Added StrideSpan type (a span with a stride). Added makeSpan() function to TypelessBuffer.
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source/mijin/container/stride_span.hpp
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232
source/mijin/container/stride_span.hpp
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#pragma once
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#if !defined(MIJIN_CONTAINER_STRIDE_SPAN_HPP_INCLUDED)
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#define MIJIN_CONTAINER_STRIDE_SPAN_HPP_INCLUDED 1
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#include <cstddef>
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#include <iterator>
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#include <type_traits>
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#include "../debug/assert.hpp"
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namespace mijin
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{
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//
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// public defines
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//
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//
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// public constants
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//
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//
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// public types
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//
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template<typename T, typename U>
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[[nodiscard]] std::ptrdiff_t bytediff(T* first, U* second) noexcept
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{
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return std::bit_cast<std::byte*>(second) - std::bit_cast<std::byte*>(first);
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}
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template<typename T>
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[[nodiscard]] T* byteoffset(T* old, std::ptrdiff_t offset) noexcept
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{
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return std::bit_cast<T*>(std::bit_cast<std::byte*>(old) + offset);
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}
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template<typename T>
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class StrideSpanIterator
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{
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public:
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using difference_type = std::ptrdiff_t;
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using value_type = T;
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private:
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T* ele_ = nullptr;
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std::size_t strideBytes_ = 0;
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#if MIJIN_CHECKED_ITERATORS
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T* start_ = nullptr;
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T* end_ = nullptr;
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#endif
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public:
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StrideSpanIterator() = default;
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constexpr StrideSpanIterator(T* ele, std::size_t strideBytes, [[maybe_unused]] T* start, [[maybe_unused]] T* end)
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: ele_(ele), strideBytes_(strideBytes)
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#if MIJIN_CHECKED_ITERATORS
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, start_(start), end_(end)
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#endif
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{
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MIJIN_ASSERT(strideBytes_!= 0 && bytediff(start_, end_) % strideBytes_ == 0, "StrideSpan: stride elements don't match supplied pointers.");
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}
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StrideSpanIterator(const StrideSpanIterator&) = default;
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StrideSpanIterator& operator=(const StrideSpanIterator&) = default;
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StrideSpanIterator& operator+=(difference_type diff);
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StrideSpanIterator& operator-=(difference_type diff) {
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return *this += -diff;
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}
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constexpr auto operator<=>(const StrideSpanIterator&) const noexcept = default;
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[[nodiscard]] T& operator*() const;
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[[nodiscard]] T* operator->() const;
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StrideSpanIterator& operator++();
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StrideSpanIterator operator++(int);
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StrideSpanIterator& operator--();
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StrideSpanIterator operator--(int);
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[[nodiscard]] difference_type operator-(const StrideSpanIterator& other) const { return bytediff(other.ele_, ele_) / strideBytes_; }
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[[nodiscard]] StrideSpanIterator operator+(difference_type diff) const;
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[[nodiscard]] StrideSpanIterator operator-(difference_type diff) const { return (*this + -diff); }
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[[nodiscard]] T& operator[](difference_type diff) const { return *(*this + diff); }
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};
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template<typename T>
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inline StrideSpanIterator<T> operator+(std::iter_difference_t<T> diff, const StrideSpanIterator<T>& iter) {
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return iter + diff;
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}
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static_assert(std::random_access_iterator<StrideSpanIterator<int>>);
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template<typename T>
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class StrideSpan
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{
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public:
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using element_type = T;
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using value_type = std::remove_cv_t<T>;
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using size_type = std::size_t;
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using difference_type = std::ptrdiff_t;
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using pointer = T*;
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using const_pointer = const T*;
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using reference = T&;
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using const_reference = const T&;
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using iterator = StrideSpanIterator<T>;
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using const_iterator = StrideSpanIterator<const T>;
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private:
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T* begin_ = nullptr;
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T* end_ = nullptr;
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std::size_t strideBytes_ = 0;
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public:
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StrideSpan() = default;
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StrideSpan(const StrideSpan&) = default;
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StrideSpan(T* begin, T* end, std::size_t strideBytes) noexcept : begin_(begin), end_(end), strideBytes_(strideBytes) {
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MIJIN_ASSERT(strideBytes_ > 0, "Stride elements must be >0.");
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MIJIN_ASSERT(strideBytes_ % alignof(T) == 0, "Stride must be a multiple of element align.");
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MIJIN_ASSERT(bytediff(begin_, end_) % strideBytes_ == 0, "Difference of begin and end must be a multiple of stride bytes.");
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}
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StrideSpan& operator=(const StrideSpan&) = default;
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auto operator<=>(const StrideSpan&) const noexcept = default;
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reference operator[](size_type index);
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const_reference operator[](size_type index) const;
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[[nodiscard]] constexpr size_type size() const noexcept { return bytediff(begin_, end_) / strideBytes_; }
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[[nodiscard]] iterator begin() { return StrideSpanIterator<T>(begin_, strideBytes_, begin_, end_); }
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[[nodiscard]] const_iterator begin() const { return StrideSpanIterator<const T>(begin_, strideBytes_, begin_, end_); }
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[[nodiscard]] const_iterator cbegin() const { return StrideSpanIterator<const T>(begin_, strideBytes_, begin_, end_); }
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[[nodiscard]] iterator end() { return StrideSpanIterator<T>(end_, strideBytes_, begin_, end_); }
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[[nodiscard]] const_iterator end() const { return StrideSpanIterator<const T>(end_, strideBytes_, begin_, end_); }
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[[nodiscard]] const_iterator cend() const { return StrideSpanIterator<const T>(end_, strideBytes_, begin_, end_); }
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};
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//
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// public functions
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//
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template<typename T>
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StrideSpanIterator<T>& StrideSpanIterator<T>::operator+=(difference_type diff)
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{
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#if MIJIN_CHECKED_ITERATORS
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MIJIN_ASSERT(byteoffset(ele_, diff * strideBytes_) <= end_ && byteoffset(ele_, diff * strideBytes_) >= start_,
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"Moving iterator out-of-bounds.");
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#endif
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ele_ = byteoffset(ele_, diff * strideBytes_);
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return *this;
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}
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template<typename T>
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T& StrideSpanIterator<T>::operator*() const
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{
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#if MIJIN_CHECKED_ITERATORS
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MIJIN_ASSERT(ele_ >= start_ && ele_ < end_, "Attempting to dereference invalid iterator.");
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#endif
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return *ele_;
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}
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template<typename T>
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T* StrideSpanIterator<T>::operator->() const
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{
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#if MIJIN_CHECKED_ITERATORS
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MIJIN_ASSERT(ele_ >= start_ && ele_ < end_, "Attempting to dereference invalid iterator.");
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#endif
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return ele_;
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}
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template<typename T>
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StrideSpanIterator<T>& StrideSpanIterator<T>::operator++()
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{
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#if MIJIN_CHECKED_ITERATORS
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MIJIN_ASSERT(ele_ < end_, "Attempting to move iterator past end.");
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#endif
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ele_ = byteoffset(ele_, strideBytes_);
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return *this;
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}
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template<typename T>
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StrideSpanIterator<T> StrideSpanIterator<T>::operator++(int)
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{
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StrideSpanIterator copy(*this);
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++(*this);
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return copy;
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}
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template<typename T>
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StrideSpanIterator<T>& StrideSpanIterator<T>::operator--()
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{
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#if MIJIN_CHECKED_ITERATORS
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MIJIN_ASSERT(ele_ > start_, "Attempting to move iterator before start.");
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#endif
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ele_ = byteoffset(ele_, -strideBytes_);
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return *this;
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}
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template<typename T>
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StrideSpanIterator<T> StrideSpanIterator<T>::operator--(int)
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{
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StrideSpanIterator copy(*this);
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--(*this);
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return copy;
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}
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template<typename T>
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StrideSpanIterator<T> StrideSpanIterator<T>::operator+(difference_type diff) const
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{
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#if MIJIN_CHECKED_ITERATORS
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MIJIN_ASSERT((byteoffset(ele_ + strideBytes_ * diff) <= end_) && (byteoffset(ele_, strideBytes_ * diff) >= start_),
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"Creating out-of-bounds iterator.");
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#endif
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return StrideSpanIterator(byteoffset(ele_, diff * strideBytes_), strideBytes_,
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#if MIJIN_CHECKED_ITERATORS
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start_, end_
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#else
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nullptr, nullptr
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#endif
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);
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}
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template<typename T>
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auto StrideSpan<T>::operator[](size_type index) -> reference
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{
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MIJIN_ASSERT(index < size(), "Attempting to access StrideSpan out of bounds.");
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return *byteoffset(begin_, index * strideBytes_);
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}
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template<typename T>
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auto StrideSpan<T>::operator[](size_type index) const -> const_reference
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{
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MIJIN_ASSERT(index < size(), "Attempting to access StrideSpan out of bounds.");
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return byteoffset(begin_, index * strideBytes_);
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}
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} // namespace mijin
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#endif // !defined(MIJIN_CONTAINER_STRIDE_SPAN_HPP_INCLUDED)
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@ -5,6 +5,7 @@
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#define MIJIN_CONTAINER_TYPELESS_BUFFER_HPP_INCLUDED 1
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#include <cstddef>
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#include <span>
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#include <vector>
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#include "../debug/assert.hpp"
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@ -41,6 +42,12 @@ public:
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template<typename T>
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[[nodiscard]] BufferView<T> makeBufferView() { return BufferView<T>(this); }
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template<typename T>
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[[nodiscard]] std::span<T> makeSpan();
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template<typename T>
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[[nodiscard]] std::span<const T> makeSpan() const;
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};
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template<typename T>
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@ -99,6 +106,25 @@ public:
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// public functions
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//
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template<typename T>
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std::span<T> TypelessBuffer::makeSpan()
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{
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MIJIN_ASSERT(bytes_.size() % sizeof(T) == 0, "Buffer cannot be divided into elements of this type.");
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return {
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std::bit_cast<T*>(bytes_.data()),
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std::bit_cast<T*>(bytes_.data() + bytes_.size())
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};
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}
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template<typename T>
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std::span<const T> TypelessBuffer::makeSpan() const
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{
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MIJIN_ASSERT(bytes_.size() % sizeof(T) == 0, "Buffer cannot be divided into elements of this type.");
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return {
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std::bit_cast<const T*>(bytes_.data()),
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std::bit_cast<const T*>(bytes_.data() + bytes_.size())
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};
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}
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} // namespace mijin
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#endif // !defined(MIJIN_CONTAINER_TYPELESS_BUFFER_HPP_INCLUDED)
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