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Array.h (3274B)

      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 <cstddef>
     13 
     14 #include <iterator>
     15 #include <ostream>
     16 #include <utility>
     17 
     18 #include "mozilla/Assertions.h"
     19 #include "mozilla/Attributes.h"
     20 #include "mozilla/Likely.h"
     21 
     22 namespace mozilla {
     23 
     24 template <typename T, size_t _Length>
     25 class MOZ_GSL_OWNER Array {
     26  T mArr[_Length];
     27 
     28 public:
     29  using ElementType = T;
     30  static constexpr size_t Length = _Length;
     31 
     32  constexpr Array() = default;
     33 
     34  template <typename... Args>
     35  MOZ_IMPLICIT constexpr Array(Args&&... aArgs)
     36      : mArr{std::forward<Args>(aArgs)...} {
     37    static_assert(sizeof...(aArgs) == Length,
     38                  "The number of arguments should be equal to the template "
     39                  "parameter Length");
     40  }
     41 
     42  constexpr T& operator[](size_t aIndex) MOZ_LIFETIME_BOUND {
     43    if (MOZ_UNLIKELY(aIndex >= Length)) {
     44      detail::InvalidArrayIndex_CRASH(aIndex, Length);
     45    }
     46    return mArr[aIndex];
     47  }
     48 
     49  constexpr const T& operator[](size_t aIndex) const MOZ_LIFETIME_BOUND {
     50    if (MOZ_UNLIKELY(aIndex >= Length)) {
     51      detail::InvalidArrayIndex_CRASH(aIndex, Length);
     52    }
     53    return mArr[aIndex];
     54  }
     55 
     56  bool operator==(const Array<T, Length>& aOther) const {
     57    for (size_t i = 0; i < Length; i++) {
     58      if (mArr[i] != aOther[i]) {
     59        return false;
     60      }
     61    }
     62    return true;
     63  }
     64 
     65  typedef T* iterator;
     66  typedef const T* const_iterator;
     67  typedef std::reverse_iterator<T*> reverse_iterator;
     68  typedef std::reverse_iterator<const T*> const_reverse_iterator;
     69 
     70  // Methods for range-based for loops.
     71  iterator begin() { return mArr; }
     72  constexpr const_iterator begin() const { return mArr; }
     73  constexpr const_iterator cbegin() const { return begin(); }
     74  iterator end() { return mArr + Length; }
     75  constexpr const_iterator end() const { return mArr + Length; }
     76  constexpr const_iterator cend() const { return end(); }
     77 
     78  // Method for std::size.
     79  constexpr size_t size() const { return Length; }
     80 
     81  // Methods for reverse iterating.
     82  reverse_iterator rbegin() { return reverse_iterator(end()); }
     83  const_reverse_iterator rbegin() const {
     84    return const_reverse_iterator(end());
     85  }
     86  const_reverse_iterator crbegin() const { return rbegin(); }
     87  reverse_iterator rend() { return reverse_iterator(begin()); }
     88  const_reverse_iterator rend() const {
     89    return const_reverse_iterator(begin());
     90  }
     91  const_reverse_iterator crend() const { return rend(); }
     92 };
     93 
     94 template <typename T>
     95 class Array<T, 0> {
     96 public:
     97  T& operator[](size_t aIndex) { MOZ_CRASH("indexing into zero-length array"); }
     98 
     99  const T& operator[](size_t aIndex) const {
    100    MOZ_CRASH("indexing into zero-length array");
    101  }
    102 };
    103 
    104 // MOZ_DBG support
    105 
    106 template <typename T, size_t Length>
    107 std::ostream& operator<<(std::ostream& aOut, const Array<T, Length>& aArray) {
    108  return aOut << Span(aArray);
    109 }
    110 
    111 } /* namespace mozilla */
    112 
    113 #endif /* mozilla_Array_h */