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Atmosphere/libraries/libvapours/include/vapours/span.hpp
2020-03-20 17:04:01 -07:00

225 lines
10 KiB
C++

/*
* Copyright (c) 2018-2020 Atmosphère-NX
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope 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, see <http://www.gnu.org/licenses/>.
*/
#pragma once
#include <vapours/common.hpp>
#include <vapours/assert.hpp>
namespace ams {
/* TODO C++20 switch to template<typename T> using Span = std::span<T> */
namespace impl {
template<typename Span>
class SpanConstIterator;
template<typename Span, typename Derived, typename Reference>
class SpanIteratorImpl {
public:
friend class SpanConstIterator<Span>;
using index_type = typename Span::index_type;
using difference_type = typename Span::difference_type;
using value_type = typename std::remove_cv<typename Span::element_type>::type;
using pointer = typename std::add_pointer<Reference>::type;
using reference = Reference;
using iterator_category = std::random_access_iterator_tag;
private:
const Span *span = nullptr;
index_type index = 0;
public:
constexpr ALWAYS_INLINE SpanIteratorImpl() = default;
constexpr ALWAYS_INLINE SpanIteratorImpl(const Span *s, index_type idx) : span(s), index(idx) { /* ... */ }
constexpr ALWAYS_INLINE pointer operator->() const {
return this->span->data() + this->index;
}
constexpr ALWAYS_INLINE reference operator*() const {
return *this->operator->();
}
constexpr ALWAYS_INLINE Derived operator++(int) {
auto prev = static_cast<Derived &>(*this);
++(*this);
return prev;
}
constexpr ALWAYS_INLINE Derived operator--(int) {
auto prev = static_cast<Derived &>(*this);
--(*this);
return prev;
}
constexpr ALWAYS_INLINE Derived &operator++() { ++this->index; return static_cast<Derived &>(*this); }
constexpr ALWAYS_INLINE Derived &operator--() { --this->index; return static_cast<Derived &>(*this); }
constexpr ALWAYS_INLINE Derived &operator+=(difference_type n) { this->index += n; return static_cast<Derived &>(*this); }
constexpr ALWAYS_INLINE Derived &operator-=(difference_type n) { this->index -= n; return static_cast<Derived &>(*this); }
constexpr ALWAYS_INLINE Derived operator+(difference_type n) const { auto r = static_cast<const Derived &>(*this); return r += n; }
constexpr ALWAYS_INLINE Derived operator-(difference_type n) const { auto r = static_cast<const Derived &>(*this); return r -= n; }
constexpr ALWAYS_INLINE friend Derived operator+(difference_type n, Derived it) { return it + n; }
constexpr ALWAYS_INLINE difference_type operator-(Derived rhs) const { AMS_ASSERT(this->span == rhs.span); return this->index - rhs.index; }
constexpr ALWAYS_INLINE reference operator[](difference_type n) const { return *(*this + n); }
constexpr ALWAYS_INLINE friend bool operator==(Derived lhs, Derived rhs) {
return lhs.span == rhs.span && lhs.index == rhs.index;
}
constexpr ALWAYS_INLINE friend bool operator<(Derived lhs, Derived rhs) {
AMS_ASSERT(lhs.span == rhs.span);
return lhs.index < rhs.index;
}
constexpr ALWAYS_INLINE friend bool operator!=(Derived lhs, Derived rhs) { return !(lhs == rhs); }
constexpr ALWAYS_INLINE friend bool operator>(Derived lhs, Derived rhs) { return rhs < lhs; }
constexpr ALWAYS_INLINE friend bool operator<=(Derived lhs, Derived rhs) { return !(lhs > rhs); }
constexpr ALWAYS_INLINE friend bool operator>=(Derived lhs, Derived rhs) { return !(lhs < rhs); }
};
template<typename Span>
class SpanIterator : public SpanIteratorImpl<Span, SpanIterator<Span>, typename Span::element_type&> {
public:
using SpanIteratorImpl<Span, SpanIterator<Span>, typename Span::element_type&>::SpanIteratorImpl;
};
template<typename Span>
class SpanConstIterator : public SpanIteratorImpl<Span, SpanConstIterator<Span>, const typename Span::element_type&> {
public:
using SpanIteratorImpl<Span, SpanConstIterator<Span>, const typename Span::element_type&>::SpanIteratorImpl;
constexpr ALWAYS_INLINE SpanConstIterator() = default;
constexpr ALWAYS_INLINE SpanConstIterator(const SpanIterator<Span> &rhs) : SpanConstIterator(rhs.span, rhs.index) { /* ... */ }
};
}
template<typename T>
class Span {
public:
using element_type = T;
using value_type = typename std::remove_cv<element_type>::type;
using index_type = std::ptrdiff_t;
using difference_type = std::ptrdiff_t;
using pointer = element_type *;
using reference = element_type &;
using iterator = ::ams::impl::SpanIterator<Span>;
using const_iterator = ::ams::impl::SpanConstIterator<Span>;
using reverse_iterator = std::reverse_iterator<iterator>;
using const_reverse_iterator = std::reverse_iterator<const_iterator>;
private:
T *ptr;
index_type num_elements;
public:
constexpr ALWAYS_INLINE Span() : ptr(), num_elements() { /* ... */ }
constexpr ALWAYS_INLINE Span(T *p, index_type size) : ptr(p), num_elements(size) {
AMS_ASSERT(this->num_elements > 0 || this->ptr == nullptr);
}
constexpr ALWAYS_INLINE Span(T *start, T *end) : Span(start, end - start) { /* ... */ }
template<size_t Size>
constexpr ALWAYS_INLINE Span(T (&arr)[Size]) : Span(static_cast<T *>(arr), static_cast<index_type>(Size)) { /* ... */ }
template<size_t Size>
constexpr ALWAYS_INLINE Span(std::array<value_type, Size> &arr) : Span(arr.data(), static_cast<index_type>(Size)) { /* ... */ }
template<size_t Size>
constexpr ALWAYS_INLINE Span(const std::array<value_type, Size> &arr) : Span(arr.data(), static_cast<index_type>(Size)) { /* ... */ }
template<typename U, typename = typename std::enable_if<std::is_convertible<U(*)[], T(*)[]>::value>::type>
constexpr ALWAYS_INLINE Span(const Span<U> &rhs) : Span(rhs.data(), rhs.size()) { /* ... */ }
public:
constexpr ALWAYS_INLINE iterator begin() const { return { this, 0 }; }
constexpr ALWAYS_INLINE iterator end() const { return { this, this->num_elements }; }
constexpr ALWAYS_INLINE const_iterator cbegin() const { return { this, 0 }; }
constexpr ALWAYS_INLINE const_iterator cend() const { return { this, this->num_elements }; }
constexpr ALWAYS_INLINE reverse_iterator rbegin() const { return reverse_iterator(this->end()); }
constexpr ALWAYS_INLINE reverse_iterator rend() const { return reverse_iterator(this->begin()); }
constexpr ALWAYS_INLINE const_reverse_iterator crbegin() const { return reverse_iterator(this->cend()); }
constexpr ALWAYS_INLINE const_reverse_iterator crend() const { return reverse_iterator(this->cbegin()); }
constexpr ALWAYS_INLINE pointer data() const { return this->ptr; }
constexpr ALWAYS_INLINE index_type size() const { return this->num_elements; }
constexpr ALWAYS_INLINE index_type size_bytes() const { return this->size() * sizeof(T); }
constexpr ALWAYS_INLINE bool empty() const { return this->size() == 0; }
constexpr ALWAYS_INLINE T &operator[](index_type idx) const {
AMS_ASSERT(idx < this->size());
return this->ptr[idx];
}
constexpr ALWAYS_INLINE T &operator()(index_type idx) const { return (*this)[idx]; }
constexpr ALWAYS_INLINE Span first(index_type size) const {
AMS_ASSERT(size <= this->size());
return { this->ptr, size };
}
constexpr ALWAYS_INLINE Span last(index_type size) const {
AMS_ASSERT(size <= this->size());
return { this->ptr + (this->size() - size), size };
}
constexpr ALWAYS_INLINE Span subspan(index_type idx, index_type size) const {
AMS_ASSERT(size <= this->size());
AMS_ASSERT(this->size() - size >= idx);
return { this->ptr + idx, size };
}
constexpr ALWAYS_INLINE Span subspan(index_type idx) const {
AMS_ASSERT(idx <= this->size());
return { this->ptr + idx, this->size() - idx };
}
};
template<typename T>
constexpr ALWAYS_INLINE Span<T> MakeSpan(T *start, T *end) {
return { start, end };
}
template<typename T>
constexpr ALWAYS_INLINE Span<T> MakeSpan(T *p, typename Span<T>::index_type size) {
return { p, size };
}
template<typename T, size_t Size>
constexpr ALWAYS_INLINE Span<T> MakeSpan(T (&arr)[Size]) {
return Span<T>(arr);
}
template<typename T, size_t Size>
constexpr ALWAYS_INLINE Span<T> MakeSpan(std::array<T, Size> &arr) {
return Span<T>(arr);
}
template<typename T, size_t Size>
constexpr ALWAYS_INLINE Span<const T> MakeSpan(const std::array<T, Size> &arr) {
return Span<const T>(arr);
}
}