## CGAL::Tree_anchor<Data, Window>

### Definition

Tree_anchor is also derived from Tree_base. Therefore, it provides the same methods as Range_tree_d and Segment_tree_d, but does nothing; it can be used as a recursion anchor for those classes. Therefore, instantiate Sublayer_type of Range_tree_d (Segment_tree_d respectively) with Tree_anchor and the container classes for the data items (Data and Window).

### Definition

Tree_anchor<Data, Window>::Data
| container Data.
Tree_anchor<Data, Window>::Window
| container Window.

### Creation

#include <CGAL/Tree_base.h>

Tree_anchor<Data, Window> a;

### Operations

template<class OutputIterator>
OutputIterator | a.window_query ( Window win, OutputIterator result)
template<class OutputIterator>
OutputIterator | a.enclosing_query ( Window win, OutputIterator result)
bool | a.is_valid () | returns true;

Protected Operations

bool | a.is_inside ( Window win, Data object)
|  | returns true.
bool | a.is_anchor () | returns true.

### Example

The following figures show a number of rectangles and a 2-dimensional segment tree built on them.

<
Two dimensional interval data. |  | Two dimensional segment tree according to the interval data.