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/NullPtr.h"
  11 #include "mozilla/RangedPtr.h"
  12
  13 #include <stddef.h>
  14
  15 namespace mozilla {
  16
  17 // Range<T> is a tuple containing a pointer and a length.
  18 template <typename T>
  19 class Range
  20 {
  21     RangedPtr<T> mStart;
  22     RangedPtr<T> mEnd;
  23
  24     typedef void (Range::* ConvertibleToBool)();
  25     void nonNull() {}
  26
  27   public:
  28     Range() : mStart(nullptr, 0), mEnd(nullptr, 0) {}
  29     Range(T* p, size_t len)
  30       : mStart(p, p, p + len),
  31         mEnd(p + len, p, p + len)
  32     {}
  33
  34     RangedPtr<T> start() const { return mStart; }
  35     RangedPtr<T> end() const { return mEnd; }
  36     size_t length() const { return mEnd - mStart; }
  37
  38     T& operator[](size_t offset) {
  39       return mStart[offset];
  40     }
  41
  42     const T& operator[](size_t offset) const {
  43       return mStart[offset];
  44     }
  45
  46     operator ConvertibleToBool() const { return mStart ? &Range::nonNull : 0; }
  47 };
  48
  49 } // namespace mozilla
  50
  51 #endif /* mozilla_Range_h */