整理
This commit is contained in:
698
include/boost/range/adaptor/strided.hpp
Normal file
698
include/boost/range/adaptor/strided.hpp
Normal file
@@ -0,0 +1,698 @@
|
||||
// Boost.Range library
|
||||
//
|
||||
// Copyright Neil Groves 2007. Use, modification and
|
||||
// distribution is subject to the Boost Software License, Version
|
||||
// 1.0. (See accompanying file LICENSE_1_0.txt or copy at
|
||||
// http://www.boost.org/LICENSE_1_0.txt)
|
||||
//
|
||||
//
|
||||
// For more information, see http://www.boost.org/libs/range/
|
||||
//
|
||||
#ifndef BOOST_RANGE_ADAPTOR_STRIDED_HPP_INCLUDED
|
||||
#define BOOST_RANGE_ADAPTOR_STRIDED_HPP_INCLUDED
|
||||
|
||||
#include <boost/range/adaptor/argument_fwd.hpp>
|
||||
#include <boost/range/iterator_range.hpp>
|
||||
#include <boost/iterator/iterator_facade.hpp>
|
||||
#include <boost/iterator/enable_if_convertible.hpp>
|
||||
#include <iterator>
|
||||
|
||||
namespace boost
|
||||
{
|
||||
namespace range_detail
|
||||
{
|
||||
// strided_iterator for wrapping a forward traversal iterator
|
||||
template<class BaseIterator, class Category>
|
||||
class strided_iterator
|
||||
: public iterator_facade<
|
||||
strided_iterator<BaseIterator, Category>
|
||||
, typename iterator_value<BaseIterator>::type
|
||||
, forward_traversal_tag
|
||||
, typename iterator_reference<BaseIterator>::type
|
||||
, typename iterator_difference<BaseIterator>::type
|
||||
>
|
||||
{
|
||||
friend class ::boost::iterator_core_access;
|
||||
|
||||
typedef iterator_facade<
|
||||
strided_iterator<BaseIterator, Category>
|
||||
, typename iterator_value<BaseIterator>::type
|
||||
, forward_traversal_tag
|
||||
, typename iterator_reference<BaseIterator>::type
|
||||
, typename iterator_difference<BaseIterator>::type
|
||||
> super_t;
|
||||
|
||||
public:
|
||||
typedef typename super_t::difference_type difference_type;
|
||||
typedef typename super_t::reference reference;
|
||||
typedef BaseIterator base_iterator;
|
||||
typedef std::forward_iterator_tag iterator_category;
|
||||
|
||||
strided_iterator()
|
||||
: m_it()
|
||||
, m_last()
|
||||
, m_stride()
|
||||
{
|
||||
}
|
||||
|
||||
strided_iterator(base_iterator it,
|
||||
base_iterator last,
|
||||
difference_type stride)
|
||||
: m_it(it)
|
||||
, m_last(last)
|
||||
, m_stride(stride)
|
||||
{
|
||||
}
|
||||
|
||||
template<class OtherIterator>
|
||||
strided_iterator(
|
||||
const strided_iterator<OtherIterator, Category>& other,
|
||||
typename iterators::enable_if_convertible<
|
||||
OtherIterator,
|
||||
base_iterator
|
||||
>::type* = 0
|
||||
)
|
||||
: m_it(other.base())
|
||||
, m_last(other.base_end())
|
||||
, m_stride(other.get_stride())
|
||||
{
|
||||
}
|
||||
|
||||
base_iterator base() const
|
||||
{
|
||||
return m_it;
|
||||
}
|
||||
|
||||
base_iterator base_end() const
|
||||
{
|
||||
return m_last;
|
||||
}
|
||||
|
||||
difference_type get_stride() const
|
||||
{
|
||||
return m_stride;
|
||||
}
|
||||
|
||||
private:
|
||||
void increment()
|
||||
{
|
||||
for (difference_type i = 0;
|
||||
(m_it != m_last) && (i < m_stride); ++i)
|
||||
{
|
||||
++m_it;
|
||||
}
|
||||
}
|
||||
|
||||
reference dereference() const
|
||||
{
|
||||
return *m_it;
|
||||
}
|
||||
|
||||
template<class OtherIterator>
|
||||
bool equal(
|
||||
const strided_iterator<OtherIterator, Category>& other,
|
||||
typename iterators::enable_if_convertible<
|
||||
OtherIterator,
|
||||
base_iterator
|
||||
>::type* = 0) const
|
||||
{
|
||||
return m_it == other.m_it;
|
||||
}
|
||||
|
||||
base_iterator m_it;
|
||||
base_iterator m_last;
|
||||
difference_type m_stride;
|
||||
};
|
||||
|
||||
// strided_iterator for wrapping a bidirectional iterator
|
||||
template<class BaseIterator>
|
||||
class strided_iterator<BaseIterator, bidirectional_traversal_tag>
|
||||
: public iterator_facade<
|
||||
strided_iterator<BaseIterator, bidirectional_traversal_tag>
|
||||
, typename iterator_value<BaseIterator>::type
|
||||
, bidirectional_traversal_tag
|
||||
, typename iterator_reference<BaseIterator>::type
|
||||
, typename iterator_difference<BaseIterator>::type
|
||||
>
|
||||
{
|
||||
friend class ::boost::iterator_core_access;
|
||||
|
||||
typedef iterator_facade<
|
||||
strided_iterator<BaseIterator, bidirectional_traversal_tag>
|
||||
, typename iterator_value<BaseIterator>::type
|
||||
, bidirectional_traversal_tag
|
||||
, typename iterator_reference<BaseIterator>::type
|
||||
, typename iterator_difference<BaseIterator>::type
|
||||
> super_t;
|
||||
public:
|
||||
typedef typename super_t::difference_type difference_type;
|
||||
typedef typename super_t::reference reference;
|
||||
typedef BaseIterator base_iterator;
|
||||
typedef typename boost::make_unsigned<difference_type>::type
|
||||
size_type;
|
||||
typedef std::bidirectional_iterator_tag iterator_category;
|
||||
|
||||
strided_iterator()
|
||||
: m_it()
|
||||
, m_offset()
|
||||
, m_index()
|
||||
, m_stride()
|
||||
{
|
||||
}
|
||||
|
||||
strided_iterator(base_iterator it,
|
||||
size_type index,
|
||||
difference_type stride)
|
||||
: m_it(it)
|
||||
, m_offset()
|
||||
, m_index(index)
|
||||
, m_stride(stride)
|
||||
{
|
||||
if (stride && ((m_index % stride) != 0))
|
||||
m_index += (stride - (m_index % stride));
|
||||
}
|
||||
|
||||
template<class OtherIterator>
|
||||
strided_iterator(
|
||||
const strided_iterator<
|
||||
OtherIterator,
|
||||
bidirectional_traversal_tag
|
||||
>& other,
|
||||
typename iterators::enable_if_convertible<
|
||||
OtherIterator,
|
||||
base_iterator
|
||||
>::type* = 0
|
||||
)
|
||||
: m_it(other.base())
|
||||
, m_offset(other.get_offset())
|
||||
, m_index(other.get_index())
|
||||
, m_stride(other.get_stride())
|
||||
{
|
||||
}
|
||||
|
||||
base_iterator base() const
|
||||
{
|
||||
return m_it;
|
||||
}
|
||||
|
||||
difference_type get_offset() const
|
||||
{
|
||||
return m_offset;
|
||||
}
|
||||
|
||||
size_type get_index() const
|
||||
{
|
||||
return m_index;
|
||||
}
|
||||
|
||||
difference_type get_stride() const
|
||||
{
|
||||
return m_stride;
|
||||
}
|
||||
|
||||
private:
|
||||
void increment()
|
||||
{
|
||||
m_offset += m_stride;
|
||||
}
|
||||
|
||||
void decrement()
|
||||
{
|
||||
m_offset -= m_stride;
|
||||
}
|
||||
|
||||
reference dereference() const
|
||||
{
|
||||
update();
|
||||
return *m_it;
|
||||
}
|
||||
|
||||
void update() const
|
||||
{
|
||||
std::advance(m_it, m_offset);
|
||||
m_index += m_offset;
|
||||
m_offset = 0;
|
||||
}
|
||||
|
||||
template<class OtherIterator>
|
||||
bool equal(
|
||||
const strided_iterator<
|
||||
OtherIterator,
|
||||
bidirectional_traversal_tag
|
||||
>& other,
|
||||
typename iterators::enable_if_convertible<
|
||||
OtherIterator,
|
||||
base_iterator
|
||||
>::type* = 0) const
|
||||
{
|
||||
return (m_index + m_offset) ==
|
||||
(other.get_index() + other.get_offset());
|
||||
}
|
||||
|
||||
mutable base_iterator m_it;
|
||||
mutable difference_type m_offset;
|
||||
mutable size_type m_index;
|
||||
difference_type m_stride;
|
||||
};
|
||||
|
||||
// strided_iterator implementation for wrapping a random access iterator
|
||||
template<class BaseIterator>
|
||||
class strided_iterator<BaseIterator, random_access_traversal_tag>
|
||||
: public iterator_facade<
|
||||
strided_iterator<BaseIterator, random_access_traversal_tag>
|
||||
, typename iterator_value<BaseIterator>::type
|
||||
, random_access_traversal_tag
|
||||
, typename iterator_reference<BaseIterator>::type
|
||||
, typename iterator_difference<BaseIterator>::type
|
||||
>
|
||||
{
|
||||
friend class ::boost::iterator_core_access;
|
||||
|
||||
typedef iterator_facade<
|
||||
strided_iterator<BaseIterator, random_access_traversal_tag>
|
||||
, typename iterator_value<BaseIterator>::type
|
||||
, random_access_traversal_tag
|
||||
, typename iterator_reference<BaseIterator>::type
|
||||
, typename iterator_difference<BaseIterator>::type
|
||||
> super_t;
|
||||
public:
|
||||
typedef typename super_t::difference_type difference_type;
|
||||
typedef typename super_t::reference reference;
|
||||
typedef BaseIterator base_iterator;
|
||||
typedef std::random_access_iterator_tag iterator_category;
|
||||
|
||||
strided_iterator()
|
||||
: m_it()
|
||||
, m_first()
|
||||
, m_index(0)
|
||||
, m_stride()
|
||||
{
|
||||
}
|
||||
|
||||
strided_iterator(
|
||||
base_iterator first,
|
||||
base_iterator it,
|
||||
difference_type stride
|
||||
)
|
||||
: m_it(it)
|
||||
, m_first(first)
|
||||
, m_index(stride ? (it - first) : difference_type())
|
||||
, m_stride(stride)
|
||||
{
|
||||
if (stride && ((m_index % stride) != 0))
|
||||
m_index += (stride - (m_index % stride));
|
||||
}
|
||||
|
||||
template<class OtherIterator>
|
||||
strided_iterator(
|
||||
const strided_iterator<
|
||||
OtherIterator,
|
||||
random_access_traversal_tag
|
||||
>& other,
|
||||
typename iterators::enable_if_convertible<
|
||||
OtherIterator,
|
||||
base_iterator
|
||||
>::type* = 0
|
||||
)
|
||||
: m_it(other.base())
|
||||
, m_first(other.base_begin())
|
||||
, m_index(other.get_index())
|
||||
, m_stride(other.get_stride())
|
||||
{
|
||||
}
|
||||
|
||||
base_iterator base_begin() const
|
||||
{
|
||||
return m_first;
|
||||
}
|
||||
|
||||
base_iterator base() const
|
||||
{
|
||||
return m_it;
|
||||
}
|
||||
|
||||
difference_type get_stride() const
|
||||
{
|
||||
return m_stride;
|
||||
}
|
||||
|
||||
difference_type get_index() const
|
||||
{
|
||||
return m_index;
|
||||
}
|
||||
|
||||
private:
|
||||
void increment()
|
||||
{
|
||||
m_index += m_stride;
|
||||
}
|
||||
|
||||
void decrement()
|
||||
{
|
||||
m_index -= m_stride;
|
||||
}
|
||||
|
||||
void advance(difference_type offset)
|
||||
{
|
||||
m_index += (m_stride * offset);
|
||||
}
|
||||
|
||||
// Implementation detail: only update the actual underlying iterator
|
||||
// at the point of dereference. This is done so that the increment
|
||||
// and decrement can overshoot the valid sequence as is required
|
||||
// by striding. Since we can do all comparisons just with the index
|
||||
// simply, and all dereferences must be within the valid range.
|
||||
void update() const
|
||||
{
|
||||
m_it = m_first + m_index;
|
||||
}
|
||||
|
||||
template<class OtherIterator>
|
||||
difference_type distance_to(
|
||||
const strided_iterator<
|
||||
OtherIterator,
|
||||
random_access_traversal_tag
|
||||
>& other,
|
||||
typename iterators::enable_if_convertible<
|
||||
OtherIterator, base_iterator>::type* = 0) const
|
||||
{
|
||||
BOOST_ASSERT((other.m_index - m_index) % m_stride == difference_type());
|
||||
return (other.m_index - m_index) / m_stride;
|
||||
}
|
||||
|
||||
template<class OtherIterator>
|
||||
bool equal(
|
||||
const strided_iterator<
|
||||
OtherIterator,
|
||||
random_access_traversal_tag
|
||||
>& other,
|
||||
typename iterators::enable_if_convertible<
|
||||
OtherIterator, base_iterator>::type* = 0) const
|
||||
{
|
||||
return m_index == other.m_index;
|
||||
}
|
||||
|
||||
reference dereference() const
|
||||
{
|
||||
update();
|
||||
return *m_it;
|
||||
}
|
||||
|
||||
private:
|
||||
mutable base_iterator m_it;
|
||||
base_iterator m_first;
|
||||
difference_type m_index;
|
||||
difference_type m_stride;
|
||||
};
|
||||
|
||||
template<class Rng, class Difference> inline
|
||||
strided_iterator<
|
||||
typename range_iterator<Rng>::type,
|
||||
forward_traversal_tag
|
||||
>
|
||||
make_begin_strided_iterator(
|
||||
Rng& rng,
|
||||
Difference stride,
|
||||
forward_traversal_tag)
|
||||
{
|
||||
return strided_iterator<
|
||||
typename range_iterator<Rng>::type,
|
||||
forward_traversal_tag
|
||||
>(boost::begin(rng), boost::end(rng), stride);
|
||||
}
|
||||
|
||||
template<class Rng, class Difference> inline
|
||||
strided_iterator<
|
||||
typename range_iterator<const Rng>::type,
|
||||
forward_traversal_tag
|
||||
>
|
||||
make_begin_strided_iterator(
|
||||
const Rng& rng,
|
||||
Difference stride,
|
||||
forward_traversal_tag)
|
||||
{
|
||||
return strided_iterator<
|
||||
typename range_iterator<const Rng>::type,
|
||||
forward_traversal_tag
|
||||
>(boost::begin(rng), boost::end(rng), stride);
|
||||
}
|
||||
|
||||
template<class Rng, class Difference> inline
|
||||
strided_iterator<
|
||||
typename range_iterator<Rng>::type,
|
||||
forward_traversal_tag
|
||||
>
|
||||
make_end_strided_iterator(
|
||||
Rng& rng,
|
||||
Difference stride,
|
||||
forward_traversal_tag)
|
||||
{
|
||||
return strided_iterator<
|
||||
typename range_iterator<Rng>::type,
|
||||
forward_traversal_tag
|
||||
>(boost::end(rng), boost::end(rng), stride);
|
||||
}
|
||||
|
||||
template<class Rng, class Difference> inline
|
||||
strided_iterator<
|
||||
typename range_iterator<const Rng>::type,
|
||||
forward_traversal_tag
|
||||
>
|
||||
make_end_strided_iterator(
|
||||
const Rng& rng,
|
||||
Difference stride,
|
||||
forward_traversal_tag)
|
||||
{
|
||||
return strided_iterator<
|
||||
typename range_iterator<const Rng>::type,
|
||||
forward_traversal_tag
|
||||
>(boost::end(rng), boost::end(rng), stride);
|
||||
}
|
||||
|
||||
template<class Rng, class Difference> inline
|
||||
strided_iterator<
|
||||
typename range_iterator<Rng>::type,
|
||||
bidirectional_traversal_tag
|
||||
>
|
||||
make_begin_strided_iterator(
|
||||
Rng& rng,
|
||||
Difference stride,
|
||||
bidirectional_traversal_tag)
|
||||
{
|
||||
typedef typename range_difference<Rng>::type difference_type;
|
||||
|
||||
return strided_iterator<
|
||||
typename range_iterator<Rng>::type,
|
||||
bidirectional_traversal_tag
|
||||
>(boost::begin(rng), difference_type(), stride);
|
||||
}
|
||||
|
||||
template<class Rng, class Difference> inline
|
||||
strided_iterator<
|
||||
typename range_iterator<const Rng>::type,
|
||||
bidirectional_traversal_tag
|
||||
>
|
||||
make_begin_strided_iterator(
|
||||
const Rng& rng,
|
||||
Difference stride,
|
||||
bidirectional_traversal_tag)
|
||||
{
|
||||
typedef typename range_difference<const Rng>::type difference_type;
|
||||
|
||||
return strided_iterator<
|
||||
typename range_iterator<const Rng>::type,
|
||||
bidirectional_traversal_tag
|
||||
>(boost::begin(rng), difference_type(), stride);
|
||||
}
|
||||
|
||||
template<class Rng, class Difference> inline
|
||||
strided_iterator<
|
||||
typename range_iterator<Rng>::type,
|
||||
bidirectional_traversal_tag
|
||||
>
|
||||
make_end_strided_iterator(
|
||||
Rng& rng,
|
||||
Difference stride,
|
||||
bidirectional_traversal_tag)
|
||||
{
|
||||
return strided_iterator<
|
||||
typename range_iterator<Rng>::type,
|
||||
bidirectional_traversal_tag
|
||||
>(boost::end(rng), boost::size(rng), stride);
|
||||
}
|
||||
|
||||
template<class Rng, class Difference> inline
|
||||
strided_iterator<
|
||||
typename range_iterator<const Rng>::type,
|
||||
bidirectional_traversal_tag
|
||||
>
|
||||
make_end_strided_iterator(
|
||||
const Rng& rng,
|
||||
Difference stride,
|
||||
bidirectional_traversal_tag)
|
||||
{
|
||||
return strided_iterator<
|
||||
typename range_iterator<const Rng>::type,
|
||||
bidirectional_traversal_tag
|
||||
>(boost::end(rng), boost::size(rng), stride);
|
||||
}
|
||||
|
||||
template<class Rng, class Difference> inline
|
||||
strided_iterator<
|
||||
typename range_iterator<Rng>::type,
|
||||
random_access_traversal_tag
|
||||
>
|
||||
make_begin_strided_iterator(
|
||||
Rng& rng,
|
||||
Difference stride,
|
||||
random_access_traversal_tag)
|
||||
{
|
||||
return strided_iterator<
|
||||
typename range_iterator<Rng>::type,
|
||||
random_access_traversal_tag
|
||||
>(boost::begin(rng), boost::begin(rng), stride);
|
||||
}
|
||||
|
||||
template<class Rng, class Difference> inline
|
||||
strided_iterator<
|
||||
typename range_iterator<const Rng>::type,
|
||||
random_access_traversal_tag
|
||||
>
|
||||
make_begin_strided_iterator(
|
||||
const Rng& rng,
|
||||
Difference stride,
|
||||
random_access_traversal_tag)
|
||||
{
|
||||
return strided_iterator<
|
||||
typename range_iterator<const Rng>::type,
|
||||
random_access_traversal_tag
|
||||
>(boost::begin(rng), boost::begin(rng), stride);
|
||||
}
|
||||
|
||||
template<class Rng, class Difference> inline
|
||||
strided_iterator<
|
||||
typename range_iterator<Rng>::type,
|
||||
random_access_traversal_tag
|
||||
>
|
||||
make_end_strided_iterator(
|
||||
Rng& rng,
|
||||
Difference stride,
|
||||
random_access_traversal_tag)
|
||||
{
|
||||
return strided_iterator<
|
||||
typename range_iterator<Rng>::type,
|
||||
random_access_traversal_tag
|
||||
>(boost::begin(rng), boost::end(rng), stride);
|
||||
}
|
||||
|
||||
template<class Rng, class Difference> inline
|
||||
strided_iterator<
|
||||
typename range_iterator<const Rng>::type,
|
||||
random_access_traversal_tag
|
||||
>
|
||||
make_end_strided_iterator(
|
||||
const Rng& rng,
|
||||
Difference stride,
|
||||
random_access_traversal_tag)
|
||||
{
|
||||
return strided_iterator<
|
||||
typename range_iterator<const Rng>::type,
|
||||
random_access_traversal_tag
|
||||
>(boost::begin(rng), boost::end(rng), stride);
|
||||
}
|
||||
|
||||
template<
|
||||
class Rng,
|
||||
class Category =
|
||||
typename iterators::pure_iterator_traversal<
|
||||
typename range_iterator<Rng>::type
|
||||
>::type
|
||||
>
|
||||
class strided_range
|
||||
: public iterator_range<
|
||||
range_detail::strided_iterator<
|
||||
typename range_iterator<Rng>::type,
|
||||
Category
|
||||
>
|
||||
>
|
||||
{
|
||||
typedef range_detail::strided_iterator<
|
||||
typename range_iterator<Rng>::type,
|
||||
Category
|
||||
> iter_type;
|
||||
typedef iterator_range<iter_type> super_t;
|
||||
public:
|
||||
template<class Difference>
|
||||
strided_range(Difference stride, Rng& rng)
|
||||
: super_t(
|
||||
range_detail::make_begin_strided_iterator(
|
||||
rng, stride,
|
||||
typename iterator_traversal<
|
||||
typename range_iterator<Rng>::type
|
||||
>::type()),
|
||||
range_detail::make_end_strided_iterator(
|
||||
rng, stride,
|
||||
typename iterator_traversal<
|
||||
typename range_iterator<Rng>::type
|
||||
>::type()))
|
||||
{
|
||||
BOOST_ASSERT( stride >= 0 );
|
||||
}
|
||||
};
|
||||
|
||||
template<class Difference>
|
||||
class strided_holder : public holder<Difference>
|
||||
{
|
||||
public:
|
||||
explicit strided_holder(Difference value)
|
||||
: holder<Difference>(value)
|
||||
{
|
||||
}
|
||||
};
|
||||
|
||||
template<class Rng, class Difference>
|
||||
inline strided_range<Rng>
|
||||
operator|(Rng& rng, const strided_holder<Difference>& stride)
|
||||
{
|
||||
return strided_range<Rng>(stride.val, rng);
|
||||
}
|
||||
|
||||
template<class Rng, class Difference>
|
||||
inline strided_range<const Rng>
|
||||
operator|(const Rng& rng, const strided_holder<Difference>& stride)
|
||||
{
|
||||
return strided_range<const Rng>(stride.val, rng);
|
||||
}
|
||||
|
||||
} // namespace range_detail
|
||||
|
||||
using range_detail::strided_range;
|
||||
|
||||
namespace adaptors
|
||||
{
|
||||
|
||||
namespace
|
||||
{
|
||||
const range_detail::forwarder<range_detail::strided_holder>
|
||||
strided = range_detail::forwarder<
|
||||
range_detail::strided_holder>();
|
||||
}
|
||||
|
||||
template<class Range, class Difference>
|
||||
inline strided_range<Range>
|
||||
stride(Range& rng, Difference step)
|
||||
{
|
||||
return strided_range<Range>(step, rng);
|
||||
}
|
||||
|
||||
template<class Range, class Difference>
|
||||
inline strided_range<const Range>
|
||||
stride(const Range& rng, Difference step)
|
||||
{
|
||||
return strided_range<const Range>(step, rng);
|
||||
}
|
||||
|
||||
} // namespace 'adaptors'
|
||||
} // namespace 'boost'
|
||||
|
||||
#endif
|
||||
Reference in New Issue
Block a user