from types import GeneratorType
from django.utils.copycompat import deepcopy
class MergeDict(object):
"""
A simple class for creating new "virtual" dictionaries that actually look
up values in more than one dictionary, passed in the constructor.
If a key appears in more than one of the given dictionaries, only the
first occurrence will be used.
"""
def __init__(self, *dicts):
self.dicts = dicts
def __getitem__(self, key):
for dict_ in self.dicts:
try:
return dict_[key]
except KeyError:
pass
raise KeyError
def __copy__(self):
return self.__class__(*self.dicts)
def get(self, key, default=None):
try:
return self[key]
except KeyError:
return default
def getlist(self, key):
for dict_ in self.dicts:
if key in dict_.keys():
return dict_.getlist(key)
return []
def iteritems(self):
seen = set()
for dict_ in self.dicts:
for item in dict_.iteritems():
k, v = item
if k in seen:
continue
seen.add(k)
yield item
def iterkeys(self):
for k, v in self.iteritems():
yield k
def itervalues(self):
for k, v in self.iteritems():
yield v
def items(self):
return list(self.iteritems())
def keys(self):
return list(self.iterkeys())
def values(self):
return list(self.itervalues())
def has_key(self, key):
for dict_ in self.dicts:
if key in dict_:
return True
return False
__contains__ = has_key
__iter__ = iterkeys
def copy(self):
"""Returns a copy of this object."""
return self.__copy__()
class SortedDict(dict):
"""
A dictionary that keeps its keys in the order in which they're inserted.
"""
def __new__(cls, *args, **kwargs):
instance = super(SortedDict, cls).__new__(cls, *args, **kwargs)
instance.keyOrder = []
return instance
def __init__(self, data=None):
if data is None:
data = {}
elif isinstance(data, GeneratorType):
# Unfortunately we need to be able to read a generator twice. Once
# to get the data into self with our super().__init__ call and a
# second time to setup keyOrder correctly
data = list(data)
super(SortedDict, self).__init__(data)
if isinstance(data, dict):
self.keyOrder = data.keys()
else:
self.keyOrder = []
for key, value in data:
if key not in self.keyOrder:
self.keyOrder.append(key)
def __deepcopy__(self, memo):
return self.__class__([(key, deepcopy(value, memo))
for key, value in self.iteritems()])
def __setitem__(self, key, value):
if key not in self:
self.keyOrder.append(key)
super(SortedDict, self).__setitem__(key, value)
def __delitem__(self, key):
super(SortedDict, self).__delitem__(key)
self.keyOrder.remove(key)
def __iter__(self):
return iter(self.keyOrder)
def pop(self, k, *args):
result = super(SortedDict, self).pop(k, *args)
try:
self.keyOrder.remove(k)
except ValueError:
# Key wasn't in the dictionary in the first place. No problem.
pass
return result
def popitem(self):
result = super(SortedDict, self).popitem()
self.keyOrder.remove(result[0])
return result
def items(self):
return zip(self.keyOrder, self.values())
def iteritems(self):
for key in self.keyOrder:
yield key, self[key]
def keys(self):
return self.keyOrder[:]
def iterkeys(self):
return iter(self.keyOrder)
def values(self):
return map(self.__getitem__, self.keyOrder)
def itervalues(self):
for key in self.keyOrder:
yield self[key]
def update(self, dict_):
for k, v in dict_.iteritems():
self[k] = v
def setdefault(self, key, default):
if key not in self:
self.keyOrder.append(key)
return super(SortedDict, self).setdefault(key, default)
def value_for_index(self, index):
"""Returns the value of the item at the given zero-based index."""
return self[self.keyOrder[index]]
def insert(self, index, key, value):
"""Inserts the key, value pair before the item with the given index."""
if key in self.keyOrder:
n = self.keyOrder.index(key)
del self.keyOrder[n]
if n < index:
index -= 1
self.keyOrder.insert(index, key)
super(SortedDict, self).__setitem__(key, value)
def copy(self):
"""Returns a copy of this object."""
# This way of initializing the copy means it works for subclasses, too.
obj = self.__class__(self)
obj.keyOrder = self.keyOrder[:]
return obj
def __repr__(self):
"""
Replaces the normal dict.__repr__ with a version that returns the keys
in their sorted order.
"""
return '{%s}' % ', '.join(['%r: %r' % (k, v) for k, v in self.items()])
def clear(self):
super(SortedDict, self).clear()
self.keyOrder = []
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.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("Key %r not found in %r" % (key, self))
try:
return list_[-1]
except IndexError:
return []
def __setitem__(self, key, value):
super(MultiValueDict, self).__setitem__(key, [value])
def __copy__(self):
return self.__class__(super(MultiValueDict, self).items())
def __deepcopy__(self, memo=None):
import django.utils.copycompat as copy
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'] = dict([(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):
"""
Returns the list of values for the passed key. If key doesn't exist,
then an empty list is returned.
"""
try:
return super(MultiValueDict, self).__getitem__(key)
except KeyError:
return []
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
return self[key]
def setlistdefault(self, key, default_list=()):
if key not in self:
self.setlist(key, default_list)
return self.getlist(key)
def appendlist(self, key, value):
"""Appends an item to the internal list associated with key."""
self.setlistdefault(key, [])
super(MultiValueDict, self).__setitem__(key, self.getlist(key) + [value])
def items(self):
"""
Returns a list of (key, value) pairs, where value is the last item in
the list associated with the key.
"""
return [(key, self[key]) for key in self.keys()]
def iteritems(self):
"""
Yields (key, value) pairs, where value is the last item in the list
associated with the key.
"""
for key in self.keys():
yield (key, self[key])
def lists(self):
"""Returns a list of (key, list) pairs."""
return super(MultiValueDict, self).items()
def iterlists(self):
"""Yields (key, list) pairs."""
return super(MultiValueDict, self).iteritems()
def values(self):
"""Returns a list of the last value on every key list."""
return [self[key] for key in self.keys()]
def itervalues(self):
"""Yield the last value on every key list."""
for key in self.iterkeys():
yield self[key]
def copy(self):
"""Returns a copy of this object."""
return self.__deepcopy__()
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 kwargs.iteritems():
self.setlistdefault(key, []).append(value)
class DotExpandedDict(dict):
"""
A special dictionary constructor that takes a dictionary in which the keys
may contain dots to specify inner dictionaries. It's confusing, but this
example should make sense.
>>> d = DotExpandedDict({'person.1.firstname': ['Simon'], \
'person.1.lastname': ['Willison'], \
'person.2.firstname': ['Adrian'], \
'person.2.lastname': ['Holovaty']})
>>> d
{'person': {'1': {'lastname': ['Willison'], 'firstname': ['Simon']}, '2': {'lastname': ['Holovaty'], 'firstname': ['Adrian']}}}
>>> d['person']
{'1': {'lastname': ['Willison'], 'firstname': ['Simon']}, '2': {'lastname': ['Holovaty'], 'firstname': ['Adrian']}}
>>> d['person']['1']
{'lastname': ['Willison'], 'firstname': ['Simon']}
# Gotcha: Results are unpredictable if the dots are "uneven":
>>> DotExpandedDict({'c.1': 2, 'c.2': 3, 'c': 1})
{'c': 1}
"""
def __init__(self, key_to_list_mapping):
for k, v in key_to_list_mapping.items():
current = self
bits = k.split('.')
for bit in bits[:-1]:
current = current.setdefault(bit, {})
# Now assign value to current position
try:
current[bits[-1]] = v
except TypeError: # Special-case if current isn't a dict.
current = {bits[-1]: v}
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
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