Implement leaves traversal

Octree/include/CGAL/Octree/Tree_walker_criterion.h

@@ -27,6 +27,25 @@ namespace CGAL {
     return &((*n->parent())[index + 1]);
   }
 
+  template<class Node>
+  const Node *next_sibling_up(const Node *n) {
+
+    if (!n)
+      return nullptr;
+
+    auto up = n->parent();
+
+    while (nullptr != up) {
+
+      if (nullptr != next_sibling(up))
+        return next_sibling(up);
+
+      up = up->parent();
+    }
+
+    return nullptr;
+  }
+
   template<class Node>
   const Node *deepest_first_child(const Node *n) {
 
@@ -56,17 +75,7 @@ namespace CGAL {
 
         if (nullptr == next) {
 
-          auto up = n->parent();
-
-          while (nullptr != up) {
-
-            if (nullptr != next_sibling(up))
-              return next_sibling(up);
-
-            up = up->parent();
-          }
-
-          return nullptr;
+          return next_sibling_up(n);
         }
 
         return next;
@@ -99,6 +108,26 @@ namespace CGAL {
       return next;
     }
   };
+
+  struct Leaves {
+
+    template<class Node>
+    const Node *first(const Node *root) {
+
+      return deepest_first_child(root);
+    }
+
+    template<class Node>
+    const Node *operator()(const Node *n) {
+
+      auto next = deepest_first_child(next_sibling(n));
+
+      if (!next)
+        next = deepest_first_child(next_sibling_up(n));
+
+      return next;
+    }
+  };
 }
 
 #endif //OCTREE_TREE_WALKER_CRITERION_H

Octree/test/Octree/test_tree_walk.cpp

@@ -69,10 +69,27 @@ int test_postorder_print() {
   return 0;
 }
 
+int test_leaves_print() {
+
+  std::cout << "~~~~~~~~~~~~~~~~~~~~~~~~~~" << std::endl;
+
+  auto points = create_example_point_collection();
+
+  auto point_map = points.point_map();
+  Octree octree(points, point_map);
+  octree.refine(10, 1);
+
+  auto tree_walker = CGAL::Leaves();
+  octree.print(std::cout, tree_walker.first(&octree.root()), tree_walker);
+
+  return 0;
+}
+
 int main(void) {
 
   test_preorder_print();
   test_postorder_print();
+  test_leaves_print();
 
   return 0;
 }