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53e6db90 DC |
1 | """ A universal module with functions / classes without dependencies. """ |
2 | import functools | |
3 | import re | |
4 | import os | |
5 | ||
6 | ||
7 | _sep = os.path.sep | |
8 | if os.path.altsep is not None: | |
9 | _sep += os.path.altsep | |
10 | _path_re = re.compile(r'(?:\.[^{0}]+|[{0}]__init__\.py)$'.format(re.escape(_sep))) | |
11 | del _sep | |
12 | ||
13 | ||
14 | def to_list(func): | |
15 | def wrapper(*args, **kwargs): | |
16 | return list(func(*args, **kwargs)) | |
17 | return wrapper | |
18 | ||
19 | ||
20 | def to_tuple(func): | |
21 | def wrapper(*args, **kwargs): | |
22 | return tuple(func(*args, **kwargs)) | |
23 | return wrapper | |
24 | ||
25 | ||
26 | def unite(iterable): | |
27 | """Turns a two dimensional array into a one dimensional.""" | |
28 | return set(typ for types in iterable for typ in types) | |
29 | ||
30 | ||
31 | class UncaughtAttributeError(Exception): | |
32 | """ | |
33 | Important, because `__getattr__` and `hasattr` catch AttributeErrors | |
34 | implicitly. This is really evil (mainly because of `__getattr__`). | |
35 | Therefore this class originally had to be derived from `BaseException` | |
36 | instead of `Exception`. But because I removed relevant `hasattr` from | |
37 | the code base, we can now switch back to `Exception`. | |
38 | ||
39 | :param base: return values of sys.exc_info(). | |
40 | """ | |
41 | ||
42 | ||
43 | def safe_property(func): | |
44 | return property(reraise_uncaught(func)) | |
45 | ||
46 | ||
47 | def reraise_uncaught(func): | |
48 | """ | |
49 | Re-throw uncaught `AttributeError`. | |
50 | ||
51 | Usage: Put ``@rethrow_uncaught`` in front of the function | |
52 | which does **not** suppose to raise `AttributeError`. | |
53 | ||
54 | AttributeError is easily get caught by `hasattr` and another | |
55 | ``except AttributeError`` clause. This becomes problem when you use | |
56 | a lot of "dynamic" attributes (e.g., using ``@property``) because you | |
57 | can't distinguish if the property does not exist for real or some code | |
58 | inside of the "dynamic" attribute through that error. In a well | |
59 | written code, such error should not exist but getting there is very | |
60 | difficult. This decorator is to help us getting there by changing | |
61 | `AttributeError` to `UncaughtAttributeError` to avoid unexpected catch. | |
62 | This helps us noticing bugs earlier and facilitates debugging. | |
63 | """ | |
64 | @functools.wraps(func) | |
65 | def wrapper(*args, **kwds): | |
66 | try: | |
67 | return func(*args, **kwds) | |
68 | except AttributeError as e: | |
69 | raise UncaughtAttributeError(e) from e | |
70 | return wrapper | |
71 | ||
72 | ||
73 | class PushBackIterator: | |
74 | def __init__(self, iterator): | |
75 | self.pushes = [] | |
76 | self.iterator = iterator | |
77 | self.current = None | |
78 | ||
79 | def push_back(self, value): | |
80 | self.pushes.append(value) | |
81 | ||
82 | def __iter__(self): | |
83 | return self | |
84 | ||
85 | def __next__(self): | |
86 | if self.pushes: | |
87 | self.current = self.pushes.pop() | |
88 | else: | |
89 | self.current = next(self.iterator) | |
90 | return self.current |