1 files changed, 76 insertions, 0 deletions
diff --git a/layout/generic/nsIntervalSet.cpp b/layout/generic/nsIntervalSet.cpp
new file mode 100644
index 0000000000..9cb61253a7
--- /dev/null
+++ b/layout/generic/nsIntervalSet.cpp
@@ -0,0 +1,76 @@
+/* -*- 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 */
+
+#include "nsIntervalSet.h"
+#include <new>
+#include <algorithm>
+#include "mozilla/PresShell.h"  // for allocation
+
+using namespace mozilla;
+
+nsIntervalSet::nsIntervalSet(PresShell* aPresShell)
+    : mList(nullptr), mPresShell(aPresShell) {}
+
+nsIntervalSet::~nsIntervalSet() {
+  Interval* current = mList;
+  while (current) {
+    Interval* trash = current;
+    current = current->mNext;
+    FreeInterval(trash);
+  }
+}
+
+void* nsIntervalSet::AllocateInterval() {
+  return mPresShell->AllocateByObjectID(eArenaObjectID_nsIntervalSet_Interval,
+                                        sizeof(Interval));
+}
+
+void nsIntervalSet::FreeInterval(nsIntervalSet::Interval* aInterval) {
+  NS_ASSERTION(aInterval, "null interval");
+
+  aInterval->Interval::~Interval();
+  mPresShell->FreeByObjectID(eArenaObjectID_nsIntervalSet_Interval, aInterval);
+}
+
+void nsIntervalSet::IncludeInterval(coord_type aBegin, coord_type aEnd) {
+  auto newInterval = static_cast<Interval*>(AllocateInterval());
+  new (newInterval) Interval(aBegin, aEnd);
+
+  Interval** current = &mList;
+  while (*current && (*current)->mEnd < aBegin) current = &(*current)->mNext;
+
+  newInterval->mNext = *current;
+  *current = newInterval;
+
+  Interval* subsumed = newInterval->mNext;
+  while (subsumed && subsumed->mBegin <= aEnd) {
+    newInterval->mBegin = std::min(newInterval->mBegin, subsumed->mBegin);
+    newInterval->mEnd = std::max(newInterval->mEnd, subsumed->mEnd);
+    newInterval->mNext = subsumed->mNext;
+    FreeInterval(subsumed);
+    subsumed = newInterval->mNext;
+  }
+}
+
+bool nsIntervalSet::Intersects(coord_type aBegin, coord_type aEnd) const {
+  Interval* current = mList;
+  while (current && current->mBegin <= aEnd) {
+    if (current->mEnd >= aBegin) return true;
+    current = current->mNext;
+  }
+  return false;
+}
+
+bool nsIntervalSet::Contains(coord_type aBegin, coord_type aEnd) const {
+  Interval* current = mList;
+  while (current && current->mBegin <= aBegin) {
+    if (current->mEnd >= aEnd) return true;
+    current = current->mNext;
+  }
+  return false;
+}