django.utils.datastructures 源代码
import copy
from collections import OrderedDict
class OrderedSet:
"""
A set which keeps the ordering of the inserted items.
Currently backs onto OrderedDict.
"""
def __init__(self, iterable=None):
self.dict = OrderedDict.fromkeys(iterable or ())
def add(self, item):
self.dict[item] = None
def remove(self, item):
del self.dict[item]
def discard(self, item):
try:
self.remove(item)
except KeyError:
pass
def __iter__(self):
return iter(self.dict)
def __contains__(self, item):
return item in self.dict
def __bool__(self):
return bool(self.dict)
def __len__(self):
return len(self.dict)
class MultiValueDictKeyError(KeyError):
pass
class MultiValueDict(dict):
"""
A subclass of dictionary customized to handle multiple values for the
same key.
>>> d = MultiValueDict({'name': ['Adrian', 'Simon'], 'position': ['Developer']})
>>> d['name']
'Simon'
>>> d.getlist('name')
['Adrian', 'Simon']
>>> d.getlist('doesnotexist')
[]
>>> d.getlist('doesnotexist', ['Adrian', 'Simon'])
['Adrian', 'Simon']
>>> d.get('lastname', 'nonexistent')
'nonexistent'
>>> d.setlist('lastname', ['Holovaty', 'Willison'])
This class exists to solve the irritating problem raised by cgi.parse_qs,
which returns a list for every key, even though most Web forms submit
single name-value pairs.
"""
def __init__(self, key_to_list_mapping=()):
super().__init__(key_to_list_mapping)
def __repr__(self):
return "<%s: %s>" % (self.__class__.__name__, super().__repr__())
def __getitem__(self, key):
"""
Return the last data value for this key, or [] if it's an empty list;
raise KeyError if not found.
"""
try:
list_ = super().__getitem__(key)
except KeyError:
raise MultiValueDictKeyError(key)
try:
return list_[-1]
except IndexError:
return []
def __setitem__(self, key, value):
super().__setitem__(key, [value])
def __copy__(self):
return self.__class__([
(k, v[:])
for k, v in self.lists()
])
def __deepcopy__(self, memo):
result = self.__class__()
memo[id(self)] = result
for key, value in dict.items(self):
dict.__setitem__(result, copy.deepcopy(key, memo),
copy.deepcopy(value, memo))
return result
def __getstate__(self):
return {**self.__dict__, '_data': {k: self._getlist(k) for k in self}}
def __setstate__(self, obj_dict):
data = obj_dict.pop('_data', {})
for k, v in data.items():
self.setlist(k, v)
self.__dict__.update(obj_dict)
def get(self, key, default=None):
"""
Return the last data value for the passed key. If key doesn't exist
or value is an empty list, return `default`.
"""
try:
val = self[key]
except KeyError:
return default
if val == []:
return default
return val
def _getlist(self, key, default=None, force_list=False):
"""
Return a list of values for the key.
Used internally to manipulate values list. If force_list is True,
return a new copy of values.
"""
try:
values = super().__getitem__(key)
except KeyError:
if default is None:
return []
return default
else:
if force_list:
values = list(values) if values is not None else None
return values
def getlist(self, key, default=None):
"""
Return the list of values for the key. If key doesn't exist, return a
default value.
"""
return self._getlist(key, default, force_list=True)
def setlist(self, key, list_):
super().__setitem__(key, list_)
def setdefault(self, key, default=None):
if key not in self:
self[key] = default
# Do not return default here because __setitem__() may store
# another value -- QueryDict.__setitem__() does. Look it up.
return self[key]
def setlistdefault(self, key, default_list=None):
if key not in self:
if default_list is None:
default_list = []
self.setlist(key, default_list)
# Do not return default_list here because setlist() may store
# another value -- QueryDict.setlist() does. Look it up.
return self._getlist(key)
def appendlist(self, key, value):
"""Append an item to the internal list associated with key."""
self.setlistdefault(key).append(value)
def items(self):
"""
Yield (key, value) pairs, where value is the last item in the list
associated with the key.
"""
for key in self:
yield key, self[key]
def lists(self):
"""Yield (key, list) pairs."""
return iter(super().items())
def values(self):
"""Yield the last value on every key list."""
for key in self:
yield self[key]
def copy(self):
"""Return a shallow copy of this object."""
return copy.copy(self)
def update(self, *args, **kwargs):
"""Extend rather than replace existing key lists."""
if len(args) > 1:
raise TypeError("update expected at most 1 argument, got %d" % len(args))
if args:
other_dict = args[0]
if isinstance(other_dict, MultiValueDict):
for key, value_list in other_dict.lists():
self.setlistdefault(key).extend(value_list)
else:
try:
for key, value in other_dict.items():
self.setlistdefault(key).append(value)
except TypeError:
raise ValueError("MultiValueDict.update() takes either a MultiValueDict or dictionary")
for key, value in kwargs.items():
self.setlistdefault(key).append(value)
def dict(self):
"""Return current object as a dict with singular values."""
return {key: self[key] for key in self}
class ImmutableList(tuple):
"""
A tuple-like object that raises useful errors when it is asked to mutate.
Example::
>>> a = ImmutableList(range(5), warning="You cannot mutate this.")
>>> a[3] = '4'
Traceback (most recent call last):
...
AttributeError: You cannot mutate this.
"""
def __new__(cls, *args, warning='ImmutableList object is immutable.', **kwargs):
self = tuple.__new__(cls, *args, **kwargs)
self.warning = warning
return self
def complain(self, *wargs, **kwargs):
if isinstance(self.warning, Exception):
raise self.warning
else:
raise AttributeError(self.warning)
# All list mutation functions complain.
__delitem__ = complain
__delslice__ = complain
__iadd__ = complain
__imul__ = complain
__setitem__ = complain
__setslice__ = complain
append = complain
extend = complain
insert = complain
pop = complain
remove = complain
sort = complain
reverse = complain
class DictWrapper(dict):
"""
Wrap accesses to a dictionary so that certain values (those starting with
the specified prefix) are passed through a function before being returned.
The prefix is removed before looking up the real value.
Used by the SQL construction code to ensure that values are correctly
quoted before being used.
"""
def __init__(self, data, func, prefix):
super().__init__(data)
self.func = func
self.prefix = prefix
def __getitem__(self, key):
"""
Retrieve the real value after stripping the prefix string (if
present). If the prefix is present, pass the value through self.func
before returning, otherwise return the raw value.
"""
use_func = key.startswith(self.prefix)
if use_func:
key = key[len(self.prefix):]
value = super().__getitem__(key)
if use_func:
return self.func(value)
return value
