gecko-dev/mfbt/EnumeratedArray.h

82 lines
2.1 KiB
C++

/* -*- 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 "mozilla/Array.h"
#include "mozilla/TypedEnum.h"
namespace mozilla {
/**
* EnumeratedArray is a fixed-size array container for use when an
* array is indexed by a specific enum class, as currently implemented
* by MOZ_BEGIN_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:
*
* MOZ_BEGIN_ENUM_CLASS(AnimalSpecies)
* Cow,
* Sheep,
* Count
* MOZ_END_ENUM_CLASS(AnimalSpecies)
*
* EnumeratedArray<AnimalSpecies, AnimalSpecies::Count, int> headCount;
*
* headCount[AnimalSpecies::Cow] = 17;
* headCount[AnimalSpecies::Sheep] = 30;
*
*/
template<typename IndexType,
MOZ_TEMPLATE_ENUM_CLASS_ENUM_TYPE(IndexType) SizeAsEnumValue,
typename ValueType>
class EnumeratedArray
{
public:
static const size_t Size = size_t(SizeAsEnumValue);
private:
Array<ValueType, Size> mArray;
public:
EnumeratedArray() {}
explicit EnumeratedArray(const EnumeratedArray& aOther)
{
for (size_t i = 0; i < Size; i++)
mArray[i] = aOther.mArray[i];
}
explicit EnumeratedArray(const ValueType (&aOther)[Size])
{
for (size_t i = 0; i < Size; i++)
mArray[i] = aOther[i];
}
ValueType& operator[](IndexType aIndex)
{
return mArray[size_t(aIndex)];
}
const ValueType& operator[](IndexType aIndex) const
{
return mArray[size_t(aIndex)];
}
};
} // namespace mozilla
#endif // mozilla_EnumeratedArray_h