Introduce VisiblePositionTemplate template class

Source/core/editing/VisiblePosition.h

 /*
  * Copyright (C) 2004, 2008 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 49 matching lines @@
 // placed at start of line.
 //
 // Example of affinity:
 //    abc^def where "^" represent |Position|
 // When above text line wrapped after "abc"
 //    abc|  UPSTREAM |VisiblePosition|
 //    |def  DOWNSTREAM |VisiblePosition|
 //
 // NOTE: UPSTREAM affinity will be used only if pos is at end of a wrapped line,
 // otherwise it will be converted to DOWNSTREAM.
-class CORE_EXPORT VisiblePosition final {
+template <typename Strategy>
+class CORE_TEMPLATE_CLASS_EXPORT VisiblePositionTemplate final {
     DISALLOW_ALLOCATION();
 public:
-    VisiblePosition();
+    VisiblePositionTemplate();
 
     // Node: Other than |createVisiblePosition()|, we should not use
     // |createWithoutCanonicalization()|.
-    static VisiblePosition createWithoutCanonicalization(const PositionWithAffinity& canonicalized);
+    static VisiblePositionTemplate createWithoutCanonicalization(const PositionWithAffinityTemplate<Strategy>& canonicalized);
 
     // Intentionally delete |operator==()| and |operator!=()| for reducing
     // compilation error message.
     // TODO(yosin) We'll have |equals()| when we have use cases of checking
     // equality of both position and affinity.
-    bool operator==(const VisiblePosition&) const = delete;
-    bool operator!=(const VisiblePosition&) const = delete;
+    bool operator==(const VisiblePositionTemplate&) const = delete;
+    bool operator!=(const VisiblePositionTemplate&) const = delete;
 
     bool isNull() const { return m_positionWithAffinity.isNull(); }
     bool isNotNull() const { return m_positionWithAffinity.isNotNull(); }
     bool isOrphan() const { return deepEquivalent().isOrphan(); }
 
-    Position deepEquivalent() const { return m_positionWithAffinity.position(); }
-    Position toParentAnchoredPosition() const { return deepEquivalent().parentAnchoredEquivalent(); }
-    PositionWithAffinity toPositionWithAffinity() const { return m_positionWithAffinity; }
+    PositionAlgorithm<Strategy> deepEquivalent() const { return m_positionWithAffinity.position(); }
+    PositionAlgorithm<Strategy> toParentAnchoredPosition() const { return deepEquivalent().parentAnchoredEquivalent(); }
+    PositionWithAffinityTemplate<Strategy> toPositionWithAffinity() const { return m_positionWithAffinity; }
     TextAffinity affinity() const { return m_positionWithAffinity.affinity(); }
 
-    DECLARE_TRACE();
+    DEFINE_INLINE_TRACE()
+    {
+        visitor->trace(m_positionWithAffinity);
+    }
 
 #ifndef NDEBUG
     void debugPosition(const char* msg = "") const;
     void formatForDebugger(char* buffer, unsigned length) const;
     void showTreeForThis() const;
 #endif
 
 private:
-    explicit VisiblePosition(const PositionWithAffinity&);
+    explicit VisiblePositionTemplate(const PositionWithAffinityTemplate<Strategy>&);
 
-    PositionWithAffinity m_positionWithAffinity;
+    PositionWithAffinityTemplate<Strategy> m_positionWithAffinity;
 };
 
+extern template class CORE_EXTERN_TEMPLATE_EXPORT VisiblePositionTemplate<EditingStrategy>;
+
+using VisiblePosition = VisiblePositionTemplate<EditingStrategy>;
+
 CORE_EXPORT VisiblePosition createVisiblePosition(const Position&, TextAffinity = VP_DEFAULT_AFFINITY);
 CORE_EXPORT VisiblePosition createVisiblePosition(const PositionWithAffinity&);
 CORE_EXPORT VisiblePosition createVisiblePosition(const PositionInComposedTree&, TextAffinity = VP_DEFAULT_AFFINITY);
 
 } // namespace blink
 
 #ifndef NDEBUG
 // Outside the WebCore namespace for ease of invocation from gdb.
 void showTree(const blink::VisiblePosition*);
 void showTree(const blink::VisiblePosition&);
 #endif
 
 #endif // VisiblePosition_h