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+// Copyright (c) 2010 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.
+
+/*
+  CppBoundClass class:
+  This base class serves as a parent for C++ classes designed to be bound to
+  JavaScript objects.
+
+  Subclasses should define the constructor to build the property and method
+  lists needed to bind this class to a JS object.  They should also declare
+  and define member variables and methods to be exposed to JS through
+  that object.
+
+  See cpp_binding_example.{h|cc} for an example.
+*/
+
+#ifndef WEBKIT_GLUE_CPP_BOUNDCLASS_H__
+#define WEBKIT_GLUE_CPP_BOUNDCLASS_H__
+
+#include <map>
+#include <vector>
+
+#include "webkit/glue/cpp_variant.h"
+
+#include "base/callback.h"
+#include "base/scoped_ptr.h"
+
+namespace WebKit {
+class WebFrame;
+}
+
+typedef std::vector<CppVariant> CppArgumentList;
+
+// CppBoundClass lets you map Javascript method calls and property accesses
+// directly to C++ method calls and CppVariant* variable access.
+class CppBoundClass {
+ public:
+  class PropertyCallback {
+   public:
+    virtual ~PropertyCallback() { }
+
+    // Sets |value| to the value of the property. Returns false in case of
+    // failure. |value| is always non-NULL.
+    virtual bool GetValue(CppVariant* value) = 0;
+
+    // sets the property value to |value|. Returns false in case of failure.
+    virtual bool SetValue(const CppVariant& value) = 0;
+  };
+
+  // The constructor should call BindMethod, BindProperty, and
+  // SetFallbackMethod as needed to set up the methods, properties, and
+  // fallback method.
+  CppBoundClass() : bound_to_frame_(false) { }
+  virtual ~CppBoundClass();
+
+  // Return a CppVariant representing this class, for use with BindProperty().
+  // The variant type is guaranteed to be NPVariantType_Object.
+  CppVariant* GetAsCppVariant();
+
+  // Given a WebFrame, BindToJavascript builds the NPObject that will represent
+  // the class and binds it to the frame's window under the given name.  This
+  // should generally be called from the WebView delegate's
+  // WindowObjectCleared(). A class so bound will be accessible to JavaScript
+  // as window.<classname>. The owner of the CppBoundObject is responsible for
+  // keeping the object around while the frame is alive, and for destroying it
+  // afterwards.
+  void BindToJavascript(
+      WebKit::WebFrame* frame, const std::wstring& classname);
+
+  // The type of callbacks.
+  typedef Callback2<const CppArgumentList&, CppVariant*>::Type Callback;
+  typedef Callback1<CppVariant*>::Type GetterCallback;
+
+  // Used by a test.  Returns true if a method with name |name| exists,
+  // regardless of whether a fallback is registered.
+  bool IsMethodRegistered(const std::string& name) const;
+
+ protected:
+  // Bind the Javascript method called |name| to the C++ callback |callback|.
+  void BindCallback(const std::string& name, Callback* callback);
+
+  // A wrapper for BindCallback, to simplify the common case of binding a
+  // method on the current object.  Though not verified here, |method|
+  // must be a method of this CppBoundClass subclass.
+  template<typename T>
+  void BindMethod(const std::string& name,
+      void (T::*method)(const CppArgumentList&, CppVariant*)) {
+    Callback* callback =
+        NewCallback<T, const CppArgumentList&, CppVariant*>(
+            static_cast<T*>(this), method);
+    BindCallback(name, callback);
+  }
+
+  // Bind Javascript property |name| to the C++ getter callback |callback|.
+  // This can be used to create read-only properties.
+  void BindGetterCallback(const std::string& name, GetterCallback* callback);
+
+  // A wrapper for BindGetterCallback, to simplify the common case of binding a
+  // property on the current object.  Though not verified here, |method|
+  // must be a method of this CppBoundClass subclass.
+  template<typename T>
+  void BindProperty(const std::string& name, void (T::*method)(CppVariant*)) {
+    GetterCallback* callback =
+        NewCallback<T, CppVariant*>(static_cast<T*>(this), method);
+    BindGetterCallback(name, callback);
+  }
+
+  // Bind the Javascript property called |name| to a CppVariant |prop|.
+  void BindProperty(const std::string& name, CppVariant* prop);
+
+  // Bind Javascript property called |name| to a PropertyCallback |callback|.
+  // CppBoundClass assumes control over the life time of the |callback|.
+  void BindProperty(const std::string& name, PropertyCallback* callback);
+
+  // Set the fallback callback, which is called when when a callback is
+  // invoked that isn't bound.
+  // If it is NULL (its default value), a JavaScript exception is thrown in
+  // that case (as normally expected). If non NULL, the fallback method is
+  // invoked and the script continues its execution.
+  // Passing NULL for |callback| clears out any existing binding.
+  // It is used for tests and should probably only be used in such cases
+  // as it may cause unexpected behaviors (a JavaScript object with a
+  // fallback always returns true when checked for a method's
+  // existence).
+  void BindFallbackCallback(Callback* fallback_callback) {
+    fallback_callback_.reset(fallback_callback);
+  }
+
+  // A wrapper for BindFallbackCallback, to simplify the common case of
+  // binding a method on the current object.  Though not verified here,
+  // |method| must be a method of this CppBoundClass subclass.
+  // Passing NULL for |method| clears out any existing binding.
+  template<typename T>
+  void BindFallbackMethod(
+      void (T::*method)(const CppArgumentList&, CppVariant*)) {
+    if (method) {
+      Callback* callback =
+          NewCallback<T, const CppArgumentList&, CppVariant*>(
+              static_cast<T*>(this), method);
+      BindFallbackCallback(callback);
+    } else {
+      BindFallbackCallback(NULL);
+    }
+  }
+
+  // Some fields are protected because some tests depend on accessing them,
+  // but otherwise they should be considered private.
+
+  typedef std::map<NPIdentifier, PropertyCallback*> PropertyList;
+  typedef std::map<NPIdentifier, Callback*> MethodList;
+  // These maps associate names with property and method pointers to be
+  // exposed to JavaScript.
+  PropertyList properties_;
+  MethodList methods_;
+
+  // The callback gets invoked when a call is made to an nonexistent method.
+  scoped_ptr<Callback> fallback_callback_;
+
+ private:
+  // NPObject callbacks.
+  friend struct CppNPObject;
+  bool HasMethod(NPIdentifier ident) const;
+  bool Invoke(NPIdentifier ident, const NPVariant* args, size_t arg_count,
+              NPVariant* result);
+  bool HasProperty(NPIdentifier ident) const;
+  bool GetProperty(NPIdentifier ident, NPVariant* result) const;
+  bool SetProperty(NPIdentifier ident, const NPVariant* value);
+
+  // A lazily-initialized CppVariant representing this class.  We retain 1
+  // reference to this object, and it is released on deletion.
+  CppVariant self_variant_;
+
+  // True if our np_object has been bound to a WebFrame, in which case it must
+  // be unregistered with V8 when we delete it.
+  bool bound_to_frame_;
+
+  DISALLOW_COPY_AND_ASSIGN(CppBoundClass);
+};
+
+#endif  // CPP_BOUNDCLASS_H__