def test_pep():
if sys.version_info < (3, 8):
pytest.skip('No Assignment expressions in python < 3.8')
source = '''
def name(p1, p2, /, p_or_kw, *, kw): pass
def name(p1, p2=None, /, p_or_kw=None, *, kw): pass
def name(p1, p2=None, /, *, kw): pass
def name(p1, p2=None, /): pass
def name(p1, p2, /, p_or_kw): pass
def name(p1, p2, /): pass
def name(p_or_kw, *, kw): pass
def name(*, kw): pass
def standard_arg(arg):
print(arg)
def pos_only_arg(arg, /):
print(arg)
def kwd_only_arg(*, arg):
print(arg)
def combined_example(pos_only, /, standard, *, kwd_only):
print(pos_only, standard, kwd_only)
'''
expected_ast = ast.parse(source)
actual_ast = unparse(expected_ast)
compare_ast(expected_ast, ast.parse(actual_ast))
def test_match_unparse():
if sys.version_info < (3, 10):
pytest.skip('Match statement not in python < 3.10')
source = '''
match a:
case (0 as a) as b: pass
match a:
case _:pass
match a:
case 0|(0|0): pass
case (0|0)|0: pass
case 0|0|0: pass
match (lambda: a)():
case [action, obj]:pass
match a:= h:
case [action, obj]:pass
case {**rest}: pass
'''
expected_ast = ast.parse(source)
actual_ast = unparse(expected_ast)
compare_ast(expected_ast, ast.parse(actual_ast))
def assert_code(expected_ast, actual_ast):
try:
compare_ast(expected_ast, actual_ast)
except CompareError as e:
print(e)
print(unparse(actual_ast))
raise
def test_file(path):
try:
with open(path, 'rb') as f:
source = f.read()
except IOError:
pytest.skip('IOError opening file')
try:
original_ast = ast.parse(source, path)
except SyntaxError:
pytest.skip('Invalid syntax in file')
# Test unparsing
unparse(original_ast)
# Test transforms
minify(source, filename=path)
def test_pep():
if sys.version_info < (3, 9):
pytest.skip('Decorator expression not allowed in python <3.9')
source = """
buttons = [QPushButton(f'Button {i}') for i in range(10)]
# Do stuff with the list of buttons...
@buttons[0].clicked.connect
def spam():
...
@buttons[1].clicked.connect
def eggs():
...
# Do stuff with the list of buttons...
@(f, g)
def a(): pass
@(f, g)
class A:pass
@lambda func: (lambda *p: func(*p).u())
def g(n): pass
@s := lambda func: (lambda *p: func(*p).u())
def g(name): pass
@s
def r(n, t):
pass
@lambda f: lambda *p: f or f(*p).u()
def g(name): pass
@lambda f: lambda *p: \
[_ for _ in [ \
f(*p),
] if _][0]
def c(): pass
@lambda f: lambda *p: \
list(filter(lambda _: _,[
(a := t()) and False,
f(*p),
(b := t()) and False,
]))[0]
def c(): pass
"""
expected_ast = ast.parse(source)
actual_ast = unparse(expected_ast)
compare_ast(expected_ast, ast.parse(actual_ast))
def hoist(source):
module = ast.parse(source)
add_namespace(module)
bind_names(module)
resolve_names(module)
allow_rename_locals(module, False)
allow_rename_globals(module, False)
rename_literals(module)
rename(module)
print(unparse(module))
return module
def test_fstring_empty_str():
if sys.version_info < (3, 6):
pytest.skip('f-string expressions not allowed in python < 3.6')
source = r'''
f"""\
{fg_br}"""
'''
print(source)
expected_ast = ast.parse(source)
actual_ast = unparse(expected_ast)
compare_ast(expected_ast, ast.parse(actual_ast))
def test_await_fstring():
if sys.version_info < (3, 7):
pytest.skip(
'Await in f-string expressions not allowed in python < 3.7')
source = '''
async def a(): return 'hello'
async def b(): return f'{await b()}'
'''
expected_ast = ast.parse(source)
actual_ast = unparse(expected_ast)
compare_ast(expected_ast, ast.parse(actual_ast))
def test_dict_expanson():
if sys.version_info < (3, 5):
pytest.skip('dict expansion not allowed in python < 3.5')
source = [
r'{**a>>9}', r'{**(a or b)}', r'{**(a and b)}', r'{**a+b}',
r'{**(lambda a:a)}', r'{**(a<b)}', r'{**(yield a())}',
r'{**(a if a else a)}'
]
for expression in source:
expected_ast = ast.parse(expression)
minified = unparse(expected_ast)
compare_ast(expected_ast, ast.parse(minified))
assert expression == minified
def test_return():
if sys.version_info < (3, 0):
pytest.skip('Iterable unpacking in return not allowed in python < 3.0')
elif sys.version_info < (3, 8):
# Parenthesis are required
source = 'def a():return(True,*[False])'
else:
# Parenthesis not required
source = 'def a():return True,*[False]'
expected_ast = ast.parse(source)
minified = unparse(expected_ast)
compare_ast(expected_ast, ast.parse(minified))
assert source == minified
def test_pep():
if sys.version_info < (3, 8):
pytest.skip('No Assignment expressions in python < 3.8')
source = '''
if a := True:
print(a)
if self._is_special and (ans := self._check_nans(context=context)):
return ans
results = [(x, y, x/y) for x in input_data if (y := f(x)) > 0]
stuff = [[y := f(x), x/y] for x in range(5)]
'''
expected_ast = ast.parse(source)
actual_ast = unparse(expected_ast)
compare_ast(expected_ast, ast.parse(actual_ast))
def test_slice():
"""AST for slices was changed in 3.9"""
source = '''
x[name]
x[1:2]
x[1:2, 3]
x[()]
x[1:2, 2:2]
x[a, ..., b:c]
x[a, ..., b]
x[(a, b)]
x[a:b,]
'''
expected_ast = ast.parse(source)
actual_ast = unparse(expected_ast)
compare_ast(expected_ast, ast.parse(actual_ast))
def test_pep635_unparse():
if sys.version_info < (3, 10):
pytest.skip('Match statement not in python < 3.10')
source = '''
match x:
case host, port:
mode = "http"
case host, port, mode:
pass
match node:
case BinOp("+", a, BinOp("*", b, c)):
pass
match json_pet:
case {"type": "cat", "name": name, "pattern": pattern}:
return Cat(name, pattern)
case {"type": "dog", "name": name, "breed": breed}:
return Dog(name, breed)
case _:
raise ValueError("Not a suitable pet")
def sort(seq):
match seq:
case [] | [_]:
return seq
case [x, y] if x <= y:
return seq
case [x, y]:
return [y, x]
case [x, y, z] if x <= y <= z:
return seq
case [x, y, z] if x >= y >= z:
return [z, y, x]
case [p, *rest]:
a = sort([x for x in rest if x <= p])
b = sort([x for x in rest if p < x])
return a + [p] + b
def simplify_expr(tokens):
match tokens:
case [('('|'[') as l, *expr, (')'|']') as r] if (l+r) in ('()', '[]'):
return simplify_expr(expr)
case [0, ('+'|'-') as op, right]:
return UnaryOp(op, right)
case [(int() | float() as left) | Num(left), '+', (int() | float() as right) | Num(right)]:
return Num(left + right)
case [(int() | float()) as value]:
return Num(value)
def simplify(expr):
match expr:
case ('/', 0, 0):
return expr
case ('*'|'/', 0, _):
return 0
case ('+'|'-', x, 0) | ('+', 0, x) | ('*', 1, x) | ('*'|'/', x, 1):
return x
return expr
def simplify(expr):
match expr:
case ('+', 0, x):
return x
case ('+' | '-', x, 0):
return x
case ('and', True, x):
return x
case ('and', False, x):
return False
case ('or', False, x):
return x
case ('or', True, x):
return True
case ('not', ('not', x)):
return x
return expr
def average(*args):
match args:
case [x, y]: # captures the two elements of a sequence
return (x + y) / 2
case [x]: # captures the only element of a sequence
return x
case []:
return 0
case a: # captures the entire sequence
return sum(a) / len(a)
def is_closed(sequence):
match sequence:
case [_]: # any sequence with a single element
return True
case [start, *_, end]: # a sequence with at least two elements
return start == end
case _: # anything
return False
def handle_reply(reply):
match reply:
case (HttpStatus.OK, MimeType.TEXT, body):
process_text(body)
case (HttpStatus.OK, MimeType.APPL_ZIP, body):
text = deflate(body)
process_text(text)
case (HttpStatus.MOVED_PERMANENTLY, new_URI):
resend_request(new_URI)
case (HttpStatus.NOT_FOUND):
raise ResourceNotFound()
def change_red_to_blue(json_obj):
match json_obj:
case { 'color': ('red' | '#FF0000') }:
json_obj['color'] = 'blue'
case { 'children': children }:
for child in children:
change_red_to_blue(child)
'''
expected_ast = ast.parse(source)
actual_ast = unparse(expected_ast)
compare_ast(expected_ast, ast.parse(actual_ast))
def test_pep646_unparse():
if sys.version_info < (3, 10):
pytest.skip('Match statement not in python < 3.10')
source = '''
match command.split():
case [action]:
pass
case [action, obj]:
pass
match command.split():
case ["quit"]:
print("Goodbye!")
quit_game()
case ["look"]:
current_room.describe()
case ["get", obj]:
character.get(obj, current_room)
case ["go", direction]:
current_room = current_room.neighbor(direction)
match command.split():
case ["drop", *objects]:
for obj in objects:
character.drop(obj, current_room)
match command.split():
case ["quit"]: pass
case ["go", direction]: pass
case ["drop", *objects]: pass
case _:
print(f"Sorry, I couldn't understand {command!r}")
match command.split():
case ["north"] | ["go", "north"]:
current_room = current_room.neighbor("north")
case ["get", obj] | ["pick", "up", obj] | ["pick", obj, "up"]:
pass
match command.split():
case ["go", ("north" | "south" | "east" | "west")]:
current_room = current_room.neighbor(...)
match command.split():
case ["go", ("north" | "south" | "east" | "west") as direction]:
current_room = current_room.neighbor(direction)
match command.split():
case ["go", direction] if direction in current_room.exits:
current_room = current_room.neighbor(direction)
case ["go", _]:
print("Sorry, you can't go that way")
match event.get():
case Click(position=(x, y)):
handle_click_at(x, y)
case KeyPress(key_name="Q") | Quit():
game.quit()
case KeyPress(key_name="up arrow"):
game.go_north()
case KeyPress():
pass # Ignore other keystrokes
case other_event:
raise ValueError(f"Unrecognized event: {other_event}")
match event.get():
case Click((x, y)):
handle_click_at(x, y)
match event.get():
case Click((x, y), button=Button.LEFT): # This is a left click
handle_click_at(x, y)
case Click():
pass # ignore other clicks
match action:
case {"text": message, "color": c}:
ui.set_text_color(c)
ui.display(message)
case {"sleep": duration}:
ui.wait(duration)
case {"sound": url, "format": "ogg"}:
ui.play(url)
case {"sound": _, "format": _}:
warning("Unsupported audio format")
match action:
case {"text": str(message), "color": str(c)}:
ui.set_text_color(c)
ui.display(message)
case {"sleep": float(duration)}:
ui.wait(duration)
case {"sound": str(url), "format": "ogg"}:
ui.play(url)
case {"sound": _, "format": _}:
warning("Unsupported audio format")
match status:
case 400:
return "Bad request"
case 404:
return "Not found"
case 418:
return "I'm a teapot"
case 401 | 403 | 404:
return "Not allowed"
case _:
return "Something's wrong with the Internet"
match point:
case (0, 0):
print("Origin")
case (0, y):
print(f"Y={y}")
case (x, 0):
print(f"X={x}")
case (x, y):
print(f"X={x}, Y={y}")
case _:
raise ValueError("Not a point")
match point:
case Point(x=0, y=0):
print("Origin")
case Point(x=0, y=y):
print(f"Y={y}")
case Point(x=x, y=0):
print(f"X={x}")
case Point():
print("Somewhere else")
case _:
print("Not a point")
match points:
case []:
print("No points")
case [Point(0, 0)]:
print("The origin")
case [Point(x, y)]:
print(f"Single point {x}, {y}")
case [Point(0, y1), Point(0, y2)]:
print(f"Two on the Y axis at {y1}, {y2}")
case _:
print("Something else")
match point:
case Point(x, y) if x == y:
print(f"Y=X at {x}")
case Point(x, y):
print(f"Not on the diagonal")
match color:
case Color.RED:
print("I see red!")
case Color.GREEN:
print("Grass is green")
case Color.BLUE:
print("I'm feeling the blues :(")
'''
expected_ast = ast.parse(source)
actual_ast = unparse(expected_ast)
compare_ast(expected_ast, ast.parse(actual_ast))
