def test_or_shortcircuit():
source = ['(or #t never-reached)']
exp = parse_tokens(tokenize(source))[0]
try:
eval_in_env(exp, Environment([]))
except Exception as e:
assert str(e) != 'unknown variable "never-reached"'
def repl():
color_print('****************************************', 'blue')
color_print('lis.py - a simple Lisp written in Python', 'blue')
color_print('(c) Nick Collins, 2013', 'blue')
color_print('****************************************', 'blue')
env = Environment([])
while True:
try:
user_input = raw_input('lis.py> ')
exp = parse_tokens(tokenize([user_input]))[0]
tmp_env = Environment([], env)
color_print(eval_in_env(exp, tmp_env), 'green')
env = tmp_env
except EOFError:
color_print('\nLeaving lis.py.', 'blue')
break
except LisNameError as e:
color_print(e, 'red')
except LisSyntaxError as e:
color_print(e, 'red')
except Exception as e:
color_print(e, 'red')
print('*** Invalid input ***')
def test_add():
source = ['(+ 1 3 5)']
exp = parse_tokens(tokenize(source))[0]
assert eval_in_env(exp, Environment([])) == 9
def test_and_false():
source = ['(and (> 2 1) (= 1 2) #t)']
exp = parse_tokens(tokenize(source))[0]
assert eval_in_env(exp, Environment([])) == False
def test_divide():
source = ['(/ 10 3)']
exp = parse_tokens(tokenize(source))[0]
assert eval_in_env(exp, Environment([])) == 3
def test_gt():
source0, source1 = ['(> 2 2)'], ['(> 3 2)']
exp0 = parse_tokens(tokenize(source0))[0]
exp1 = parse_tokens(tokenize(source1))[0]
assert eval_in_env(exp0, Environment([])) == False
assert eval_in_env(exp1, Environment([])) == True
def test_multiply():
source = ['(* 1 3 5)']
exp = parse_tokens(tokenize(source))[0]
assert eval_in_env(exp, Environment([])) == 15
def test_subtract():
source = ['(- 10 14)']
exp = parse_tokens(tokenize(source))[0]
assert eval_in_env(exp, Environment([])) == -4
env = tmp_env
except EOFError:
color_print('\nLeaving lis.py.', 'blue')
break
except LisNameError as e:
color_print(e, 'red')
except LisSyntaxError as e:
color_print(e, 'red')
except Exception as e:
color_print(e, 'red')
print('*** Invalid input ***')
# RUN INTERPRETER ======================
if __name__ == '__main__':
parser = argparse.ArgumentParser()
parser.add_argument('source', nargs = '?', default=None, help='source file')
args = parser.parse_args()
if args.source:
try:
with open(args.source, 'r') as source:
tokens = tokenize(source)
program = parse_tokens(tokens)
eval_loop(program)
except IOError as e:
color_print(e, 'red')
color_print('Invalid source file', 'red')
else:
repl()
def test_parse_unexpected_closing_paren():
source = ['(define add 3))']
tokens = tokenize(source)
with pytest.raises(LisSyntaxError) as e:
exp = parse_tokens(tokens)
def test_nullcheck():
source = ['(null? null)']
exp = parse_tokens(tokenize(source))[0]
assert eval_in_env(exp, []) == True
def test_nullcheck_2():
source = ['(null? (cons 1 null))']
exp = parse_tokens(tokenize(source))[0]
assert eval_in_env(exp, []) == False
def test_list():
source = ['(list 1 2 (+ 1 2) 4)']
exp = parse_tokens(tokenize(source))[0]
assert eval_in_env(exp, []) == [1, 2, 3, 4]
def test_cdr():
source = ['(cdr (cons 1 null))']
exp = parse_tokens(tokenize(source))[0]
assert eval_in_env(exp, []) == []
def test_car():
source = ['(car (cons 1 null))']
exp = parse_tokens(tokenize(source))[0]
assert eval_in_env(exp, Environment([])) == 1
def test_or_false():
source = ['(or (> 2 10) (= 1 2) #f)']
exp = parse_tokens(tokenize(source))[0]
assert eval_in_env(exp, Environment([])) == False
def test_parse_add():
source = ['(define a (+ 3 3))']
tokens = tokenize(source)
exp = parse_tokens(tokens)
assert exp == [['define', 'a', ['+', 3, 3]]]
def test_nullcheck_3():
source = ['(null? (cdr (list 1)))']
exp = parse_tokens(tokenize(source))[0]
assert eval_in_env(exp, []) == True
def test_parse_define_lambda():
source = ['(define add (lambda (x y) (+ x y)))']
tokens = tokenize(source)
exp = parse_tokens(tokens)
assert exp == [['define', 'add', ['lambda', ['x', 'y'], ['+', 'x', 'y']]]]
def test_cons():
source = ['(cons (+ 1 3 5) null)']
exp = parse_tokens(tokenize(source))[0]
assert eval_in_env(exp, Environment([])) == [9]
def test_parse_define():
source = ['(define a 3)']
tokens = tokenize(source)
exp = parse_tokens(tokens)
assert exp == [['define', 'a', 3]]
