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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
/* EnumeratedArray is like Array, but indexed by a typed enum. */
#ifndef mozilla_EnumeratedArray_h
#define mozilla_EnumeratedArray_h
#include <utility>
#include "mozilla/Array.h"
#include "EnumTypeTraits.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, int, AnimalSpecies::Count> headCount;
*
* headCount[AnimalSpecies::Cow] = 17;
* headCount[AnimalSpecies::Sheep] = 30;
*
* If the enum class has contiguous values and provides a specialization of
* mozilla::MaxContiguousEnumValue then the size will be calculated as the max
* value + 1.
*/
template <typename Enum, typename ValueType,
size_t Size = ContiguousEnumSize<Enum>::value>
class EnumeratedArray {
private:
static_assert(UnderlyingValue(MinContiguousEnumValue<Enum>::value) == 0,
"All indexes would need to be corrected if min != 0");
using ArrayType = Array<ValueType, Size>;
ArrayType mArray;
public:
constexpr EnumeratedArray() = default;
template <typename... Args>
MOZ_IMPLICIT constexpr EnumeratedArray(Args&&... aArgs)
: mArray{std::forward<Args>(aArgs)...} {}
constexpr ValueType& operator[](Enum aIndex) {
return mArray[size_t(aIndex)];
}
constexpr const ValueType& operator[](Enum aIndex) const {
return mArray[size_t(aIndex)];
}
using iterator = typename ArrayType::iterator;
using const_iterator = typename ArrayType::const_iterator;
using reverse_iterator = typename ArrayType::reverse_iterator;
using const_reverse_iterator = typename ArrayType::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