Listing 1: 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;
    static tree_node
    *add_tree
        (tree_node *t, char const *w,
         unsigned n);
    static void
    put_tree(tree_node const *t);
    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);
    }