1 files changed, 89 insertions, 0 deletions
diff --git a/system/framework/Range.h b/system/framework/Range.h
new file mode 100644
index 000000000..c286bc974
--- /dev/null
+++ b/system/framework/Range.h
@@ -0,0 +1,89 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_Range_h
+#define mozilla_Range_h
+
+#include "mozilla/RangedPtr.h"
+#include "mozilla/TypeTraits.h"
+#include "mozilla/Span.h"
+
+#include <stddef.h>
+
+namespace mozilla {
+
+// Range<T> is a tuple containing a pointer and a length.
+template <typename T>
+class Range
+{
+  const RangedPtr<T> mStart;
+  const RangedPtr<T> mEnd;
+
+public:
+  Range() : mStart(nullptr, 0), mEnd(nullptr, 0) {}
+  Range(T* aPtr, size_t aLength)
+    : mStart(aPtr, aPtr, aPtr + aLength),
+      mEnd(aPtr + aLength, aPtr, aPtr + aLength)
+  {}
+  Range(const RangedPtr<T>& aStart, const RangedPtr<T>& aEnd)
+    : mStart(aStart.get(), aStart.get(), aEnd.get()),
+      mEnd(aEnd.get(), aStart.get(), aEnd.get())
+  {
+    // Only accept two RangedPtrs within the same range.
+    aStart.checkIdenticalRange(aEnd);
+    MOZ_ASSERT(aStart <= aEnd);
+  }
+
+  template<typename U,
+           class = typename EnableIf<IsConvertible<U (*)[], T (*)[]>::value,
+                                     int>::Type>
+  MOZ_IMPLICIT Range(const Range<U>& aOther)
+    : mStart(aOther.mStart),
+      mEnd(aOther.mEnd)
+  {}
+
+  MOZ_IMPLICIT Range(Span<T> aSpan)
+    : Range(aSpan.Elements(), aSpan.Length())
+  {
+  }
+
+  template<typename U,
+           class = typename EnableIf<IsConvertible<U (*)[], T (*)[]>::value,
+                                     int>::Type>
+  MOZ_IMPLICIT Range(const Span<U>& aSpan)
+    : Range(aSpan.Elements(), aSpan.Length())
+  {
+  }
+
+  RangedPtr<T> begin() const { return mStart; }
+  RangedPtr<T> end() const { return mEnd; }
+  size_t length() const { return mEnd - mStart; }
+
+  T& operator[](size_t aOffset) const { return mStart[aOffset]; }
+
+  explicit operator bool() const { return mStart != nullptr; }
+
+  operator Span<T>() { return Span<T>(mStart.get(), length()); }
+
+  operator Span<const T>() const { return Span<T>(mStart.get(), length()); }
+};
+
+template<class T>
+Span<T>
+MakeSpan(Range<T>& aRange)
+{
+  return aRange;
+}
+
+template<class T>
+Span<const T>
+MakeSpan(const Range<T>& aRange)
+{
+  return aRange;
+}
+
+} // namespace mozilla
+
+#endif /* mozilla_Range_h */