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/*=========================================================================
Program: Visualization Toolkit
Module: vtkConstantImplicitBackend.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.
=========================================================================*/
// Funded by CEA, DAM, DIF, F-91297 Arpajon, France
#ifndef vtkConstantImplicitBackend_h
#define vtkConstantImplicitBackend_h
#include "vtkSetGet.h"
/**
* \struct vtkConstantImplicitBackend
* \brief A utility structure serving as a backend for constant implicit arrays
*
* This structure can be classified as a closure and can be called using syntax similar to a
* function.
*
* At construction it takes one parameter which is the constant value that it returns from its main
* function call regardless of index.
*
* An example of potential usage in a vtkImplicitArray
* ```
* double constant = some_number;
* vtkNew<vtkImplicitArray<vtkConstantImplicitBackend<double>>> constArray;
* constArray->SetBackend(std::make_shared<vtkConstantImplicitBackend<double>>(constant));
* constArray->SetNumberOfTuples(however_many_you_want);
* constArray->SetNumberOfComponents(whatever_youd_like);
* double value = constArray->GetTypedComponent(index_in_tuple_range, index_in_component_range);
* CHECK(constant == value); // always true
* ```
*/
template <typename ValueType>
struct vtkConstantImplicitBackend final
{
/**
* A non-trivially contructible constructor
*
* \param val the constant value to return for all indeces
*/
vtkConstantImplicitBackend(ValueType val)
: Value(val)
{
}
/**
* The main call method for the backend
*
* \return the constant value
*/
ValueType operator()(int vtkNotUsed(index)) const { return this->Value; }
/**
* The constant value stored in the backend
*/
const ValueType Value;
};
#endif // vtkConstantImplicitBackend_h
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