def test_symbols():
p = Parser()
x1 = p.add_symbol('sym')
x2 = p.add_token('tok')
x3 = p.add_anon_symbol(':sym')
x4 = p.add_anon_symbol(':sym1')
# test basic numbering assumption
# symbols and tokens are attributed sequentially
# using the same counter
assert x2 == x1 + 1
# anon symbols have negative value
assert x3 != x2 + 1
assert x4 == x3 - 1
assert x3 < 0
y1 = p.add_symbol('sym')
assert y1 == x1
y2 = p.add_token('tok')
assert y2 == x2
y3 = p.add_symbol(':sym')
assert y3 == x3
y4 = p.add_symbol(':sym1')
assert y4 == x4
