mfbt/Range.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 #ifndef mozilla_Range_h
   8 #define mozilla_Range_h
   9
  10 #include "mozilla/RangedPtr.h"
  11
  12 #include <stddef.h>
  13
  14 namespace mozilla {
  15
  16 // Range<T> is a tuple containing a pointer and a length.
  17 template <typename T>
  18 class Range
  19 {
  20   const RangedPtr<T> mStart;
  21   const RangedPtr<T> mEnd;
  22
  23   typedef void (Range::* ConvertibleToBool)();
  24   void nonNull() {}
  25
  26 public:
  27   Range() : mStart(nullptr, 0), mEnd(nullptr, 0) {}
  28   Range(T* aPtr, size_t aLength)
  29     : mStart(aPtr, aPtr, aPtr + aLength),
  30       mEnd(aPtr + aLength, aPtr, aPtr + aLength)
  31   {}
  32
  33   RangedPtr<T> start() const { return mStart; }
  34   RangedPtr<T> end() const { return mEnd; }
  35   size_t length() const { return mEnd - mStart; }
  36
  37   T& operator[](size_t aOffset) const { return mStart[aOffset]; }
  38
  39   operator ConvertibleToBool() const { return mStart ? &Range::nonNull : 0; }
  40 };
  41
  42 } // namespace mozilla
  43
  44 #endif /* mozilla_Range_h */