1 files changed, 49 insertions, 0 deletions
diff --git a/mfbt/Range.h b/mfbt/Range.h
new file mode 100644
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--- /dev/null
+++ b/mfbt/Range.h
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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: set ts=8 sw=4 et tw=78:
+ *
+ * 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/NullPtr.h"
+#include "mozilla/RangedPtr.h"
+
+#include <stddef.h>
+
+namespace mozilla {
+
+// Range<T> is a tuple containing a pointer and a length.
+template <typename T>
+class Range
+{
+    RangedPtr<T> mStart;
+    RangedPtr<T> mEnd;
+
+    typedef void (Range::* ConvertibleToBool)();
+    void nonNull() {}
+
+  public:
+    Range() : mStart(nullptr, 0), mEnd(nullptr, 0) {}
+    Range(T* p, size_t len)
+      : mStart(p, p, p + len),
+        mEnd(p + len, p, p + len)
+    {}
+
+    RangedPtr<T> start() const { return mStart; }
+    RangedPtr<T> end() const { return mEnd; }
+    size_t length() const { return mEnd - mStart; }
+
+    T& operator[](size_t offset) {
+      return mStart[offset];
+    }
+
+    operator ConvertibleToBool() const { return mStart ? &Range::nonNull : 0; }
+};
+
+} // namespace mozilla
+
+#endif // mozilla_Range_h_
+