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95 lines
3.1 KiB
C++
95 lines
3.1 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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/* EnumeratedArray is like Array, but indexed by a typed enum. */
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#ifndef mozilla_EnumeratedArray_h
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#define mozilla_EnumeratedArray_h
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#include <utility>
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#include "mozilla/Array.h"
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#include "EnumTypeTraits.h"
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namespace mozilla {
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/**
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* EnumeratedArray is a fixed-size array container for use when an
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* array is indexed by a specific enum class.
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*
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* This provides type safety by guarding at compile time against accidentally
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* indexing such arrays with unrelated values. This also removes the need
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* for manual casting when using a typed enum value to index arrays.
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*
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* Aside from the typing of indices, EnumeratedArray is similar to Array.
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*
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* Example:
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*
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* enum class AnimalSpecies {
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* Cow,
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* Sheep,
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* Count
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* };
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*
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* EnumeratedArray<AnimalSpecies, int, AnimalSpecies::Count> headCount;
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*
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* headCount[AnimalSpecies::Cow] = 17;
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* headCount[AnimalSpecies::Sheep] = 30;
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*
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* If the enum class has contiguous values and provides a specialization of
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* mozilla::MaxContiguousEnumValue then the size will be calculated as the max
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* value + 1.
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*/
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template <typename Enum, typename ValueType,
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size_t Size = ContiguousEnumSize<Enum>::value>
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class EnumeratedArray {
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private:
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static_assert(UnderlyingValue(MinContiguousEnumValue<Enum>::value) == 0,
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"All indexes would need to be corrected if min != 0");
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using ArrayType = Array<ValueType, Size>;
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ArrayType mArray;
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public:
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constexpr EnumeratedArray() = default;
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template <typename... Args>
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MOZ_IMPLICIT constexpr EnumeratedArray(Args&&... aArgs)
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: mArray{std::forward<Args>(aArgs)...} {}
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ValueType& operator[](Enum aIndex) { return mArray[size_t(aIndex)]; }
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const ValueType& operator[](Enum aIndex) const {
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return mArray[size_t(aIndex)];
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}
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using iterator = typename ArrayType::iterator;
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using const_iterator = typename ArrayType::const_iterator;
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using reverse_iterator = typename ArrayType::reverse_iterator;
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using const_reverse_iterator = typename ArrayType::const_reverse_iterator;
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// Methods for range-based for loops.
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iterator begin() { return mArray.begin(); }
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const_iterator begin() const { return mArray.begin(); }
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const_iterator cbegin() const { return mArray.cbegin(); }
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iterator end() { return mArray.end(); }
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const_iterator end() const { return mArray.end(); }
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const_iterator cend() const { return mArray.cend(); }
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// Methods for reverse iterating.
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reverse_iterator rbegin() { return mArray.rbegin(); }
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const_reverse_iterator rbegin() const { return mArray.rbegin(); }
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const_reverse_iterator crbegin() const { return mArray.crbegin(); }
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reverse_iterator rend() { return mArray.rend(); }
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const_reverse_iterator rend() const { return mArray.rend(); }
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const_reverse_iterator crend() const { return mArray.crend(); }
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};
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} // namespace mozilla
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#endif // mozilla_EnumeratedArray_h
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