VTK-m  1.8
Public Types | Public Member Functions | List of all members
vtkm::cont::ArrayPortal< T > Class Template Reference

A class that points to and access and array of data. More...

#include <ArrayPortal.h>

Public Types

using ValueType = T
 The type of each value in the array. More...
 

Public Member Functions

VTKM_EXEC_CONT vtkm::Id GetNumberOfValues () const
 The total number of values in the array. More...
 
VTKM_EXEC_CONT ValueType Get (vtkm::Id index) const
 Gets a value from the array. More...
 
VTKM_EXEC_CONT void Set (vtkm::Id index, const ValueType &value) const
 Sets a value in the array. More...
 

Detailed Description

template<typename T>
class vtkm::cont::ArrayPortal< T >

A class that points to and access and array of data.

The ArrayPortal class itself does not exist; this code is provided for documentation purposes only.

An ArrayPortal object acts like a pointer to a random-access container (that is, an array) and also lets you set and get values in that array. In many respects an ArrayPortal is similar in concept to that of iterators but with a much simpler interface and no internal concept of position. Otherwise, ArrayPortal objects may be passed and copied around so that multiple entities may be accessing the same array.

An ArrayPortal differs from an ArrayHandle in that the ArrayPortal is a much lighterweight object and that it does not manage things like allocation and control/execution sharing. An ArrayPortal also differs from a Storage in that it does not actually contain the data but rather points to it. In this way the ArrayPortal can be copied and passed and still point to the same data.

Most VTKm users generally do not need to do much or anything with ArrayPortal objects. It is mostly an internal mechanism. However, an ArrayPortal can be used to pass constant input data to an ArrayHandle.

Although portals are defined in the execution environment, they are also used in the control environment for accessing data on the host.

Since utilities like IsWritableArrayHandle checks for the existence of a Set method on a portal, if the portal is backed by a read-only ArrayHandle, the Set method must not be defined. If the portal may or may not be writable (e.g., ArrayHandleCast may be casting a read-only OR read-write array), the Set method may be conditionally removed using SFINAE.

The ArrayPortalToIterators utilities wrap ArrayPortals in STL-style iterators. If an ArrayPortal implementation wishes to provide a custom iterator type, it may define an IteratorType type alias along with the methods IteratorType GetIteratorBegin() and IteratorType GetIteratorEnd(). These are not required members, but if present, will allow additional optimizations for certain portals.

Member Typedef Documentation

◆ ValueType

template<typename T >
using vtkm::cont::ArrayPortal< T >::ValueType = T

The type of each value in the array.

Member Function Documentation

◆ Get()

template<typename T >
VTKM_EXEC_CONT ValueType vtkm::cont::ArrayPortal< T >::Get ( vtkm::Id  index) const

Gets a value from the array.

◆ GetNumberOfValues()

template<typename T >
VTKM_EXEC_CONT vtkm::Id vtkm::cont::ArrayPortal< T >::GetNumberOfValues ( ) const

The total number of values in the array.

They are index from 0 to GetNumberOfValues()-1.

◆ Set()

template<typename T >
VTKM_EXEC_CONT void vtkm::cont::ArrayPortal< T >::Set ( vtkm::Id  index,
const ValueType value 
) const

Sets a value in the array.

If it is not possible to set a value in the array, this method must not be defined.


The documentation for this class was generated from the following file: