Line data    Source code

       1             : /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
       2             : /* vim: set ts=8 sts=2 et sw=2 tw=80: */
       3             : /* This Source Code Form is subject to the terms of the Mozilla Public
       4             :  * License, v. 2.0. If a copy of the MPL was not distributed with this
       5             :  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
       6             : 
       7             : /* EnumeratedArray is like Array, but indexed by a typed enum. */
       8             : 
       9             : #ifndef mozilla_EnumeratedArray_h
      10             : #define mozilla_EnumeratedArray_h
      11             : 
      12             : #include "mozilla/Array.h"
      13             : #include "mozilla/Move.h"
      14             : 
      15             : namespace mozilla {
      16             : 
      17             : /**
      18             :  * EnumeratedArray is a fixed-size array container for use when an
      19             :  * array is indexed by a specific enum class.
      20             :  *
      21             :  * This provides type safety by guarding at compile time against accidentally
      22             :  * indexing such arrays with unrelated values. This also removes the need
      23             :  * for manual casting when using a typed enum value to index arrays.
      24             :  *
      25             :  * Aside from the typing of indices, EnumeratedArray is similar to Array.
      26             :  *
      27             :  * Example:
      28             :  *
      29             :  *   enum class AnimalSpecies {
      30             :  *     Cow,
      31             :  *     Sheep,
      32             :  *     Count
      33             :  *   };
      34             :  *
      35             :  *   EnumeratedArray<AnimalSpecies, AnimalSpecies::Count, int> headCount;
      36             :  *
      37             :  *   headCount[AnimalSpecies::Cow] = 17;
      38             :  *   headCount[AnimalSpecies::Sheep] = 30;
      39             :  *
      40             :  */
      41             : template<typename IndexType,
      42             :          IndexType SizeAsEnumValue,
      43             :          typename ValueType>
      44         100 : class EnumeratedArray
      45             : {
      46             : public:
      47             :   static const size_t kSize = size_t(SizeAsEnumValue);
      48             : 
      49             : private:
      50             :   typedef Array<ValueType, kSize> ArrayType;
      51             : 
      52             :   ArrayType mArray;
      53             : 
      54             : public:
      55        1045 :   EnumeratedArray() {}
      56             : 
      57             :   template <typename... Args>
      58           8 :   MOZ_IMPLICIT EnumeratedArray(Args&&... aArgs)
      59           8 :     : mArray{mozilla::Forward<Args>(aArgs)...}
      60           8 :   {}
      61             : 
      62           1 :   explicit EnumeratedArray(const EnumeratedArray& aOther)
      63           1 :   {
      64          97 :     for (size_t i = 0; i < kSize; i++) {
      65          96 :       mArray[i] = aOther.mArray[i];
      66             :     }
      67           1 :   }
      68             : 
      69           6 :   EnumeratedArray(EnumeratedArray&& aOther)
      70           6 :   {
      71         582 :     for (size_t i = 0; i < kSize; i++) {
      72         576 :       mArray[i] = Move(aOther.mArray[i]);
      73             :     }
      74           6 :   }
      75             : 
      76     7154539 :   ValueType& operator[](IndexType aIndex)
      77             :   {
      78     7154539 :     return mArray[size_t(aIndex)];
      79             :   }
      80             : 
      81       53547 :   const ValueType& operator[](IndexType aIndex) const
      82             :   {
      83       53547 :     return mArray[size_t(aIndex)];
      84             :   }
      85             : 
      86             :   EnumeratedArray& operator =(EnumeratedArray&& aOther)
      87             :   {
      88             :     for (size_t i = 0; i < kSize; i++) {
      89             :       mArray[i] = Move(aOther.mArray[i]);
      90             :     }
      91             :     return *this;
      92             :   }
      93             : 
      94             :   typedef typename ArrayType::iterator               iterator;
      95             :   typedef typename ArrayType::const_iterator         const_iterator;
      96             :   typedef typename ArrayType::reverse_iterator       reverse_iterator;
      97             :   typedef typename ArrayType::const_reverse_iterator const_reverse_iterator;
      98             : 
      99             :   // Methods for range-based for loops.
     100         127 :   iterator begin() { return mArray.begin(); }
     101         105 :   const_iterator begin() const { return mArray.begin(); }
     102             :   const_iterator cbegin() const { return mArray.cbegin(); }
     103         127 :   iterator end() { return mArray.end(); }
     104         105 :   const_iterator end() const { return mArray.end(); }
     105             :   const_iterator cend() const { return mArray.cend(); }
     106             : 
     107             :   // Methods for reverse iterating.
     108             :   reverse_iterator rbegin() { return mArray.rbegin(); }
     109             :   const_reverse_iterator rbegin() const { return mArray.rbegin(); }
     110             :   const_reverse_iterator crbegin() const { return mArray.crbegin(); }
     111             :   reverse_iterator rend() { return mArray.rend(); }
     112             :   const_reverse_iterator rend() const { return mArray.rend(); }
     113             :   const_reverse_iterator crend() const { return mArray.crend(); }
     114             : };
     115             : 
     116             : } // namespace mozilla
     117             : 
     118             : #endif // mozilla_EnumeratedArray_h