[DMC #4] Add SingletonMarkerListImpl

third_party/WebKit/Source/core/editing/markers/SingletonMarkerListImpl.cpp

Index: third_party/WebKit/Source/core/editing/markers/SingletonMarkerListImpl.cpp
diff --git a/third_party/WebKit/Source/core/editing/markers/SingletonMarkerListImpl.cpp b/third_party/WebKit/Source/core/editing/markers/SingletonMarkerListImpl.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..2351881c2e771a8fa53179a43aca70bd43713649
--- /dev/null
+++ b/third_party/WebKit/Source/core/editing/markers/SingletonMarkerListImpl.cpp
@@ -0,0 +1,90 @@
+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "core/editing/markers/SingletonMarkerListImpl.h"
+
+namespace blink {
+
+bool SingletonMarkerListImpl::IsEmpty() const {
+  return !marker_;
+}
+
+void SingletonMarkerListImpl::Add(DocumentMarker* marker) {
+  DCHECK(IsEmpty());
+  marker_ = marker;
+}
+
+void SingletonMarkerListImpl::Clear() {
+  marker_.Clear();
+}
+
+void SingletonMarkerListImpl::AppendMarkersToInputList(
+    DocumentMarkerVector* list) const {
+  if (marker_)
+    list->push_back(marker_);
+}
+
+bool SingletonMarkerListImpl::MoveMarkers(int length,
+                                          DocumentMarkerList* dst_list) {
+  DCHECK_GT(length, 0);
+  unsigned end_offset = length - 1;
+
+  if (!marker_)
+    return false;
+
+  if (marker_->StartOffset() > end_offset)
+    return false;
+
+  if (marker_->EndOffset() > end_offset)
+    marker_->SetEndOffset(end_offset);
+
+  dst_list->Add(marker_);
+  marker_.Clear();
+
+  return true;
+}
+
+bool SingletonMarkerListImpl::RemoveMarkers(unsigned start_offset, int length) {
+  if (!marker_)
+    return false;
+
+  unsigned end_offset = start_offset + length;
+  if (marker_->EndOffset() <= start_offset ||
+      marker_->StartOffset() >= end_offset)
+    return false;
+
+  marker_.Clear();
+  return true;
+}
+
+bool SingletonMarkerListImpl::ShiftMarkers(unsigned offset,
+                                           unsigned old_length,
+                                           unsigned new_length) {
+  if (!marker_)
+    return false;
+
+  Optional<DocumentMarker::MarkerOffsets> result =
+      marker_->ComputeOffsetsAfterShift(offset, old_length, new_length);
+
+  if (result == WTF::kNullopt) {
+    marker_.Clear();
+    return true;
+  }
+
+  if (marker_->StartOffset() == result.value().start_offset &&
+      marker_->EndOffset() == result.value().end_offset)
+    return false;
+
+  marker_->SetStartOffset(result.value().start_offset);
+  marker_->SetEndOffset(result.value().end_offset);
+
+  return true;
+}
+
+DEFINE_TRACE(SingletonMarkerListImpl) {
+  visitor->Trace(marker_);
+  DocumentMarkerList::Trace(visitor);
+}
+
+}  // namespace blink