MYOL-TB2-prog3-Py/main.py

import sys

from antlr4 import *

from HelloLexer import HelloLexer
from HelloParser import HelloParser
from HelloListener import HelloListener

from TreesUser import TreesUser # contains Marina's PrettyPrint()

def main(argv):
    if len(argv) == 1:
        inpstream = StdinStream()
    else:
        inpname = argv[1]
        inpstream = FileStream(inpname)
    # The lexer analyses the characters on inpstream and produces tokens
    lexer = HelloLexer(inpstream)
    # on the token stream (belonging to a standard ANTLR class)
    tokstream = CommonTokenStream(lexer)
    # The parser produces an abstract syntax tree
    parser = HelloParser(tokstream)
    # When we execute the parse, we need to give it the starting rule of our grammar,
    listener = HelloListener()

    # which in our case is 'greeting' (as defined in hello.g4)
    tree = parser.greeting()
    tree = parser.bye()

    # traditional Lisp-style parse tree
    print(TreesUser.toStringTree(tree, None, parser))
    # pretty-print the parse tree
    print(TreesUser.PrettyPrint(tree, None, parser))
if __name__ == '__main__':
    main(sys.argv)