mirror of
https://github.com/boostorg/iterator.git
synced 2025-07-04 08:16:31 +02:00
72 lines
2.3 KiB
C++
72 lines
2.3 KiB
C++
|
// (C) Copyright Toon Knapen 2001. Permission to copy, use,
|
||
|
|
// modify, sell and distribute this software is granted provided this
|
||
|
|
// copyright notice appears in all copies. This software is provided
|
||
|
|
// "as is" without express or implied warranty, and with no claim as
|
||
|
|
// to its suitability for any purpose.
|
||
|
|
//
|
||
|
|
|
||
|
|
#include <boost/iterator_adaptors.hpp>
|
||
|
|
|
||
|
|
namespace boost {
|
||
|
|
|
||
|
|
template < typename OrderIt >
|
||
|
|
struct permutation_iterator_policies : public default_iterator_policies
|
||
|
|
{
|
||
|
|
permutation_iterator_policies() {}
|
||
|
|
|
||
|
|
permutation_iterator_policies(OrderIt order_it)
|
||
|
|
: order_it_( order_it )
|
||
|
|
{}
|
||
|
|
|
||
|
|
template <class IteratorAdaptor>
|
||
|
|
typename IteratorAdaptor::reference dereference(const IteratorAdaptor& x) const
|
||
|
|
{ return *(x.base() + *order_it_); }
|
||
|
|
|
||
|
|
template <class IteratorAdaptor>
|
||
|
|
void increment(IteratorAdaptor& x)
|
||
|
|
{ ++order_it_; }
|
||
|
|
|
||
|
|
template <class IteratorAdaptor>
|
||
|
|
void decrement(IteratorAdaptor& x)
|
||
|
|
{ --order_it_; }
|
||
|
|
|
||
|
|
template <class IteratorAdaptor, class DifferenceType>
|
||
|
|
void advance(IteratorAdaptor& x, DifferenceType n)
|
||
|
|
{ std::advance( order_it_, n ); }
|
||
|
|
|
||
|
|
template <class IteratorAdaptor1, class IteratorAdaptor2>
|
||
|
|
typename IteratorAdaptor1::difference_type
|
||
|
|
distance(const IteratorAdaptor1& x, const IteratorAdaptor2& y) const
|
||
|
|
{ return std::distance( x.policies().order_it_, y.policies().order_it_ ); }
|
||
|
|
|
||
|
|
template <class IteratorAdaptor1, class IteratorAdaptor2>
|
||
|
|
bool equal(const IteratorAdaptor1& x, const IteratorAdaptor2& y) const
|
||
|
|
{ return x.policies().order_it_ == y.policies().order_it_; }
|
||
|
|
|
||
|
|
OrderIt order_it_;
|
||
|
|
};
|
||
|
|
|
||
|
|
/// generate an iterator that will access the elements
|
||
|
|
/// behind the random-access iterator RAIt in the
|
||
|
|
/// order specified by the OrderIt iterator.
|
||
|
|
/// preconditions:
|
||
|
|
/// The OrderIt::value_type will be used in iterator arithmetic
|
||
|
|
template < typename RAIt, typename OrderIt >
|
||
|
|
struct permutation_iterator_generator
|
||
|
|
{
|
||
|
|
typedef boost::iterator_adaptor
|
||
|
|
< RAIt,
|
||
|
|
permutation_iterator_policies< OrderIt >
|
||
|
|
> type;
|
||
|
|
};
|
||
|
|
|
||
|
|
template < class OrderIt, class RAIt >
|
||
|
|
inline typename permutation_iterator_generator< RAIt, OrderIt >::type
|
||
|
|
make_permutation_iterator(RAIt base, OrderIt order)
|
||
|
|
{
|
||
|
|
typedef typename permutation_iterator_generator< RAIt, OrderIt >::type result_t;
|
||
|
|
return result_t( base, order );
|
||
|
|
}
|
||
|
|
|
||
|
|
} // namespace boost
|