__title__ = 'fobi.data_structures'
__author__ = 'Artur Barseghyan <artur.barseghyan@gmail.com>'
__copyright__ = 'Copyright (c) 2014 Artur Barseghyan'
__license__ = 'GPL 2.0/LGPL 2.1'
__all__ = ('SortableDict', )
import copy
import six
[docs]class SortableDict(dict):
"""
A dictionary that keeps its keys in the order in which they're
inserted. Very similar to (and partly based on) ``SortedDict`` of
the ``Django``, but has several additional methods implemented,
such as: ``insert_before_key`` and ``insert_after_key``.
"""
def __new__(cls, *args, **kwargs):
instance = super(SortableDict, cls).__new__(cls, *args, **kwargs)
instance.key_order = []
return instance
def __init__(self, data=None):
if data is None or isinstance(data, dict):
data = data or []
super(SortableDict, self).__init__(data)
self.key_order = list(data) if data else []
else:
super(SortableDict, self).__init__()
super_set = super(SortableDict, self).__setitem__
for key, value in data:
# Take the ordering from first key
if key not in self:
self.key_order.append(key)
# But override with last value in data (dict() does this)
super_set(key, value)
def __deepcopy__(self, memo):
return self.__class__([(key, copy.deepcopy(value, memo))
for key, value in self.items()])
def __copy__(self):
# The Python's default copy implementation will alter the state
# of self. The reason for this seems complex but is likely related to
# subclassing dict.
return self.copy()
def __setitem__(self, key, value):
if key not in self:
self.key_order.append(key)
super(SortableDict, self).__setitem__(key, value)
def __delitem__(self, key):
super(SortableDict, self).__delitem__(key)
self.key_order.remove(key)
def __iter__(self):
return iter(self.key_order)
def __reversed__(self):
return reversed(self.key_order)
[docs] def pop(self, k, *args):
result = super(SortableDict, self).pop(k, *args)
try:
self.key_order.remove(k)
except ValueError:
# Key wasn't in the dictionary in the first place. No problem.
pass
return result
[docs] def popitem(self):
result = super(SortableDict, self).popitem()
self.key_order.remove(result[0])
return result
def _iteritems(self):
for key in self.key_order:
yield key, self[key]
def _iterkeys(self):
for key in self.key_order:
yield key
def _itervalues(self):
for key in self.key_order:
yield self[key]
if six.PY3:
items = _iteritems
keys = _iterkeys
values = _itervalues
else:
iteritems = _iteritems
iterkeys = _iterkeys
itervalues = _itervalues
[docs] def items(self):
return [(k, self[k]) for k in self.key_order]
[docs] def keys(self):
return self.key_order[:]
[docs] def values(self):
return [self[k] for k in self.key_order]
[docs] def update(self, dict_):
for k, v in six.iteritems(dict_):
self[k] = v
[docs] def setdefault(self, key, default):
if key not in self:
self.key_order.append(key)
return super(SortableDict, self).setdefault(key, default)
[docs] def value_for_index(self, index):
"""Returns the value of the item at the given zero-based index."""
# This, and insert() are deprecated because they cannot be implemented
# using collections.OrderedDict (Python 2.7 and up), which we'll
# eventually switch to
return self[self.key_order[index]]
[docs] def insert(self, index, key, value):
"""Inserts the key, value pair before the item with the given index."""
if key in self.key_order:
n = self.key_order.index(key)
del self.key_order[n]
if n < index:
index -= 1
self.key_order.insert(index, key)
super(SortableDict, self).__setitem__(key, value)
[docs] def copy(self):
"""Returns a copy of this object."""
# This way of initializing the copy means it works for subclasses, too.
return self.__class__(self)
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 six.iteritems(self)])
[docs] def clear(self):
super(SortableDict, self).clear()
self.key_order = []
# *************************************************************************
# ************************** Additional methods ***************************
# *************************************************************************
[docs] def insert_before_key(self, target_key, key, value,
fail_silently=True,
offset=0):
"""
Inserts the {``key``: ``value``} before the ``target_key``.
:param immutable target_key:
:param immutable key:
:param mutable value:
:param boolean fail_silently:
:param int offset:
:return bool:
"""
if target_key in self.key_order:
index = self.key_order.index(target_key) + offset
self.insert(index, key, value)
return True
elif not fail_silently:
raise ValueError(
"Target key ``{0}`` does not exist.".format(target_key))
else:
return False
[docs] def insert_after_key(self, target_key, key, value, fail_silently=True):
"""
Inserts the {``key``: ``value``} after the ``target_key``.
:param immutable target_key:
:param immutable key:
:param mutable value:
:param boolean fail_silently:
:param int offset:
:return bool:
"""
return self.insert_before_key(target_key=target_key,
key=key,
value=value,
fail_silently=fail_silently,
offset=1)
[docs] def move_before_key(self, source_key, target_key,
fail_silently=True,
offset=0):
"""
Moves the {``key``: ``value``} before the given ``source_key``.
:param immutable source_key:
:param immutable target_key:
:param boolean fail_silently:
:param int offset:
:return bool:
"""
if target_key in self.key_order and source_key in self.key_order:
source_value = self.pop(source_key)
return self.insert_before_key(target_key, source_key, source_value,
fail_silently=True,
offset=offset)
elif not fail_silently:
raise ValueError("Non existing keys: {0}, {1}.".format(source_key,
target_key))
else:
return False
[docs] def move_after_key(self, source_key, target_key, fail_silently=True):
"""
Moves the {``key``: ``value``} after the given ``source_key``.
:param immutable source_key:
:param immutable target_key:
:param boolean fail_silently:
:return bool:
"""
return self.move_before_key(source_key=source_key,
target_key=target_key,
fail_silently=fail_silently,
offset=1)