exercise13_28.h

#ifndef ex13_28_h
#define ex13_28_h

#include <string>
using std::string;

class TreeNode
{
public:
	TreeNode() : value(string()), count(new int(1)), left(nullptr), right(nullptr) {}
	TreeNode(const TreeNode &rhs) : value(rhs.value), count(rhs.count), left(rhs.left), right(rhs.right) { ++*count; }
	TreeNode& operator=(const TreeNode &rhs);
	~TreeNode()
	{
		if (--*count == 0)
		{
			if (left)
			{
				delete left;
				left = nullptr;
			}
			if (right)
			{
				delete right;
				right = nullptr;
			}
			delete count;
			count = nullptr;
		}
	}

private:
	std::string value;
	int         *count;
	TreeNode    *left;
	TreeNode    *right;
};

TreeNode& TreeNode::operator=(const TreeNode &rhs)
{
	++*rhs.count;
	if (--*count == 0)
	{
		if (left)
		{
			delete left;
		}
		if (right)
		{
			delete right;
		}

		delete count;
	}
	value = rhs.value;
	left = rhs.left;
	right = rhs.right;
	count = rhs.count;
	return *this;
}


class BinStrTree
{
public:
	BinStrTree() : root(new TreeNode()) {}
	BinStrTree(const BinStrTree &bst) : root(new TreeNode(*bst.root)) {}
	BinStrTree& operator=(const BinStrTree &bst);
	~BinStrTree() { delete root; }

private:
	TreeNode *root;
};

BinStrTree& BinStrTree::operator=(const BinStrTree &bst)
{
	TreeNode *new_root = new TreeNode(*bst.root);
	delete root;
	root = new_root;
	return *this;
}


#endif