diff options
Diffstat (limited to 'Lib/shelve.py')
| -rw-r--r-- | Lib/shelve.py | 64 |
1 files changed, 38 insertions, 26 deletions
diff --git a/Lib/shelve.py b/Lib/shelve.py index b53dc8b7a8e..1010be1e09d 100644 --- a/Lib/shelve.py +++ b/Lib/shelve.py @@ -56,12 +56,17 @@ entries in the cache, and empty the cache (d.sync() also synchronizes the persistent dictionary on disk, if feasible). """ -from pickle import DEFAULT_PROTOCOL, Pickler, Unpickler +from pickle import DEFAULT_PROTOCOL, dumps, loads from io import BytesIO import collections.abc -__all__ = ["Shelf", "BsdDbShelf", "DbfilenameShelf", "open"] +__all__ = ["ShelveError", "Shelf", "BsdDbShelf", "DbfilenameShelf", "open"] + + +class ShelveError(Exception): + pass + class _ClosedDict(collections.abc.MutableMapping): 'Marker for a closed dict. Access attempts raise a ValueError.' @@ -82,7 +87,7 @@ class Shelf(collections.abc.MutableMapping): """ def __init__(self, dict, protocol=None, writeback=False, - keyencoding="utf-8"): + keyencoding="utf-8", *, serializer=None, deserializer=None): self.dict = dict if protocol is None: protocol = DEFAULT_PROTOCOL @@ -91,6 +96,16 @@ class Shelf(collections.abc.MutableMapping): self.cache = {} self.keyencoding = keyencoding + if serializer is None and deserializer is None: + self.serializer = dumps + self.deserializer = loads + elif (serializer is None) ^ (deserializer is None): + raise ShelveError("serializer and deserializer must be " + "defined together") + else: + self.serializer = serializer + self.deserializer = deserializer + def __iter__(self): for k in self.dict.keys(): yield k.decode(self.keyencoding) @@ -110,8 +125,8 @@ class Shelf(collections.abc.MutableMapping): try: value = self.cache[key] except KeyError: - f = BytesIO(self.dict[key.encode(self.keyencoding)]) - value = Unpickler(f).load() + f = self.dict[key.encode(self.keyencoding)] + value = self.deserializer(f) if self.writeback: self.cache[key] = value return value @@ -119,10 +134,8 @@ class Shelf(collections.abc.MutableMapping): def __setitem__(self, key, value): if self.writeback: self.cache[key] = value - f = BytesIO() - p = Pickler(f, self._protocol) - p.dump(value) - self.dict[key.encode(self.keyencoding)] = f.getvalue() + serialized_value = self.serializer(value, self._protocol) + self.dict[key.encode(self.keyencoding)] = serialized_value def __delitem__(self, key): del self.dict[key.encode(self.keyencoding)] @@ -191,33 +204,29 @@ class BsdDbShelf(Shelf): """ def __init__(self, dict, protocol=None, writeback=False, - keyencoding="utf-8"): - Shelf.__init__(self, dict, protocol, writeback, keyencoding) + keyencoding="utf-8", *, serializer=None, deserializer=None): + Shelf.__init__(self, dict, protocol, writeback, keyencoding, + serializer=serializer, deserializer=deserializer) def set_location(self, key): (key, value) = self.dict.set_location(key) - f = BytesIO(value) - return (key.decode(self.keyencoding), Unpickler(f).load()) + return (key.decode(self.keyencoding), self.deserializer(value)) def next(self): (key, value) = next(self.dict) - f = BytesIO(value) - return (key.decode(self.keyencoding), Unpickler(f).load()) + return (key.decode(self.keyencoding), self.deserializer(value)) def previous(self): (key, value) = self.dict.previous() - f = BytesIO(value) - return (key.decode(self.keyencoding), Unpickler(f).load()) + return (key.decode(self.keyencoding), self.deserializer(value)) def first(self): (key, value) = self.dict.first() - f = BytesIO(value) - return (key.decode(self.keyencoding), Unpickler(f).load()) + return (key.decode(self.keyencoding), self.deserializer(value)) def last(self): (key, value) = self.dict.last() - f = BytesIO(value) - return (key.decode(self.keyencoding), Unpickler(f).load()) + return (key.decode(self.keyencoding), self.deserializer(value)) class DbfilenameShelf(Shelf): @@ -227,9 +236,11 @@ class DbfilenameShelf(Shelf): See the module's __doc__ string for an overview of the interface. """ - def __init__(self, filename, flag='c', protocol=None, writeback=False): + def __init__(self, filename, flag='c', protocol=None, writeback=False, *, + serializer=None, deserializer=None): import dbm - Shelf.__init__(self, dbm.open(filename, flag), protocol, writeback) + Shelf.__init__(self, dbm.open(filename, flag), protocol, writeback, + serializer=serializer, deserializer=deserializer) def clear(self): """Remove all items from the shelf.""" @@ -238,8 +249,8 @@ class DbfilenameShelf(Shelf): self.cache.clear() self.dict.clear() - -def open(filename, flag='c', protocol=None, writeback=False): +def open(filename, flag='c', protocol=None, writeback=False, *, + serializer=None, deserializer=None): """Open a persistent dictionary for reading and writing. The filename parameter is the base filename for the underlying @@ -252,4 +263,5 @@ def open(filename, flag='c', protocol=None, writeback=False): See the module's __doc__ string for an overview of the interface. """ - return DbfilenameShelf(filename, flag, protocol, writeback) + return DbfilenameShelf(filename, flag, protocol, writeback, + serializer=serializer, deserializer=deserializer) |