indexing
	description: "Objects that Generates random numbers"
	author: "Florian Keusch, fkeusch@student.ethz.ch"
	date: "$Date$"
	revision: "$Revision$"

class
	RANDOM_NUMBER_GENERATOR

create
	make

feature {NONE} -- Random Access

	rand: RANDOM
		-- random number gen
		
	timer: TIME	
		-- time at initialization
		
	init_seed: INTEGER
		-- the init seed of the random number generator
		
	next_nr: INTEGER
		-- the number of the next random number



feature -- init

	make is
			-- initializes the random number generator
		do
				-- create timer with system time
			create timer.make_now
			init_seed := timer.milli_second
			create rand.make
			rand.set_seed (init_seed)
			next_nr := 1
		end

	remake (seed: INTEGER) is
			-- reinitialize with new seed
		do
			rand.make
			rand.set_seed(seed)
			next_nr := 1
		end
		

feature -- functions

	next_int_mod  (n: INTEGER) : INTEGER is
			-- get the next random integer value mod n
			-- if n is 101 you get numbers from 0 to 100
			-- NOTE: n should be prime to get good results
			-- for example n := 101
		require
			n_not_void: n /= Void
		do
			result := rand.next_random (next_nr) \\ n
			next_nr := next_nr + 1
		end
	
	next_int_mod_minus_1 (n:INTEGER) : INTEGER is
			-- the same as next_int_mode but without zero
		require
			n_not_void: n /= Void
		local
			i: INTEGER
		do
			i := rand.next_random (next_nr) \\ n
			next_nr := next_nr + 1
			if i = 0 then
				result := next_int_mod_minus_1 (n)
			else
				result := i
			end
		end
		
		

	next_int: INTEGER is
			-- get the next random integer value
		do
			result := rand.next_random (next_nr)
			next_nr := next_nr + 1
		end
		
	next_double: DOUBLE is
			-- get the next random double value
			-- normalized between 0 and 1
		do
			result := rand.double_i_th (next_nr)
			next_nr := next_nr + 1
		end
		
		
	next_real: REAL is
			-- get the next random real value
			-- normalized between 0 and 1
		do
			result := rand.real_i_th (next_nr)
			next_nr := next_nr + 1
		end
	
	next_bool: BOOLEAN is
			-- get random boolean value
		local
			tmp: REAL
			temp: INTEGER
		do
			tmp := rand.real_i_th (next_nr)
			temp := tmp.rounded
			result := (temp = 1)
			next_nr := next_nr + 1
		end
		
		
		
		
		
		

end -- class RANDOM_NUMBER_GENERATOR