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from collections import MutableMapping
from linked_tree import LinkedBinaryTree
class MapBase(MutableMapping):
class _Item(object):
__slots__ = '_key', '_value'
def __init__(self, k, v):
self._key = k
self._value = v
def __eq__(self, other):
return self._key == other._key
def __lt__(self, other):
return self._key < other._key
def __gt__(self, other):
return self._key > other._key
class TreeMap(LinkedBinaryTree, MapBase):
class Position(LinkedBinaryTree.Position):
def key(self):
return self.element()._key
def value(self):
return self.element()._value
def _subtree_search(self, p, k):
"""
:param p:
:param k:
:return: 在子树中搜索值为 k 的节点，未搜索到返回最后搜索路经的最终位置
"""
p_value = p.key()
if p_value == k:
return p
elif p_value > k:
if self.left(p):
return self._subtree_search(self.left(p), k)
else:
if self.right(p):
return self._subtree_search(self.right(p), k)
return p
def _subtree_first_position(self, p):
"""
:return: 返回子树迭代时，第一个位置节点
"""
walk = p
while self.left(walk):
walk = self.left(walk)
return walk
def _subtree_last_position(self, p):
"""
:param p:
:return: 返回子树迭代时，最后一个位置节点
"""
walk = p
while self.right(walk):
walk = self.right(walk)
return walk
################# 引导方法 #######################
def first(self):
"""
:return: 返回树迭代序列的第一个节点
"""
return self._subtree_first_position(self.root()) if len(self) > 0 else None
def last(self):
"""
:return: 返回树迭代序列的最后一个节点
"""
return self._subtree_last_position(self.root()) if len(self) > 0 else None
def before(self, p):
"""
:param p:
:return: 返回迭代序列中位于 p 之前的，最大节点
"""
self._validate(p)
if self.left(p):
return self._subtree_last_position(self.left(p))
else:
walk = p
ancestor = self.parent(walk)
while ancestor and self.left(ancestor) is walk:
walk = ancestor
ancestor = self.parent(ancestor)
return ancestor
def after(self, p):
"""
:param p:
:return: 返回迭代序列中位于 p 之后的，最小节点
"""
self._validate(p)
if self.right(p):
self._subtree_first_position(self.right(p))
else:
walk = p
ancestor = self.parent(walk)
while ancestor and self.right(ancestor) is walk:
walk = ancestor
ancestor = self.parent(ancestor)
return ancestor
def find_position(self, k):
"""
:param k:
:return: 查找值等于 k 的位置节点
"""
if self.is_empty():
return None
else:
p = self._subtree_search(self.root(), k)
# avl 平衡树的钩子函数
self._rebalance_access(p)
return p
####################### 有序映射 ######################
def find_min(self):
"""
:return: 查找树中的最小值
"""
if self.is_empty():
return None
else:
p = self.first()
return p.key(), p.value()
def find_ge(self, k):
"""
:param k:
:return: 查找大于等于 k 的最小节点
"""
p = self.find_position(k)
if p and p.key() < k:
p = self.after(p)
return p.key(), p.value() if p else None, None
def find_range(self, start, stop):
"""
:param start:
:param stop:
:return: 查找值位于 start <= k < stop 的节点
"""
if not self.is_empty():
if start is None:
p = self.first()
else:
p = self.find_position(start)
if p and p.key() < start:
p = self.after(p)
while p and (stop is None or p.key() < stop):
yield p.key(), p.value()
p = self.after(p)
########################### 增删改查节点操作 ################
def __getitem__(self, item):
"""
:param item:
:return: 查找 item 映射的值
"""
if not self.is_empty():
p = self.find_position(item)
self._rebalance_access(p)
if p.key() == item:
return p.value()
raise KeyError('Key Error:' + repr(item))
def __setitem__(self, key, value):
"""
:param key:
:param value:
:return: 设置键 key 的值为 value
"""
if self.is_empty():
leaf = self._add_root(self._Item(key, value))
else:
p = self.find_position(key)
if p.key() == key:
p.element()._value = value
self._rebalance_access(p)
return
else:
item = self._Item(key, value)
if p.key() < key:
leaf = self._add_right(p, item)
else:
leaf = self._add_left(p, item)
self._rebalance_insert(leaf)
def __iter__(self):
"""
:return: 产生键的一个迭代
"""
p = self.first()
while p:
yield p.key()
p = self.after(p)
def delete(self, p):
"""
:param p:
:return: 删除位置节点 p
"""
self._validate(p)
if self.left(p) and self.right(p):
r = self._subtree_last_position(self.left(p))
self._replace(p, r.element())
p = r
parent = self.parent(p)
self._delete(p)
self._rebalance_delete(parent)
def __delitem__(self, key):
"""
:param key:
:return: 删除键 key
"""
if not self.is_empty():
p = self._subtree_search(self.root(), key)
if p.key() == key:
self.delete(p)
return
self._rebalance_access(p)
raise KeyError('Key Error: ' + repr(key))
################### 平衡二叉树的钩子函数 ###############
def _rebalance_delete(self, p):
pass
def _rebalance_insert(self, p):
pass
def _rebalance_access(self, p):
pass
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