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/*=========================================================================
Program: Visualization Toolkit
Module: vtkDataAssemblyVisitor.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.
=========================================================================*/
/**
* @class vtkDataAssemblyVisitor
* @brief visitor API for vtkDataAssembly
*
* vtkDataAssemblyVisitor defines a visitor API for vtkDataAssembly. A concrete
* subclass of vtkDataAssemblyVisitor can be passed to `vtkDataAssembly::Visit`
* to execute custom code on each node in the data-assembly.
*
* `vtkDataAssembly::Visit` will call `vtkDataAssemblyVisitor::Visit` on each
* node in the assembly (or chosen subtree). The traversal order, i.e.
* depth-first or breadth-first, is selected by the arguments passed to
* `vtkDataAssembly::Visit`. Before traversing a sub-tree for a particular node,
* `vtkDataAssemblyVisitor::GetTraverseSubtree` is called, if it returns false,
* the subtree is skipped. If it returns true, then then
* `vtkDataAssemblyVisitor::BeginSubTree` is called, followed by calls to
* `vtkDataAssemblyVisitor::Visit` for each of the child nodes, and finally
* `vtkDataAssemblyVisitor::EndSubTree` is called.
*
* In depth-first order, the subtree traversal is recursive. Thus, after
* `BeginSubTree` is called for specific node, all its children and their
* subtrees are traversed before `EndSubTree` gets called for that node.
*
* In breadth-first order, a first-in-first-out queue is used. A node is
* visited, i.e. `vtkDataAssemblyVisitor::Visit` called on it, then if
* `GetTraverseSubtree` returns true, `Visit` gets called on all its immediate
* children one after another followed by `EndSubTree` on the parent node.
* As each of the child nodes are visited, they get added to the queue.
* Now, for each node in the queue, the process repeats i.e.
* `GetTraverseSubtree` is called, followed by the subtree traversal for that
* node. This continues until the queue empty.
*
* @sa vtkDataAssembly
*/
#ifndef vtkDataAssemblyVisitor_h
#define vtkDataAssemblyVisitor_h
#include "vtkCommonDataModelModule.h" // for export macros
#include "vtkObject.h"
#include <memory> // for std::unique_ptr
#include <vector> // for std::vector
VTK_ABI_NAMESPACE_BEGIN
class vtkDataAssembly;
class VTKCOMMONDATAMODEL_EXPORT vtkDataAssemblyVisitor : public vtkObject
{
public:
vtkTypeMacro(vtkDataAssemblyVisitor, vtkObject);
void PrintSelf(ostream& os, vtkIndent indent) override;
protected:
vtkDataAssemblyVisitor();
~vtkDataAssemblyVisitor() override;
/**
* Provides access to the assembly during traversal, otherwise returns
* nullptr.
*/
const vtkDataAssembly* GetAssembly() const { return this->Assembly; }
/**
* Returns the current traversal order.
*/
int GetTraversalOrder() const { return this->TraversalOrder; }
/**
* Called on every node being visited. @arg nodeid is the id of the node being
* visited.
*
*/
virtual void Visit(int nodeid) = 0;
/**
* Called to check if the subtree anchored at `nodeid` is to be traversed.
* Default implementation returns true. Subclasses can override this method to
* skip traversing 'dead' branches.
*/
virtual bool GetTraverseSubtree(int vtkNotUsed(nodeid)) { return true; }
///@{
/**
* Methods called at the start and end of a subtree traversal.
*/
virtual void BeginSubTree(int vtkNotUsed(nodeid)) {}
virtual void EndSubTree(int vtkNotUsed(nodeid)) {}
///@}
///@{
/**
* API to access information from the current node being processed.
* It's preferred to use this API rather than API on vtkDataAssembly when
* working with the current node for improved performance.
*/
const char* GetCurrentNodeName() const;
std::vector<unsigned int> GetCurrentDataSetIndices() const;
///@}
private:
vtkDataAssemblyVisitor(const vtkDataAssemblyVisitor&) = delete;
void operator=(const vtkDataAssemblyVisitor&) = delete;
class vtkInternals;
std::unique_ptr<vtkInternals> Internals;
const vtkDataAssembly* Assembly;
int TraversalOrder;
friend class vtkDataAssembly;
};
VTK_ABI_NAMESPACE_END
#endif
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