mismatch.hpp

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/*
Copyright (c) 2015, Scott Zuyderduyn
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//----------------------------------------------------------------------------
// algo/mismatch.hpp
//
// Extension of std::mismatch that recognizes device memory and can be called from
// host or device code.
//
// Author: Scott D. Zuyderduyn, Ph.D. (scott.zuyderduyn@utoronto.ca)
//----------------------------------------------------------------------------

#pragma once
#ifndef ECUDA_ALGO_MISMATCH_HPP
#define ECUDA_ALGO_MISMATCH_HPP

#include <algorithm>
#include <vector>

#include "../global.hpp"
#include "../iterator.hpp"
#include "../utility.hpp"

namespace ecuda {

namespace impl {

template<class InputIterator1,class InputIterator2>
inline __HOST__ __DEVICE__ ecuda::pair<InputIterator1,InputIterator2>
mismatch( InputIterator1 first1, InputIterator1 last1, InputIterator2 first2, ecuda::pair<ecuda::false_type,ecuda::false_type> ) // host/host memory
{
    #ifdef __CUDA_ARCH__
    return ecuda::pair<InputIterator1,InputIterator2>(first1,first2); // never called from device code
    #else
    // just defer to STL
    std::pair<InputIterator1,InputIterator2> p = std::mismatch( first1, last1, first2 );
    return ecuda::pair<InputIterator1,InputIterator2>(p.first,p.second);
    #endif
}

ECUDA_SUPPRESS_HD_WARNINGS
template<class InputIterator1,class InputIterator2>
__HOST__ __DEVICE__ ecuda::pair<InputIterator1,InputIterator2>
mismatch( InputIterator1 first1, InputIterator1 last1, InputIterator2 first2, ecuda::pair<ecuda::false_type,ecuda::true_type> ) // host/device memory
{
    #ifdef __CUDA_ARCH__
    return ecuda::pair<InputIterator1,InputIterator2>(first1,first2); // never called from device code
    #else
    typedef typename ecuda::remove_const<typename ecuda::iterator_traits<InputIterator2>::value_type>::type value_type2;
    typedef std::vector< value_type2, host_allocator<value_type2> > vector_type2;
    vector_type2 v2( ecuda::distance(first1,last1) );
    ecuda::copy( first2, first2+v2.size(), v2.begin() );
    std::pair<InputIterator1,typename vector_type2::iterator> p = std::mismatch( first1, last1, v2.begin() );
    ecuda::advance( first2, ecuda::distance(v2.begin(),p.second) );
    return ecuda::pair<InputIterator1,InputIterator2>( p.first, first2 );
    #endif
}

template<class InputIterator1,class InputIterator2>
__HOST__ __DEVICE__ ecuda::pair<InputIterator1,InputIterator2>
mismatch( InputIterator1 first1, InputIterator1 last1, InputIterator2 first2, ecuda::pair<ecuda::true_type,ecuda::false_type> ) // device/host memory
{
    #ifdef __CUDA_ARCH__
    return ecuda::pair<InputIterator1,InputIterator2>(first1,first2); // never called from device code
    #else
    InputIterator2 last2 = first2;
    ecuda::advance( last2, ecuda::distance(first1,last1) );
    ecuda::pair<InputIterator2,InputIterator1> p = mismatch( first2, last2, first1, ecuda::pair<ecuda::false_type,ecuda::true_type>() );
    return ecuda::pair<InputIterator1,InputIterator2>( p.second, p.first );
    #endif
}

ECUDA_SUPPRESS_HD_WARNINGS
template<class InputIterator1,class InputIterator2>
__HOST__ __DEVICE__ ecuda::pair<InputIterator1,InputIterator2>
mismatch( InputIterator1 first1, InputIterator1 last1, InputIterator2 first2, ecuda::pair<ecuda::true_type,ecuda::true_type> ) // device/device memory
{
    #ifdef __CUDA_ARCH__
    while( (first1 != last1) && (*first1 == *first2) ) { ++first1; ++first2; }
    return ecuda::pair<InputIterator1,InputIterator2>(first1,first2);
    #else
    typedef typename ecuda::remove_const<typename ecuda::iterator_traits<InputIterator1>::value_type>::type value_type1;
    typedef std::vector< value_type1, host_allocator<value_type1> > vector_type1;
    vector_type1 v1( ecuda::distance(first1,last1) );
    typedef typename ecuda::remove_const<typename ecuda::iterator_traits<InputIterator2>::value_type>::type value_type2;
    typedef std::vector< value_type2, host_allocator<value_type2> > vector_type2;
    vector_type2 v2( v1.size() );
    ecuda::copy( first1, last1, v1.begin() );
    InputIterator2 last2 = first2;
    ecuda::advance( last2, ecuda::distance(first1,last1) );
    ecuda::copy( first2, last2, v2.begin() );
    std::pair<typename vector_type1::iterator,typename vector_type2::iterator> p = std::mismatch( v1.begin(), v1.end(), v2.begin() );
    ecuda::advance( first1, ecuda::distance(v1.begin(),p.first) );
    ecuda::advance( first2, ecuda::distance(v2.begin(),p.second) );
    return ecuda::pair<InputIterator1,InputIterator2>( first1, first2 );
    #endif
}

} // namespace impl

ECUDA_SUPPRESS_HD_WARNINGS
template<class InputIterator1,class InputIterator2>
inline __HOST__ __DEVICE__ ecuda::pair<InputIterator1,InputIterator2>
mismatch( InputIterator1 first1, InputIterator1 last1, InputIterator2 first2 )
{
    return impl::mismatch(
                    first1, last1,
                    first2,
                    ecuda::pair<typename ecuda::iterator_traits<InputIterator1>::is_device_iterator,typename ecuda::iterator_traits<InputIterator2>::is_device_iterator>()
                );
}

} // namespace ecuda

#endif