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Struct thrust::host_execution_policy

host_execution_policy is the base class for all Thrust parallel execution policies which are derived from Thrust’s default host backend system configured with the THRUST_HOST_SYSTEM macro.

Custom user-defined backends which wish to inherit the functionality of Thrust’s host backend system should derive a policy from this type in order to interoperate with Thrust algorithm dispatch.

The following code snippet demonstrates how to derive a standalone custom execution policy from thrust::host_execution_policy to implement a backend which specializes for_each while inheriting the behavior of every other algorithm from the host system:

#include <thrust/execution_policy.h>
#include <iostream>

// define a type derived from thrust::host_execution_policy to distinguish our custom execution policy:
struct my_policy : thrust::host_execution_policy<my_policy> {};

// overload for_each on my_policy
template<typename Iterator, typename Function>
Iterator for_each(my_policy, Iterator first, Iterator last, Function f)
  std::cout << "Hello, world from for_each(my_policy)!" << std::endl;

  for(; first < last; ++first)

  return first;

struct ignore_argument
  void operator()(int) {}

int main()
  int data[4];

  // dispatch thrust::for_each using our custom policy:
  my_policy exec;
  thrust::for_each(exec, data, data + 4, ignore_argument());

  // dispatch thrust::transform whose behavior our policy inherits
  thrust::transform(exec, data, data, + 4, data, thrust::identity<int>());

  return 0;

Inherits From: thrust::system::__THRUST_HOST_SYSTEM_NAMESPACE::execution_policy< DerivedPolicy >


#include <thrust/execution_policy.h>
template <typename DerivedPolicy> struct thrust::host_execution_policy { };