example2.py

"""This is an example of using a PDA to parse strings with
well-formed parentheses."""
from PDA import *
from State import *

accept5 = State(state_type="Accept")
pop4 = State(state_type="Pop")
pop3 = State(state_type="Pop")
push2 = State(state_type="Push")
read1 = State(state_type="Read")

# add transitions for 'a', 'b', and the 'end' of the tape.
read1.add_transition(push2, character="(")
read1.add_transition(pop3, character=")")
read1.add_transition(pop4, character="!")

push2.add_transition(read1, character="X")
pop3.add_transition(read1, character="X")

pop4.add_transition(accept5, character="!")

start_state = State(state_type="Start", next_state=read1)

my_pda = PDA(start_state)

tape_word = "(((((((()))(((())))()()((())))))))!"
my_pda.start(tape=tape_word, stack=['!'], verbose=False)