State.py

from Constants import Direction

MAX_M = 30
MAX_C = 30
CAP_BOAT = 20
CNST = None


class State(object):

	def __init__(self, missionaries, cannibals, dir, missionariesPassed, cannibalsPassed, level, CONSTS,moves):
		self.missionaries = missionaries
		self.cannibals = cannibals
		self.dir = dir
		self.action = ""
		self.level = level
		self.missionariesPassed = missionariesPassed
		self.cannibalsPassed = cannibalsPassed
		self.CONSTANTS = CONSTS

		self.moves = moves

		global MAX_M
		global MAX_C
		global CAP_BOAT
		global CNST

		if not CONSTS is None:
			CNST = CONSTS

			MAX_M = CONSTS.MAX_M
			MAX_C = CONSTS.MAX_C
			CAP_BOAT = CONSTS.CAP_BOAT

	# pass True to count forward
	def successors(self):
		listChild = []
		if not self.isValid() or self.isGoalState():
			return listChild
		if self.dir == Direction.OLD_TO_NEW:
			sgn = -1
			direction = "from the original shore to the new shore"
		else:
			sgn = 1
			direction = "back from the new shore to the original shore"
		for i in self.moves:
			(m, c) = i
			self.addValidSuccessors(listChild, m, c, sgn, direction)
		return listChild

	def addValidSuccessors(self, listChild, m, c, sgn, direction):
		newState = State(self.missionaries + sgn * m, self.cannibals + sgn * c, self.dir + sgn * 1,
							self.missionariesPassed - sgn * m, self.cannibalsPassed - sgn * c, self.level + 1,
							self.CONSTANTS,self.moves)
		if newState.isValid():
			newState.action = " take %d missionaries and %d cannibals %s." % (m, c, direction)
			listChild.append(newState)

	def isValid(self):
		# obvious
		if self.missionaries < 0 or self.cannibals < 0 or self.missionaries > MAX_M or self.cannibals > MAX_C or (
				self.dir != 0 and self.dir != 1):
			return False

		# then check whether missionaries outnumbered by cannibals in any shore
		if (self.cannibals > self.missionaries > 0) or (
				self.cannibalsPassed > self.missionariesPassed > 0):  # more cannibals then missionaries on original shore
			return False

		return True

	def isGoalState(self):
		return self.cannibals == 0 and self.missionaries == 0 and self.dir == Direction.NEW_TO_OLD

	def __repr__(self):
		return "\n%s\n\n< @Depth:%d State (%d, %d, %d, %d, %d) >" % (
			self.action, self.level, self.missionaries, self.cannibals, self.dir, self.missionariesPassed,
			self.cannibalsPassed)

	def __eq__(self, other):
		return self.missionaries == other.missionaries and self.cannibals == other.cannibals and self.dir == other.dir

	def __hash__(self):
		return hash((self.missionaries, self.cannibals, self.dir))

	def __ne__(self, other):
		return not (self == other)


TERMINAL_STATE = State(-1, -1, Direction.NEW_TO_OLD, -1, -1, 0, CNST,None)
# INITIAL_STATE = State(MAX_M, MAX_C, Direction.OLD_TO_NEW, 0, 0, 0, CNST)