def _js_let(ast: LetAst) -> str:
if not ast.vardefs:
return _to_js(ast.body)
# immediately invoked function expression
iife = CallAst(
LambdaAst('', [ast.vardefs[0].name], LetAst(ast.vardefs[1:],
ast.body)),
[ast.vardefs[0].define or LiteralAst(False)])
return f'({_to_js(iife)})'
def _cps_let(let_ast: LetAst, k: Callable[[Ast], Ast]) -> Ast:
if not let_ast.vardefs:
return to_cps(let_ast.body, k)
return to_cps(
CallAst(
LambdaAst('', [let_ast.vardefs[0].name],
LetAst(let_ast.vardefs[1:], let_ast.body)), [
let_ast.vardefs[0].define
if let_ast.vardefs[0].define else LiteralAst(False)
]), k)
def test__cps_let(self):
# let_ast = LetAst(
# [VarDefAst('a', LiteralAst(1)), VarDefAst('b', LiteralAst("a"))],
# LiteralAst(False))
let_ast = LetAst(
[],
LiteralAst(False),
)
cps_ast = _cps_let(let_ast, lambda x: x)
self.assertEqual(cps_ast, LiteralAst(False))
let_ast = LetAst([VarDefAst('a', LiteralAst(1))], VarAst('a'))
cps_ast = _cps_let(let_ast, lambda x: x)
self.assertEqual(
cps_ast,
CallAst(
LambdaAst(
'', [cps_ast.func.params[0], 'a'],
CallAst(VarAst(cps_ast.func.params[0]), [VarAst('a')])), [
LambdaAst('', [cps_ast.args[0].params[0]],
VarAst(cps_ast.args[0].params[0])),
LiteralAst(1)
]))
def test_to_cps(self):
js_raw_ast = JsAst("aa")
cps_ast = _cps_js_raw(js_raw_ast, lambda x: x)
self.assertEqual(cps_ast, js_raw_ast)
atom_ast = LiteralAst(1.0)
cps_ast = to_cps(atom_ast, lambda x: x)
self.assertEqual(atom_ast, cps_ast)
let_ast = LetAst([], LiteralAst(False))
cps_ast = to_cps(let_ast, lambda x: x)
self.assertEqual(cps_ast, LiteralAst(False))
prog_ast = ProgAst([])
cps_ast = to_cps(prog_ast, lambda x: x)
self.assertEqual(cps_ast, LiteralAst(False))
prog_ast = ProgAst([LiteralAst(1)])
cps_ast = to_cps(prog_ast, lambda x: x)
self.assertEqual(cps_ast, LiteralAst(1))
prog_ast = ProgAst([LiteralAst(1), LiteralAst(2)])
cps_ast = to_cps(prog_ast, lambda x: x)
self.assertEqual(cps_ast, ProgAst([LiteralAst(1), LiteralAst(2)]))
if_ast = IfAst(LiteralAst(1), LiteralAst(2), LiteralAst(3))
cps_ast: CallAst = to_cps(if_ast, lambda x: x)
expected_ast = CallAst(
LambdaAst(
'', cps_ast.func.params,
IfAst(LiteralAst(1),
CallAst(VarAst(cps_ast.func.params[0]), [LiteralAst(2)]),
CallAst(VarAst(cps_ast.func.params[0]),
[LiteralAst(3)]))), [
LambdaAst('', cps_ast.args[0].params,
VarAst(cps_ast.args[0].params[0]))
])
self.assertEqual(cps_ast, expected_ast)
lambda_ast = LambdaAst('', ['x', 'y'], LiteralAst(1))
cps_ast = to_cps(lambda_ast, lambda x: x)
expected_ast = LambdaAst(
'', [cps_ast.params[0]] + ['x', 'y'],
CallAst(VarAst(cps_ast.params[0]), [LiteralAst(1)]))
self.assertEqual(cps_ast, expected_ast)
binary_ast = BinaryAst('+', LiteralAst(1), LiteralAst(2))
cps_ast = to_cps(binary_ast, lambda x: x)
self.assertEqual(cps_ast, binary_ast)
parse = Parser(TokenStream(InputStream("a = foo(10);")))
cps_ast = to_cps(parse(), lambda x: x)
expected_ast = CallAst(VarAst('foo'), [
LambdaAst(
'', [cps_ast.args[0].params[0]],
AssignAst(VarAst('a'), VarAst(cps_ast.args[0].params[0]))),
LiteralAst(10)
])
self.assertEqual(cps_ast, expected_ast)
def _parse_let(self) -> Union[CallAst, LetAst]:
"""
When it is a named let, if an arg is not followed by some expression,
then a false value is assigned to the arg by the parser.
:return:
"""
self._skip_kw('let')
if self._token_stream.peek().type == 'var':
name = self._token_stream.next().value
vardefs = self._delimited('(', ')', ',', self._parse_vardef)
varnames = [vardef.name for vardef in vardefs]
defines = [vardef.define if vardef.define else LiteralAst(False)
for vardef in vardefs]
return CallAst(
LambdaAst(
name,
varnames,
self._parse_expression()),
defines)
vardefs = self._delimited('(', ')', ',', self._parse_vardef)
body = self._parse_expression()
return LetAst(vardefs, body)
def test_evaluate(self):
ast = LiteralAst(1.0)
environment = Environment()
evaluate(ast, environment, lambda value: self.assertEqual(value, 1.0))
ast = LiteralAst(True)
environment = Environment()
evaluate(ast, environment, self.assertTrue)
ast = LiteralAst(False)
environment = Environment()
evaluate(ast, environment, self.assertFalse)
ast = LiteralAst("aaa")
evaluate(ast, Environment(),
lambda value: self.assertEqual(value, "aaa"))
ast = BinaryAst('+', LiteralAst(1), LiteralAst(2))
evaluate(ast, Environment(),
lambda value: self.assertEqual(value, 3.0))
ast = ProgAst([])
evaluate(ast, Environment(), self.assertFalse)
ast = ProgAst([LiteralAst(1)])
evaluate(ast, Environment(),
lambda value: self.assertEqual(value, 1.0))
ast = ProgAst([LiteralAst(1), LiteralAst(2)])
evaluate(ast, Environment(),
lambda value: self.assertEqual(value, 2.0))
ast = AssignAst(LiteralAst(1), LiteralAst("a"))
with self.assertRaises(Exception):
evaluate(ast, Environment(), lambda value: value)
ast = ProgAst([AssignAst(VarAst('a'), LiteralAst("foo")), VarAst('a')])
evaluate(ast, Environment(),
lambda value: self.assertEqual(value, "foo"))
ast = AssignAst(VarAst("a"), LiteralAst("foo"))
with self.assertRaises(Exception):
evaluate(ast, Environment(Environment()), lambda value: value)
ast = CallAst(
LambdaAst("", ["a"], VarAst("a")),
[LiteralAst(1)],
)
evaluate(ast, Environment(),
lambda value: self.assertEqual(value, 1.0))
ast = CallAst(LambdaAst("", ["a"], VarAst("a")), [LiteralAst("abc")])
evaluate(ast, Environment(),
lambda value: self.assertEqual(value, "abc"))
# # (λ loop (n) if n > 0 then n + loop(n - 1) else 0) (10)
ast = CallAst(
LambdaAst(
"loop", ["n"],
IfAst(
BinaryAst(">", VarAst("n"), LiteralAst(0)),
BinaryAst(
"+", VarAst("n"),
CallAst(VarAst("loop"),
[BinaryAst('-', VarAst('n'), LiteralAst(1))])),
LiteralAst(0))), [LiteralAst(10)])
evaluate(ast, Environment(),
lambda value: self.assertEqual(value, 55.0))
# # let (x) x;
ast = LetAst([VarDefAst("x", None)], VarAst("x"))
evaluate(ast, Environment(), self.assertFalse)
# # let (x = 2, y = x + 1, z = x + y) x + y + z
ast = LetAst([
VarDefAst("x", LiteralAst(2)),
VarDefAst("y", BinaryAst("+", VarAst("x"), LiteralAst(1))),
VarDefAst("z", BinaryAst("+", VarAst("x"), VarAst("y")))
], BinaryAst("+", BinaryAst("+", VarAst("x"), VarAst("y")),
VarAst("z")))
evaluate(ast, Environment(),
lambda value: self.assertEqual(value, 10.0))
# # the second expression will result an errors,
# since x, y, z are bound to the let body
# # let (x = 2, y = x + 1, z = x + y) x + y + z; x + y + z
ast = ProgAst([
LetAst([
VarDefAst('x', LiteralAst(2)),
VarDefAst('y', BinaryAst('+', VarAst('x'), LiteralAst(1))),
VarDefAst('z', BinaryAst('+', VarAst('x'), VarAst('y')))
],
BinaryAst('+', BinaryAst('+', VarAst('x'), VarAst('y')),
VarAst('z'))),
BinaryAst('+', BinaryAst('+', VarAst('x'), VarAst('y')),
VarAst('z'))
])
with self.assertRaises(Exception):
evaluate(ast, Environment(), lambda value: value)
ast = IfAst(LiteralAst(""), LiteralAst(1), None)
evaluate(ast, Environment(),
lambda value: self.assertEqual(value, 1.0))
ast = IfAst(LiteralAst(False), LiteralAst(1), LiteralAst(2))
evaluate(ast, Environment(),
lambda value: self.assertEqual(value, 2.0))
ast = IfAst(LiteralAst(False), LiteralAst(1), LiteralAst(False))
evaluate(ast, Environment(), self.assertFalse)
ast = {"type": "foo", "value": 'foo'}
with self.assertRaises(Exception):
evaluate(ast, Environment(), lambda value: value)
# fib = λ(n) if n < 2 then n else fib(n - 1) + fib(n - 2);
# fib(6);
#
ast = ProgAst([
AssignAst(
VarAst('fib'),
LambdaAst(
'n', ['n'],
IfAst(
BinaryAst('<', VarAst('n'), LiteralAst(2)),
VarAst('n'),
BinaryAst(
'+',
CallAst(
VarAst('fib'),
[BinaryAst('-', VarAst('n'), LiteralAst(1))]),
CallAst(
VarAst('fib'),
[BinaryAst('-', VarAst('n'), LiteralAst(2))
]))))),
CallAst(VarAst('fib'), [LiteralAst(6)])
])
evaluate(ast, Environment(),
lambda value: self.assertEqual(value, 8.0))
ast = IfAst(LiteralAst(False), LiteralAst(1), LiteralAst(False))
evaluate(ast, Environment(), self.assertFalse)
ast = CallAst(LiteralAst(1), [])
with self.assertRaises(Exception):
evaluate(ast, Environment(), self.assertFalse)
code = """
2 + twice(3, 4)
"""
global_env = Environment()
for name, func in primitive.items():
global_env.define(name, func)
parser = Parser(TokenStream(InputStream(code)))
evaluate(parser(), global_env, lambda result: result)
def test_evaluate(self):
ast = LiteralAst(1.0)
environment = Environment()
self.assertEqual(evaluate(ast, environment), 1.0)
ast = LiteralAst(True)
environment = Environment()
self.assertEqual(evaluate(ast, environment), True)
ast = LiteralAst(False)
environment = Environment()
self.assertEqual(evaluate(ast, environment), False)
ast = LiteralAst("aaa")
self.assertEqual(evaluate(ast, Environment()), "aaa")
ast = BinaryAst('+', LiteralAst(1), LiteralAst(2))
self.assertEqual(evaluate(ast, Environment()), 3.0)
ast = ProgAst([])
self.assertEqual(evaluate(ast, Environment()), False)
ast = ProgAst([LiteralAst(1)])
self.assertEqual(evaluate(ast, Environment()), 1.0)
ast = ProgAst([LiteralAst(1), LiteralAst(2)])
self.assertEqual(evaluate(ast, Environment()), 2.0)
ast = AssignAst(LiteralAst(1), LiteralAst("a"))
with self.assertRaises(Exception):
evaluate(ast, Environment())
ast = ProgAst([AssignAst(VarAst('a'), LiteralAst("foo")), VarAst('a')])
self.assertEqual(evaluate(ast, Environment()), "foo")
ast = AssignAst(VarAst("a"), LiteralAst("foo"))
with self.assertRaises(Exception):
evaluate(ast, Environment(Environment()))
ast = CallAst(
LambdaAst("", ["a"], VarAst("a")),
[LiteralAst(1)],
)
self.assertEqual(evaluate(ast, Environment()), 1.0)
ast = CallAst(
LambdaAst("", ["a"], VarAst("a")),
[LiteralAst("abc")],
)
self.assertEqual(evaluate(ast, Environment()), "abc")
# (λ loop (n) if n > 0 then n + loop(n - 1) else 0) (10)
ast = CallAst(
LambdaAst(
"loop",
["n"],
IfAst(
BinaryAst(">", VarAst("n"), LiteralAst(0)),
BinaryAst(
"+", VarAst("n"),
CallAst(VarAst("loop"),
[BinaryAst('-', VarAst('n'), LiteralAst(1))])),
LiteralAst(0),
),
), [LiteralAst(10)])
self.assertEqual(evaluate(ast, Environment()), 55.0)
# let (x) x;
ast = LetAst([VarDefAst("x", None)], VarAst("x"))
self.assertEqual(evaluate(ast, Environment()), False)
# let (x = 2, y = x + 1, z = x + y) x + y + z
ast = LetAst([
VarDefAst("x", LiteralAst(2)),
VarDefAst("y", BinaryAst("+", VarAst("x"), LiteralAst(1))),
VarDefAst("z", BinaryAst("+", VarAst("x"), VarAst("y"))),
],
BinaryAst(
"+",
BinaryAst("+", VarAst("x"), VarAst("y")),
VarAst("z"),
))
self.assertEqual(evaluate(ast, Environment()), 10.0)
# the second expression will result an errors,
# since x, y, z are bound to the let body
# let (x = 2, y = x + 1, z = x + y) x + y + z; x + y + z
ast = ProgAst([
LetAst(
[
VarDefAst('x', LiteralAst(2)),
VarDefAst('y', BinaryAst('+', VarAst('x'), LiteralAst(1))),
VarDefAst('z', BinaryAst('+', VarAst('x'), VarAst('y'))),
],
BinaryAst(
'+',
BinaryAst('+', VarAst('x'), VarAst('y')),
VarAst('z'),
),
),
BinaryAst(
'+',
BinaryAst('+', VarAst('x'), VarAst('y')),
VarAst('z'),
),
])
with self.assertRaises(Exception):
evaluate(ast, Environment())
ast = IfAst(
LiteralAst(""),
LiteralAst(1),
None,
)
self.assertEqual(evaluate(ast, Environment()), 1.0)
ast = IfAst(
LiteralAst(False),
LiteralAst(1),
LiteralAst(2),
)
self.assertEqual(evaluate(ast, Environment()), 2.0)
ast = IfAst(
LiteralAst(False),
LiteralAst(1),
LiteralAst(False),
)
self.assertEqual(evaluate(ast, Environment()), False)
ast = {"type": "foo", "value": 'foo'}
with self.assertRaises(Exception):
evaluate(ast, Environment())