text: /*=========================================================================
  
    Program:   Visualization Toolkit
    Module:    vtkTree.h
  
    Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
    All rights reserved.
    See Copyright.txt or http://www.kitware.com/Copyright.htm for details.
  
       This software is distributed WITHOUT ANY WARRANTY; without even
       the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
       PURPOSE.  See the above copyright notice for more information.
  
  =========================================================================*/
  /*-------------------------------------------------------------------------
    Copyright 2008 Sandia Corporation.
    Under the terms of Contract DE-AC04-94AL85000 with Sandia Corporation,
    the U.S. Government retains certain rights in this software.
  -------------------------------------------------------------------------*/
  /**
   * @class   vtkTree
   * @brief   A rooted tree data structure.
   *
   *
   * vtkTree is a connected directed graph with no cycles. A tree is a type of
   * directed graph, so works with all graph algorithms.
   *
   * vtkTree is a read-only data structure.
   * To construct a tree, create an instance of vtkMutableDirectedGraph.
   * Add vertices and edges with AddVertex() and AddEdge(). You may alternately
   * start by adding a single vertex as the root then call graph->AddChild(parent)
   * which adds a new vertex and connects the parent to the child.
   * The tree MUST have all edges in the proper direction, from parent to child.
   * After building the tree, call tree->CheckedShallowCopy(graph) to copy the
   * structure into a vtkTree. This method will return false if the graph is
   * an invalid tree.
   *
   * vtkTree provides some convenience methods for obtaining the parent and
   * children of a vertex, for finding the root, and determining if a vertex
   * is a leaf (a vertex with no children).
   *
   * @sa
   * vtkDirectedGraph vtkMutableDirectedGraph vtkGraph
   */
  
  #ifndef vtkTree_h
  #define vtkTree_h
  
  #include "vtkCommonDataModelModule.h" // For export macro
  #include "vtkDirectedAcyclicGraph.h"
  
  class vtkIdTypeArray;
  
  class VTKCOMMONDATAMODEL_EXPORT vtkTree : public vtkDirectedAcyclicGraph
  {
  public:
    static vtkTree* New();
    vtkTypeMacro(vtkTree, vtkDirectedAcyclicGraph);
    void PrintSelf(ostream& os, vtkIndent indent) override;
  
    /**
     * Return what type of dataset this is.
     */
    int GetDataObjectType() override { return VTK_TREE; }
  
    //@{
    /**
     * Get the root vertex of the tree.
     */
    vtkGetMacro(Root, vtkIdType);
    //@}
  
    /**
     * Get the number of children of a vertex.
     */
    vtkIdType GetNumberOfChildren(vtkIdType v) { return this->GetOutDegree(v); }
  
    /**
     * Get the i-th child of a parent vertex.
     */
    vtkIdType GetChild(vtkIdType v, vtkIdType i);
  
    /**
     * Get the child vertices of a vertex.
     * This is a convenience method that functions exactly like
     * GetAdjacentVertices.
     */
    void GetChildren(vtkIdType v, vtkAdjacentVertexIterator* it) { this->GetAdjacentVertices(v, it); }
  
    /**
     * Get the parent of a vertex.
     */
    vtkIdType GetParent(vtkIdType v);
  
    /**
     * Get the edge connecting the vertex to its parent.
     */
    vtkEdgeType GetParentEdge(vtkIdType v);
  
    /**
     * Get the level of the vertex in the tree.  The root vertex has level 0.
     * Returns -1 if the vertex id is < 0 or greater than the number of vertices
     * in the tree.
     */
    vtkIdType GetLevel(vtkIdType v);
  
    /**
     * Return whether the vertex is a leaf (i.e. it has no children).
     */
    bool IsLeaf(vtkIdType vertex);
  
    //@{
    /**
     * Retrieve a graph from an information vector.
     */
    static vtkTree* GetData(vtkInformation* info);
    static vtkTree* GetData(vtkInformationVector* v, int i = 0);
    //@}
  
    /**
     * Reorder the children of a parent vertex.
     * The children array must contain all the children of parent,
     * just in a different order.
     * This does not change the topology of the tree.
     */
    virtual void ReorderChildren(vtkIdType parent, vtkIdTypeArray* children);
  
  protected:
    vtkTree();
    ~vtkTree() override;
  
    /**
     * Check the storage, and accept it if it is a valid
     * tree.
     */
    bool IsStructureValid(vtkGraph* g) override;
  
    /**
     * The root of the tree.
     */
    vtkIdType Root;
  
  private:
    vtkTree(const vtkTree&) = delete;
    void operator=(const vtkTree&) = delete;
  };
  
  #endif
  