comparison DEPENDENCIES/generic/include/boost/range/adaptor/strided.hpp @ 16:2665513ce2d3

Add boost headers

+// 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_adaptor.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_adaptor<
+                strided_iterator<BaseIterator, Category>
+              , BaseIterator
+              , use_default
+              , boost::forward_traversal_tag
+            >
+        {
+            friend class ::boost::iterator_core_access;
+
+            typedef iterator_adaptor<
+                        strided_iterator<BaseIterator, Category>
+                      , BaseIterator
+                      , use_default
+                      , boost::forward_traversal_tag
+                    > super_t;
+
+        public:
+            typedef BOOST_DEDUCED_TYPENAME std::iterator_traits<BaseIterator>::difference_type difference_type;
+            typedef BaseIterator base_iterator;
+
+            strided_iterator()
+                : m_last()
+                , m_stride()
+            {
+            }
+
+            strided_iterator(base_iterator first, base_iterator it, base_iterator last, difference_type stride)
+                : super_t(it)
+                , m_last(last)
+                , m_stride(stride)
+            {
+            }
+
+            template<class OtherIterator>
+            strided_iterator(const strided_iterator<OtherIterator, Category>& other,
+                             BOOST_DEDUCED_TYPENAME enable_if_convertible<OtherIterator, base_iterator>::type* = 0)
+                : super_t(other)
+                , m_last(other.base_end())
+                , m_stride(other.get_stride())
+            {
+            }
+
+            base_iterator base_end() const { return m_last; }
+            difference_type get_stride() const { return m_stride; }
+
+        private:
+            void increment()
+            {
+                base_iterator& it = this->base_reference();
+                for (difference_type i = 0; (it != m_last) && (i < m_stride); ++i)
+                    ++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_adaptor<
+                strided_iterator<BaseIterator, bidirectional_traversal_tag>
+              , BaseIterator
+              , use_default
+              , bidirectional_traversal_tag
+            >
+        {
+            friend class ::boost::iterator_core_access;
+
+            typedef iterator_adaptor<
+                        strided_iterator<BaseIterator, bidirectional_traversal_tag>
+                      , BaseIterator
+                      , use_default
+                      , bidirectional_traversal_tag
+                    > super_t;
+        public:
+            typedef BOOST_DEDUCED_TYPENAME std::iterator_traits<BaseIterator>::difference_type difference_type;
+            typedef BaseIterator base_iterator;
+
+            strided_iterator()
+                : m_first()
+                , m_last()
+                , m_stride()
+            {
+            }
+
+            strided_iterator(base_iterator first, base_iterator it, base_iterator last, difference_type stride)
+                : super_t(it)
+                , m_first(first)
+                , m_last(last)
+                , m_stride(stride)
+            {
+            }
+
+            template<class OtherIterator>
+            strided_iterator(const strided_iterator<OtherIterator, bidirectional_traversal_tag>& other,
+                             BOOST_DEDUCED_TYPENAME enable_if_convertible<OtherIterator, base_iterator>::type* = 0)
+                : super_t(other.base())
+                , m_first(other.base_begin())
+                , m_last(other.base_end())
+                , m_stride(other.get_stride())
+            {
+            }
+
+            base_iterator base_begin() const { return m_first; }
+            base_iterator base_end() const { return m_last; }
+            difference_type get_stride() const { return m_stride; }
+
+        private:
+            void increment()
+            {
+                base_iterator& it = this->base_reference();
+                for (difference_type i = 0; (it != m_last) && (i < m_stride); ++i)
+                    ++it;
+            }
+
+            void decrement()
+            {
+                base_iterator& it = this->base_reference();
+                for (difference_type i = 0; (it != m_first) && (i < m_stride); ++i)
+                    --it;
+            }
+
+            base_iterator m_first;
+            base_iterator m_last;
+            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_adaptor<
+                        strided_iterator<BaseIterator, random_access_traversal_tag>
+                      , BaseIterator
+                      , use_default
+                      , random_access_traversal_tag
+                    >
+        {
+            friend class ::boost::iterator_core_access;
+
+            typedef iterator_adaptor<
+                        strided_iterator<BaseIterator, random_access_traversal_tag>
+                      , BaseIterator
+                      , use_default
+                      , random_access_traversal_tag
+                    > super_t;
+        public:
+            typedef BOOST_DEDUCED_TYPENAME super_t::difference_type difference_type;
+            typedef BaseIterator base_iterator;
+
+            strided_iterator()
+                : m_first()
+                , m_last()
+                , m_index(0)
+                , m_stride()
+            {
+            }
+
+            strided_iterator(BaseIterator first, BaseIterator it, BaseIterator last, difference_type stride)
+                : super_t(it)
+                , m_first(first)
+                , m_last(last)
+                , m_index(stride ? (it - first) / stride : 0)
+                , m_stride(stride)
+            {
+            }
+
+            template<class OtherIterator>
+            strided_iterator(const strided_iterator<OtherIterator, random_access_traversal_tag>& other,
+                             BOOST_DEDUCED_TYPENAME enable_if_convertible<OtherIterator, BaseIterator>::type* = 0)
+                : super_t(other.base())
+                , m_first(other.base_begin())
+                , m_last(other.base_end())
+                , m_index(other.get_index())
+                , m_stride(other.get_stride())
+            {
+            }
+
+            base_iterator base_begin() const { return m_first; }
+            base_iterator base_end() const { return m_last; }
+            difference_type get_stride() const { return m_stride; }
+            difference_type get_index() const { return m_index; }
+
+        private:
+            void increment()
+            {
+                m_index += m_stride;
+                if (m_index < (m_last - m_first))
+                    this->base_reference() = m_first + m_index;
+                else
+                    this->base_reference() = m_last;
+            }
+
+            void decrement()
+            {
+                m_index -= m_stride;
+                if (m_index >= 0)
+                    this->base_reference() = m_first + m_index;
+                else
+                    this->base_reference() = m_first;
+            }
+
+            void advance(difference_type offset)
+            {
+                offset *= m_stride;
+                m_index += offset;
+                if (m_index < 0)
+                    this->base_reference() = m_first;
+                else if (m_index > (m_last - m_first))
+                    this->base_reference() = m_last;
+                else
+                    this->base_reference() = m_first + m_index;
+            }
+
+            template<class OtherIterator>
+            difference_type distance_to(const strided_iterator<OtherIterator, random_access_traversal_tag>& other,
+                                        BOOST_DEDUCED_TYPENAME enable_if_convertible<OtherIterator, BaseIterator>::type* = 0) const
+            {
+                if (other.base() >= this->base())
+                    return (other.base() - this->base() + (m_stride - 1)) / m_stride;
+                return (other.base() - this->base() - (m_stride - 1)) / m_stride;
+            }
+
+            bool equal(const strided_iterator& other) const
+            {
+                return this->base() == other.base();
+            }
+
+        private:
+            base_iterator m_first;
+            base_iterator m_last;
+            difference_type m_index;
+            difference_type m_stride;
+        };
+
+        template<class BaseIterator, class Difference> inline
+        strided_iterator<BaseIterator, BOOST_DEDUCED_TYPENAME iterator_traversal<BaseIterator>::type>
+        make_strided_iterator(BaseIterator first, BaseIterator it,
+                              BaseIterator last, Difference stride)
+        {
+            BOOST_ASSERT( stride >= 0 );
+            typedef BOOST_DEDUCED_TYPENAME iterator_traversal<BaseIterator>::type traversal_tag;
+            return strided_iterator<BaseIterator, traversal_tag>(first, it, last, stride);
+        }
+
+        template< class Rng
+                , class Category = BOOST_DEDUCED_TYPENAME iterator_traversal<
+                                    BOOST_DEDUCED_TYPENAME range_iterator<Rng>::type
+                                   >::type
+         >
+        class strided_range
+            : public iterator_range<
+                        range_detail::strided_iterator<
+                            BOOST_DEDUCED_TYPENAME range_iterator<Rng>::type,
+                            Category
+                        >
+                     >
+        {
+            typedef range_detail::strided_iterator<
+                        BOOST_DEDUCED_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(make_strided_iterator(boost::begin(rng), boost::begin(rng), boost::end(rng), stride),
+                          make_strided_iterator(boost::begin(rng), boost::end(rng), boost::end(rng), stride))
+            {
+                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