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#
# 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', rel_to=__file__, 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)
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