def test_quotes(self):
code = """
(define his-name ''(kenjin che))
"""
self.assertEqual(
parse(code),
['define', 'his-name', ['quote', ['quote', ['kenjin', 'che']]]])
def test_simple(self):
code = """
(define (gcd a b)
(if (= b 0)
a
(gcd b (rem a b))))
"""
self.assertEqual(parse(code), [
'define', ['gcd', 'a', 'b'],
['if', ['=', 'b', 0], 'a', ['gcd', 'b', ['rem', 'a', 'b']]]
])
def test_string(self):
code = """
(define (fib n)
"Computes nth fibonacci number"
(if (< n 2)
n
(+ (fib (- n 1)) (fib (- n 2)))))
"""
self.assertEqual(parse(code), [
'define', ['fib', 'n'], '"Computes nth fibonacci number"',
[
'if', ['<', 'n', 2], 'n',
['+', ['fib', ['-', 'n', 1]], ['fib', ['-', 'n', 2]]]
]
])
def test_gcd(self):
code = """
(test-b
(test (op =) (reg b) (const 0))
(branch (label gcd-done))
(assign t (op rem) (reg a) (reg b))
(assign a (reg b))
(assign b (reg t))
(goto (label test-b))
gcd-done)
"""
m = Machine(["a", "b", "t"], [("rem", lambda x, y: x % y),
("=", lambda x, y: x == y)], parse(code))
m.get_register('a').value = 206
m.get_register('b').value = 40
m.start()
self.assertEqual(m.get_register('a').value, 2)
def test_gcd(self):
code = """
(test-b
(test (op =) (reg b) (const 0))
(branch (label gcd-done))
(assign t (op rem) (reg a) (reg b))
(assign a (reg b))
(assign b (reg t))
(goto (label test-b))
gcd-done)
"""
m = Machine(["a", "b", "t"],
[("rem", lambda x, y: x % y),
("=", lambda x, y: x == y)],
parse(code))
m.get_register('a').value = 206
m.get_register('b').value = 40
m.start()
self.assertEqual(m.get_register('a').value, 2)
def test_fib(self):
code = """
(fib-start
(assign continue (label fib-done))
fib-loop
(test (op <) (reg n) (const 2))
(branch (label immediate-answer))
(save continue)
(assign continue (label afterfib-n-1))
(save n)
(assign n (op -) (reg n) (const 1))
(goto (label fib-loop))
afterfib-n-1
(restore n)
(restore continue)
(assign n (op -) (reg n) (const 2))
(save continue)
(assign continue (label afterfib-n-2))
(save val)
(goto (label fib-loop))
afterfib-n-2
(assign n (reg val))
(restore val)
(restore continue)
(assign val (op +) (reg val) (reg n))
(goto (reg continue))
immediate-answer
(assign val (reg n))
(goto (reg continue))
fib-done)
"""
m = Machine(['n', 'val', 'continue'],
[('<', lambda a, b: a < b),
('-', lambda a, b: a - b),
('+', lambda a, b: a + b)],
parse(code))
m.get_register('n').value = 10
m.start()
self.assertEqual(m.get_register('val').value, 55)
def test_fib(self):
code = """
(fib-start
(assign continue (label fib-done))
fib-loop
(test (op <) (reg n) (const 2))
(branch (label immediate-answer))
(save continue)
(assign continue (label afterfib-n-1))
(save n)
(assign n (op -) (reg n) (const 1))
(goto (label fib-loop))
afterfib-n-1
(restore n)
(restore continue)
(assign n (op -) (reg n) (const 2))
(save continue)
(assign continue (label afterfib-n-2))
(save val)
(goto (label fib-loop))
afterfib-n-2
(assign n (reg val))
(restore val)
(restore continue)
(assign val (op +) (reg val) (reg n))
(goto (reg continue))
immediate-answer
(assign val (reg n))
(goto (reg continue))
fib-done)
"""
m = Machine(['n', 'val', 'continue'], [('<', lambda a, b: a < b),
('-', lambda a, b: a - b),
('+', lambda a, b: a + b)],
parse(code))
m.get_register('n').value = 10
m.start()
self.assertEqual(m.get_register('val').value, 55)
Vanilla Scheme interpreter for SICP Chapter 4
ctrl-d to exit,
Happy Hacking!!
""")
code_to_eval = []
while True:
if code_to_eval == []:
print(PROMPT, end='')
try:
code = input()
except EOFError:
print('Goodbye!!')
break
else:
code_to_eval.append(code)
expr = parse(' '.join(code_to_eval))
# succeeds to parse
if expr != None:
try:
value = vseval(expr, GLOBAL_ENV)
except UnboundVar as e:
print('Unbound Variable: ', e)
except Exception as e:
print('Error: ', e)
else:
print("=> ", end='')
print(value)
finally:
code_to_eval = []
def ev(exp, env=GLOBAL_ENV):
return vseval(parse(exp), env)
# (list 'set-variable-value! set-variable-value!)
# (list 'define-variable! define-variable!)
# (list 'primitive-procedure? primitive-procedure?)
# (list 'apply-primitive-procedure apply-primitive-procedure)
# (list 'prompt-for-input prompt-for-input)
# (list 'announce-output announce-output)
# (list 'user-print user-print)
# (list 'empty-arglist empty-arglist)
# (list 'adjoin-arg adjoin-arg)
# (list 'last-operand? last-operand?)
# (list 'no-more-exps? no-more-exps?) ;for non-tail-recursive machine
# (list 'get-global-environment get-global-environment))
eval_operations = [
("read", lambda: parse(input())),
('self-evaluating?', is_self_evaluating),
('quoted?', lambda exp: exp[0] == 'quote'),
('text-of-quotation', text_of_quotation),
]
eval_code = """
(read-eval-print-loop
(perform (op initialize-stack))
(perform
(op prompt-for-input) (const ";;; EC-Eval input:"))
(assign exp (op read))
ctrl-d to exit,
Happy Hacking!!
""")
code_to_eval = []
while True:
if code_to_eval == []:
print(PROMPT, end='')
try:
code = input()
except EOFError:
print('Goodbye!!')
break
else:
code_to_eval.append(code)
expr = parse(' '.join(code_to_eval))
# succeeds to parse
if expr != None:
try:
value = vseval(expr, GLOBAL_ENV)
except UnboundVar as e:
print('Unbound Variable: ', e)
except Exception as e:
print('Error: ', e)
else:
print("=> ", end='')
print(value)
finally:
code_to_eval = []
def test_dot(self):
self.assertEqual(parse("(a . b)"), ['a', ['dot', 'b']])
with self.assertRaises(ValueError):
print(parse("(a . b c)"))
def test_simpler(self):
self.assertEqual(parse('3'), 3)
self.assertEqual(parse('-3.34'), -3.34)
self.assertEqual(parse('"abc"'), '"abc"')
self.assertEqual(parse("'a"), ['quote', 'a'])
def ev(exp, env=GLOBAL_ENV):
return vseval(parse(exp), env)
# (list 'lookup-variable-value lookup-variable-value)
# (list 'set-variable-value! set-variable-value!)
# (list 'define-variable! define-variable!)
# (list 'primitive-procedure? primitive-procedure?)
# (list 'apply-primitive-procedure apply-primitive-procedure)
# (list 'prompt-for-input prompt-for-input)
# (list 'announce-output announce-output)
# (list 'user-print user-print)
# (list 'empty-arglist empty-arglist)
# (list 'adjoin-arg adjoin-arg)
# (list 'last-operand? last-operand?)
# (list 'no-more-exps? no-more-exps?) ;for non-tail-recursive machine
# (list 'get-global-environment get-global-environment))
eval_operations = [
("read", lambda: parse(input())),
('self-evaluating?', is_self_evaluating),
('quoted?', lambda exp: exp[0] == 'quote'),
('text-of-quotation', text_of_quotation),
]
eval_code = """
(read-eval-print-loop
(perform (op initialize-stack))
(perform
(op prompt-for-input) (const ";;; EC-Eval input:"))
(assign exp (op read))
(assign env (op get-global-environment))
(assign continue (label print-result))
(goto (label eval-dispatch))
print-result
