mfbt/Range.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
   2  * vim: set ts=8 sw=4 et tw=78:
   3  *
   4  * This Source Code Form is subject to the terms of the Mozilla Public
   5  * License, v. 2.0. If a copy of the MPL was not distributed with this
   6  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   7
   8 #ifndef mozilla_Range_h_
   9 #define mozilla_Range_h_
  10
  11 #include "mozilla/NullPtr.h"
  12 #include "mozilla/RangedPtr.h"
  13
  14 #include <stddef.h>
  15
  16 namespace mozilla {
  17
  18 // Range<T> is a tuple containing a pointer and a length.
  19 template <typename T>
  20 class Range
  21 {
  22     RangedPtr<T> mStart;
  23     RangedPtr<T> mEnd;
  24
  25     typedef void (Range::* ConvertibleToBool)();
  26     void nonNull() {}
  27
  28   public:
  29     Range() : mStart(nullptr, 0), mEnd(nullptr, 0) {}
  30     Range(T* p, size_t len)
  31       : mStart(p, p, p + len),
  32         mEnd(p + len, p, p + len)
  33     {}
  34
  35     RangedPtr<T> start() const { return mStart; }
  36     RangedPtr<T> end() const { return mEnd; }
  37     size_t length() const { return mEnd - mStart; }
  38
  39     T& operator[](size_t offset) {
  40       return mStart[offset];
  41     }
  42
  43     operator ConvertibleToBool() const { return mStart ? &Range::nonNull : 0; }
  44 };
  45
  46 } // namespace mozilla
  47
  48 #endif // mozilla_Range_h_
  49