Listing 1: The cross_reference_table class definition with tree_node, add_tree, and put_tree as private members

// table.h - cross-reference table interface
     
class cross_reference_table
    {
public:
    cross_reference_table();
    void add(char const *w, unsigned n); 
    void put() const;
private:
    struct tree_node;
    tree_node *add_tree(tree_node *t, char const *w, unsigned n);
    void put_tree(tree_node const *t) const; 
    tree_node *root;
    };
     
inline
cross_reference_table::cross_reference_table()
    {
    root = NULL;
    }
     
inline
void
cross_reference_table::add(char const *w, unsigned n)
    {
    root = add_tree(root, w, n);
    }
     
inline
void cross_reference_table::put() const
    {
    put_tree(root);
    }

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