From 49620ef421cadb350e559ba261259808f6653408 Mon Sep 17 00:00:00 2001
From: Olivier BICHLER <olivier.bichler@cea.fr>
Date: Wed, 6 Dec 2023 18:00:46 +0100
Subject: [PATCH] Added future_std::span, a C++11 implementation of C++20 span
---
include/aidge/utils/future_std/span.hpp | 618 ++++++++++++++++++++++++
1 file changed, 618 insertions(+)
create mode 100644 include/aidge/utils/future_std/span.hpp
diff --git a/include/aidge/utils/future_std/span.hpp b/include/aidge/utils/future_std/span.hpp
new file mode 100644
index 000000000..ba8d6c031
--- /dev/null
+++ b/include/aidge/utils/future_std/span.hpp
@@ -0,0 +1,618 @@
+
+/*
+This is an implementation of C++20's std::span
+http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/n4820.pdf
+*/
+
+// Copyright Tristan Brindle 2018.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file ../../LICENSE_1_0.txt or copy at
+// https://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef AIDGE_CORE_UTILS_FUTURE_STD_SPAN_H_
+#define AIDGE_CORE_UTILS_FUTURE_STD_SPAN_H_
+
+#include <array>
+#include <cstddef>
+#include <cstdint>
+#include <type_traits>
+
+#ifndef TCB_SPAN_NO_EXCEPTIONS
+// Attempt to discover whether we're being compiled with exception support
+#if !(defined(__cpp_exceptions) || defined(__EXCEPTIONS) || defined(_CPPUNWIND))
+#define TCB_SPAN_NO_EXCEPTIONS
+#endif
+#endif
+
+#ifndef TCB_SPAN_NO_EXCEPTIONS
+#include <cstdio>
+#include <stdexcept>
+#endif
+
+// Various feature test macros
+
+#ifndef TCB_SPAN_NAMESPACE_NAME
+#define TCB_SPAN_NAMESPACE_NAME future_std
+#endif
+
+#if __cplusplus >= 201703L || (defined(_MSVC_LANG) && _MSVC_LANG >= 201703L)
+#define TCB_SPAN_HAVE_CPP17
+#endif
+
+#if __cplusplus >= 201402L || (defined(_MSVC_LANG) && _MSVC_LANG >= 201402L)
+#define TCB_SPAN_HAVE_CPP14
+#endif
+
+namespace TCB_SPAN_NAMESPACE_NAME {
+
+// Establish default contract checking behavior
+#if !defined(TCB_SPAN_THROW_ON_CONTRACT_VIOLATION) && \
+ !defined(TCB_SPAN_TERMINATE_ON_CONTRACT_VIOLATION) && \
+ !defined(TCB_SPAN_NO_CONTRACT_CHECKING)
+#if defined(NDEBUG) || !defined(TCB_SPAN_HAVE_CPP14)
+#define TCB_SPAN_NO_CONTRACT_CHECKING
+#else
+#define TCB_SPAN_TERMINATE_ON_CONTRACT_VIOLATION
+#endif
+#endif
+
+#if defined(TCB_SPAN_THROW_ON_CONTRACT_VIOLATION)
+struct contract_violation_error : std::logic_error {
+ explicit contract_violation_error(const char* msg) : std::logic_error(msg)
+ {}
+};
+
+inline void contract_violation(const char* msg)
+{
+ throw contract_violation_error(msg);
+}
+
+#elif defined(TCB_SPAN_TERMINATE_ON_CONTRACT_VIOLATION)
+[[noreturn]] inline void contract_violation(const char* /*unused*/)
+{
+ std::terminate();
+}
+#endif
+
+#if !defined(TCB_SPAN_NO_CONTRACT_CHECKING)
+#define TCB_SPAN_STRINGIFY(cond) #cond
+#define TCB_SPAN_EXPECT(cond) \
+ cond ? (void) 0 : contract_violation("Expected " TCB_SPAN_STRINGIFY(cond))
+#else
+#define TCB_SPAN_EXPECT(cond)
+#endif
+
+#if defined(TCB_SPAN_HAVE_CPP17) || defined(__cpp_inline_variables)
+#define TCB_SPAN_INLINE_VAR inline
+#else
+#define TCB_SPAN_INLINE_VAR
+#endif
+
+#if defined(TCB_SPAN_HAVE_CPP14) || \
+ (defined(__cpp_constexpr) && __cpp_constexpr >= 201304)
+#define TCB_SPAN_HAVE_CPP14_CONSTEXPR
+#endif
+
+#if defined(TCB_SPAN_HAVE_CPP14_CONSTEXPR)
+#define TCB_SPAN_CONSTEXPR14 constexpr
+#else
+#define TCB_SPAN_CONSTEXPR14
+#endif
+
+#if defined(TCB_SPAN_HAVE_CPP14_CONSTEXPR) && \
+ (!defined(_MSC_VER) || _MSC_VER > 1900)
+#define TCB_SPAN_CONSTEXPR_ASSIGN constexpr
+#else
+#define TCB_SPAN_CONSTEXPR_ASSIGN
+#endif
+
+#if defined(TCB_SPAN_NO_CONTRACT_CHECKING)
+#define TCB_SPAN_CONSTEXPR11 constexpr
+#else
+#define TCB_SPAN_CONSTEXPR11 TCB_SPAN_CONSTEXPR14
+#endif
+
+#if defined(TCB_SPAN_HAVE_CPP17) || defined(__cpp_deduction_guides)
+#define TCB_SPAN_HAVE_DEDUCTION_GUIDES
+#endif
+
+#if defined(TCB_SPAN_HAVE_CPP17) || defined(__cpp_lib_byte)
+#define TCB_SPAN_HAVE_STD_BYTE
+#endif
+
+#if defined(TCB_SPAN_HAVE_CPP17) || defined(__cpp_lib_array_constexpr)
+#define TCB_SPAN_HAVE_CONSTEXPR_STD_ARRAY_ETC
+#endif
+
+#if defined(TCB_SPAN_HAVE_CONSTEXPR_STD_ARRAY_ETC)
+#define TCB_SPAN_ARRAY_CONSTEXPR constexpr
+#else
+#define TCB_SPAN_ARRAY_CONSTEXPR
+#endif
+
+#ifdef TCB_SPAN_HAVE_STD_BYTE
+using byte = std::byte;
+#else
+using byte = unsigned char;
+#endif
+
+#if defined(TCB_SPAN_HAVE_CPP17)
+#define TCB_SPAN_NODISCARD [[nodiscard]]
+#else
+#define TCB_SPAN_NODISCARD
+#endif
+
+TCB_SPAN_INLINE_VAR constexpr std::size_t dynamic_extent = SIZE_MAX;
+
+template <typename ElementType, std::size_t Extent = dynamic_extent>
+class span;
+
+namespace detail {
+
+template <typename E, std::size_t S>
+struct span_storage {
+ constexpr span_storage() noexcept = default;
+
+ constexpr span_storage(E* p_ptr, std::size_t /*unused*/) noexcept
+ : ptr(p_ptr)
+ {}
+
+ E* ptr = nullptr;
+ static constexpr std::size_t size = S;
+};
+
+template <typename E>
+struct span_storage<E, dynamic_extent> {
+ constexpr span_storage() noexcept = default;
+
+ constexpr span_storage(E* p_ptr, std::size_t p_size) noexcept
+ : ptr(p_ptr), size(p_size)
+ {}
+
+ E* ptr = nullptr;
+ std::size_t size = 0;
+};
+
+// Reimplementation of C++17 std::size() and std::data()
+#if defined(TCB_SPAN_HAVE_CPP17) || \
+ defined(__cpp_lib_nonmember_container_access)
+using std::data;
+using std::size;
+#else
+template <class C>
+constexpr auto size(const C& c) -> decltype(c.size())
+{
+ return c.size();
+}
+
+template <class T, std::size_t N>
+constexpr std::size_t size(const T (&)[N]) noexcept
+{
+ return N;
+}
+
+template <class C>
+constexpr auto data(C& c) -> decltype(c.data())
+{
+ return c.data();
+}
+
+template <class C>
+constexpr auto data(const C& c) -> decltype(c.data())
+{
+ return c.data();
+}
+
+template <class T, std::size_t N>
+constexpr T* data(T (&array)[N]) noexcept
+{
+ return array;
+}
+
+template <class E>
+constexpr const E* data(std::initializer_list<E> il) noexcept
+{
+ return il.begin();
+}
+#endif // TCB_SPAN_HAVE_CPP17
+
+#if defined(TCB_SPAN_HAVE_CPP17) || defined(__cpp_lib_void_t)
+using std::void_t;
+#else
+template <typename...>
+using void_t = void;
+#endif
+
+template <typename T>
+using uncvref_t =
+ typename std::remove_cv<typename std::remove_reference<T>::type>::type;
+
+template <typename>
+struct is_span : std::false_type {};
+
+template <typename T, std::size_t S>
+struct is_span<span<T, S>> : std::true_type {};
+
+template <typename>
+struct is_std_array : std::false_type {};
+
+template <typename T, std::size_t N>
+struct is_std_array<std::array<T, N>> : std::true_type {};
+
+template <typename, typename = void>
+struct has_size_and_data : std::false_type {};
+
+template <typename T>
+struct has_size_and_data<T, void_t<decltype(detail::size(std::declval<T>())),
+ decltype(detail::data(std::declval<T>()))>>
+ : std::true_type {};
+
+template <typename C, typename U = uncvref_t<C>>
+struct is_container {
+ static constexpr bool value =
+ !is_span<U>::value && !is_std_array<U>::value &&
+ !std::is_array<U>::value && has_size_and_data<C>::value;
+};
+
+template <typename T>
+using remove_pointer_t = typename std::remove_pointer<T>::type;
+
+template <typename, typename, typename = void>
+struct is_container_element_type_compatible : std::false_type {};
+
+template <typename T, typename E>
+struct is_container_element_type_compatible<
+ T, E,
+ typename std::enable_if<
+ !std::is_same<
+ typename std::remove_cv<decltype(detail::data(std::declval<T>()))>::type,
+ void>::value &&
+ std::is_convertible<
+ remove_pointer_t<decltype(detail::data(std::declval<T>()))> (*)[],
+ E (*)[]>::value
+ >::type>
+ : std::true_type {};
+
+template <typename, typename = size_t>
+struct is_complete : std::false_type {};
+
+template <typename T>
+struct is_complete<T, decltype(sizeof(T))> : std::true_type {};
+
+} // namespace detail
+
+template <typename ElementType, std::size_t Extent>
+class span {
+ static_assert(std::is_object<ElementType>::value,
+ "A span's ElementType must be an object type (not a "
+ "reference type or void)");
+ static_assert(detail::is_complete<ElementType>::value,
+ "A span's ElementType must be a complete type (not a forward "
+ "declaration)");
+ static_assert(!std::is_abstract<ElementType>::value,
+ "A span's ElementType cannot be an abstract class type");
+
+ using storage_type = detail::span_storage<ElementType, Extent>;
+
+public:
+ // constants and types
+ using element_type = ElementType;
+ using value_type = typename std::remove_cv<ElementType>::type;
+ using size_type = std::size_t;
+ using difference_type = std::ptrdiff_t;
+ using pointer = element_type*;
+ using const_pointer = const element_type*;
+ using reference = element_type&;
+ using const_reference = const element_type&;
+ using iterator = pointer;
+ using reverse_iterator = std::reverse_iterator<iterator>;
+
+ static constexpr size_type extent = Extent;
+
+ // [span.cons], span constructors, copy, assignment, and destructor
+ template <
+ std::size_t E = Extent,
+ typename std::enable_if<(E == dynamic_extent || E <= 0), int>::type = 0>
+ constexpr span() noexcept
+ {}
+
+ TCB_SPAN_CONSTEXPR11 span(pointer ptr, size_type count)
+ : storage_(ptr, count)
+ {
+ TCB_SPAN_EXPECT(extent == dynamic_extent || count == extent);
+ }
+
+ TCB_SPAN_CONSTEXPR11 span(pointer first_elem, pointer last_elem)
+ : storage_(first_elem, last_elem - first_elem)
+ {
+ TCB_SPAN_EXPECT(extent == dynamic_extent ||
+ last_elem - first_elem ==
+ static_cast<std::ptrdiff_t>(extent));
+ }
+
+ template <std::size_t N, std::size_t E = Extent,
+ typename std::enable_if<
+ (E == dynamic_extent || N == E) &&
+ detail::is_container_element_type_compatible<
+ element_type (&)[N], ElementType>::value,
+ int>::type = 0>
+ constexpr span(element_type (&arr)[N]) noexcept : storage_(arr, N)
+ {}
+
+ template <typename T, std::size_t N, std::size_t E = Extent,
+ typename std::enable_if<
+ (E == dynamic_extent || N == E) &&
+ detail::is_container_element_type_compatible<
+ std::array<T, N>&, ElementType>::value,
+ int>::type = 0>
+ TCB_SPAN_ARRAY_CONSTEXPR span(std::array<T, N>& arr) noexcept
+ : storage_(arr.data(), N)
+ {}
+
+ template <typename T, std::size_t N, std::size_t E = Extent,
+ typename std::enable_if<
+ (E == dynamic_extent || N == E) &&
+ detail::is_container_element_type_compatible<
+ const std::array<T, N>&, ElementType>::value,
+ int>::type = 0>
+ TCB_SPAN_ARRAY_CONSTEXPR span(const std::array<T, N>& arr) noexcept
+ : storage_(arr.data(), N)
+ {}
+
+ template <
+ typename Container, std::size_t E = Extent,
+ typename std::enable_if<
+ E == dynamic_extent && detail::is_container<Container>::value &&
+ detail::is_container_element_type_compatible<
+ Container&, ElementType>::value,
+ int>::type = 0>
+ constexpr span(Container& cont)
+ : storage_(detail::data(cont), detail::size(cont))
+ {}
+
+ template <
+ typename Container, std::size_t E = Extent,
+ typename std::enable_if<
+ E == dynamic_extent && detail::is_container<Container>::value &&
+ detail::is_container_element_type_compatible<
+ const Container&, ElementType>::value,
+ int>::type = 0>
+ constexpr span(const Container& cont)
+ : storage_(detail::data(cont), detail::size(cont))
+ {}
+
+ constexpr span(const span& other) noexcept = default;
+
+ template <typename OtherElementType, std::size_t OtherExtent,
+ typename std::enable_if<
+ (Extent == dynamic_extent || OtherExtent == dynamic_extent ||
+ Extent == OtherExtent) &&
+ std::is_convertible<OtherElementType (*)[],
+ ElementType (*)[]>::value,
+ int>::type = 0>
+ constexpr span(const span<OtherElementType, OtherExtent>& other) noexcept
+ : storage_(other.data(), other.size())
+ {}
+
+ ~span() noexcept = default;
+
+ TCB_SPAN_CONSTEXPR_ASSIGN span&
+ operator=(const span& other) noexcept = default;
+
+ // [span.sub], span subviews
+ template <std::size_t Count>
+ TCB_SPAN_CONSTEXPR11 span<element_type, Count> first() const
+ {
+ TCB_SPAN_EXPECT(Count <= size());
+ return {data(), Count};
+ }
+
+ template <std::size_t Count>
+ TCB_SPAN_CONSTEXPR11 span<element_type, Count> last() const
+ {
+ TCB_SPAN_EXPECT(Count <= size());
+ return {data() + (size() - Count), Count};
+ }
+
+ template <std::size_t Offset, std::size_t Count = dynamic_extent>
+ using subspan_return_t =
+ span<ElementType, Count != dynamic_extent
+ ? Count
+ : (Extent != dynamic_extent ? Extent - Offset
+ : dynamic_extent)>;
+
+ template <std::size_t Offset, std::size_t Count = dynamic_extent>
+ TCB_SPAN_CONSTEXPR11 subspan_return_t<Offset, Count> subspan() const
+ {
+ TCB_SPAN_EXPECT(Offset <= size() &&
+ (Count == dynamic_extent || Offset + Count <= size()));
+ return {data() + Offset,
+ Count != dynamic_extent ? Count : size() - Offset};
+ }
+
+ TCB_SPAN_CONSTEXPR11 span<element_type, dynamic_extent>
+ first(size_type count) const
+ {
+ TCB_SPAN_EXPECT(count <= size());
+ return {data(), count};
+ }
+
+ TCB_SPAN_CONSTEXPR11 span<element_type, dynamic_extent>
+ last(size_type count) const
+ {
+ TCB_SPAN_EXPECT(count <= size());
+ return {data() + (size() - count), count};
+ }
+
+ TCB_SPAN_CONSTEXPR11 span<element_type, dynamic_extent>
+ subspan(size_type offset, size_type count = dynamic_extent) const
+ {
+ TCB_SPAN_EXPECT(offset <= size() &&
+ (count == dynamic_extent || offset + count <= size()));
+ return {data() + offset,
+ count == dynamic_extent ? size() - offset : count};
+ }
+
+ // [span.obs], span observers
+ constexpr size_type size() const noexcept { return storage_.size; }
+
+ constexpr size_type size_bytes() const noexcept
+ {
+ return size() * sizeof(element_type);
+ }
+
+ TCB_SPAN_NODISCARD constexpr bool empty() const noexcept
+ {
+ return size() == 0;
+ }
+
+ // [span.elem], span element access
+ TCB_SPAN_CONSTEXPR11 reference operator[](size_type idx) const
+ {
+ TCB_SPAN_EXPECT(idx < size());
+ return *(data() + idx);
+ }
+
+ TCB_SPAN_CONSTEXPR11 reference front() const
+ {
+ TCB_SPAN_EXPECT(!empty());
+ return *data();
+ }
+
+ TCB_SPAN_CONSTEXPR11 reference back() const
+ {
+ TCB_SPAN_EXPECT(!empty());
+ return *(data() + (size() - 1));
+ }
+
+ constexpr pointer data() const noexcept { return storage_.ptr; }
+
+ // [span.iterators], span iterator support
+ constexpr iterator begin() const noexcept { return data(); }
+
+ constexpr iterator end() const noexcept { return data() + size(); }
+
+ TCB_SPAN_ARRAY_CONSTEXPR reverse_iterator rbegin() const noexcept
+ {
+ return reverse_iterator(end());
+ }
+
+ TCB_SPAN_ARRAY_CONSTEXPR reverse_iterator rend() const noexcept
+ {
+ return reverse_iterator(begin());
+ }
+
+private:
+ storage_type storage_{};
+};
+
+#ifdef TCB_SPAN_HAVE_DEDUCTION_GUIDES
+
+/* Deduction Guides */
+template <class T, size_t N>
+span(T (&)[N])->span<T, N>;
+
+template <class T, size_t N>
+span(std::array<T, N>&)->span<T, N>;
+
+template <class T, size_t N>
+span(const std::array<T, N>&)->span<const T, N>;
+
+template <class Container>
+span(Container&)->span<typename std::remove_reference<
+ decltype(*detail::data(std::declval<Container&>()))>::type>;
+
+template <class Container>
+span(const Container&)->span<const typename Container::value_type>;
+
+#endif // TCB_HAVE_DEDUCTION_GUIDES
+
+template <typename ElementType, std::size_t Extent>
+constexpr span<ElementType, Extent>
+make_span(span<ElementType, Extent> s) noexcept
+{
+ return s;
+}
+
+template <typename T, std::size_t N>
+constexpr span<T, N> make_span(T (&arr)[N]) noexcept
+{
+ return {arr};
+}
+
+template <typename T, std::size_t N>
+TCB_SPAN_ARRAY_CONSTEXPR span<T, N> make_span(std::array<T, N>& arr) noexcept
+{
+ return {arr};
+}
+
+template <typename T, std::size_t N>
+TCB_SPAN_ARRAY_CONSTEXPR span<const T, N>
+make_span(const std::array<T, N>& arr) noexcept
+{
+ return {arr};
+}
+
+template <typename Container>
+constexpr span<typename std::remove_reference<
+ decltype(*detail::data(std::declval<Container&>()))>::type>
+make_span(Container& cont)
+{
+ return {cont};
+}
+
+template <typename Container>
+constexpr span<const typename Container::value_type>
+make_span(const Container& cont)
+{
+ return {cont};
+}
+
+template <typename ElementType, std::size_t Extent>
+span<const byte, ((Extent == dynamic_extent) ? dynamic_extent
+ : sizeof(ElementType) * Extent)>
+as_bytes(span<ElementType, Extent> s) noexcept
+{
+ return {reinterpret_cast<const byte*>(s.data()), s.size_bytes()};
+}
+
+template <
+ class ElementType, size_t Extent,
+ typename std::enable_if<!std::is_const<ElementType>::value, int>::type = 0>
+span<byte, ((Extent == dynamic_extent) ? dynamic_extent
+ : sizeof(ElementType) * Extent)>
+as_writable_bytes(span<ElementType, Extent> s) noexcept
+{
+ return {reinterpret_cast<byte*>(s.data()), s.size_bytes()};
+}
+
+template <std::size_t N, typename E, std::size_t S>
+constexpr auto get(span<E, S> s) -> decltype(s[N])
+{
+ return s[N];
+}
+
+} // namespace TCB_SPAN_NAMESPACE_NAME
+
+namespace std {
+
+template <typename ElementType, size_t Extent>
+class tuple_size<TCB_SPAN_NAMESPACE_NAME::span<ElementType, Extent>>
+ : public integral_constant<size_t, Extent> {};
+
+template <typename ElementType>
+class tuple_size<TCB_SPAN_NAMESPACE_NAME::span<
+ ElementType, TCB_SPAN_NAMESPACE_NAME::dynamic_extent>>; // not defined
+
+template <size_t I, typename ElementType, size_t Extent>
+class tuple_element<I, TCB_SPAN_NAMESPACE_NAME::span<ElementType, Extent>> {
+public:
+ static_assert(Extent != TCB_SPAN_NAMESPACE_NAME::dynamic_extent &&
+ I < Extent,
+ "");
+ using type = ElementType;
+};
+
+} // end namespace std
+
+#endif // AIDGE_CORE_UTILS_FUTURE_STD_SPAN_H_
--
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