Explicit management of FrameSelection availability

third_party/WebKit/Source/core/editing/SelectionEditor.cpp

Index: third_party/WebKit/Source/core/editing/SelectionEditor.cpp
diff --git a/third_party/WebKit/Source/core/editing/SelectionEditor.cpp b/third_party/WebKit/Source/core/editing/SelectionEditor.cpp
index 0dc76f0fef3b9f52cab367db903ee52d1a675f81..54f028814e5dc4e06f815a4b136d0fe1932d3736 100644
--- a/third_party/WebKit/Source/core/editing/SelectionEditor.cpp
+++ b/third_party/WebKit/Source/core/editing/SelectionEditor.cpp
@@ -36,15 +36,33 @@ SelectionEditor::SelectionEditor(FrameSelection& frameSelection)
     : m_frameSelection(frameSelection)
     , m_observingVisibleSelection(false)
 {
+    clearVisibleSelection();
 }
 
 SelectionEditor::~SelectionEditor()
 {
 }
 
+void SelectionEditor::clearVisibleSelection()
+{
+    m_selection = VisibleSelection();
+    m_selectionInFlatTree = VisibleSelectionInFlatTree();
+    if (!shouldAlwaysUseDirectionalSelection())
+        return;
+    m_selection.setIsDirectional(true);
+    m_selectionInFlatTree.setIsDirectional(true);
+}
+
 void SelectionEditor::dispose()
 {
     resetLogicalRange();
+    clearVisibleSelection();
+}
+
+const Document& SelectionEditor::document() const
+{
+    DCHECK(m_document);
+    return *m_document;
 }
 
 LocalFrame* SelectionEditor::frame() const
@@ -55,17 +73,28 @@ LocalFrame* SelectionEditor::frame() const
 template <>
 const VisibleSelection& SelectionEditor::visibleSelection<EditingStrategy>() const
 {
+    DCHECK_EQ(frame()->document(), document());
+    DCHECK_EQ(frame(), document().frame());
+    if (m_selection.isNone())
+        return m_selection;
+    DCHECK_EQ(m_selection.base().document(), document());
     return m_selection;
 }
 
 template <>
 const VisibleSelectionInFlatTree& SelectionEditor::visibleSelection<EditingInFlatTreeStrategy>() const
 {
+    DCHECK_EQ(frame()->document(), document());
+    DCHECK_EQ(frame(), document().frame());
+    if (m_selectionInFlatTree.isNone())
+        return m_selectionInFlatTree;
+    DCHECK_EQ(m_selectionInFlatTree.base().document(), document());
     return m_selectionInFlatTree;
 }
 
 void SelectionEditor::setVisibleSelection(const VisibleSelection& newSelection, FrameSelection::SetSelectionOptions options)
 {
+    DCHECK(newSelection.isValidFor(document())) << newSelection;
     resetLogicalRange();
     m_selection = newSelection;
     if (options & FrameSelection::DoNotAdjustInFlatTree) {
@@ -78,25 +107,38 @@ void SelectionEditor::setVisibleSelection(const VisibleSelection& newSelection,
 
 void SelectionEditor::setVisibleSelection(const VisibleSelectionInFlatTree& newSelection, FrameSelection::SetSelectionOptions options)
 {
+    DCHECK(newSelection.isValidFor(document())) << newSelection;
     DCHECK(!(options & FrameSelection::DoNotAdjustInFlatTree));
     resetLogicalRange();
     m_selectionInFlatTree = newSelection;
     SelectionAdjuster::adjustSelectionInDOMTree(&m_selection, m_selectionInFlatTree);
 }
 
-void SelectionEditor::setIsDirectional(bool isDirectional)
-{
-    m_selection.setIsDirectional(isDirectional);
-    m_selectionInFlatTree.setIsDirectional(isDirectional);
-}
-
 void SelectionEditor::setWithoutValidation(const Position& base, const Position& extent)
 {
     resetLogicalRange();
+    if (base.isNotNull())
+        DCHECK_EQ(base.document(), document());
+    if (extent.isNotNull())
+        DCHECK_EQ(extent.document(), document());
     m_selection.setWithoutValidation(base, extent);
     m_selectionInFlatTree.setWithoutValidation(toPositionInFlatTree(base), toPositionInFlatTree(extent));
 }
 
+void SelectionEditor::documentAttached(Document* document)
+{
+    DCHECK(document);
+    DCHECK(!m_document) << m_document;
+    m_document = document;
+}
+
+void SelectionEditor::documentDetached(const Document& document)
+{
+    DCHECK_EQ(m_document, &document);
+    dispose();
+    m_document = nullptr;
+}
+
 void SelectionEditor::resetLogicalRange()
 {
     // Non-collapsed ranges are not allowed to start at the end of a line that
@@ -109,6 +151,7 @@ void SelectionEditor::resetLogicalRange()
 
 void SelectionEditor::setLogicalRange(Range* range)
 {
+    DCHECK_EQ(range->ownerDocument(), document());
     DCHECK(!m_logicalRange) << "A logical range should be one.";
     m_logicalRange = range;
 }
@@ -120,14 +163,22 @@ Range* SelectionEditor::firstRange() const
     return firstRangeOf(m_selection);
 }
 
+bool SelectionEditor::shouldAlwaysUseDirectionalSelection() const
+{
+    return frame()->editor().behavior().shouldConsiderSelectionAsDirectional();
+}
+
 void SelectionEditor::updateIfNeeded()
 {
+    DCHECK(m_selection.isValidFor(document())) << m_selection;
+    DCHECK(m_selectionInFlatTree.isValidFor(document())) << m_selection;
     m_selection.updateIfNeeded();
     m_selectionInFlatTree.updateIfNeeded();
 }
 
 DEFINE_TRACE(SelectionEditor)
 {
+    visitor->trace(m_document);
     visitor->trace(m_frameSelection);
     visitor->trace(m_selection);
     visitor->trace(m_selectionInFlatTree);