def demo():
from parser import tokenize, parse_exp
source = '(* 6 (+ 3 4))'
tokens = tokenize(source)
expr = parse_exp(tokens)
result = evaluate(expr)
print(result)
def repl(input_fn=input):
"""Read-Eval-Print-Loop"""
print(f'To exit, type {QUIT_COMMAND}', file=sys.stderr)
while True:
# ___________________________________________ Read
try:
line = input_fn('> ')
except EOFError:
break
if line == QUIT_COMMAND:
break
if not line:
continue
# ___________________________________________ Eval
current_exp = parse_exp(tokenize(line))
if isinstance(current_exp, list) and current_exp[0] == 'define':
result = define_function(current_exp[1:])
else:
try:
result = evaluate({}, current_exp)
except (errors.UndefinedVariable, errors.UndefinedFunction) as exc:
print('***', exc)
continue
# ___________________________________________ Print
print(result)
def repl(input_fn=input):
"""Read-Eval-Print-Loop"""
print(f'To exit, type {QUIT_COMMAND}', file=sys.stderr)
while True:
# ___________________________________________ Read
try:
line = input_fn('> ')
except EOFError:
break
if line == QUIT_COMMAND:
break
if not line:
continue
# ___________________________________________ Eval
current_exp = parse_exp(tokenize(line))
try:
value = evaluate(current_exp)
except errors.UndefinedVariable as exc:
print('***', exc)
continue
# ___________________________________________ Print
print(value)
def repl(input_fn=input):
"""Read-Eval-Print-Loop"""
print(f'To exit, type {QUIT_COMMAND}', file=sys.stderr)
while True:
# ___________________________________________ Read
try:
source = multiline_input('> ',
'... ',
quit_cmd=QUIT_COMMAND,
input_fn=input_fn)
except (EOFError, QuitRequest):
break
except errors.UnexpectedCloseParen as exc:
print('***', exc)
continue
if not source:
continue
# ___________________________________________ Eval
current_exp = parse_exp(tokenize(source))
if isinstance(current_exp, list) and current_exp[0] == 'define':
result = define_function(current_exp[1:])
else:
try:
result = evaluate({}, current_exp)
except errors.EvaluatorException as exc:
print('***', exc)
continue
# ___________________________________________ Print
print(result)
def run(source_file, env=None):
"""Read and execute opened source file"""
source = source_file.read()
if env is None:
env = {}
tokens = tokenize(source)
while tokens:
try:
current_exp = parse_exp(tokens)
except errors.UnexpectedCloseParen as exc:
print('***', exc, file=sys.stderr)
break
if isinstance(current_exp, list) and current_exp[0] == 'define':
define_function(current_exp[1:])
else:
try:
evaluate(env, current_exp)
except errors.EvaluatorException as exc:
print('***', exc, file=sys.stderr)
continue
def test_parse_unexpected_end_of_source():
tokens = tokenize('(')
with raises(errors.UnexpectedEndOfSource) as excinfo:
parse_exp(tokens)
assert "Unexpected end of source code." == str(excinfo.value)
def test_parse_unexpected_close_parenthesis():
tokens = tokenize(')')
with raises(errors.UnexpectedCloseParen) as excinfo:
parse_exp(tokens)
assert "Unexpected close parenthesis." == str(excinfo.value)
def test_parse_exp_application(source, ast):
got = parse_exp(tokenize(source))
assert ast == got
def test_parse_exp_atoms(source, ast):
got = parse_exp(tokenize(source))
assert ast == got
