mfbt/Array.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 /* A compile-time constant-length array with bounds-checking assertions. */
   8
   9 #ifndef mozilla_Array_h
  10 #define mozilla_Array_h
  11
  12 #include "mozilla/Assertions.h"
  13 #include "mozilla/Attributes.h"
  14
  15 #include <stddef.h>
  16
  17 namespace mozilla {
  18
  19 template<typename T, size_t Length>
  20 class Array
  21 {
  22     T arr[Length];
  23
  24   public:
  25     T& operator[](size_t i) {
  26       MOZ_ASSERT(i < Length);
  27       return arr[i];
  28     }
  29
  30     const T& operator[](size_t i) const {
  31       MOZ_ASSERT(i < Length);
  32       return arr[i];
  33     }
  34 };
  35
  36 template<typename T>
  37 class Array<T, 0>
  38 {
  39   public:
  40     T& operator[](size_t i) {
  41       MOZ_ASSUME_UNREACHABLE("indexing into zero-length array");
  42     }
  43
  44     const T& operator[](size_t i) const {
  45       MOZ_ASSUME_UNREACHABLE("indexing into zero-length array");
  46     }
  47 };
  48
  49 }  /* namespace mozilla */
  50
  51 #endif /* mozilla_Array_h */