mfbt/RangedArray.h

   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 /*
   8  * A compile-time constant-length array, with bounds-checking assertions -- but
   9  * unlike mozilla::Array, with indexes biased by a constant.
  10  *
  11  * Thus where mozilla::Array<int, 3> is a three-element array indexed by [0, 3),
  12  * mozilla::RangedArray<int, 8, 3> is a three-element array indexed by [8, 11).
  13  */
  14
  15 #ifndef mozilla_RangedArray_h
  16 #define mozilla_RangedArray_h
  17
  18 #include "mozilla/Array.h"
  19
  20 namespace mozilla {
  21
  22 template <typename T, size_t MinIndex, size_t Length>
  23 class RangedArray {
  24  private:
  25   typedef Array<T, Length> ArrayType;
  26   ArrayType mArr;
  27
  28  public:
  29   T& operator[](size_t aIndex) {
  30     MOZ_ASSERT(aIndex == MinIndex || aIndex > MinIndex);
  31     return mArr[aIndex - MinIndex];
  32   }
  33
  34   const T& operator[](size_t aIndex) const {
  35     MOZ_ASSERT(aIndex == MinIndex || aIndex > MinIndex);
  36     return mArr[aIndex - MinIndex];
  37   }
  38
  39   typedef typename ArrayType::iterator iterator;
  40   typedef typename ArrayType::const_iterator const_iterator;
  41   typedef typename ArrayType::reverse_iterator reverse_iterator;
  42   typedef typename ArrayType::const_reverse_iterator const_reverse_iterator;
  43
  44   // Methods for range-based for loops.
  45   iterator begin() { return mArr.begin(); }
  46   const_iterator begin() const { return mArr.begin(); }
  47   const_iterator cbegin() const { return mArr.cbegin(); }
  48   iterator end() { return mArr.end(); }
  49   const_iterator end() const { return mArr.end(); }
  50   const_iterator cend() const { return mArr.cend(); }
  51
  52   // Methods for reverse iterating.
  53   reverse_iterator rbegin() { return mArr.rbegin(); }
  54   const_reverse_iterator rbegin() const { return mArr.rbegin(); }
  55   const_reverse_iterator crbegin() const { return mArr.crbegin(); }
  56   reverse_iterator rend() { return mArr.rend(); }
  57   const_reverse_iterator rend() const { return mArr.rend(); }
  58   const_reverse_iterator crend() const { return mArr.crend(); }
  59 };
  60
  61 }  // namespace mozilla
  62
  63 #endif  // mozilla_RangedArray_h