Add Traversal concept

Octree/doc/Octree/Concepts/Traversal.h

@@ -1,4 +1,48 @@
 #ifndef DOCUMENTATION_TRAVERSAL_H
 #define DOCUMENTATION_TRAVERSAL_H
 
+/*!
+ * \ingroup PkgOctreeConcepts
+ * \cgalConcept
+ *
+ * \brief Provides the functions needed to traverse the nodes of an octree using a Traversal_iterator.
+ *
+ * A traversal is used to define a specific walk of the tree (e.g. Preorder, Postorder) iteratively
+ * rather than recursively.
+ *
+ * \todo Link to relevant classes
+ * \sa `CGAL::Octree::Traversal_iterator<Value>`
+ */
+class Traversal {
+public:
+
+  /// \name Methods
+  /// @{
+
+  /*!
+   * \brief uses a reference to the root of the tree to determine the first node of the sequence
+   *
+   * \todo The template params should be simplified
+   * \tparam Point_index
+   * \param root a const pointer to the root node
+   * \return a const pointer to the first node
+   */
+  template<class Point_index>
+  const Node <Point_index> *first(const Node <Point_index> *root) const {}
+
+  /*!
+   * \brief uses a reference to the current node to determine the next node of the sequence
+   *
+   * \todo The template params should be simplified
+   * \tparam Point_index
+   * \param n a const pointer to the current node
+   * \return a const pointer to the next node
+   */
+  template<class Point_index>
+  const Node <Point_index> *next(const Node <Point_index> *n) const {}
+
+  /// @}
+
+};
+
 #endif //DOCUMENTATION_TRAVERSAL_H