如何解决错误C2039

我正在尝试获取插入到树中的字符串的count个重复实例。我直接从课本上修改代码，这对我来说似乎很复杂，但我知道的不多。第141行中的countDupes方法导致C2039错误，指出countDupes不是AvlNode的成员。如果有人能好心地告诉我该怎么做或给我指明方向，我会永远爱你。下面的片段看起来很长，但大部分都是评论。提前谢谢。

#ifndef AVL_TREE_H
#define AVL_TREE_H
#include "except.h"
#include <algorithm>
#include <iostream> 
using namespace std;

template <typename Comparable>
class AvlTree
{
public:
int wordCount = 0;
int repeatedWordCount = 1;
AvlTree() : root{ nullptr }
{ }
AvlTree(const AvlTree & rhs) : root{ nullptr }
{
    root = clone(rhs.root);
}
AvlTree(AvlTree && rhs) : root{ rhs.root }
{
    rhs.root = nullptr;
}
~AvlTree()
{
    makeEmpty();
}

/**
* Test if the tree is logically empty.
* Return true if empty, false otherwise.
*/
bool isEmpty() const
{
    return root == nullptr;
}
/**
* Print the tree contents in sorted order.
*/
void printTree() const
{
    if (isEmpty())
        cout << "Empty tree" << endl;
    else
        printTree(root) ;
    cout << endl << "Total Words: " << wordCount << "t" << endl;;
}
/**
* Make the tree logically empty.
*/
void makeEmpty()
{
    makeEmpty(root);
}
/**
* Insert x into the tree, count duplicates
*/
void insert(const Comparable & x)
{
    insert(x, root);
    wordCount++;
    countDupes();
}
/**
* Insert x into the tree
*/
void insert(Comparable && x)
{
    insert(std::move(x), root);
    wordCount++;
    countDupes();
}
void countDupes()
{
    repeatedWordCount = repeatedWordCount + 1;
}

int getWordCount()
{
    return wordCount;
}
private:
struct AvlNode
{
    Comparable element;
    AvlNode   *left;
    AvlNode   *right;
    int       height;
    AvlNode(const Comparable & ele, AvlNode *lt, AvlNode *rt, int h = 0)
        : element{ ele }, left{ lt }, right{ rt }, height{ h } { }
    AvlNode(Comparable && ele, AvlNode *lt, AvlNode *rt, int h = 0)
        : element{ std::move(ele) }, left{ lt }, right{ rt }, height{ h } { }
};
AvlNode *root;

/**
* Internal method to insert into a subtree.
* x is the item to insert.
* t is the node that roots the subtree.
* Set the new root of the subtree.
*/
void insert(const Comparable & x, AvlNode * & t)
{
    if (t == nullptr)
        t = new AvlNode{ x, nullptr, nullptr };
    else if (x < t->element)
        insert(x, t->left);
    else if (t->element < x)
        insert(x, t->right);
    else if (t->element == x)
        t->countDupes();
    balance(t);
}
/**
* Internal method to insert into a subtree.
* x is the item to insert.
* t is the node that roots the subtree.
* Set the new root of the subtree.
*/
void insert(Comparable && x, AvlNode * & t)
{
    if (t == nullptr)
        t = new AvlNode{ std::move(x), nullptr, nullptr };
    else if (x < t->element)
        insert(std::move(x), t->left);
    else if (t->element < x)
        insert(std::move(x), t->right);
    else if (t->element == x)
        t->countDupes();
    balance(t);
}
static const int ALLOWED_IMBALANCE = 1;
// Assume t is balanced or within one of being balanced
void balance(AvlNode * & t)
{
    if (t == nullptr)
        return;
    if (height(t->left) - height(t->right) > ALLOWED_IMBALANCE)
    if (height(t->left->left) >= height(t->left->right))
        rotateWithLeftChild(t);
    else
        doubleWithLeftChild(t);
    else
    if (height(t->right) - height(t->left) > ALLOWED_IMBALANCE)
    if (height(t->right->right) >= height(t->right->left))
        rotateWithRightChild(t);
    else
        doubleWithRightChild(t);
    t->height = max(height(t->left), height(t->right)) + 1;
}
/**
* Internal method to find the smallest item in a subtree t.
* Return node containing the smallest item.
*/
AvlNode * findMin(AvlNode *t) const
{
    if (t == nullptr)
        return nullptr;
    if (t->left == nullptr)
        return t;
    return findMin(t->left);
}
/**
* Internal method to find the largest item in a subtree t.
* Return node containing the largest item.
*/
AvlNode * findMax(AvlNode *t) const
{
    if (t != nullptr)
    while (t->right != nullptr)
        t = t->right;
    return t;
}

/**
* Internal method to test if an item is in a subtree.
* x is item to search for.
* t is the node that roots the tree.
*/
bool contains(const Comparable & x, AvlNode *t) const
{
    if (t == nullptr)
        return false;
    else if (x < t->element)
        return contains(x, t->left);
    else if (t->element < x)
        return contains(x, t->right);
    else
        return true;    // Match
}
/****** NONRECURSIVE VERSION*************************
bool contains( const Comparable & x, AvlNode *t ) const
{
while( t != nullptr )
if( x < t->element )
t = t->left;
else if( t->element < x )
t = t->right;
else
return true;    // Match
return false;   // No match
}
*****************************************************/
/**
* Internal method to make subtree empty.
*/
void makeEmpty(AvlNode * & t)
{
    if (t != nullptr)
    {
        makeEmpty(t->left);
        makeEmpty(t->right);
        delete t;
    }
    t = nullptr;
}
/**
* Internal method to print a subtree rooted at t in sorted order.
*/
void printTree(AvlNode *t) const
{
    if (t != nullptr)
    {
        printTree(t->left);
        cout << t->element << "t t t " << repeatedWordCount << endl;
        printTree(t->right);
    }
}
// Avl manipulations
/**
* Return the height of node t or -1 if nullptr.
*/
int height(AvlNode *t) const
{
    return t == nullptr ? -1 : t->height;
}
int max(int lhs, int rhs) const
{
    return lhs > rhs ? lhs : rhs;
}
/**
* Rotate binary tree node with left child.
* For AVL trees, this is a single rotation for case 1.
* Update heights, then set new root.
*/
void rotateWithLeftChild(AvlNode * & k2)
{
    AvlNode *k1 = k2->left;
    k2->left = k1->right;
    k1->right = k2;
    k2->height = max(height(k2->left), height(k2->right)) + 1;
    k1->height = max(height(k1->left), k2->height) + 1;
    k2 = k1;
}
/**
* Rotate binary tree node with right child.
* For AVL trees, this is a single rotation for case 4.
* Update heights, then set new root.
*/
void rotateWithRightChild(AvlNode * & k1)
{
    AvlNode *k2 = k1->right;
    k1->right = k2->left;
    k2->left = k1;
    k1->height = max(height(k1->left), height(k1->right)) + 1;
    k2->height = max(height(k2->right), k1->height) + 1;
    k1 = k2;
}
/**
* Double rotate binary tree node: first left child.
* with its right child; then node k3 with new left child.
* For AVL trees, this is a double rotation for case 2.
* Update heights, then set new root.
*/
void doubleWithLeftChild(AvlNode * & k3)
{
    rotateWithRightChild(k3->left);
    rotateWithLeftChild(k3);
}
/**
* Double rotate binary tree node: first right child.
* with its left child; then node k1 with new right child.
* For AVL trees, this is a double rotation for case 3.
* Update heights, then set new root.
*/
void doubleWithRightChild(AvlNode * & k1)
{
    rotateWithLeftChild(k1->right);
    rotateWithRightChild(k1);
}
};
#endif