virtual tree *branch(int branch_number) const;
//!< Returns the specified branch of this tree.
- /*!< NIL is returned if the "branch_number" refers to a branch that
+ /*!< NULL_POINTER is returned if the "branch_number" refers to a branch that
does not exist. */
virtual int which(tree *branch_to_find) const;
virtual tree *parent() const;
//!< Returns the tree node that is the immediate ancestor of this one.
- /*!< if this is the root node, then NIL is returned. */
+ /*!< if this is the root node, then NULL_POINTER is returned. */
virtual tree *root() const;
//!< Locates and returns the absolute root of the tree containing this tree.
tree *next();
//!< Returns a pointer to the next tree in the direction of traversal.
- /*!< If the traversal is finished, NIL is returned. */
+ /*!< If the traversal is finished, NULL_POINTER is returned. */
void whack(tree *to_whack);
//!< destroys the tree "to_whack".
bool next_node(tree *&to_return);
//!< sets "to_return" to the next tree in the direction of tree traversal.
/*!< if the next node could not be found in one invocation of next_node,
- then "to_return" is set to NIL. the function returns a boolean which
+ then "to_return" is set to NULL_POINTER. the function returns a boolean which
is true only if the iteration process can be continued by another call
to next_node. if the function returns false, the iteration is
- complete and "to_return" will always be NIL. */
+ complete and "to_return" will always be NULL_POINTER. */
};
iterator start(traversal_directions direction) const;