1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/mfbt/EnumeratedArray.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,81 @@
1.4 +/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
1.5 +/* vim: set ts=8 sts=2 et sw=2 tw=80: */
1.6 +/* This Source Code Form is subject to the terms of the Mozilla Public
1.7 + * License, v. 2.0. If a copy of the MPL was not distributed with this
1.8 + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
1.9 +
1.10 +/* EnumeratedArray is like Array, but indexed by a typed enum. */
1.11 +
1.12 +#ifndef mozilla_EnumeratedArray_h
1.13 +#define mozilla_EnumeratedArray_h
1.14 +
1.15 +#include "mozilla/Array.h"
1.16 +#include "mozilla/TypedEnum.h"
1.17 +
1.18 +namespace mozilla {
1.19 +
1.20 +/**
1.21 + * EnumeratedArray is a fixed-size array container for use when an
1.22 + * array is indexed by a specific enum class, as currently implemented
1.23 + * by MOZ_BEGIN_ENUM_CLASS.
1.24 + *
1.25 + * This provides type safety by guarding at compile time against accidentally
1.26 + * indexing such arrays with unrelated values. This also removes the need
1.27 + * for manual casting when using a typed enum value to index arrays.
1.28 + *
1.29 + * Aside from the typing of indices, EnumeratedArray is similar to Array.
1.30 + *
1.31 + * Example:
1.32 + *
1.33 + * MOZ_BEGIN_ENUM_CLASS(AnimalSpecies)
1.34 + * Cow,
1.35 + * Sheep,
1.36 + * Count
1.37 + * MOZ_END_ENUM_CLASS(AnimalSpecies)
1.38 + *
1.39 + * EnumeratedArray<AnimalSpecies, AnimalSpecies::Count, int> headCount;
1.40 + *
1.41 + * headCount[AnimalSpecies::Cow] = 17;
1.42 + * headCount[AnimalSpecies::Sheep] = 30;
1.43 + *
1.44 + */
1.45 +template<typename IndexType,
1.46 + MOZ_TEMPLATE_ENUM_CLASS_ENUM_TYPE(IndexType) SizeAsEnumValue,
1.47 + typename ValueType>
1.48 +class EnumeratedArray
1.49 +{
1.50 + public:
1.51 + static const size_t Size = size_t(SizeAsEnumValue);
1.52 +
1.53 + private:
1.54 + Array<ValueType, Size> mArray;
1.55 +
1.56 + public:
1.57 + EnumeratedArray() {}
1.58 +
1.59 + explicit EnumeratedArray(const EnumeratedArray& aOther)
1.60 + {
1.61 + for (size_t i = 0; i < Size; i++)
1.62 + mArray[i] = aOther.mArray[i];
1.63 + }
1.64 +
1.65 + explicit EnumeratedArray(const ValueType (&aOther)[Size])
1.66 + {
1.67 + for (size_t i = 0; i < Size; i++)
1.68 + mArray[i] = aOther[i];
1.69 + }
1.70 +
1.71 + ValueType& operator[](IndexType aIndex)
1.72 + {
1.73 + return mArray[size_t(aIndex)];
1.74 + }
1.75 +
1.76 + const ValueType& operator[](IndexType aIndex) const
1.77 + {
1.78 + return mArray[size_t(aIndex)];
1.79 + }
1.80 +};
1.81 +
1.82 +} // namespace mozilla
1.83 +
1.84 +#endif // mozilla_EnumeratedArray_h
