1 files changed, 137 insertions, 0 deletions
diff --git a/dom/media/mp4/MP4Interval.h b/dom/media/mp4/MP4Interval.h
new file mode 100644
index 0000000000..70e6daeadd
--- /dev/null
+++ b/dom/media/mp4/MP4Interval.h
@@ -0,0 +1,137 @@
+/* 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 INTERVAL_H_
+#define INTERVAL_H_
+
+#include "nsTArray.h"
+#include <algorithm>
+#include <nsString.h>
+
+namespace mozilla {
+
+template <typename T>
+struct MP4Interval {
+  MP4Interval() : start{}, end{} {}
+  MP4Interval(T aStart, T aEnd) : start(aStart), end(aEnd) {
+    MOZ_ASSERT(aStart <= aEnd);
+  }
+  T Length() { return end - start; }
+  MP4Interval Intersection(const MP4Interval& aOther) const {
+    T s = start > aOther.start ? start : aOther.start;
+    T e = end < aOther.end ? end : aOther.end;
+    if (s > e) {
+      return MP4Interval();
+    }
+    return MP4Interval(s, e);
+  }
+  bool Contains(const MP4Interval& aOther) const {
+    return aOther.start >= start && aOther.end <= end;
+  }
+  bool operator==(const MP4Interval& aOther) const {
+    return start == aOther.start && end == aOther.end;
+  }
+  bool operator!=(const MP4Interval& aOther) const {
+    return !(*this == aOther);
+  }
+  bool IsNull() const { return end == start; }
+  MP4Interval Extents(const MP4Interval& aOther) const {
+    if (IsNull()) {
+      return aOther;
+    }
+    return MP4Interval(std::min(start, aOther.start),
+                       std::max(end, aOther.end));
+  }
+
+  T start;
+  T end;
+
+  nsCString ToString() {
+    return nsPrintfCString("[%s, %s]", start.ToString().get(),
+                           end.ToString().get());
+  }
+
+  static void SemiNormalAppend(nsTArray<MP4Interval<T>>& aIntervals,
+                               MP4Interval<T> aMP4Interval) {
+    if (!aIntervals.IsEmpty() &&
+        aIntervals.LastElement().end == aMP4Interval.start) {
+      aIntervals.LastElement().end = aMP4Interval.end;
+    } else {
+      aIntervals.AppendElement(aMP4Interval);
+    }
+  }
+
+  static void Normalize(const nsTArray<MP4Interval<T>>& aIntervals,
+                        nsTArray<MP4Interval<T>>* aNormalized) {
+    if (!aNormalized || !aIntervals.Length()) {
+      MOZ_ASSERT(aNormalized);
+      return;
+    }
+    MOZ_ASSERT(aNormalized->IsEmpty());
+
+    nsTArray<MP4Interval<T>> sorted = aIntervals.Clone();
+    sorted.Sort(Compare());
+
+    MP4Interval<T> current = sorted[0];
+    for (size_t i = 1; i < sorted.Length(); i++) {
+      MOZ_ASSERT(sorted[i].start <= sorted[i].end);
+      if (current.Contains(sorted[i])) {
+        continue;
+      }
+      if (current.end >= sorted[i].start) {
+        current.end = sorted[i].end;
+      } else {
+        aNormalized->AppendElement(current);
+        current = sorted[i];
+      }
+    }
+    aNormalized->AppendElement(current);
+  }
+
+  static void Intersection(const nsTArray<MP4Interval<T>>& a0,
+                           const nsTArray<MP4Interval<T>>& a1,
+                           nsTArray<MP4Interval<T>>* aIntersection) {
+    MOZ_ASSERT(IsNormalized(a0));
+    MOZ_ASSERT(IsNormalized(a1));
+    size_t i0 = 0;
+    size_t i1 = 0;
+    while (i0 < a0.Length() && i1 < a1.Length()) {
+      MP4Interval i = a0[i0].Intersection(a1[i1]);
+      if (i.Length()) {
+        aIntersection->AppendElement(i);
+      }
+      if (a0[i0].end < a1[i1].end) {
+        i0++;
+        // Assert that the array is sorted
+        MOZ_ASSERT(i0 == a0.Length() || a0[i0 - 1].start < a0[i0].start);
+      } else {
+        i1++;
+        // Assert that the array is sorted
+        MOZ_ASSERT(i1 == a1.Length() || a1[i1 - 1].start < a1[i1].start);
+      }
+    }
+  }
+
+  static bool IsNormalized(const nsTArray<MP4Interval<T>>& aIntervals) {
+    for (size_t i = 1; i < aIntervals.Length(); i++) {
+      if (aIntervals[i - 1].end >= aIntervals[i].start) {
+        return false;
+      }
+    }
+    return true;
+  }
+
+  struct Compare {
+    bool Equals(const MP4Interval<T>& a0, const MP4Interval<T>& a1) const {
+      return a0.start == a1.start && a0.end == a1.end;
+    }
+
+    bool LessThan(const MP4Interval<T>& a0, const MP4Interval<T>& a1) const {
+      return a0.start < a1.start;
+    }
+  };
+};
+}  // namespace mozilla
+
+#endif