comparison DEPENDENCIES/generic/include/boost/gil/step_iterator.hpp @ 16:2665513ce2d3

Add boost headers

+/*
+    Copyright 2005-2007 Adobe Systems Incorporated
+   
+    Use, modification and distribution are 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).
+
+    See http://opensource.adobe.com/gil for most recent version including documentation.
+*/
+
+/*************************************************************************************************/
+
+#ifndef GIL_STEP_ITERATOR_H
+#define GIL_STEP_ITERATOR_H
+
+////////////////////////////////////////////////////////////////////////////////////////
+/// \file               
+/// \brief pixel step iterator
+/// \author Lubomir Bourdev and Hailin Jin \n
+///         Adobe Systems Incorporated
+/// \date   2005-2007 \n Last updated on September 18, 2007
+///
+////////////////////////////////////////////////////////////////////////////////////////
+
+#include <cstddef>
+#include <iterator>
+#include <boost/iterator/iterator_facade.hpp>
+#include "gil_config.hpp"
+#include "utilities.hpp"
+#include "pixel_iterator.hpp"
+#include "pixel_iterator_adaptor.hpp"
+
+namespace boost { namespace gil {
+
+/// \defgroup PixelIteratorModelStepPtr step iterators
+/// \ingroup PixelIteratorModel
+/// \brief Iterators that allow for specifying the step between two adjacent values
+
+
+namespace detail {
+
+/// \ingroup PixelIteratorModelStepPtr
+/// \brief An adaptor over an existing iterator that changes the step unit
+///
+/// (i.e. distance(it,it+1)) by a given predicate. Instead of calling base's 
+/// operators ++, --, +=, -=, etc. the adaptor is using the passed policy object SFn
+/// for advancing and for computing the distance between iterators.
+
+template <typename Derived,  // type of the derived class
+          typename Iterator, // Models Iterator
+          typename SFn>      // A policy object that can compute the distance between two iterators of type Iterator
+                             // and can advance an iterator of type Iterator a given number of Iterator's units  
+class step_iterator_adaptor : public iterator_adaptor<Derived, Iterator, use_default, use_default, use_default, typename SFn::difference_type> {
+public:
+    typedef iterator_adaptor<Derived, Iterator, use_default, use_default, use_default, typename SFn::difference_type> parent_t;
+    typedef typename std::iterator_traits<Iterator>::difference_type base_difference_type;
+    typedef typename SFn::difference_type                           difference_type;
+    typedef typename std::iterator_traits<Iterator>::reference       reference;
+
+    step_iterator_adaptor() {}
+    step_iterator_adaptor(const Iterator& it, SFn step_fn=SFn()) : parent_t(it), _step_fn(step_fn) {}
+
+    difference_type step() const { return _step_fn.step(); }
+
+protected:
+    SFn _step_fn;
+private:
+    friend class boost::iterator_core_access;
+
+    void increment() { _step_fn.advance(this->base_reference(),1); }
+    void decrement() { _step_fn.advance(this->base_reference(),-1); }
+    void advance(base_difference_type d) { _step_fn.advance(this->base_reference(),d); }
+    difference_type distance_to(const step_iterator_adaptor& it) const { return _step_fn.difference(this->base_reference(),it.base_reference()); }
+};
+
+// although iterator_adaptor defines these, the default implementation computes distance and compares for zero.
+// it is often faster to just apply the relation operator to the base
+template <typename D,typename Iterator,typename SFn> inline
+bool operator>(const step_iterator_adaptor<D,Iterator,SFn>& p1, const step_iterator_adaptor<D,Iterator,SFn>& p2) { 
+    return p1.step()>0 ? p1.base()> p2.base() : p1.base()< p2.base(); 
+}
+
+template <typename D,typename Iterator,typename SFn> inline
+bool operator<(const step_iterator_adaptor<D,Iterator,SFn>& p1, const step_iterator_adaptor<D,Iterator,SFn>& p2) { 
+    return p1.step()>0 ? p1.base()< p2.base() : p1.base()> p2.base(); 
+}
+
+template <typename D,typename Iterator,typename SFn> inline
+bool operator>=(const step_iterator_adaptor<D,Iterator,SFn>& p1, const step_iterator_adaptor<D,Iterator,SFn>& p2) { 
+    return p1.step()>0 ? p1.base()>=p2.base() : p1.base()<=p2.base(); 
+}
+
+template <typename D,typename Iterator,typename SFn> inline
+bool operator<=(const step_iterator_adaptor<D,Iterator,SFn>& p1, const step_iterator_adaptor<D,Iterator,SFn>& p2) { 
+    return p1.step()>0 ? p1.base()<=p2.base() : p1.base()>=p2.base(); 
+}
+
+template <typename D,typename Iterator,typename SFn> inline
+bool operator==(const step_iterator_adaptor<D,Iterator,SFn>& p1, const step_iterator_adaptor<D,Iterator,SFn>& p2) { 
+    return p1.base()==p2.base(); 
+}
+
+template <typename D,typename Iterator,typename SFn> inline
+bool operator!=(const step_iterator_adaptor<D,Iterator,SFn>& p1, const step_iterator_adaptor<D,Iterator,SFn>& p2) { 
+    return p1.base()!=p2.base(); 
+}
+
+} // namespace detail
+
+////////////////////////////////////////////////////////////////////////////////////////
+///                 MEMORY-BASED STEP ITERATOR
+////////////////////////////////////////////////////////////////////////////////////////
+
+/// \class memory_based_step_iterator
+/// \ingroup PixelIteratorModelStepPtr PixelBasedModel
+/// \brief Iterator with dynamically specified step in memory units (bytes or bits). Models StepIteratorConcept, IteratorAdaptorConcept, MemoryBasedIteratorConcept, PixelIteratorConcept, HasDynamicXStepTypeConcept
+///
+/// A refinement of step_iterator_adaptor that uses a dynamic parameter for the step 
+/// which is specified in memory units, such as bytes or bits
+///
+/// Pixel step iterators are used to provide iteration over non-adjacent pixels. 
+/// Common use is a vertical traversal, where the step is the row stride.
+///
+/// Another application is as a sub-channel view. For example, a red intensity image over 
+/// interleaved RGB data would use a step iterator adaptor with step sizeof(channel_t)*3
+/// In the latter example the step size could be fixed at compile time for efficiency.
+/// Compile-time fixed step can be implemented by providing a step function object that takes the step as a template
+////////////////////////////////////////////////////////////////////////////////////////
+
+/// \ingroup PixelIteratorModelStepPtr
+/// \brief function object that returns the memory unit distance between two iterators and advances a given iterator a given number of mem units (bytes or bits)
+template <typename Iterator>
+struct memunit_step_fn {
+    typedef std::ptrdiff_t difference_type;
+
+    memunit_step_fn(difference_type step=memunit_step(Iterator())) : _step(step) {}
+
+    difference_type difference(const Iterator& it1, const Iterator& it2) const { return memunit_distance(it1,it2)/_step; }
+    void            advance(Iterator& it, difference_type d)             const { memunit_advance(it,d*_step); } 
+    difference_type step()                                               const { return _step; }
+
+    void            set_step(std::ptrdiff_t step) { _step=step; }
+private:
+    GIL_CLASS_REQUIRE(Iterator, boost::gil, MemoryBasedIteratorConcept)
+    difference_type _step;
+};
+
+template <typename Iterator>
+class memory_based_step_iterator : public detail::step_iterator_adaptor<memory_based_step_iterator<Iterator>, 
+                                                                            Iterator, 
+                                                                            memunit_step_fn<Iterator> > {
+    GIL_CLASS_REQUIRE(Iterator, boost::gil, MemoryBasedIteratorConcept)
+public:
+    typedef detail::step_iterator_adaptor<memory_based_step_iterator<Iterator>, 
+                                          Iterator, 
+                                          memunit_step_fn<Iterator> > parent_t;
+    typedef typename parent_t::reference                            reference;
+    typedef typename parent_t::difference_type                      difference_type;
+    typedef Iterator                                                x_iterator;
+
+    memory_based_step_iterator() : parent_t(Iterator()) {}
+    memory_based_step_iterator(Iterator it, std::ptrdiff_t memunit_step) : parent_t(it, memunit_step_fn<Iterator>(memunit_step)) {}
+    template <typename I2> 
+    memory_based_step_iterator(const memory_based_step_iterator<I2>& it)
+        : parent_t(it.base(), memunit_step_fn<Iterator>(it.step())) {}
+
+    /// For some reason operator[] provided by iterator_adaptor returns a custom class that is convertible to reference
+    /// We require our own reference because it is registered in iterator_traits
+    reference operator[](difference_type d) const { return *(*this+d); }
+
+    void set_step(std::ptrdiff_t memunit_step) { this->_step_fn.set_step(memunit_step); }
+
+    x_iterator& base()              { return parent_t::base_reference(); }
+    x_iterator const& base() const  { return parent_t::base_reference(); }
+};
+
+template <typename Iterator>
+struct const_iterator_type<memory_based_step_iterator<Iterator> > {
+    typedef memory_based_step_iterator<typename const_iterator_type<Iterator>::type>  type;
+};
+
+template <typename Iterator>
+struct iterator_is_mutable<memory_based_step_iterator<Iterator> > : public iterator_is_mutable<Iterator> {};
+
+
+/////////////////////////////
+//  IteratorAdaptorConcept
+/////////////////////////////
+
+template <typename Iterator>
+struct is_iterator_adaptor<memory_based_step_iterator<Iterator> > : public mpl::true_{};
+
+template <typename Iterator>
+struct iterator_adaptor_get_base<memory_based_step_iterator<Iterator> > {
+    typedef Iterator type;
+};
+
+template <typename Iterator, typename NewBaseIterator>
+struct iterator_adaptor_rebind<memory_based_step_iterator<Iterator>,NewBaseIterator> {
+    typedef memory_based_step_iterator<NewBaseIterator> type;
+};
+
+/////////////////////////////
+//  PixelBasedConcept
+/////////////////////////////
+
+template <typename Iterator>
+struct color_space_type<memory_based_step_iterator<Iterator> > : public color_space_type<Iterator> {};
+
+template <typename Iterator>
+struct channel_mapping_type<memory_based_step_iterator<Iterator> > : public channel_mapping_type<Iterator> {};
+
+template <typename Iterator>
+struct is_planar<memory_based_step_iterator<Iterator> > : public is_planar<Iterator> {};
+
+template <typename Iterator>
+struct channel_type<memory_based_step_iterator<Iterator> > : public channel_type<Iterator> {};
+
+/////////////////////////////
+//  MemoryBasedIteratorConcept
+/////////////////////////////
+template <typename Iterator>
+struct byte_to_memunit<memory_based_step_iterator<Iterator> > : public byte_to_memunit<Iterator> {};
+
+template <typename Iterator>
+inline std::ptrdiff_t memunit_step(const memory_based_step_iterator<Iterator>& p) { return p.step(); }
+
+template <typename Iterator>
+inline std::ptrdiff_t memunit_distance(const memory_based_step_iterator<Iterator>& p1, 
+                                    const memory_based_step_iterator<Iterator>& p2) { 
+    return memunit_distance(p1.base(),p2.base()); 
+}
+
+template <typename Iterator>
+inline void memunit_advance(memory_based_step_iterator<Iterator>& p, 
+                         std::ptrdiff_t diff) { 
+    memunit_advance(p.base(), diff);
+}
+
+template <typename Iterator>
+inline memory_based_step_iterator<Iterator> 
+memunit_advanced(const memory_based_step_iterator<Iterator>& p, 
+              std::ptrdiff_t diff) {
+    return memory_based_step_iterator<Iterator>(memunit_advanced(p.base(), diff),p.step());
+}
+
+template <typename Iterator>
+inline typename std::iterator_traits<Iterator>::reference 
+memunit_advanced_ref(const memory_based_step_iterator<Iterator>& p, 
+                  std::ptrdiff_t diff) { 
+    return memunit_advanced_ref(p.base(), diff);
+}
+
+/////////////////////////////
+//  HasDynamicXStepTypeConcept
+/////////////////////////////
+
+template <typename Iterator>
+struct dynamic_x_step_type<memory_based_step_iterator<Iterator> > {
+    typedef memory_based_step_iterator<Iterator> type;
+};
+
+// For step iterators, pass the function object to the base
+template <typename Iterator, typename Deref>
+struct iterator_add_deref<memory_based_step_iterator<Iterator>,Deref> {
+    GIL_CLASS_REQUIRE(Deref, boost::gil, PixelDereferenceAdaptorConcept)
+
+    typedef memory_based_step_iterator<typename iterator_add_deref<Iterator, Deref>::type> type;
+
+    static type make(const memory_based_step_iterator<Iterator>& it, const Deref& d) { return type(iterator_add_deref<Iterator, Deref>::make(it.base(),d),it.step()); }
+};
+
+////////////////////////////////////////////////////////////////////////////////////////
+/// make_step_iterator
+////////////////////////////////////////////////////////////////////////////////////////
+
+template <typename I> typename dynamic_x_step_type<I>::type make_step_iterator(const I& it, std::ptrdiff_t step);
+
+namespace detail {
+
+// if the iterator is a plain base iterator (non-adaptor), wraps it in memory_based_step_iterator
+template <typename I> 
+typename dynamic_x_step_type<I>::type make_step_iterator_impl(const I& it, std::ptrdiff_t step, mpl::false_) {
+    return memory_based_step_iterator<I>(it, step);
+}
+
+// If the iterator is compound, put the step in its base
+template <typename I> 
+typename dynamic_x_step_type<I>::type make_step_iterator_impl(const I& it, std::ptrdiff_t step, mpl::true_) {
+    return make_step_iterator(it.base(), step);
+}
+
+// If the iterator is memory_based_step_iterator, change the step
+template <typename BaseIt> 
+memory_based_step_iterator<BaseIt> make_step_iterator_impl(const memory_based_step_iterator<BaseIt>& it, std::ptrdiff_t step, mpl::true_) {
+    return memory_based_step_iterator<BaseIt>(it.base(), step);
+}
+}
+
+/// \brief Constructs a step iterator from a base iterator and a step.
+///
+/// To construct a step iterator from a given iterator Iterator and a given step, if Iterator does not
+/// already have a dynamic step, we wrap it in a memory_based_step_iterator. Otherwise we 
+/// do a compile-time traversal of the chain of iterator adaptors to locate the step iterator
+/// and then set it step to the new one.
+///
+/// The step iterator of Iterator is not always memory_based_step_iterator<Iterator>. For example, Iterator may
+/// already be a memory_based_step_iterator, in which case it will be inefficient to stack them;
+/// we can obtain the same result by multiplying their steps. Note that for Iterator to be a
+/// step iterator it does not necessarily have to have the form memory_based_step_iterator<J>.
+/// The step iterator can be wrapped inside another iterator. Also, it may not have the
+/// type memory_based_step_iterator, but it could be a user-provided type.
+template <typename I>  // Models MemoryBasedIteratorConcept, HasDynamicXStepTypeConcept
+typename dynamic_x_step_type<I>::type make_step_iterator(const I& it, std::ptrdiff_t step) {
+    return detail::make_step_iterator_impl(it, step, typename is_iterator_adaptor<I>::type());
+}
+
+} }  // namespace boost::gil
+
+#endif