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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* EnumeratedArray is like Array, but indexed by a typed enum. */
+
+#ifndef mozilla_EnumeratedArray_h
+#define mozilla_EnumeratedArray_h
+
+#include <utility>
+
+#include "mozilla/Array.h"
+
+namespace mozilla {
+
+/**
+ * EnumeratedArray is a fixed-size array container for use when an
+ * array is indexed by a specific enum class.
+ *
+ * This provides type safety by guarding at compile time against accidentally
+ * indexing such arrays with unrelated values. This also removes the need
+ * for manual casting when using a typed enum value to index arrays.
+ *
+ * Aside from the typing of indices, EnumeratedArray is similar to Array.
+ *
+ * Example:
+ *
+ * enum class AnimalSpecies {
+ * Cow,
+ * Sheep,
+ * Count
+ * };
+ *
+ * EnumeratedArray<AnimalSpecies, AnimalSpecies::Count, int> headCount;
+ *
+ * headCount[AnimalSpecies::Cow] = 17;
+ * headCount[AnimalSpecies::Sheep] = 30;
+ *
+ */
+template <typename IndexType, IndexType SizeAsEnumValue, typename ValueType>
+class EnumeratedArray {
+ public:
+ static const size_t kSize = size_t(SizeAsEnumValue);
+
+ private:
+ typedef Array<ValueType, kSize> ArrayType;
+
+ ArrayType mArray;
+
+ public:
+ EnumeratedArray() = default;
+
+ template <typename... Args>
+ MOZ_IMPLICIT constexpr EnumeratedArray(Args&&... aArgs)
+ : mArray{std::forward<Args>(aArgs)...} {}
+
+ ValueType& operator[](IndexType aIndex) { return mArray[size_t(aIndex)]; }
+
+ const ValueType& operator[](IndexType aIndex) const {
+ return mArray[size_t(aIndex)];
+ }
+
+ typedef typename ArrayType::iterator iterator;
+ typedef typename ArrayType::const_iterator const_iterator;
+ typedef typename ArrayType::reverse_iterator reverse_iterator;
+ typedef typename ArrayType::const_reverse_iterator const_reverse_iterator;
+
+ // Methods for range-based for loops.
+ iterator begin() { return mArray.begin(); }
+ const_iterator begin() const { return mArray.begin(); }
+ const_iterator cbegin() const { return mArray.cbegin(); }
+ iterator end() { return mArray.end(); }
+ const_iterator end() const { return mArray.end(); }
+ const_iterator cend() const { return mArray.cend(); }
+
+ // Methods for reverse iterating.
+ reverse_iterator rbegin() { return mArray.rbegin(); }
+ const_reverse_iterator rbegin() const { return mArray.rbegin(); }
+ const_reverse_iterator crbegin() const { return mArray.crbegin(); }
+ reverse_iterator rend() { return mArray.rend(); }
+ const_reverse_iterator rend() const { return mArray.rend(); }
+ const_reverse_iterator crend() const { return mArray.crend(); }
+};
+
+} // namespace mozilla
+
+#endif // mozilla_EnumeratedArray_h