webkit的js对象扩展（二）——binding方式创建自定义对象（多实例）

今天刚好有时间，把创建多实例对象的方法写一下，也就是可以像new Date()一样。关于new操作符有一篇讲的很详细，大家可以先看下http://www.pushiming.com/blog/2009/10/the-new-operator/

了解new操作符后大家应该已经知道，必须有一个构造器才能执行new操作。所以比单实例要多了一个过程，就是要创建构造器，下面我把步骤给贴出来。

以MultiObject为例。

1.添加MultiObject.h文件

 #ifndef MultiObject_h
 #define MultiObject_h
 #include <wtf/PassRefPtr.h>
 #include <wtf/RefCounted.h>
 #include <wtf/RefPtr.h>

 namespace WebCore {

 class Frame;
 class String;

 class MultiObject : public RefCounted<MultiObject> {

     public:
         static PassRefPtr<MultiObject> create(Frame* frame)
         {
             return adoptRef(new MultiObject(frame));
         }

         ~MultiObject();

         void disconnectFrame();
         Frame* frame() const { return m_frame; }

         String description() const;
     private:
         MultiObject(Frame*);
         Frame* m_frame;
 };
 }

 #endif

2.添加MultiObject.cpp文件

 #include "MultiObject.h"

 #include "PlatformString.h"

 #include "Frame.h"
 #include "Page.h"
 #include "RangerIFrameWidget.h"
 #include "config.h"

 namespace WebCore {

     MultiObject::MultiObject(Frame* frame)
         : m_frame(frame)
     {
     }

     MultiObject::~MultiObject()
     {
         disconnectFrame();
     }

     void MultiObject::disconnectFrame()
     {
         m_frame = 0;
     }

     String MultiObject::description() const    //对象的属性
     {
         return "Hello World!";
     }
 }

3.添加MultiObject.idl文件

 module window {
     interface [
 CustomConstructor
 ] MultiObject{
         readonly attribute DOMString description;
     };
 }

4.修改DOMWindow.h文件

添加声明如下：

 attribute [JSCCustomGetter] MultiObjectConstructor MultiObject;

WebCore/bindings/js

5.添加JSMultiObjectConstructor.h

 #ifndef __JSMultiObjectConstructor_h__
 #define __JSMultiObjectConstructor_h__

 #include "JSDOMBinding.h"

 namespace WebCore {

 class JSMultiObjectConstructor : public DOMConstructorObject {
 public:
     JSMultiObjectConstructor(JSC::ExecState*, JSDOMGlobalObject*);
     static const JSC::ClassInfo s_info;
 private:
     virtual JSC::ConstructType getConstructData(JSC::ConstructData&);
     virtual const JSC::ClassInfo* classInfo() const { return &s_info; }
 };

 } // namespace WebCore

 #endif//__JSMultiObjectConstructor_h__

6.添加JSMultiObjectConstructor.cpp

 #include "config.h"
 #include "JSMultiObjectConstructor.h"
 #include "JSMultiObject.h"
 #include "ScriptExecutionContext.h"
 #include "MultiObject.h"
 #include <runtime/Error.h>
 #include "JSDOMWindowBase.h"

 using namespace JSC;

 namespace WebCore {

 ASSERT_CLASS_FITS_IN_CELL(JSMultiObjectConstructor);

 const ClassInfo JSMultiObjectConstructor::s_info = { "MultiObjectConstructor", 0, 0, 0 };

 JSMultiObjectConstructor::JSMultiObjectConstructor(ExecState* exec, JSDOMGlobalObject* globalObject)
     : DOMConstructorObject(JSMultiObjectConstructor::createStructure(globalObject->objectPrototype()), globalObject)
 {
     putDirect(exec->propertyNames().prototype, JSMultiObjectPrototype::self(exec, globalObject), None);
 }

 static JSObject* constructMultiObject(ExecState* exec, JSObject* constructor, const ArgList&)
 {
     JSMultiObjectConstructor* jsConstructor = static_cast<JSMultiObjectConstructor*>(constructor);
     JSDOMWindowBase* window = static_cast<JSDOMWindowBase*>(jsConstructor->globalObject());
     if (!window || !window->impl() || !window->impl()->frame())
         return Error::create(exec, ReferenceError, "Can not create MultiObject...", -1, -1, UString());
     RefPtr<MultiObject> MultiObject = MultiObject::create(window->impl()->frame());
     if (!MultiObject.get())
         return Error::create(exec, ReferenceError, "Not support MultiObject...", -1, -1, UString());
     return CREATE_DOM_OBJECT_WRAPPER(exec, jsConstructor->globalObject(), MultiObject, MultiObject.get());
 }

 ConstructType JSMultiObjectConstructor::getConstructData(ConstructData& constructData)
 {
     constructData.native.function = constructMultiObject;
     return ConstructTypeHost;
 }

 } // namespace WebCore

7.修改JSDOMWindowCustom.cpp

 #include "JSMultiObjectConstructor.h"


 JSValue JSDOMWindow::multiObject(ExecState* exec) const
 {
     return getDOMConstructor<JSMultiObjectConstructor>(exec, this);
 }

OK，再修改相应的CMakeLists.txt就行了。

注意：头文件包含依据自己的项目。