django1/django/utils/datastructures.py

270 lines
8.4 KiB
Python

class MergeDict(object):
"""
A simple class for creating new "virtual" dictionaries that actualy look
up values in more than one dictionary, passed in the constructor.
"""
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 __contains__(self, key):
return self.has_key(key)
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:
try:
return dict.getlist(key)
except KeyError:
pass
raise KeyError
def items(self):
item_list = []
for dict in self.dicts:
item_list.extend(dict.items())
return item_list
def has_key(self, key):
for dict in self.dicts:
if key in dict:
return True
return False
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 __init__(self, data=None):
if data is None: data = {}
dict.__init__(self, data)
self.keyOrder = data.keys()
def __setitem__(self, key, value):
dict.__setitem__(self, key, value)
if key not in self.keyOrder:
self.keyOrder.append(key)
def __delitem__(self, key):
dict.__delitem__(self, key)
self.keyOrder.remove(key)
def __iter__(self):
for k in self.keyOrder:
yield k
def items(self):
return zip(self.keyOrder, self.values())
def keys(self):
return self.keyOrder[:]
def values(self):
return [dict.__getitem__(self, k) for k in self.keyOrder]
def update(self, dict):
for k, v in dict.items():
self.__setitem__(k, v)
def setdefault(self, key, default):
if key not in self.keyOrder:
self.keyOrder.append(key)
return dict.setdefault(self, 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 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()])
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=()):
dict.__init__(self, key_to_list_mapping)
def __repr__(self):
return "<MultiValueDict: %s>" % dict.__repr__(self)
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_ = dict.__getitem__(self, 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):
dict.__setitem__(self, key, [value])
def __copy__(self):
return self.__class__(dict.items(self))
def __deepcopy__(self, memo=None):
import 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 get(self, key, default=None):
"Returns the default value if the requested data doesn't exist"
try:
val = self[key]
except KeyError:
return default
if val == []:
return default
return val
def getlist(self, key):
"Returns an empty list if the requested data doesn't exist"
try:
return dict.__getitem__(self, key)
except KeyError:
return []
def setlist(self, key, list_):
dict.__setitem__(self, 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, [])
dict.__setitem__(self, 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 lists(self):
"Returns a list of (key, list) pairs."
return dict.items(self)
def values(self):
"Returns a list of the last value on every key list."
return [self[key] for key in self.keys()]
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': {'firstname': ['Simon'], 'lastname': ['Willison'],
'2': {'firstname': ['Adrian'], 'lastname': ['Holovaty']}
>>> d['person']['1']
{'firstname': ['Simon'], 'lastname': ['Willison']}
# 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}