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Concept: point #787

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56 changes: 22 additions & 34 deletions include/boost/gil/concepts/point.hpp
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Original file line number Diff line number Diff line change
@@ -1,5 +1,6 @@
//
// Copyright 2005-2007 Adobe Systems Incorporated
// Copyright 2026 Samuel Debionne
//
// Distributed under the Boost Software License, Version 1.0
// See accompanying file LICENSE_1_0.txt or copy at
Expand All @@ -8,9 +9,13 @@
#ifndef BOOST_GIL_CONCEPTS_POINT_HPP
#define BOOST_GIL_CONCEPTS_POINT_HPP

#include <boost/gil/concepts/basic.hpp>
#include <boost/gil/concepts/concept_check.hpp>
#include <boost/gil/detail/config.hpp>

#if !defined(BOOST_GIL_HAS_CONCEPTS)
# error C++ 20 standard required.
#endif

#include <concepts>
#include <cstddef>

#if defined(BOOST_CLANG)
Expand All @@ -27,7 +32,7 @@
namespace boost { namespace gil {

// Forward declarations
template <typename T>
template <BOOST_GIL_CONSTRAINT(std::regular) T>
class point;

template <std::size_t K, typename T>
Expand Down Expand Up @@ -58,33 +63,21 @@ T& axis_value(point<T>& p);
/// \ingroup PointConcept
///
template <typename P>
struct PointNDConcept
concept PointNDConcept = requires(P point, typename P::template axis<0>::coord_t ft, typename P::template axis<P::num_dimensions - 1>::coord_t lt)
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@sdebionne sdebionne Jan 23, 2026

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concept should be lower case?

{
void constraints()
{
gil_function_requires<Regular<P>>();

using value_type = typename P::value_type;
ignore_unused_variable_warning(value_type{});

static const std::size_t N = P::num_dimensions;
ignore_unused_variable_warning(N);
using FT = typename P::template axis<0>::coord_t;
using LT = typename P::template axis<N - 1>::coord_t;
FT ft = gil::axis_value<0>(point);
axis_value<0>(point) = ft;
LT lt = axis_value<N - 1>(point);
axis_value<N - 1>(point) = lt;

//value_type v=point[0];
//ignore_unused_variable_warning(v);
}
P point;
typename P::value_type;
requires std::regular<typename P::value_type>;
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@sdebionne sdebionne Jan 23, 2026

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Better write with concept conjunctions?

concept PointNDConcept = std::regular<typename P::value_type> && requires(P point, typename...


P::num_dimensions;
ft = gil::axis_value<0>(point);
axis_value<0>(point) = ft;
lt = axis_value<P::num_dimensions - 1>(point);
axis_value<P::num_dimensions - 1>(point) = lt;
};

/// \brief 2-dimensional point concept
/// \code
/// concept Point2DConcept<typename T> : PointNDConcept<T>
/// concept Point2DConcept<typename T> : PointNDConcept<T>N
/// {
/// where num_dimensions == 2;
/// where SameType<axis<0>::type, axis<1>::type>;
Expand All @@ -100,16 +93,11 @@ struct PointNDConcept
/// \ingroup PointConcept
///
template <typename P>
struct Point2DConcept
concept Point2DConcept = PointNDConcept<P> && requires(P point)
{
void constraints()
{
gil_function_requires<PointNDConcept<P>>();
static_assert(P::num_dimensions == 2, "");
point.x = point.y;
point[0] = point[1];
}
P point;
requires P::num_dimensions == 2;
point.x = point.y;
point[0] = point[1];
};

}} // namespace boost::gil
Expand Down
23 changes: 23 additions & 0 deletions include/boost/gil/detail/config.hpp
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@@ -0,0 +1,23 @@
//
// Copyright 2026 Samuel Debionne
//
// Distributed under 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
//
#ifndef BOOST_GIL_DETAIL_CONFIG_HPP
#define BOOST_GIL_DETAIL_CONFIG_HPP

#include <boost/config.hpp>

#if !defined(BOOST_NO_CXX20_HDR_CONCEPTS) && defined(__cpp_lib_concepts)
#define BOOST_GIL_HAS_CONCEPTS
#endif

#ifdef BOOST_GIL_HAS_CONCEPTS
#define BOOST_GIL_CONSTRAINT(C) C
#else
#define BOOST_GIL_CONSTRAINT(C) typename
#endif

#endif
3 changes: 3 additions & 0 deletions include/boost/gil/detail/std_common_type.hpp
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Expand Up @@ -34,6 +34,9 @@ struct std_common_type
>::type;
};

template <typename T, typename U>
using std_common_type_t = std_common_type<T, U>::type;

}}} // namespace boost::gil::detail

#endif
2 changes: 1 addition & 1 deletion include/boost/gil/locator.hpp
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Expand Up @@ -24,7 +24,7 @@ template <typename P> std::ptrdiff_t memunit_step(const P*);
template <typename P> P* memunit_advanced(const P* p, std::ptrdiff_t diff);
template <typename P> P& memunit_advanced_ref(P* p, std::ptrdiff_t diff);
template <typename Iterator, typename D> struct iterator_add_deref;
template <typename T> class point;
template <BOOST_GIL_CONSTRAINT(std::regular) T> class point;
namespace detail {
// helper class specialized for each axis of pixel_2d_locator
template <std::size_t D, typename Loc> class locator_axis;
Expand Down
25 changes: 14 additions & 11 deletions include/boost/gil/point.hpp
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Expand Up @@ -9,11 +9,11 @@
#define BOOST_GIL_POINT_HPP

#include <boost/gil/utilities.hpp>
#include <boost/gil/detail/config.hpp>
#include <boost/gil/detail/std_common_type.hpp>

#include <boost/config.hpp>

#include <cstddef>
#include <concepts>
#include <type_traits>

namespace boost { namespace gil {
Expand All @@ -31,7 +31,7 @@ namespace boost { namespace gil {
/// \brief 2D point both axes of which have the same dimension type
/// \ingroup PointModel
/// Models: Point2DConcept
template <typename T>
template <BOOST_GIL_CONSTRAINT(std::regular) T>
class point
{
public:
Expand Down Expand Up @@ -109,62 +109,65 @@ class point
};

/// Alias template for backward compatibility with Boost <=1.68.
template <typename T>
template <std::regular T>
using point2 = point<T>;

/// Common type to represent 2D dimensions or in-memory size of image or view.
/// @todo TODO: rename to dims_t or dimensions_t for purpose clarity?
using point_t = point<std::ptrdiff_t>;

template <typename T>
template <std::regular T>
T point<T>::* const point<T>::mem_array[point<T>::num_dimensions] =
{
&point<T>::x,
&point<T>::y
};

/// \ingroup PointModel
template <typename T>
template <std::regular T>
BOOST_FORCEINLINE
bool operator==(const point<T>& p1, const point<T>& p2)
{
return p1.x == p2.x && p1.y == p2.y;
}

/// \ingroup PointModel
template <typename T>
template <std::regular T>
BOOST_FORCEINLINE
bool operator!=(const point<T>& p1, const point<T>& p2)
{
return p1.x != p2.x || p1.y != p2.y;
}

/// \ingroup PointModel
template <typename T>
template <std::regular T>
BOOST_FORCEINLINE
point<T> operator+(const point<T>& p1, const point<T>& p2)
{
return { p1.x + p2.x, p1.y + p2.y };
}

/// \ingroup PointModel
template <typename T>
template <std::regular T>
BOOST_FORCEINLINE
point<T> operator-(const point<T>& p)
{
return { -p.x, -p.y };
}

/// \ingroup PointModel
template <typename T>
template <std::regular T>
BOOST_FORCEINLINE
point<T> operator-(const point<T>& p1, const point<T>& p2)
{
return { p1.x - p2.x, p1.y - p2.y };
}

template <typename T>
concept arithmetic = std::is_arithmetic_v<T>;

/// \ingroup PointModel
template <typename T, typename D>
template <std::regular T, arithmetic D>
BOOST_FORCEINLINE
auto operator/(point<T> const& p, D d)
-> typename std::enable_if
Expand Down
58 changes: 42 additions & 16 deletions include/boost/gil/typedefs.hpp
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Expand Up @@ -9,6 +9,8 @@
#ifndef BOOST_GIL_TYPEDEFS_HPP
#define BOOST_GIL_TYPEDEFS_HPP

#include <boost/gil/detail/config.hpp>

#include <boost/gil/cmyk.hpp>
#include <boost/gil/device_n.hpp>
#include <boost/gil/gray.hpp>
Expand All @@ -22,25 +24,49 @@
# include <memory_resource>
#endif //!defined(BOOST_NO_CXX17_HDR_MEMORY_RESOURCE)

namespace boost { namespace gil {

#if defined(BOOST_GIL_HAS_CONCEPTS)
template <typename, typename>
struct pixel;
template <typename, typename>
struct planar_pixel_reference;
template <typename, typename>
struct planar_pixel_iterator;
template <typename>
class memory_based_step_iterator;
template <std::regular>
class point;
template <typename>
class memory_based_2d_locator;
template <typename>
class image_view;
template <typename, bool, typename>
class image;
#else
template <typename, typename>
struct pixel;
template <typename, typename>
struct planar_pixel_reference;
template <typename, typename>
struct planar_pixel_iterator;
template <typename>
class memory_based_step_iterator;
template <typename>
class point;
template <typename>
class memory_based_2d_locator;
template <typename>
class image_view;
template <typename, bool, typename>
class image;
#endif //defined(BOOST_GIL_HAS_CONCEPTS)

}} // namespace boost::gil

// B - bits size/signedness, CM - channel model, CS - colour space, LAYOUT - pixel layout
// Example: B = '8', CM = 'uint8_t', CS = 'bgr, LAYOUT='bgr_layout_t'
#define BOOST_GIL_DEFINE_BASE_TYPEDEFS_INTERNAL(B, CM, CS, LAYOUT) \
template <typename, typename> \
struct pixel; \
template <typename, typename> \
struct planar_pixel_reference; \
template <typename, typename> \
struct planar_pixel_iterator; \
template <typename> \
class memory_based_step_iterator; \
template <typename> \
class point; \
template <typename> \
class memory_based_2d_locator; \
template <typename> \
class image_view; \
template <typename, bool, typename> \
class image; \
using CS##B##_pixel_t = pixel<CM, LAYOUT>; \
using CS##B##c_pixel_t = pixel<CM, LAYOUT> const; \
using CS##B##_ref_t = pixel<CM, LAYOUT>&; \
Expand Down
13 changes: 4 additions & 9 deletions test/core/point/concepts.cpp
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Expand Up @@ -33,19 +33,14 @@ void test_members()

int main()
{
boost::function_requires<gil::PointNDConcept<gil::point<int>>>();
boost::function_requires<gil::PointNDConcept<gil::point_t>>();
static_assert(gil::PointNDConcept<gil::point<int>>);
static_assert(gil::PointNDConcept<gil::point_t>);

boost::function_requires<gil::Point2DConcept<gil::point<int>>>();
boost::function_requires<gil::Point2DConcept<gil::point_t>>();
static_assert(gil::Point2DConcept<gil::point<int>>);
static_assert(gil::Point2DConcept<gil::point_t>);

test_members<gil::point<int>>();
test_members<gil::point_t>();

// NOTE: point2 is deprecated, available for backward compatibility
boost::function_requires<gil::PointNDConcept<gil::point2<int>>>();
boost::function_requires<gil::Point2DConcept<gil::point2<int>>>();
test_members<gil::point2<int>>();

return 0;
}
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