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/*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software Foundation,
* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
* Copyright 2021, Blender Foundation.
*/
#pragma once
#include "BLI_assert.h"
#include "BLI_rect.h"
#include <iterator>
namespace blender::compositor {
/* Forward declarations. */
template<typename T> class BufferRangeIterator;
/**
* A range of buffer elements.
*/
template<typename T> class BufferRange {
public:
using Iterator = BufferRangeIterator<T>;
using ConstIterator = BufferRangeIterator<const T>;
private:
T *start_;
/* Number of elements in the range. */
int64_t size_;
/* Buffer element stride. */
int elem_stride_;
public:
constexpr BufferRange() = default;
/**
* Create a buffer range of elements from a given element index.
*/
constexpr BufferRange(T *buffer, int64_t start_elem_index, int64_t size, int elem_stride = 1)
: start_(buffer + start_elem_index * elem_stride), size_(size), elem_stride_(elem_stride)
{
}
constexpr friend bool operator==(const BufferRange &a, const BufferRange &b)
{
return a.start_ == b.start_ && a.size_ == b.size_ && a.elem_stride_ == b.elem_stride_;
}
/**
* Access an element in the range. Index is relative to range start.
*/
constexpr T *operator[](int64_t index) const
{
BLI_assert(index >= 0);
BLI_assert(index < this->size());
return start_ + index * elem_stride_;
}
/**
* Get the number of elements in the range.
*/
constexpr int64_t size() const
{
return size_;
}
constexpr Iterator begin()
{
return begin_iterator<Iterator>();
}
constexpr Iterator end()
{
return end_iterator<Iterator>();
}
constexpr ConstIterator begin() const
{
return begin_iterator<ConstIterator>();
}
constexpr ConstIterator end() const
{
return end_iterator<ConstIterator>();
}
private:
template<typename TIterator> constexpr TIterator begin_iterator() const
{
if (elem_stride_ == 0) {
/* Iterate a single element. */
return TIterator(start_, 1);
}
return TIterator(start_, elem_stride_);
}
template<typename TIterator> constexpr TIterator end_iterator() const
{
if (elem_stride_ == 0) {
/* Iterate a single element. */
return TIterator(start_ + 1, 1);
}
return TIterator(start_ + size_ * elem_stride_, elem_stride_);
}
};
template<typename T> class BufferRangeIterator {
public:
using iterator_category = std::input_iterator_tag;
using value_type = T *;
using pointer = T *const *;
using reference = T *const &;
using difference_type = std::ptrdiff_t;
private:
T *current_;
int elem_stride_;
public:
constexpr BufferRangeIterator() = default;
constexpr BufferRangeIterator(T *current, int elem_stride = 1)
: current_(current), elem_stride_(elem_stride)
{
}
constexpr BufferRangeIterator &operator++()
{
current_ += elem_stride_;
return *this;
}
constexpr BufferRangeIterator operator++(int) const
{
BufferRangeIterator copied_iterator = *this;
++copied_iterator;
return copied_iterator;
}
constexpr friend bool operator!=(const BufferRangeIterator &a, const BufferRangeIterator &b)
{
return a.current_ != b.current_;
}
constexpr friend bool operator==(const BufferRangeIterator &a, const BufferRangeIterator &b)
{
return a.current_ == b.current_;
}
constexpr T *operator*() const
{
return current_;
}
};
} // namespace blender::compositor
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