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/*
* Copyright 2008-2013 NVIDIA Corporation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#pragma once
#include <thrust/detail/config.h>
#include <thrust/pair.h>
#include <thrust/detail/function.h>
#include <thrust/iterator/iterator_traits.h>
THRUST_NAMESPACE_BEGIN
namespace system
{
namespace detail
{
namespace generic
{
namespace scalar
{
template<typename RandomAccessIterator, typename Size, typename T, typename BinaryPredicate>
__host__ __device__
RandomAccessIterator lower_bound_n(RandomAccessIterator first,
Size n,
const T &val,
BinaryPredicate comp)
{
// wrap comp
thrust::detail::wrapped_function<
BinaryPredicate,
bool
> wrapped_comp(comp);
Size start = 0, i;
while(start < n)
{
i = start + (n - start) / 2; // Overflow-safe variant of (a+b)/2
if(wrapped_comp(first[i], val))
{
start = i + 1;
}
else
{
n = i;
}
} // end while
return first + start;
}
// XXX generalize these upon implementation of scalar::distance & scalar::advance
template<typename RandomAccessIterator, typename T, typename BinaryPredicate>
__host__ __device__
RandomAccessIterator lower_bound(RandomAccessIterator first, RandomAccessIterator last,
const T &val,
BinaryPredicate comp)
{
typename thrust::iterator_difference<RandomAccessIterator>::type n = last - first;
return lower_bound_n(first, n, val, comp);
}
template<typename RandomAccessIterator, typename Size, typename T, typename BinaryPredicate>
__host__ __device__
RandomAccessIterator upper_bound_n(RandomAccessIterator first,
Size n,
const T &val,
BinaryPredicate comp)
{
// wrap comp
thrust::detail::wrapped_function<
BinaryPredicate,
bool
> wrapped_comp(comp);
Size start = 0, i;
while(start < n)
{
i = start + (n - start) / 2; // Overflow-safe variant of (a+b)/2
if(wrapped_comp(val, first[i]))
{
n = i;
}
else
{
start = i + 1;
}
} // end while
return first + start;
}
template<typename RandomAccessIterator, typename T, typename BinaryPredicate>
__host__ __device__
RandomAccessIterator upper_bound(RandomAccessIterator first, RandomAccessIterator last,
const T &val,
BinaryPredicate comp)
{
typename thrust::iterator_difference<RandomAccessIterator>::type n = last - first;
return upper_bound_n(first, n, val, comp);
}
template<typename RandomAccessIterator, typename T, typename BinaryPredicate>
__host__ __device__
pair<RandomAccessIterator,RandomAccessIterator>
equal_range(RandomAccessIterator first, RandomAccessIterator last,
const T &val,
BinaryPredicate comp)
{
RandomAccessIterator lb = thrust::system::detail::generic::scalar::lower_bound(first, last, val, comp);
return thrust::make_pair(lb, thrust::system::detail::generic::scalar::upper_bound(lb, last, val, comp));
}
template<typename RandomAccessIterator, typename T, typename Compare>
__host__ __device__
bool binary_search(RandomAccessIterator first, RandomAccessIterator last, const T &value, Compare comp)
{
RandomAccessIterator iter = thrust::system::detail::generic::scalar::lower_bound(first, last, value, comp);
// wrap comp
thrust::detail::wrapped_function<
Compare,
bool
> wrapped_comp(comp);
return iter != last && !wrapped_comp(value,*iter);
}
} // end scalar
} // end generic
} // end detail
} // end system
THRUST_NAMESPACE_END
#include <thrust/system/detail/generic/scalar/binary_search.inl>
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