Add EOF symbol to match end of input

Can be signified with $

Must be optional (grammars don’t have to contain it to be correct)

Need to make sure it works for both LALR and Earley, and with indentation.

[isidentical]

Any update?

[erezsh]

Just pushed this into master. You can now use $ in the LALR parser. (No Earley support yet)

Here’s an example from the tests that shows what it does:

def test_end_symbol2(self):
    grammar = """
        start: (a|b)+
        a: "a" ("x"|$)
        b: "b"
    """
    parser = _Lark(grammar)

   self.assertEqual(parser.parse('axa'), Tree('start', [Tree('a', []),Tree('a', [])]))
   self.assertRaises(UnexpectedInput, parser.parse, 'ab')