Source code for django.utils.datastructures
import copy
from collections import OrderedDict
from django.utils import six
class OrderedSet(object):
"""
A set which keeps the ordering of the inserted items.
Currently backs onto OrderedDict.
"""
def __init__(self, iterable=None):
self.dict = OrderedDict(((x, None) for x in iterable) if iterable else [])
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.keys())
def __contains__(self, item):
return item in self.dict
def __bool__(self):
return bool(self.dict)
def __nonzero__(self): # Python 2 compatibility
return type(self).__bool__(self)
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(MultiValueDict, self).__init__(key_to_list_mapping)
def __repr__(self):
return "<%s: %s>" % (self.__class__.__name__,
super(MultiValueDict, self).__repr__())
def __getitem__(self, key):
"""
Returns the last data value for this key, or [] if it's an empty list;
raises KeyError if not found.
"""
try:
list_ = super(MultiValueDict, self).__getitem__(key)
except KeyError:
raise MultiValueDictKeyError(repr(key))
try:
return list_[-1]
except IndexError:
return []
def __setitem__(self, key, value):
super(MultiValueDict, self).__setitem__(key, [value])
def __copy__(self):
return self.__class__([
(k, v[:])
for k, v in self.lists()
])
def __deepcopy__(self, memo=None):
if memo is None:
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):
obj_dict = self.__dict__.copy()
obj_dict['_data'] = {k: self.getlist(k) for k in self}
return obj_dict
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):
"""
Returns the last data value for the passed key. If key doesn't exist
or value is an empty list, then default is returned.
"""
try:
val = self[key]
except KeyError:
return default
if val == []:
return default
return val
def getlist(self, key, default=None):
"""
Returns the list of values for the passed key. If key doesn't exist,
then a default value is returned.
"""
try:
return super(MultiValueDict, self).__getitem__(key)
except KeyError:
if default is None:
return []
return default
def setlist(self, key, list_):
super(MultiValueDict, self).__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):
"""Appends an item to the internal list associated with key."""
self.setlistdefault(key).append(value)
def _iteritems(self):
"""
Yields (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 _iterlists(self):
"""Yields (key, list) pairs."""
return six.iteritems(super(MultiValueDict, self))
def _itervalues(self):
"""Yield the last value on every key list."""
for key in self:
yield self[key]
if six.PY3:
items = _iteritems
lists = _iterlists
values = _itervalues
else:
iteritems = _iteritems
iterlists = _iterlists
itervalues = _itervalues
def items(self):
return list(self.iteritems())
def lists(self):
return list(self.iterlists())
def values(self):
return list(self.itervalues())
def copy(self):
"""Returns a shallow copy of this object."""
return copy.copy(self)
def update(self, *args, **kwargs):
"""
update() extends rather than replaces existing key lists.
Also accepts keyword args.
"""
if len(args) > 1:
raise TypeError("update expected at most 1 arguments, 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 six.iteritems(kwargs):
self.setlistdefault(key).append(value)
def dict(self):
"""
Returns 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, **kwargs):
if 'warning' in kwargs:
warning = kwargs['warning']
del kwargs['warning']
else:
warning = 'ImmutableList object is immutable.'
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):
"""
Wraps 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(DictWrapper, self).__init__(data)
self.func = func
self.prefix = prefix
def __getitem__(self, key):
"""
Retrieves 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.
"""
if key.startswith(self.prefix):
use_func = True
key = key[len(self.prefix):]
else:
use_func = False
value = super(DictWrapper, self).__getitem__(key)
if use_func:
return self.func(value)
return value
