
bacd
badc
bcad
bcda
bdca
bdac
cbad
cbda
cabd
cadb
cdab
cdba
dbca
dbac
dcba
dcab
dacb
dabc