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// SPDX-FileCopyrightText: Copyright © DUNE Project contributors, see file LICENSE.md in module root
// SPDX-License-Identifier: LicenseRef-GPL-2.0-only-with-DUNE-exception
#ifndef DUNE_PYTHON_ISTL_SLICE_HH
#define DUNE_PYTHON_ISTL_SLICE_HH
#include <cassert>
#include <type_traits>
#include <dune/common/iteratorfacades.hh>
namespace Dune
{
namespace Python
{
// ArraySlice
// ----------
template< class A >
struct ArraySlice
{
typedef typename A::member_type member_type;
typedef typename A::size_type size_type;
typedef decltype( std::declval< A & >()[ 0 ] ) reference;
typedef decltype( std::declval< const A & >()[ 0 ] ) const_reference;
private:
template< class T >
struct IteratorImpl
: public RandomAccessIteratorFacade< IteratorImpl< T >, T >
{
friend class IteratorImpl< std::add_const_t< T > >;
friend class IteratorImpl< std::remove_const_t< T > >;
friend class RandomAccessIteratorFacade< IteratorImpl< std::add_const_t< T > >, std::add_const_t< T > >;
friend class RandomAccessIteratorFacade< IteratorImpl< std::remove_const_t< T > >, std::remove_const_t< T > >;
IteratorImpl () noexcept = default;
IteratorImpl ( T &array, size_type start, size_type step ) noexcept : array_( &array ), index_( start ), step_( step ) {}
IteratorImpl ( const IteratorImpl< std::remove_const_t< T > > &other ) noexcept : array_( other.array_ ), index_( other.index_ ), step_( other.step_ ) {}
private:
bool equals ( const IteratorImpl &other ) const noexcept { return (index_ == other.index_); }
std::ptrdiff_t distanceTo ( const IteratorImpl &other ) const noexcept { return (other.index_ - index_) / step_; }
reference elementAt ( std::ptrdiff_t i ) const noexcept( noexcept( std::declval< T & >()[ 0 ] ) ) { return (*array_)[ index_ ]; }
void increment () noexcept { index_ += step_; }
void decrement () noexcept { index_ -= step_; }
void advance ( std::ptrdiff_t i ) noexcept { index_ += i*step_; }
T *array_ = nullptr;
size_type index_ = 0, step_ = 0;
};
public:
typedef IteratorImpl< const A > const_iterator;
typedef IteratorImpl< A > iterator;
ArraySlice ( A &array, size_type start, size_type step, size_type size ) noexcept
: array_( array ), start_( start ), step_( step ), size_( size )
{}
reference operator[] ( size_type i ) noexcept( noexcept( std::declval< A & >()[ 0 ] ) ) { return array_[ start_ + i*step_ ]; }
const_reference operator[] ( size_type i ) const noexcept( noexcept( std::declval< const A & >()[ 0 ] ) ) { return array_[ start_ + i*step_ ]; }
const_iterator begin () const noexcept { return const_iterator( array_, start_, step_ ); }
iterator begin () noexcept { return iterator( array_, start_, step_); }
const_iterator end () const noexcept { return const_iterator( array_, start_ + step_*size_, step_ ); }
iterator end () noexcept { return iterator( array_, start_ + step_*size_, step_ ); }
const_iterator beforeEnd () const noexcept { return const_iterator( array_, start_ + step_*(size_-1), step_ ); }
iterator beforeEnd () noexcept { return iterator( array_, start_ + step_*(size_-1), step_ ); }
const_iterator beforeBegin () const noexcept { return const_iterator( array_, start_ - step_, step_ ); }
iterator beforeBegin () noexcept { return iterator( array_, start_ - step_, step_ ); }
const_iterator find ( size_type i ) const noexcept { return iterator( array_, start_ + step_*std::min( i, size_ ), step_ ); }
iterator find ( size_type i ) noexcept { return iterator( array_, start_ + step_*std::min( i, size_ ), step_ ); }
size_type size () const noexcept { return size_; }
private:
A &array_;
size_type start_, step_, size_;
};
} // namespace Python
} // namespace Dune
#endif // #ifndef DUNE_PYTHON_ISTL_SLICE_HH
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