| # | |
| # This example demonstrates relative imports with rule rewrite | |
| # see multiples.lark | |
| # | |
| # | |
| # if b is a number written in binary, and m is either 2 or 3, | |
| # the grammar aims to recognise m:b iif b is a multiple of m | |
| # | |
| # for example, 3:1001 is recognised | |
| # because 9 (0b1001) is a multiple of 3 | |
| # | |
| from lark import Lark, UnexpectedInput | |
| parser = Lark.open('multiples.lark', parser='lalr') | |
| def is_in_grammar(data): | |
| try: | |
| parser.parse(data) | |
| except UnexpectedInput: | |
| return False | |
| return True | |
| for n_dec in range(100): | |
| n_bin = bin(n_dec)[2:] | |
| assert is_in_grammar('2:{}'.format(n_bin)) == (n_dec % 2 == 0) | |
| assert is_in_grammar('3:{}'.format(n_bin)) == (n_dec % 3 == 0) | |