class Parser:
def __init__(self, input_code: str): # TODO initialize
self.symbol_table = SymbolTable()
self.symbol_table.new_scope()
self.pars_stack = Stack()
self.scanner = Scanner(input_code, symbol_table=self.symbol_table)
self.dfa = TransitionDiagram() # TODO
self.dfa.make_diagrams()
self.look_ahead = ""
self.current_token = None
self.current_token_info = None
self.pars_stack.push(self.dfa.start_state)
self.code_generator = CodeGenerator(self.symbol_table)
def run(self):
token_info, self.look_ahead = self.scanner.look_ahead()
ignored_string = ""
while True:
# print("^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^")
top = self.pars_stack.top()
# print(" Top : ", top.type, " ", top.name, " Look ahead=",self.look_ahead)
if top.type == "state":
state = top
if state.is_final:
# print(" poped", top.name)
self.pars_stack.pop()
if state.is_omega_final:
print("Parsed successfully!")
break
elif not state.is_final:
if self.look_ahead in state.goto_dict: # key exists in dict
ignored_string = ""
pre_routines = Routine.string_to_routines(state.goto_dict[self.look_ahead][PRE_ROUTINES])
post_routines = Routine.string_to_routines(state.goto_dict[self.look_ahead][POST_ROUTINES])
self.code_generator.call_routines_list(pre_routines, self.current_token_info)
next_state = state.goto_dict[self.look_ahead][STATE]
if len(next_state) == 1: # if edge is terminal
next_state = next_state[0]
# print("on a terminal edge")
# print(" poped ", self.pars_stack.top().name)
self.pars_stack.pop()
self.current_token = self.look_ahead
self.current_token_info = token_info
self.code_generator.call_routines_list(post_routines, current_token=self.current_token_info)
self.pars_stack.push(next_state)
# print(" pushed ", next_state.type, " ", next_state.name)
if not state.goto_dict[self.look_ahead][IS_EPSILON]:
token_info, self.look_ahead = self.scanner.look_ahead()
elif len(next_state) == 2:
# print("on a non-terminal edge")
# print(" poped ", self.pars_stack.top().name)
self.pars_stack.pop()
# print(" pushed ", next_state[1].name)
self.pars_stack.push(
next_state[1]) # next state in this diagram (not the nonterminal's diagram)
for routine in reversed(post_routines):
self.pars_stack.push(routine)
# print(" pushed ", next_state[0].name)
self.pars_stack.push(next_state[0]) # start state of the nonterminal
else:
print("ERROR in initializing states: next state with 0 or >2 elements")
else: # key doesnt exist in dict
ignored_string += self.look_ahead
token_info, self.look_ahead = self.scanner.look_ahead()
if self.look_ahead == "$":
print("Error: reached end of file.")
break
print("Error in line:\n Panic Mode: Error in input, ignored: ", ignored_string)
continue
else:
print("!!?")
elif top.type == "#":
self.code_generator.call_routine(top, current_token=self.current_token_info)
self.pars_stack.pop()
