Introduce isVisuallyEquivalentCandidate() as replacement of PositionAlgorithm::isCandidate()

This patch introduces |isVisuallyEquivalentCandidate()| as replacement of
|PositionAlgorithm::isCandidate()| to make what this functions for
improving readability.

Following patch will move |isVisuallyEquivalentCandidate()| to
"VisibleUnits.cpp" to reduce usages of |InlineBox| from "Position.cpp" as
part of making |PositionAlgorithm| class to free from |InlineBox|.

BUG=518738
TEST=n/a; no behavior changes

Review URL: https://codereview.chromium.org/1300303002

git-svn-id: svn://svn.chromium.org/blink/trunk@200917 bbb929c8-8fbe-4397-9dbb-9b2b20218538

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

@@ -338,7 +338,7 @@ PositionAlgorithm<Strategy> nextCandidateAlgorithm(const PositionAlgorithm<Strat
     p.increment();
     while (!p.atEnd()) {
         PositionAlgorithm<Strategy> candidate = p.computePosition();
-        if (candidate.isCandidate())
+        if (isVisuallyEquivalentCandidate(candidate))
             return candidate;
 
         p.increment();
@@ -371,7 +371,7 @@ Position nextVisuallyDistinctCandidate(const Position& position)
     p.increment();
     while (!p.atEnd()) {
         Position candidate = p.computePosition();
-        if (candidate.isCandidate() && candidate.downstream() != downstreamStart)
+        if (isVisuallyEquivalentCandidate(candidate) && candidate.downstream() != downstreamStart)
             return candidate;
 
         p.increment();
@@ -388,7 +388,7 @@ PositionAlgorithm<Strategy> previousCandidateAlgorithm(const PositionAlgorithm<S
     p.decrement();
     while (!p.atStart()) {
         PositionAlgorithm<Strategy> candidate = p.computePosition();
-        if (candidate.isCandidate())
+        if (isVisuallyEquivalentCandidate(candidate))
             return candidate;
 
         p.decrement();
@@ -422,7 +422,7 @@ PositionAlgorithm<Strategy> previousVisuallyDistinctCandidateAlgorithm(const Pos
     p.decrement();
     while (!p.atStart()) {
         PositionAlgorithm<Strategy> candidate = p.computePosition();
-        if (candidate.isCandidate() && candidate.downstream() != downstreamStart)
+        if (isVisuallyEquivalentCandidate(candidate) && candidate.downstream() != downstreamStart)
             return candidate;
 
         p.decrement();
@@ -1151,7 +1151,7 @@ static Position previousCharacterPosition(const Position& position, TextAffinity
     Element* fromRootEditableElement = position.anchorNode()->rootEditableElement();
 
     bool atStartOfLine = isStartOfLine(VisiblePosition(position, affinity));
-    bool rendered = position.isCandidate();
+    bool rendered = isVisuallyEquivalentCandidate(position);
 
     Position currentPos = position;
     while (!currentPos.atStartOfTree()) {
@@ -1161,7 +1161,7 @@ static Position previousCharacterPosition(const Position& position, TextAffinity
             return position;
 
         if (atStartOfLine || !rendered) {
-            if (currentPos.isCandidate())
+            if (isVisuallyEquivalentCandidate(currentPos))
                 return currentPos;
         } else if (rendersInDifferentPosition(position, currentPos)) {
             return currentPos;

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

@@ -1282,7 +1282,7 @@ IntRect FrameSelection::absoluteCaretBounds()
         clearCaretRect();
     } else {
         if (isTextFormControl(m_selection))
-            updateCaretRect(PositionWithAffinity(m_selection.start().isCandidate() ? m_selection.start() : Position(), m_selection.affinity()));
+            updateCaretRect(PositionWithAffinity(isVisuallyEquivalentCandidate(m_selection.start()) ? m_selection.start() : Position(), m_selection.affinity()));
         else
             updateCaretRect(VisiblePosition(m_selection.start(), m_selection.affinity()));
     }

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

@@ -492,13 +492,16 @@ PositionAlgorithm<Strategy> PositionAlgorithm<Strategy>::downstream(EditingBound
     return mostBackwardCaretPosition(*this, rule);
 }
 
+// TODO(yosin) We should move |isVisuallyEquivalentCandidate()| to
+// "VisibleUnits.cpp" to reduce |LayoutObject| dependency in "Position.cpp".
 template <typename Strategy>
-bool PositionAlgorithm<Strategy>::isCandidate() const
+static bool isVisuallyEquivalentCandidateAlgorithm(const PositionAlgorithm<Strategy>& position)
 {
-    if (isNull())
+    Node* const anchorNode = position.anchorNode();
+    if (!anchorNode)
         return false;
 
-    LayoutObject* layoutObject = anchorNode()->layoutObject();
+    LayoutObject* layoutObject = anchorNode->layoutObject();
     if (!layoutObject)
         return false;
 
@@ -509,34 +512,37 @@ bool PositionAlgorithm<Strategy>::isCandidate() const
         // TODO(leviw) The condition should be
         // m_anchorType == PositionAnchorType::BeforeAnchor, but for now we
         // still need to support legacy positions.
-        return !m_offset && !isAfterAnchor() && !nodeIsUserSelectNone(Strategy::parent(*anchorNode()));
+        if (position.isAfterAnchor())
+            return false;
+        return !position.computeEditingOffset() && !nodeIsUserSelectNone(Strategy::parent(*anchorNode));
     }
 
     if (layoutObject->isText())
-        return !nodeIsUserSelectNone(anchorNode()) && inRenderedText(*this);
+        return !nodeIsUserSelectNone(anchorNode) && inRenderedText(position);
 
     if (layoutObject->isSVG()) {
         // We don't consider SVG elements are contenteditable except for
-        // associated layoutObject returns isText() true, e.g. LayoutSVGInlineText.
+        // associated |layoutObject| returns |isText()| true,
+        // e.g. |LayoutSVGInlineText|.
         return false;
     }
 
-    if (isRenderedHTMLTableElement(anchorNode()) || Strategy::editingIgnoresContent(anchorNode()))
-        return (atFirstEditingPositionForNode() || atLastEditingPositionForNode()) && !nodeIsUserSelectNone(Strategy::parent(*anchorNode()));
+    if (isRenderedHTMLTableElement(anchorNode) || Strategy::editingIgnoresContent(anchorNode))
+        return (position.atFirstEditingPositionForNode() || position.atLastEditingPositionForNode()) && !nodeIsUserSelectNone(Strategy::parent(*anchorNode));
 
-    if (isHTMLHtmlElement(*m_anchorNode))
+    if (isHTMLHtmlElement(*anchorNode))
         return false;
 
     if (layoutObject->isLayoutBlockFlow() || layoutObject->isFlexibleBox() || layoutObject->isLayoutGrid()) {
-        if (toLayoutBlock(layoutObject)->logicalHeight() || isHTMLBodyElement(*m_anchorNode)) {
+        if (toLayoutBlock(layoutObject)->logicalHeight() || isHTMLBodyElement(*anchorNode)) {
             if (!hasRenderedNonAnonymousDescendantsWithHeight(layoutObject))
-                return atFirstEditingPositionForNode() && !nodeIsUserSelectNone(anchorNode());
-            return m_anchorNode->hasEditableStyle() && !nodeIsUserSelectNone(anchorNode()) && atEditingBoundary(*this);
+                return position.atFirstEditingPositionForNode() && !nodeIsUserSelectNone(anchorNode);
+            return anchorNode->hasEditableStyle() && !nodeIsUserSelectNone(anchorNode) && atEditingBoundary(position);
         }
     } else {
-        LocalFrame* frame = m_anchorNode->document().frame();
+        LocalFrame* frame = anchorNode->document().frame();
         bool caretBrowsing = frame->settings() && frame->settings()->caretBrowsingEnabled();
-        return (caretBrowsing || m_anchorNode->hasEditableStyle()) && !nodeIsUserSelectNone(anchorNode()) && atEditingBoundary(*this);
+        return (caretBrowsing || anchorNode->hasEditableStyle()) && !nodeIsUserSelectNone(anchorNode) && atEditingBoundary(position);
     }
 
     return false;
@@ -544,6 +550,16 @@ bool PositionAlgorithm<Strategy>::isCandidate() const
 
 // TODO(yosin) We should move |inRenderedText()| to "VisibleUnits.h" for
 // reduce dependency of |LayoutObject| in |Position| class.
+bool isVisuallyEquivalentCandidate(const Position& position)
+{
+    return isVisuallyEquivalentCandidateAlgorithm<EditingStrategy>(position);
+}
+
+bool isVisuallyEquivalentCandidate(const PositionInComposedTree& position)
+{
+    return isVisuallyEquivalentCandidateAlgorithm<EditingInComposedTreeStrategy>(position);
+}
+
 template <typename Strategy>
 static bool inRenderedTextAlgorithm(const PositionAlgorithm<Strategy>& position)
 {

third_party/WebKit/Source/core/editing/Position.h

@@ -187,8 +187,6 @@ public:
     PositionAlgorithm<Strategy> upstream(EditingBoundaryCrossingRule = CannotCrossEditingBoundary) const;
     PositionAlgorithm<Strategy> downstream(EditingBoundaryCrossingRule = CannotCrossEditingBoundary) const;
 
-    bool isCandidate() const;
-
     static PositionAlgorithm<Strategy> beforeNode(Node* anchorNode);
     static PositionAlgorithm<Strategy> afterNode(Node* anchorNode);
     static PositionAlgorithm<Strategy> inParentBeforeNode(const Node& anchorNode);
@@ -444,6 +442,11 @@ CORE_EXPORT bool inRenderedText(const PositionInComposedTree&);
 CORE_EXPORT int uncheckedPreviousOffset(const Node*, int current);
 CORE_EXPORT int uncheckedNextOffset(const Node*, int current);
 
+// TODO(yosin) We should move |isVisuallyEquivalentCandidate()| to
+// "VisibleUnits.cpp" to reduce |LayoutObject| dependency in "Position.cpp".
+CORE_EXPORT bool isVisuallyEquivalentCandidate(const Position&);
+CORE_EXPORT bool isVisuallyEquivalentCandidate(const PositionInComposedTree&);
+
 } // namespace blink
 
 #ifndef NDEBUG

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

@@ -253,7 +253,7 @@ Position VisiblePosition::leftVisuallyDistinctCandidate() const
 
         p = Position::editingPositionOf(layoutObject->node(), offset);
 
-        if ((p.isCandidate() && p.downstream() != downstreamStart) || p.atStartOfTree() || p.atEndOfTree())
+        if ((isVisuallyEquivalentCandidate(p) && p.downstream() != downstreamStart) || p.atStartOfTree() || p.atEndOfTree())
             return p;
 
         ASSERT(p != m_deepPosition);
@@ -415,7 +415,7 @@ Position VisiblePosition::rightVisuallyDistinctCandidate() const
 
         p = Position::editingPositionOf(layoutObject->node(), offset);
 
-        if ((p.isCandidate() && p.downstream() != downstreamStart) || p.atStartOfTree() || p.atEndOfTree())
+        if ((isVisuallyEquivalentCandidate(p) && p.downstream() != downstreamStart) || p.atStartOfTree() || p.atEndOfTree())
             return p;
 
         ASSERT(p != m_deepPosition);
@@ -548,9 +548,9 @@ static PositionType canonicalizeCandidate(const PositionType& candidate)
 {
     if (candidate.isNull())
         return PositionType();
-    ASSERT(candidate.isCandidate());
+    ASSERT(isVisuallyEquivalentCandidate(candidate));
     PositionType upstream = candidate.upstream();
-    if (upstream.isCandidate())
+    if (isVisuallyEquivalentCandidate(upstream))
         return upstream;
     return candidate;
 }
@@ -582,10 +582,10 @@ static PositionType canonicalPosition(const PositionType& passedPosition)
     Node* node = position.computeContainerNode();
 
     PositionType candidate = position.upstream();
-    if (candidate.isCandidate())
+    if (isVisuallyEquivalentCandidate(candidate))
         return candidate;
     candidate = position.downstream();
-    if (candidate.isCandidate())
+    if (isVisuallyEquivalentCandidate(candidate))
         return candidate;
 
     // When neither upstream or downstream gets us to a candidate (upstream/downstream won't leave

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

@@ -107,7 +107,7 @@ static Position previousRootInlineBoxCandidatePosition(Node* node, const Visible
         Position pos = isHTMLBRElement(*previousNode) ? positionBeforeNode(previousNode) :
             Position::editingPositionOf(previousNode, caretMaxOffset(previousNode));
 
-        if (pos.isCandidate())
+        if (isVisuallyEquivalentCandidate(pos))
             return pos;
 
         previousNode = previousLeafWithSameEditability(previousNode, editableType);
@@ -129,7 +129,7 @@ static Position nextRootInlineBoxCandidatePosition(Node* node, const VisiblePosi
         Position pos;
         pos = Position::editingPositionOf(nextNode, caretMinOffset(nextNode));
 
-        if (pos.isCandidate())
+        if (isVisuallyEquivalentCandidate(pos))
             return pos;
 
         nextNode = nextLeafWithSameEditability(nextNode, editableType);
@@ -1595,10 +1595,10 @@ bool rendersInDifferentPosition(const Position& position1, const Position& posit
             return true;
     }
 
-    if (isHTMLBRElement(*position1.anchorNode()) && position2.isCandidate())
+    if (isHTMLBRElement(*position1.anchorNode()) && isVisuallyEquivalentCandidate(position2))
         return true;
 
-    if (isHTMLBRElement(*position2.anchorNode()) && position1.isCandidate())
+    if (isHTMLBRElement(*position2.anchorNode()) && isVisuallyEquivalentCandidate(position1))
         return true;
 
     if (!inSameContainingBlockFlowElement(position1.anchorNode(), position2.anchorNode()))

third_party/WebKit/Source/core/editing/commands/InsertParagraphSeparatorCommand.cpp

@@ -184,7 +184,7 @@ void InsertParagraphSeparatorCommand::doApply()
 
     // Use the leftmost candidate.
     insertionPosition = insertionPosition.upstream();
-    if (!insertionPosition.isCandidate())
+    if (!isVisuallyEquivalentCandidate(insertionPosition))
         insertionPosition = insertionPosition.downstream();
 
     // Adjust the insertion position after the delete

third_party/WebKit/Source/core/editing/commands/InsertTextCommand.cpp

@@ -177,7 +177,7 @@ void InsertTextCommand::doApply()
     deleteInsignificantText(startPosition, startPosition.downstream());
     if (!startPosition.inDocument())
         startPosition = positionBeforeStartNode;
-    if (!startPosition.isCandidate())
+    if (!isVisuallyEquivalentCandidate(startPosition))
         startPosition = startPosition.downstream();
 
     startPosition = positionAvoidingSpecialElementBoundary(startPosition);

third_party/WebKit/Source/core/layout/LayoutView.cpp

@@ -804,11 +804,11 @@ void LayoutView::commitPendingSelectionAlgorithm()
     // and will fill the gap before 'bar'.
     PositionType startPos = Strategy::selectionStart(selection);
     PositionType candidate = startPos.downstream();
-    if (candidate.isCandidate())
+    if (isVisuallyEquivalentCandidate(candidate))
         startPos = candidate;
     PositionType endPos = Strategy::selectionEnd(selection);
     candidate = endPos.upstream();
-    if (candidate.isCandidate())
+    if (isVisuallyEquivalentCandidate(candidate))
         endPos = candidate;
 
     // We can get into a state where the selection endpoints map to the same VisiblePosition when a selection is deleted