class TestEventManager(unittest.TestCase):
""" Class for testing event.EventManager from cspy """
def setUp(self):
""" Prepare the test """
self.e_mgr = EventManager()
def test_singleton(self):
""" Design pattern implemented correctly? """
self.assertEqual(self.e_mgr._Singleton__instance, EventManager()._Singleton__instance)
def test_subscription(self):
""" Events are created correctly a recieved? """
def function(**kwargs):
""" Test function """
self.assertEqual(1, kwargs['test'])
self.e_mgr.register_event('test_event')
self.e_mgr.subscribe('test_event', function)
self.e_mgr.raise_event('test_event', test=1)
class Solver(object):
""" Solve CSP problems getting all solutions """
PHASES = ['INIT', 'SOLVING', 'FINISHED']
def __init__(self):
""" Init method """
self.constraints = []
self.variables = {}
self.public_solutions = []
self.qstate = LifoQueue()
self.phase = 'INIT'
self.e_mgr = EventManager()
self.e_mgr.register_event('solver_on_init')
self.e_mgr.register_event('solver_on_end')
self.e_mgr.register_event('solver_on_solution')
self.e_mgr.register_event('solver_on_backtrack')
self.e_mgr.register_event('solver_before_set_value')
self.e_mgr.register_event('solver_after_set_value')
self.e_mgr.raise_event('solver_on_init')
def _push_state(self, variable, value):
""" Store in qstate the value of the variable it going to be set next
and the state of the all domains
"""
domain_dump = {}
for var in self.variables.itervalues():
# store a copy of the domain
domain_dump[var.id] = var.domain[:]
self.qstate.put((variable.id, value, domain_dump))
def _pop_state(self):
""" Restore previous state """
return self.qstate.get(False)
def _back_to_previous_state(self):
""" Go back to a previous valid state removing invalid values.
If qstate become empty (there is no valid state) return false
else true.
"""
while not self.qstate.empty():
state = self._pop_state()
id_var = state[0]
value = state[1]
domain_dump = state[2]
# Restore domains
for id, domain in domain_dump.iteritems():
self.variables[id]._restore(domain)
# Delete invalid value
try:
self.variables[id_var].remove_from_domain([value])
return True
except:
pass
return False
def reg_variable(self, variable):
""" Register a variable to the problem. """
self.variables[variable.id] = variable
def _public_solution(self):
""" Store in public_solutions a id_variable -> value hash """
solution = {}
for id_var, variable in self.variables.iteritems():
solution[id_var] = variable.value
self.public_solutions.append(solution)
return solution
def next_variable(self):
""" Choose what variable is the best to be instancied. """
for variable in self.variables.values():
if not variable.instancied:
return variable
def value(self, variable):
""" Choose the better value to the variable. """
return variable.min()
def solve(self):
""" Get all solutions to the problem. """
while self.iter_solve():
pass
return self.public_solutions
def iter_solve(self):
""" Get all the solutions one by one using a backtracking strategy."""
if self.phase == 'INIT':
self.phase = 'SOLVING'
elif not self._back_to_previous_state():
# No more solutions
self.e_mgr.raise_event('solver_on_end')
self.phase = 'FINISHED'
return None
while not self.all_instancied():
try:
# Heuristic
var = self.next_variable()
value = self.value(var)
self.e_mgr.raise_event('solver_before_set_value')
self._push_state(var, value)
var.set(value)
self.e_mgr.raise_event('solver_after_set_value')
except BTException, bte:
if not self._back_to_previous_state():
# No more solutions
self.phase = 'FINISHED'
self.e_mgr.raise_event('solver_on_end')
return None
else:
self.e_mgr.raise_event('solver_on_backtrack')
# Solution
solution = self._public_solution()
self.e_mgr.raise_event('solver_on_solution')
return solution
class SolverVariable():
""" Varible class for cspy Solver. Each Variable has a domain. When a variable
is set an unique event is raised.
"""
def __init__(self, id, domain):
""" Init method """
self.id = id
self.instancied = False
self.event_name = "%s_on_set_value" % id
self.e_mgr = EventManager()
self.e_mgr.register_event(self.event_name)
if len(domain) == 0:
raise BTException()
self.domain = domain
if len(domain) == 1:
self.set(domain[0])
else:
self.value = None
def _restore(self, domain):
""" Restore domain to a previous domain """
self.domain = domain
if len(domain) > 1:
self.instancied = False
self.value = None
def set(self, val):
""" Set the value to val and raise a event """
self.domain = [val]
self.value = val
self.instancied = True
self.e_mgr.raise_event(self.event_name, id=self.id, value=val)
def remove_from_domain(self, values):
""" Remove values from domain. If domain had more than one value
and after remove only have one the variable become set.
"""
# len before removing
domain_len = len(self.domain)
for value in values:
if self.in_domain(value):
self.domain.remove(value)
# No values is an invalid states
if len(self.domain) == 0:
raise BTException()
# Now the variable is set
elif len(self.domain) == 1 and domain_len > 1:
self.set(self.domain[0])
def subscribe(self, function):
""" Subscribe to variable event """
self.e_mgr.subscribe(self.event_name, function)
def in_domain(self, value):
""" Is the value in the domain? """
return value in self.domain
def min(self):
""" Min posible value of the variable"""
return min(self.domain)
def max(self):
""" Max posible value of the variable"""
return max(self.domain)
def __str__(self):
""" String representation of the variable """
return str(self.domain)
