【C++】map与set的模拟实现
文章目录
- 1.map和set的底层
- 2.红黑树的封装
-
- 2.1 红黑树的迭代器
- 2.2 红黑树的begin()、end()
- 2.3总代码
- 3.map的封装
- 4.set的封装
前置知识：RBTree(红黑树)
现已完成删除功能
1.map和set的底层
map和set的底层结构就是红黑树，所以直接在map和set中封装一棵红黑树，然后包装下其接口即可。
2.红黑树的封装
2.1 红黑树的迭代器
template<class T, class Ref, class Ptr>
struct __RBTreeIterator
{
typedef RBTreeNode<T> Node;
typedef __RBTreeIterator<T, Ref, Ptr> Self;
Node* _node;
__RBTreeIterator(Node* node)
:_node(node)
{}
Ref operator*()
{
return _node->_data;
}
Ptr operator->()
{
return &_node->_data;
}
bool operator!=(const Self& s)
{
return _node != s._node;
}
bool operator==(const Self& other) const
{
return _node == other._node;
}
Self& operator++()
{
if (_node->_right)
{
// 下一个，右树最左节点
Node* leftMin = _node->_right;
while (leftMin->_left)
{
leftMin = leftMin->_left;
}
_node = leftMin;
}
else
{
// 下一个，孩子等于父亲左的那个祖先
Node* cur = _node;
Node* parent = cur->_parent;
while (parent && cur == parent->_right)
{
cur = parent;
parent = parent->_parent;
}
_node = parent;
}
return *this;
}
};
2.2 红黑树的begin()、end()
Iterator Begin()
{
Node* leftMin = _root;
while (leftMin && leftMin->_left)
{
leftMin = leftMin->_left;
}
return Iterator(leftMin);
}
Iterator End()
{
return Iterator(nullptr);
}
ConstIterator End() const
{
return ConstIterator(nullptr);
}
ConstIterator Begin() const
{
Node* leftMin = _root;
while (leftMin && leftMin->_left)
{
leftMin = leftMin->_left;
}
return ConstIterator(leftMin);
}
2.3总代码
enum Colour
{
RED,
BLACK
};
template<class T>
struct RBTreeNode
{
RBTreeNode<T>* _left;
RBTreeNode<T>* _right;
RBTreeNode<T>* _parent;
T _data;
Colour _col;
RBTreeNode(const T& data)
:_left(nullptr)
, _right(nullptr)
, _parent(nullptr)
, _data(data)
, _col(RED)
{}
};
template<class T, class Ref, class Ptr>
struct __RBTreeIterator
{
typedef RBTreeNode<T> Node;
typedef __RBTreeIterator<T, Ref, Ptr> Self;
Node* _node;
__RBTreeIterator(Node* node)
:_node(node)
{}
Ref operator*()
{
return _node->_data;
}
Ptr operator->()
{
return &_node->_data;
}
bool operator!=(const Self& s)
{
return _node != s._node;
}
bool operator==(const Self& other) const
{
return _node == other._node;
}
Self& operator++()
{
if (_node->_right)
{
// 下一个，右树最左节点
Node* leftMin = _node->_right;
while (leftMin->_left)
{
leftMin = leftMin->_left;
}
_node = leftMin;
}
else
{
// 下一个，孩子等于父亲左的那个祖先
Node* cur = _node;
Node* parent = cur->_parent;
while (parent && cur == parent->_right)
{
cur = parent;
parent = parent->_parent;
}
_node = parent;
}
return *this;
}
};
template<class K, class T, class KeyOfT>
class RBTree
{
typedef RBTreeNode<T> Node;
public:
typedef __RBTreeIterator<T, T&, T*> Iterator;
typedef __RBTreeIterator<T, const T&, const T*> ConstIterator;
RBTree() = default;
RBTree(const RBTree<K, T, KeyOfT>& t)
{
_root = Copy(t._root);
}
// t2 = t1
RBTree<K, T, KeyOfT>& operator=(RBTree<K, T, KeyOfT> t)
{
swap(_root, t._root);
return *this;
}
~RBTree()
{
Destroy(_root);
_root = nullptr;
}
Iterator Begin()
{
Node* leftMin = _root;
while (leftMin && leftMin->_left)
{
leftMin = leftMin->_left;
}
return Iterator(leftMin);
}
Iterator End()
{
return Iterator(nullptr);
}
ConstIterator End() const
{
return ConstIterator(nullptr);
}
ConstIterator Begin() const
{
Node* leftMin = _root;
while (leftMin && leftMin->_left)
{
leftMin = leftMin->_left;
}
return ConstIterator(leftMin);
}
Iterator Find(const K& key)
{
KeyOfT kot;
Node* cur = _root;
while (cur)
{
if (kot(cur->_data) < key)
{
cur = cur->_right;
}
else if (kot(cur->_data) > key)
{
cur = cur->_left;
}
else
{
return Iterator(cur);
}
}
return End();
}
std::pair<Iterator, bool> Insert(const T& data)
{
if (_root == nullptr)
{
_root = new Node(data);
_root->_col = BLACK;
return make_pair(Iterator(_root), true);
}
KeyOfT kot;
Node* parent = nullptr;
Node* cur = _root;
while (cur)
{
// K
// pair3.map的封装
namespace my_std
{
template<class K, class V>
class map
{
struct MapKeyOfT
{
const K& operator()(const pair<K, V>& kv)
{
return kv.first;
}
};
public:
//在没有示例化的类模板里取内嵌类型的时候要加typename
//typename 让编译器等到实例化后再识别这个类型
typedef typename RBTree<K, std::pair<const K, V>, MapKeyOfT>::Iterator iterator;
typedef typename RBTree<K, const K, MapKeyOfT>::ConstIterator const_iterator;
const_iterator begin() const
{
return _t.Begin();
}
const_iterator end() const
{
return _t.End();
}
iterator begin()
{
return _t.Begin();
}
iterator end()
{
return _t.End();
}
iterator find(const K& key)
{
return _t.Find(key);
}
std::pair<iterator, bool> insert(const std::pair<K, V>& kv)
{
return _t.Insert(kv);
}
bool erase(const K& key) {
return _t.Erase(key);
}
V& operator[](const K& key)
{
pair<iterator, bool> ret = _t.Insert(make_pair(key, V()));
return ret.first->second;
}
private:
RBTree<K, pair<const K, V>, MapKeyOfT> _t;
};
4.set的封装
namespace my_std
{
template<class K>
class set
{
struct SetKeyOfT
{
const K& operator()(const K& key)
{
return key;
}
};
public:
typedef typename RBTree<K, const K, SetKeyOfT>::Iterator iterator;
typedef typename RBTree<K, const K, SetKeyOfT>::ConstIterator const_iterator;
const_iterator begin() const
{
return _t.Begin();
}
const_iterator end() const
{
return _t.End();
}
iterator begin()
{
return _t.Begin();
}
iterator end()
{
return _t.End();
}
iterator find(const K& key)
{
return _t.Find(key);
}
pair<iterator, bool> insert(const K& key)
{
return _t.Insert(key);
}
bool erase(const K& key)
{
return _t.Erase(key);
}
private:
RBTree<K, const K, SetKeyOfT> _t;
};