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-rw-r--r--layout/generic/nsIntervalSet.h72
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diff --git a/layout/generic/nsIntervalSet.h b/layout/generic/nsIntervalSet.h
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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+// vim:cindent:ts=8:et:sw=4:
+/* 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/. */
+
+/* a set of ranges on a number-line */
+
+#ifndef nsIntervalSet_h___
+#define nsIntervalSet_h___
+
+#include "nsCoord.h"
+
+namespace mozilla {
+class PresShell;
+} // namespace mozilla
+
+/*
+ * A list-based class (hopefully tree-based when I get around to it)
+ * for representing a set of ranges on a number-line.
+ */
+class nsIntervalSet {
+ public:
+ typedef nscoord coord_type;
+
+ explicit nsIntervalSet(mozilla::PresShell* aPresShell);
+ ~nsIntervalSet();
+
+ /*
+ * Include the interval [aBegin, aEnd] in the set.
+ *
+ * Removal of intervals added is not supported because that would
+ * require keeping track of the individual intervals that were
+ * added (nsIntervalMap should do that). It would be simple to
+ * implement ExcludeInterval if anyone wants it, though.
+ */
+ void IncludeInterval(coord_type aBegin, coord_type aEnd);
+
+ /*
+ * Are _some_ points in [aBegin, aEnd] contained within the set
+ * of intervals?
+ */
+ bool Intersects(coord_type aBegin, coord_type aEnd) const;
+
+ /*
+ * Are _all_ points in [aBegin, aEnd] contained within the set
+ * of intervals?
+ */
+ bool Contains(coord_type aBegin, coord_type aEnd) const;
+
+ bool IsEmpty() const { return !mList; }
+
+ private:
+ class Interval {
+ public:
+ Interval(coord_type aBegin, coord_type aEnd)
+ : mBegin(aBegin), mEnd(aEnd), mPrev(nullptr), mNext(nullptr) {}
+
+ coord_type mBegin;
+ coord_type mEnd;
+ Interval* mPrev;
+ Interval* mNext;
+ };
+
+ void* AllocateInterval();
+ void FreeInterval(Interval* aInterval);
+
+ Interval* mList;
+ mozilla::PresShell* mPresShell;
+};
+
+#endif // !defined(nsIntervalSet_h___)