Upgrade macos

macx64/include/node/v8-memory-span.h

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+// Copyright 2021 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef INCLUDE_V8_MEMORY_SPAN_H_
+#define INCLUDE_V8_MEMORY_SPAN_H_
+
+#include <stddef.h>
+
+#include <array>
+#include <iterator>
+#include <type_traits>
+
+#include "v8config.h"  // NOLINT(build/include_directory)
+
+namespace v8 {
+
+/**
+ * Points to an unowned contiguous buffer holding a known number of elements.
+ *
+ * This is similar to std::span (under consideration for C++20), but does not
+ * require advanced C++ support. In the (far) future, this may be replaced with
+ * or aliased to std::span.
+ *
+ * To facilitate future migration, this class exposes a subset of the interface
+ * implemented by std::span.
+ */
+template <typename T>
+class V8_EXPORT MemorySpan {
+ private:
+  /** Some C++ machinery, brought from the future. */
+  template <typename From, typename To>
+  using is_array_convertible = std::is_convertible<From (*)[], To (*)[]>;
+  template <typename From, typename To>
+  static constexpr bool is_array_convertible_v =
+      is_array_convertible<From, To>::value;
+
+  template <typename It>
+  using iter_reference_t = decltype(*std::declval<It&>());
+
+  template <typename It, typename = void>
+  struct is_compatible_iterator : std::false_type {};
+  template <typename It>
+  struct is_compatible_iterator<
+      It,
+      std::void_t<
+          std::is_base_of<std::random_access_iterator_tag,
+                          typename std::iterator_traits<It>::iterator_category>,
+          is_array_convertible<std::remove_reference_t<iter_reference_t<It>>,
+                               T>>> : std::true_type {};
+  template <typename It>
+  static constexpr bool is_compatible_iterator_v =
+      is_compatible_iterator<It>::value;
+
+  template <typename U>
+  static constexpr U* to_address(U* p) noexcept {
+    return p;
+  }
+
+  template <typename It,
+            typename = std::void_t<decltype(std::declval<It&>().operator->())>>
+  static constexpr auto to_address(It it) noexcept {
+    return it.operator->();
+  }
+
+ public:
+  /** The default constructor creates an empty span. */
+  constexpr MemorySpan() = default;
+
+  /** Constructor from nullptr and count, for backwards compatibility.
+   * This is not compatible with C++20 std::span.
+   */
+  constexpr MemorySpan(std::nullptr_t, size_t) {}
+
+  /** Constructor from "iterator" and count. */
+  template <typename Iterator,
+            std::enable_if_t<is_compatible_iterator_v<Iterator>, bool> = true>
+  constexpr MemorySpan(Iterator first,
+                       size_t count)  // NOLINT(runtime/explicit)
+      : data_(to_address(first)), size_(count) {}
+
+  /** Constructor from two "iterators". */
+  template <typename Iterator,
+            std::enable_if_t<is_compatible_iterator_v<Iterator> &&
+                                 !std::is_convertible_v<Iterator, size_t>,
+                             bool> = true>
+  constexpr MemorySpan(Iterator first,
+                       Iterator last)  // NOLINT(runtime/explicit)
+      : data_(to_address(first)), size_(last - first) {}
+
+  /** Implicit conversion from C-style array. */
+  template <size_t N>
+  constexpr MemorySpan(T (&a)[N]) noexcept  // NOLINT(runtime/explicit)
+      : data_(a), size_(N) {}
+
+  /** Implicit conversion from std::array. */
+  template <typename U, size_t N,
+            std::enable_if_t<is_array_convertible_v<U, T>, bool> = true>
+  constexpr MemorySpan(
+      std::array<U, N>& a) noexcept  // NOLINT(runtime/explicit)
+      : data_(a.data()), size_{N} {}
+
+  /** Implicit conversion from const std::array. */
+  template <typename U, size_t N,
+            std::enable_if_t<is_array_convertible_v<const U, T>, bool> = true>
+  constexpr MemorySpan(
+      const std::array<U, N>& a) noexcept  // NOLINT(runtime/explicit)
+      : data_(a.data()), size_{N} {}
+
+  /** Returns a pointer to the beginning of the buffer. */
+  constexpr T* data() const { return data_; }
+  /** Returns the number of elements that the buffer holds. */
+  constexpr size_t size() const { return size_; }
+
+  constexpr T& operator[](size_t i) const { return data_[i]; }
+
+  /** Returns true if the buffer is empty. */
+  constexpr bool empty() const { return size() == 0; }
+
+  class Iterator {
+   public:
+    using iterator_category = std::forward_iterator_tag;
+    using value_type = T;
+    using difference_type = std::ptrdiff_t;
+    using pointer = value_type*;
+    using reference = value_type&;
+
+    T& operator*() const { return *ptr_; }
+    T* operator->() const { return ptr_; }
+
+    bool operator==(Iterator other) const { return ptr_ == other.ptr_; }
+    bool operator!=(Iterator other) const { return !(*this == other); }
+
+    Iterator& operator++() {
+      ++ptr_;
+      return *this;
+    }
+
+    Iterator operator++(int) {
+      Iterator temp(*this);
+      ++(*this);
+      return temp;
+    }
+
+   private:
+    friend class MemorySpan<T>;
+
+    explicit Iterator(T* ptr) : ptr_(ptr) {}
+
+    T* ptr_ = nullptr;
+  };
+
+  Iterator begin() const { return Iterator(data_); }
+  Iterator end() const { return Iterator(data_ + size_); }
+
+ private:
+  T* data_ = nullptr;
+  size_t size_ = 0;
+};
+
+/**
+ * Helper function template to create an array of fixed length, initialized by
+ * the provided initializer list, without explicitly specifying the array size,
+ * e.g.
+ *
+ *   auto arr = v8::to_array<Local<String>>({v8_str("one"), v8_str("two")});
+ *
+ * In the future, this may be replaced with or aliased to std::to_array (under
+ * consideration for C++20).
+ */
+
+namespace detail {
+template <class T, std::size_t N, std::size_t... I>
+constexpr std::array<std::remove_cv_t<T>, N> to_array_lvalue_impl(
+    T (&a)[N], std::index_sequence<I...>) {
+  return {{a[I]...}};
+}
+
+template <class T, std::size_t N, std::size_t... I>
+constexpr std::array<std::remove_cv_t<T>, N> to_array_rvalue_impl(
+    T (&&a)[N], std::index_sequence<I...>) {
+  return {{std::move(a[I])...}};
+}
+}  // namespace detail
+
+template <class T, std::size_t N>
+constexpr std::array<std::remove_cv_t<T>, N> to_array(T (&a)[N]) {
+  return detail::to_array_lvalue_impl(a, std::make_index_sequence<N>{});
+}
+
+template <class T, std::size_t N>
+constexpr std::array<std::remove_cv_t<T>, N> to_array(T (&&a)[N]) {
+  return detail::to_array_rvalue_impl(std::move(a),
+                                      std::make_index_sequence<N>{});
+}
+
+}  // namespace v8
+#endif  // INCLUDE_V8_MEMORY_SPAN_H_