8#ifndef BOOST_GIL_STEP_ITERATOR_HPP
9#define BOOST_GIL_STEP_ITERATOR_HPP
11#include <boost/gil/dynamic_step.hpp>
12#include <boost/gil/pixel_iterator.hpp>
13#include <boost/gil/pixel_iterator_adaptor.hpp>
14#include <boost/gil/utilities.hpp>
16#include <boost/iterator/iterator_facade.hpp>
22namespace boost {
namespace gil {
37template <
typename Derived,
41class step_iterator_adaptor :
public iterator_adaptor<Derived, Iterator, use_default, use_default, use_default, typename SFn::difference_type>
44 using parent_t = iterator_adaptor<Derived, Iterator, use_default, use_default, use_default, typename SFn::difference_type>;
45 using base_difference_type =
typename std::iterator_traits<Iterator>::difference_type;
46 using difference_type =
typename SFn::difference_type;
47 using reference =
typename std::iterator_traits<Iterator>::reference;
49 step_iterator_adaptor() {}
50 step_iterator_adaptor(Iterator
const& it, SFn step_fn=SFn()) : parent_t(it), _step_fn(step_fn) {}
52 auto step()
const -> difference_type {
return _step_fn.step(); }
57 friend class boost::iterator_core_access;
59 void increment() { _step_fn.advance(this->base_reference(),1); }
60 void decrement() { _step_fn.advance(this->base_reference(),-1); }
61 void advance(base_difference_type d) { _step_fn.advance(this->base_reference(),d); }
63 auto distance_to(step_iterator_adaptor
const& it)
const -> difference_type
65 return _step_fn.difference(this->base_reference(),it.base_reference());
71template <
typename D,
typename Iterator,
typename SFn>
inline
73 return p1.step()>0 ? p1.base()> p2.base() : p1.base()< p2.base();
76template <
typename D,
typename Iterator,
typename SFn>
inline
77bool operator<(
const step_iterator_adaptor<D,Iterator,SFn>& p1,
const step_iterator_adaptor<D,Iterator,SFn>& p2) {
78 return p1.step()>0 ? p1.base()< p2.base() : p1.base()> p2.base();
81template <
typename D,
typename Iterator,
typename SFn>
inline
82bool operator>=(
const step_iterator_adaptor<D,Iterator,SFn>& p1,
const step_iterator_adaptor<D,Iterator,SFn>& p2) {
83 return p1.step()>0 ? p1.base()>=p2.base() : p1.base()<=p2.base();
86template <
typename D,
typename Iterator,
typename SFn>
inline
87bool operator<=(
const step_iterator_adaptor<D,Iterator,SFn>& p1,
const step_iterator_adaptor<D,Iterator,SFn>& p2) {
88 return p1.step()>0 ? p1.base()<=p2.base() : p1.base()>=p2.base();
91template <
typename D,
typename Iterator,
typename SFn>
inline
93 return p1.base()==p2.base();
96template <
typename D,
typename Iterator,
typename SFn>
inline
98 return p1.base()!=p2.base();
125template <
typename Iterator>
126struct memunit_step_fn {
127 using difference_type = std::ptrdiff_t;
129 memunit_step_fn(difference_type step=memunit_step(Iterator())) : _step(step) {}
131 auto difference(Iterator
const& it1, Iterator
const& it2)
const -> difference_type
133 return memunit_distance(it1,it2)/_step;
136 void advance(Iterator& it, difference_type d)
const { memunit_advance(it,d*_step); }
137 auto step()
const -> difference_type {
return _step; }
139 void set_step(std::ptrdiff_t step) { _step=step; }
142 difference_type _step;
145template <
typename Iterator>
148 memunit_step_fn<Iterator>>
155 using reference =
typename parent_t::reference;
156 using difference_type =
typename parent_t::difference_type;
157 using x_iterator = Iterator;
159 memory_based_step_iterator() : parent_t(Iterator()) {}
160 memory_based_step_iterator(Iterator it, std::ptrdiff_t memunit_step) : parent_t(it,
memunit_step_fn<Iterator>(memunit_step)) {}
161 template <
typename I2>
162 memory_based_step_iterator(
const memory_based_step_iterator<I2>& it)
167 auto operator[](difference_type d)
const -> reference {
return *(*
this+d); }
169 void set_step(std::ptrdiff_t memunit_step) { this->_step_fn.set_step(memunit_step); }
171 auto base() -> x_iterator& {
return parent_t::base_reference(); }
172 auto base() const -> x_iterator const& {
return parent_t::base_reference(); }
175template <
typename Iterator>
177 using type = memory_based_step_iterator<typename const_iterator_type<Iterator>::type>;
180template <
typename Iterator>
188template <
typename Iterator>
191template <
typename Iterator>
194 using type = Iterator;
197template <
typename Iterator,
typename NewBaseIterator>
200 using type = memory_based_step_iterator<NewBaseIterator>;
207template <
typename Iterator>
210template <
typename Iterator>
213template <
typename Iterator>
216template <
typename Iterator>
222template <
typename Iterator>
225template <
typename Iterator>
228template <
typename Iterator>
232 return memunit_distance(p1.base(),p2.base());
235template <
typename Iterator>
237 std::ptrdiff_t diff) {
238 memunit_advance(p.base(), diff);
241template <
typename Iterator>
248template <
typename Iterator>
250 ->
typename std::iterator_traits<Iterator>::reference
252 return memunit_advanced_ref(p.base(), diff);
259template <
typename Iterator>
261 using type = memory_based_step_iterator<Iterator>;
265template <
typename Iterator,
typename Deref>
267 BOOST_GIL_CLASS_REQUIRE(Deref, boost::gil, PixelDereferenceAdaptorConcept)
269 using type = memory_based_step_iterator<typename iterator_add_deref<Iterator, Deref>::type>;
271 static type make(
const memory_based_step_iterator<Iterator>& it,
const Deref& d)
273 return type(iterator_add_deref<Iterator, Deref>::make(it.base(),d),it.step());
287auto make_step_iterator_impl(I
const& it, std::ptrdiff_t step, std::false_type)
288 ->
typename dynamic_x_step_type<I>::type
290 return memory_based_step_iterator<I>(it, step);
295auto make_step_iterator_impl(I
const& it, std::ptrdiff_t step, std::true_type)
296 ->
typename dynamic_x_step_type<I>::type
298 return make_step_iterator(it.base(), step);
302template <
typename BaseIt>
303auto make_step_iterator_impl(
304 memory_based_step_iterator<BaseIt>
const& it,
307 -> memory_based_step_iterator<BaseIt>
309 return memory_based_step_iterator<BaseIt>(it.base(), step);
328inline auto make_step_iterator(I
const& it, std::ptrdiff_t step)
An adaptor over an existing iterator that changes the step unit.
Definition step_iterator.hpp:42
MEMORY-BASED STEP ITERATOR.
Definition step_iterator.hpp:149
auto operator[](difference_type d) const -> reference
Definition step_iterator.hpp:167
defined(BOOST_NO_CXX17_HDR_MEMORY_RESOURCE)
Definition algorithm.hpp:36
Concept of a random-access iterator that can be advanced in memory units (bytes or bits)
Definition concepts/pixel_iterator.hpp:237
Definition pixel_iterator.hpp:124
Definition color_convert.hpp:31
Returns the type of an iterator just like the input iterator, except operating over immutable values.
Definition pixel_iterator.hpp:40
Base template for types that model HasDynamicXStepTypeConcept.
Definition dynamic_step.hpp:17
metafunction predicate determining whether the given iterator is a plain one or an adaptor over anoth...
Definition pixel_iterator.hpp:28
returns the base iterator for a given iterator adaptor. Provide an specialization when introducing ne...
Definition metafunctions.hpp:36
Changes the base iterator of an iterator adaptor. Provide an specialization when introducing new iter...
Definition pixel_iterator.hpp:36
Returns the type (and creates an instance) of an iterator that invokes the given dereference adaptor ...
Definition pixel_iterator_adaptor.hpp:176
Metafunction predicate returning whether the given iterator allows for changing its values.
Definition pixel_iterator.hpp:49
function object that returns the memory unit distance between two iterators and advances a given iter...
Definition step_iterator.hpp:126