| """Helper to provide extensibility for pickle/cPickle. | |
| This is only useful to add pickle support for extension types defined in | |
| C, not for instances of user-defined classes. | |
| """ | |
| from types import ClassType as _ClassType | |
| __all__ = ["pickle", "constructor", | |
| "add_extension", "remove_extension", "clear_extension_cache"] | |
| dispatch_table = {} | |
| def pickle(ob_type, pickle_function, constructor_ob=None): | |
| if type(ob_type) is _ClassType: | |
| raise TypeError("copy_reg is not intended for use with classes") | |
| if not hasattr(pickle_function, '__call__'): | |
| raise TypeError("reduction functions must be callable") | |
| dispatch_table[ob_type] = pickle_function | |
| # The constructor_ob function is a vestige of safe for unpickling. | |
| # There is no reason for the caller to pass it anymore. | |
| if constructor_ob is not None: | |
| constructor(constructor_ob) | |
| def constructor(object): | |
| if not hasattr(object, '__call__'): | |
| raise TypeError("constructors must be callable") | |
| # Example: provide pickling support for complex numbers. | |
| try: | |
| complex | |
| except NameError: | |
| pass | |
| else: | |
| def pickle_complex(c): | |
| return complex, (c.real, c.imag) | |
| pickle(complex, pickle_complex, complex) | |
| # Support for pickling new-style objects | |
| def _reconstructor(cls, base, state): | |
| if base is object: | |
| obj = object.__new__(cls) | |
| else: | |
| obj = base.__new__(cls, state) | |
| if base.__init__ != object.__init__: | |
| base.__init__(obj, state) | |
| return obj | |
| _HEAPTYPE = 1<<9 | |
| # Python code for object.__reduce_ex__ for protocols 0 and 1 | |
| def _reduce_ex(self, proto): | |
| assert proto < 2 | |
| for base in self.__class__.__mro__: | |
| if hasattr(base, '__flags__') and not base.__flags__ & _HEAPTYPE: | |
| break | |
| else: | |
| base = object # not really reachable | |
| if base is object: | |
| state = None | |
| else: | |
| if base is self.__class__: | |
| raise TypeError, "can't pickle %s objects" % base.__name__ | |
| state = base(self) | |
| args = (self.__class__, base, state) | |
| try: | |
| getstate = self.__getstate__ | |
| except AttributeError: | |
| if getattr(self, "__slots__", None): | |
| raise TypeError("a class that defines __slots__ without " | |
| "defining __getstate__ cannot be pickled") | |
| try: | |
| dict = self.__dict__ | |
| except AttributeError: | |
| dict = None | |
| else: | |
| dict = getstate() | |
| if dict: | |
| return _reconstructor, args, dict | |
| else: | |
| return _reconstructor, args | |
| # Helper for __reduce_ex__ protocol 2 | |
| def __newobj__(cls, *args): | |
| return cls.__new__(cls, *args) | |
| def _slotnames(cls): | |
| """Return a list of slot names for a given class. | |
| This needs to find slots defined by the class and its bases, so we | |
| can't simply return the __slots__ attribute. We must walk down | |
| the Method Resolution Order and concatenate the __slots__ of each | |
| class found there. (This assumes classes don't modify their | |
| __slots__ attribute to misrepresent their slots after the class is | |
| defined.) | |
| """ | |
| # Get the value from a cache in the class if possible | |
| names = cls.__dict__.get("__slotnames__") | |
| if names is not None: | |
| return names | |
| # Not cached -- calculate the value | |
| names = [] | |
| if not hasattr(cls, "__slots__"): | |
| # This class has no slots | |
| pass | |
| else: | |
| # Slots found -- gather slot names from all base classes | |
| for c in cls.__mro__: | |
| if "__slots__" in c.__dict__: | |
| slots = c.__dict__['__slots__'] | |
| # if class has a single slot, it can be given as a string | |
| if isinstance(slots, basestring): | |
| slots = (slots,) | |
| for name in slots: | |
| # special descriptors | |
| if name in ("__dict__", "__weakref__"): | |
| continue | |
| # mangled names | |
| elif name.startswith('__') and not name.endswith('__'): | |
| names.append('_%s%s' % (c.__name__, name)) | |
| else: | |
| names.append(name) | |
| # Cache the outcome in the class if at all possible | |
| try: | |
| cls.__slotnames__ = names | |
| except: | |
| pass # But don't die if we can't | |
| return names | |
| # A registry of extension codes. This is an ad-hoc compression | |
| # mechanism. Whenever a global reference to <module>, <name> is about | |
| # to be pickled, the (<module>, <name>) tuple is looked up here to see | |
| # if it is a registered extension code for it. Extension codes are | |
| # universal, so that the meaning of a pickle does not depend on | |
| # context. (There are also some codes reserved for local use that | |
| # don't have this restriction.) Codes are positive ints; 0 is | |
| # reserved. | |
| _extension_registry = {} # key -> code | |
| _inverted_registry = {} # code -> key | |
| _extension_cache = {} # code -> object | |
| # Don't ever rebind those names: cPickle grabs a reference to them when | |
| # it's initialized, and won't see a rebinding. | |
| def add_extension(module, name, code): | |
| """Register an extension code.""" | |
| code = int(code) | |
| if not 1 <= code <= 0x7fffffff: | |
| raise ValueError, "code out of range" | |
| key = (module, name) | |
| if (_extension_registry.get(key) == code and | |
| _inverted_registry.get(code) == key): | |
| return # Redundant registrations are benign | |
| if key in _extension_registry: | |
| raise ValueError("key %s is already registered with code %s" % | |
| (key, _extension_registry[key])) | |
| if code in _inverted_registry: | |
| raise ValueError("code %s is already in use for key %s" % | |
| (code, _inverted_registry[code])) | |
| _extension_registry[key] = code | |
| _inverted_registry[code] = key | |
| def remove_extension(module, name, code): | |
| """Unregister an extension code. For testing only.""" | |
| key = (module, name) | |
| if (_extension_registry.get(key) != code or | |
| _inverted_registry.get(code) != key): | |
| raise ValueError("key %s is not registered with code %s" % | |
| (key, code)) | |
| del _extension_registry[key] | |
| del _inverted_registry[code] | |
| if code in _extension_cache: | |
| del _extension_cache[code] | |
| def clear_extension_cache(): | |
| _extension_cache.clear() | |
| # Standard extension code assignments | |
| # Reserved ranges | |
| # First Last Count Purpose | |
| # 1 127 127 Reserved for Python standard library | |
| # 128 191 64 Reserved for Zope | |
| # 192 239 48 Reserved for 3rd parties | |
| # 240 255 16 Reserved for private use (will never be assigned) | |
| # 256 Inf Inf Reserved for future assignment | |
| # Extension codes are assigned by the Python Software Foundation. |