class OrderedDict(dict):
"""
A dictionary that keeps its keys in the order in which they're inserted.
Copied from Django's SortedDict with some modifications.
"""
def __new__(cls, *args, **kwargs):
instance = super(OrderedDict, cls).__new__(cls, *args, **kwargs)
instance.keyOrder = []
return instance
def __init__(self, data=None):
if data is None:
data = {}
super(OrderedDict, 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):
from copy import deepcopy
return self.__class__([(key, deepcopy(value, memo))
for key, value in self.iteritems()])
def __setitem__(self, key, value):
super(OrderedDict, self).__setitem__(key, value)
if key not in self.keyOrder:
self.keyOrder.append(key)
def __delitem__(self, key):
super(OrderedDict, self).__delitem__(key)
self.keyOrder.remove(key)
def __iter__(self):
for k in self.keyOrder:
yield k
def pop(self, k, *args):
result = super(OrderedDict, 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(OrderedDict, 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, super(OrderedDict, self).__getitem__(key)
def keys(self):
return self.keyOrder[:]
def iterkeys(self):
return iter(self.keyOrder)
def values(self):
return [super(OrderedDict, self).__getitem__(k) for k in self.keyOrder]
def itervalues(self):
for key in self.keyOrder:
yield super(OrderedDict, self).__getitem__(key)
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 super(OrderedDict, self).setdefault(key, default)
def value_for_index(self, index):
"""Return the value of the item at the given zero-based index."""
return self[self.keyOrder[index]]
def insert(self, index, key, value):
"""Insert 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(OrderedDict, self).__setitem__(key, value)
def copy(self):
"""Return 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):
"""
Replace 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(OrderedDict, self).clear()
self.keyOrder = []
def index(self, key):
""" Return the index of a given key. """
return self.keyOrder.index(key)
def index_for_location(self, location):
""" Return index or None for a given location. """
if location == '_begin':
i = 0
elif location == '_end':
i = None
elif location.startswith('<') or location.startswith('>'):
i = self.index(location[1:])
if location.startswith('>'):
if i >= len(self):
# last item
i = None
else:
i += 1
else:
raise ValueError('Not a valid location: "%s". Location key '
'must start with a ">" or "<".' % location)
return i
def add(self, key, value, location):
""" Insert by key location. """
i = self.index_for_location(location)
if i is not None:
self.insert(i, key, value)
else:
self.__setitem__(key, value)
def link(self, key, location):
""" Change location of an existing item. """
n = self.keyOrder.index(key)
del self.keyOrder[n]
i = self.index_for_location(location)
try:
if i is not None:
self.keyOrder.insert(i, key)
else:
self.keyOrder.append(key)
except Error:
# restore to prevent data loss and reraise
self.keyOrder.insert(n, key)
raise Error
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