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 #include "mozilla/Move.h"
  15 #include "mozilla/ReverseIterator.h"
  16
  17 #include <stddef.h>
  18
  19 namespace mozilla {
  20
  21 template <typename T, size_t Length>
  22 class Array {
  23   T mArr[Length];
  24
  25  public:
  26   Array() {}
  27
  28   template <typename... Args>
  29   MOZ_IMPLICIT constexpr Array(Args&&... aArgs)
  30       : mArr{std::forward<Args>(aArgs)...} {
  31     static_assert(sizeof...(aArgs) == Length,
  32                   "The number of arguments should be equal to the template "
  33                   "parameter Length");
  34   }
  35
  36   T& operator[](size_t aIndex) {
  37     MOZ_ASSERT(aIndex < Length);
  38     return mArr[aIndex];
  39   }
  40
  41   const T& operator[](size_t aIndex) const {
  42     MOZ_ASSERT(aIndex < Length);
  43     return mArr[aIndex];
  44   }
  45
  46   bool operator==(const Array<T, Length>& aOther) const {
  47     for (size_t i = 0; i < Length; i++) {
  48       if (mArr[i] != aOther[i]) {
  49         return false;
  50       }
  51     }
  52     return true;
  53   }
  54
  55   typedef T* iterator;
  56   typedef const T* const_iterator;
  57   typedef ReverseIterator<T*> reverse_iterator;
  58   typedef ReverseIterator<const T*> const_reverse_iterator;
  59
  60   // Methods for range-based for loops.
  61   iterator begin() { return mArr; }
  62   const_iterator begin() const { return mArr; }
  63   const_iterator cbegin() const { return begin(); }
  64   iterator end() { return mArr + Length; }
  65   const_iterator end() const { return mArr + Length; }
  66   const_iterator cend() const { return end(); }
  67
  68   // Methods for reverse iterating.
  69   reverse_iterator rbegin() { return reverse_iterator(end()); }
  70   const_reverse_iterator rbegin() const {
  71     return const_reverse_iterator(end());
  72   }
  73   const_reverse_iterator crbegin() const { return rbegin(); }
  74   reverse_iterator rend() { return reverse_iterator(begin()); }
  75   const_reverse_iterator rend() const {
  76     return const_reverse_iterator(begin());
  77   }
  78   const_reverse_iterator crend() const { return rend(); }
  79 };
  80
  81 template <typename T>
  82 class Array<T, 0> {
  83  public:
  84   T& operator[](size_t aIndex) { MOZ_CRASH("indexing into zero-length array"); }
  85
  86   const T& operator[](size_t aIndex) const {
  87     MOZ_CRASH("indexing into zero-length array");
  88   }
  89 };
  90
  91 } /* namespace mozilla */
  92
  93 #endif /* mozilla_Array_h */