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 <ostream>
  18 #include <stddef.h>
  19
  20 namespace mozilla {
  21
  22 template <typename T, size_t Length>
  23 class Array {
  24   T mArr[Length];
  25
  26  public:
  27   Array() {}
  28
  29   template <typename... Args>
  30   MOZ_IMPLICIT constexpr Array(Args&&... aArgs)
  31       : mArr{std::forward<Args>(aArgs)...} {
  32     static_assert(sizeof...(aArgs) == Length,
  33                   "The number of arguments should be equal to the template "
  34                   "parameter Length");
  35   }
  36
  37   T& operator[](size_t aIndex) {
  38     MOZ_ASSERT(aIndex < Length);
  39     return mArr[aIndex];
  40   }
  41
  42   const T& operator[](size_t aIndex) const {
  43     MOZ_ASSERT(aIndex < Length);
  44     return mArr[aIndex];
  45   }
  46
  47   bool operator==(const Array<T, Length>& aOther) const {
  48     for (size_t i = 0; i < Length; i++) {
  49       if (mArr[i] != aOther[i]) {
  50         return false;
  51       }
  52     }
  53     return true;
  54   }
  55
  56   typedef T* iterator;
  57   typedef const T* const_iterator;
  58   typedef ReverseIterator<T*> reverse_iterator;
  59   typedef ReverseIterator<const T*> const_reverse_iterator;
  60
  61   // Methods for range-based for loops.
  62   iterator begin() { return mArr; }
  63   const_iterator begin() const { return mArr; }
  64   const_iterator cbegin() const { return begin(); }
  65   iterator end() { return mArr + Length; }
  66   const_iterator end() const { return mArr + Length; }
  67   const_iterator cend() const { return end(); }
  68
  69   // Methods for reverse iterating.
  70   reverse_iterator rbegin() { return reverse_iterator(end()); }
  71   const_reverse_iterator rbegin() const {
  72     return const_reverse_iterator(end());
  73   }
  74   const_reverse_iterator crbegin() const { return rbegin(); }
  75   reverse_iterator rend() { return reverse_iterator(begin()); }
  76   const_reverse_iterator rend() const {
  77     return const_reverse_iterator(begin());
  78   }
  79   const_reverse_iterator crend() const { return rend(); }
  80 };
  81
  82 template <typename T>
  83 class Array<T, 0> {
  84  public:
  85   T& operator[](size_t aIndex) { MOZ_CRASH("indexing into zero-length array"); }
  86
  87   const T& operator[](size_t aIndex) const {
  88     MOZ_CRASH("indexing into zero-length array");
  89   }
  90 };
  91
  92 // MOZ_DBG support
  93
  94 template <typename T, size_t Length>
  95 std::ostream& operator<<(std::ostream& aOut, const Array<T, Length>& aArray) {
  96   return aOut << MakeSpan(aArray);
  97 }
  98
  99 } /* namespace mozilla */
 100
 101 #endif /* mozilla_Array_h */