def assert_exp_length(ast, length):
if len(ast) > length:
msg = "Malformed %s, too many arguments: %s" % (ast[0], unparse(ast))
raise LispError(msg)
elif len(ast) < length:
msg = "Malformed %s, too few arguments: %s" % (ast[0], unparse(ast))
raise LispError(msg)
def assert_exp_length(ast, length):
if len(ast) > length:
msg = "Malformed %s, too many arguments: %s" % (ast[0], unparse(ast))
raise LispError(msg)
elif len(ast) < length:
msg = "Malformed %s, too few arguments: %s" % (ast[0], unparse(ast))
raise LispError(msg)
def unparse(ast):
"""Turns an AST back into lisp program source"""
if is_boolean(ast):
return "#t" if ast else "#f"
elif is_list(ast):
if len(ast) > 0 and ast[0] == "quote":
return "'%s" % unparse(ast[1])
else:
return "(%s)" % " ".join([unparse(x) for x in ast])
else:
# integers or symbols (or lambdas)
return str(ast)
def unparse(ast):
"""Turns an AST back into lisp program source"""
if is_boolean(ast):
return "#t" if ast else "#f"
elif is_list(ast):
if len(ast) > 0 and ast[0] == "quote":
return "'%s" % unparse(ast[1])
else:
return "(%s)" % " ".join([unparse(x) for x in ast])
else:
# integers or symbols (or lambdas)
return str(ast)
def interpret(source, env=None):
"""
Interpret a lisp program statement
Accepts a program statement as a string, interprets it, and then
returns the resulting lisp expression as string.
"""
if env is None:
env = Environment()
return unparse(evaluate(parse(source), env))
def interpret(source, env=None):
"""
Interpret a lisp program statement
Accepts a program statement as a string, interprets it, and then
returns the resulting lisp expression as string.
"""
if env is None:
env = Environment()
return unparse(evaluate(parse(source), env))
def interpret_file(filename, env=None):
"""
Interpret a lisp file
Accepts the name of a lisp file containing a series of statements.
Returns the value of the last expression of the file.
"""
if env is None:
env = Environment()
with open(filename, 'r') as sourcefile:
source = "".join(sourcefile.readlines())
asts = parse_multiple(source)
results = [evaluate(ast, env) for ast in asts]
return unparse(results[-1])
def interpret_file(filename, env=None):
"""
Interpret a lisp file
Accepts the name of a lisp file containing a series of statements.
Returns the value of the last expression of the file.
"""
if env is None:
env = Environment()
with open(filename, 'r') as sourcefile:
source = "".join(sourcefile.readlines())
asts = parse_multiple(source)
results = [evaluate(ast, env) for ast in asts]
return unparse(results[-1])
def test_unparse_quotes():
assert_equals("'foo", unparse(["quote", "foo"]))
assert_equals("'(1 2 3)",
unparse(["quote", [1, 2, 3]]))
def test_unparse_list():
assert_equals("(1 2 3)", unparse([1, 2, 3]))
assert_equals("(if #t 42 #f)",
unparse(["if", True, 42, False]))
def test_unparse_symbol():
assert_equals("+", unparse("+"))
assert_equals("foo", unparse("foo"))
assert_equals("lambda", unparse("lambda"))
def test_unparse_int():
assert_equals("1", unparse(1))
assert_equals("1337", unparse(1337))
assert_equals("-42", unparse(-42))
def test_unparse_other_quotes():
assert_equals("'foo", unparse(["quote", "foo"]))
assert_equals("'(1 2 3)", unparse(["quote", [1, 2, 3]]))
def test_unparse_symbol():
assert_equals("+", unparse("+"))
assert_equals("foo", unparse("foo"))
assert_equals("lambda", unparse("lambda"))
def test_unparse_bool():
assert_equals("#t", unparse(True))
assert_equals("#f", unparse(False))
def test_unparse_list():
assert_equals("((foo bar) baz)", unparse([["foo", "bar"], "baz"]))
def test_unparse_empty_list():
assert_equals("()", unparse([]))
def test_expand_crazy_quote_combo():
"""One final test to see that quote expansion works."""
source = "'(this ''''(makes ''no) 'sense)"
assert_equals(source, unparse(parse(source)))
def assert_boolean(p, exp=None):
if not is_boolean(p):
msg = "Boolean required, got '%s'. " % unparse(p)
if exp is not None:
msg += "Offending expression: %s" % unparse(exp)
raise LispTypeError(msg)
def assert_boolean(p, exp=None):
if not is_boolean(p):
msg = "Boolean required, got '%s'. " % unparse(p)
if exp is not None:
msg += "Offending expression: %s" % unparse(exp)
raise LispTypeError(msg)
def test_unparse_atoms():
assert_equals("123", unparse(123))
assert_equals("#t", unparse(True))
assert_equals("#f", unparse(False))
assert_equals("foo", unparse("foo"))
def test_expand_crazy_quote_combo():
"""One final test to see that quote expansion works."""
source = "'(this ''''(makes ''no) 'sense)"
assert_equals(source, unparse(parse(source)))
def test_unparse_quotes():
assert_equals(
"''(foo 'bar '(1 2))",
unparse(
["quote", ["quote", ["foo", ["quote", "bar"], ["quote", [1,
2]]]]]))
def test_unparse_atoms():
assert_equals("123", unparse(123))
assert_equals("#t", unparse(True))
assert_equals("#f", unparse(False))
assert_equals("foo", unparse("foo"))
def test_unparse_int():
assert_equals("1", unparse(1))
assert_equals("1337", unparse(1337))
assert_equals("-42", unparse(-42))
def test_unparse_list():
assert_equals("((foo bar) baz)", unparse([["foo", "bar"], "baz"]))
def test_unparse_another_list():
assert_equals("(1 2 3)", unparse([1, 2, 3]))
assert_equals("(if #t 42 #f)", unparse(["if", True, 42, False]))
def test_unparse_quotes():
assert_equals("''(foo 'bar '(1 2))", unparse(
["quote", ["quote", ["foo", ["quote", "bar"], ["quote", [1, 2]]]]]))
def test_unparse_empty_list():
assert_equals("()", unparse([]))
def test_unparse_bool():
assert_equals("#t", unparse(True))
assert_equals("#f", unparse(False))