Stream_compaction

Functions
template<typename DerivedPolicy , typename InputIterator , typename OutputIterator , typename Predicate >
OutputIterator	bolt::amp::copy_if (const bolt::amp::control &ctl, InputIterator first, InputIterator last, OutputIterator result, Predicate pred)
template<typename InputIterator , typename OutputIterator , typename Predicate >
OutputIterator	bolt::amp::copy_if (InputIterator first, InputIterator last, OutputIterator result, Predicate pred)
template<typename DerivedPolicy , typename InputIterator1 , typename InputIterator2 , typename OutputIterator , typename Predicate >
OutputIterator	bolt::amp::copy_if (const bolt::amp::control &ctl, InputIterator1 first, InputIterator1 last, InputIterator2 stencil, OutputIterator result, Predicate pred)
template<typename InputIterator1 , typename InputIterator2 , typename OutputIterator , typename Predicate >
OutputIterator	bolt::amp::copy_if (InputIterator1 first, InputIterator1 last, InputIterator2 stencil, OutputIterator result, Predicate pred)

Detailed Description

Function Documentation

template<typename DerivedPolicy , typename InputIterator , typename OutputIterator , typename Predicate >

OutputIterator bolt::amp::copy_if	(	const bolt::amp::control &	ctl,
		InputIterator	first,
		InputIterator	last,
		OutputIterator	result,
		Predicate	pred
	)

This version of copy_if copies elements from the range [first,last) to a range beginning at \ presult, except that any element which causes pred to be pred to be false is not copied.

More precisely, for every integer n such that 0 <= n < last-first, copy_if performs the assignment *result = *(first+n) and result is advanced one position if pred(*(first+n)). Otherwise, no assignment occurs and result is not advanced.

The algorithm's execution is parallelized as determined by system.

Parameters

ctl	Optional Control structure to control accelerator, debug, tuning, etc.See bolt::amp::control.
first	The beginning of the sequence from which to copy.
last	The end of the sequence from which to copy.
result	The beginning of the sequence into which to copy.
pred	The predicate to test on every value of the range [first, last).

Returns

result + n, where n is equal to the number of times pred evaluated to true in the range [first, last).

Template Parameters

InputIterator	is a model of Input Iterator, and InputIterator's value_type is convertible to Predicate's argument_type.
OutputIterator	is a model of Output Iterator.
Predicate	is a model of Predicate.

Precondition

The ranges [first, last) and [result, result + (last - first)) shall not overlap.

The following code snippet demonstrates how to use copy_if to perform stream compaction

#include <bolt/amp/copy.h>
...
struct is_even
{
  bool operator()(const int x)
  {
    return (x % 2) == 0;
  }
};
...
const int N = 6;
int V[N] = {-2, 0, -1, 0, 1, 2};
int result[4];

bolt::amp::copy_if(V, V + N, result, is_even());

// V remains {-2, 0, -1, 0, 1, 2}
// result is now {-2, 0, 0, 2}

See Also

remove_copy_if

template<typename DerivedPolicy , typename InputIterator1 , typename InputIterator2 , typename OutputIterator , typename Predicate >

OutputIterator bolt::amp::copy_if	(	const bolt::amp::control &	ctl,
		InputIterator1	first,
		InputIterator1	last,
		InputIterator2	stencil,
		OutputIterator	result,
		Predicate	pred
	)

This version of copy_if copies elements from the range [first,last) to a range beginning at result, except that any element whose corresponding stencil element causes pred to be false is not copied.

More precisely, for every integer n such that 0 <= n < last-first, copy_if performs the assignment *result = *(first+n) and result is advanced one position if pred(*(stencil+n)). Otherwise, no assignment occurs and result is not advanced.

The algorithm's execution is parallelized as determined by exec.

Parameters

ctl	Optional Control structure to control accelerator, debug, tuning, etc.See bolt::amp::control.
first	The beginning of the sequence from which to copy.
last	The end of the sequence from which to copy.
stencil	The beginning of the stencil sequence.
result	The beginning of the sequence into which to copy.
pred	The predicate to test on every value of the range [stencil, stencil + (last-first)).

Returns

result + n, where n is equal to the number of times pred evaluated to true in the range [stencil, stencil + (last-first)).

Template Parameters

DerivedPolicy	The name of the derived execution policy.
InputIterator1	is a model of Input Iterator.
InputIterator2	is a model of Input Iterator, and InputIterator2's value_type is convertible to Predicate's argument_type.
OutputIterator	is a model of Output Iterator.
Predicate	is a model of Predicate.

Precondition

The ranges [first, last) and [result, result + (last - first)) shall not overlap.

The ranges [stencil, stencil + (last - first)) and [result, result + (last - first)) shall not overlap.

#include <bolt/amp/copy.h>
#include <bolt/amp/execution_policy.h>
...
struct is_even
{
  bool operator()(const int x)
  {
    return (x % 2) == 0;
  }
};

int N = 6;
int data[N]    = { 0, 1,  2, 3, 4, 5};
int stencil[N] = {-2, 0, -1, 0, 1, 2};
int result[4];

bolt::amp::copy_if(data, data + N, stencil, result, is_even());

// data remains    = { 0, 1,  2, 3, 4, 5};
// stencil remains = {-2, 0, -1, 0, 1, 2};
// result is now     { 0, 1,  3, 5}

See Also

remove_copy_if