def perform_stack_action(self, stack: AutomatonStack,
configuration: Configuration):
MemberState.check_stack(stack)
stack.add_data(stack.get_current_content())
MemberState.add_member_to_stack(stack)
stack.remove_level()
ExpressionEndState.add_function_to_stack(stack)
def perform_stack_action(self, stack: AutomatonStack,
configuration: Configuration):
current_content = stack.get_current_content()
if not current_content:
raise ParsingError('A variable name was expected!')
stack.add_data(Argument(current_content))
stack.remove_level()
def __init__(self, start_state: State, accept_states: List[State],
state_descriptions: List[StateDescription]):
self.start_state = start_state
self.accept_states = accept_states
self.state_descriptions = state_descriptions
self.state_transition_mapping = self._create_state_transition_mapping()
self.state_default_transition_mapping = self._create_state_default_transition_mapping()
self.stack = AutomatonStack()
def add_function_to_stack(stack: AutomatonStack):
arguments = []
if not stack.data_stack:
raise ParsingError('Detected a closing parantheses without an opening one')
stack_content = stack.pop_data()
while not isinstance(stack_content, FunctionDeclaration):
arguments.insert(0, stack_content)
if not stack.data_stack:
raise ParsingError('Detected a closing parantheses without an opening one')
stack_content = stack.pop_data()
stack.add_data(stack_content.create_function(arguments))
def perform_stack_action(self, stack: AutomatonStack,
configuration: Configuration):
current_string = stack.get_current_content()
stack.add_data(
MessageComponent(MessageComponentType.STRING, current_string))
stack.remove_level()
stack.add_level()
def perform_stack_action(self, stack: AutomatonStack, configuration: Configuration):
current_content = stack.get_current_content()
if not current_content:
raise ParsingError('Empty function name is not allowed!')
stack.add_data(FunctionDeclaration(current_content))
stack.remove_level()
stack.add_level()
def perform_stack_action(self, stack: AutomatonStack,
configuration: Configuration):
stack.add_level()
def perform_stack_action(self, stack: AutomatonStack,
configuration: Configuration):
current_string = stack.get_current_content()
stack.add_data(ConstantExpression(current_string))
stack.remove_level()
stack.add_level()
def check_stack(stack: AutomatonStack):
if stack.get_current_content() == '':
ParsingError('Empty member variable detected')
def add_member_to_stack(stack: AutomatonStack):
assert len(stack.data_stack) >= 2
member = stack.pop_data()
variable = stack.pop_data()
stack.add_data(MemberExpression(variable.name, member))
def perform_stack_action(self, stack: AutomatonStack,
configuration: Configuration):
variable = stack.pop_data()
stack.add_data(FunctionDeclaration(variable.name))
def perform_stack_action(self, stack: AutomatonStack,
configuration: Configuration):
current_content = stack.get_current_content()
stack.add_data(VariableExpression(current_content))
stack.remove_level()
stack.add_level()
def add_constraint_to_stack(stack: AutomatonStack):
value = stack.pop_data()
variable = stack.pop_data()
stack.add_data(Constraint(variable, value))
class ModifiedPushdownAutomaton:
def __init__(self, start_state: State, accept_states: List[State],
state_descriptions: List[StateDescription]):
self.start_state = start_state
self.accept_states = accept_states
self.state_descriptions = state_descriptions
self.state_transition_mapping = self._create_state_transition_mapping()
self.state_default_transition_mapping = self._create_state_default_transition_mapping()
self.stack = AutomatonStack()
def _create_state_transition_mapping(self) -> Dict[State, Dict[str, Transition]]:
state_transition_mapping = {}
for state_description in self.state_descriptions:
input_state = state_description.default_state
if input_state not in state_transition_mapping:
state_transition_mapping[input_state] = {}
for transition in state_description.transitions:
input_char = transition.input_configuration.character
state_transition_mapping[input_state][input_char] = transition
return state_transition_mapping
def _create_state_default_transition_mapping(self) -> Dict[State, DefaultTransition]:
state_default_transition_mapping = {}
for state_description in self.state_descriptions:
state_default_transition_mapping[state_description.default_state] = \
state_description.default_transition
return state_default_transition_mapping
def parse(self, input_tape: str) -> List[object]:
self.stack.clear()
current_state = self.start_state
input_tape_index = 0
for input_char in input_tape:
try:
configuration = Configuration(current_state, input_char)
transition = self._find_transition(configuration)
current_state = self._apply_transition(transition, configuration)
input_tape_index += 1
except ParsingError as error:
print('State:', current_state.name)
print('Index:', input_tape_index)
print('Original Input:', input_tape)
raise error
if current_state not in self.accept_states:
print('State:', current_state.name)
raise ParsingError(f'Parser was not in a final state after the input tape was read.')
return self.stack.data_stack[:]
def _apply_transition(self, transition: Transition,
input_configuration: Configuration) -> State:
transition.perform_stack_action(self.stack, input_configuration)
output_configuration = transition.get_output_configuration(input_configuration)
self.stack.add_char(output_configuration.character)
return output_configuration.state
def _find_transition(self, configuration: Configuration):
if configuration.state not in self.state_transition_mapping or \
configuration.character not in self.state_transition_mapping[configuration.state]:
return self._find_default_transition(configuration.state)
return self.state_transition_mapping[configuration.state][configuration.character]
def _find_default_transition(self, current_state: State):
if current_state not in self.state_default_transition_mapping:
raise ParsingError(f'No default transition found for state {current_state.name}.')
return self.state_default_transition_mapping.get(current_state, None)
def perform_stack_action(self, stack: AutomatonStack,
configuration: Configuration):
stack.add_data(VariableExpression(stack.get_current_content()))
stack.remove_level()
AcceptState.check_stack(stack)
def perform_stack_action(self, stack: AutomatonStack,
configuration: Configuration):
stack.add_data(FunctionDeclaration(stack.get_current_content()))
stack.remove_level()
stack.add_level()