Source/WebCore/bindings/js/JSCallbackData.h

/*
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 *
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 * are met:
 *
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 *     notice, this list of conditions and the following disclaimer.
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 *     notice, this list of conditions and the following disclaimer in the
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 *     its contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
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 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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 */

#ifndef JSCallbackData_h
#define JSCallbackData_h

#include "JSDOMBinding.h"
#include "JSDOMGlobalObject.h"
#include "ScriptExecutionContext.h"
#include <heap/Strong.h>
#include <heap/StrongInlines.h>
#include <runtime/JSObject.h>
#include <wtf/Threading.h>

namespace WebCore {

// We have to clean up this data on the context thread because unprotecting a
// JSObject on the wrong thread without synchronization would corrupt the heap
// (and synchronization would be slow).

class JSCallbackData {
public:
    enum class CallbackType { Function, Object, FunctionOrObject };

protected:
    JSCallbackData()
#ifndef NDEBUG
        : m_thread(currentThread())
#endif
    {
    }
    
    ~JSCallbackData()
    {
#if !PLATFORM(IOS)
        ASSERT(m_thread == currentThread());
#endif
    }
    
    static JSC::JSValue invokeCallback(JSC::JSObject* callback, JSC::MarkedArgumentBuffer&, CallbackType, JSC::PropertyName functionName, NakedPtr<JSC::Exception>& returnedException);

private:
#ifndef NDEBUG
    ThreadIdentifier m_thread;
#endif
};

class JSCallbackDataStrong : public JSCallbackData {
public:
    JSCallbackDataStrong(JSC::JSObject* callback, void*)
        : m_callback(callback->globalObject()->vm(), callback)
    {
    }

    JSC::JSObject* callback() { return m_callback.get(); }
    JSDOMGlobalObject* globalObject() { return JSC::jsCast<JSDOMGlobalObject*>(m_callback->globalObject()); }

    JSC::JSValue invokeCallback(JSC::MarkedArgumentBuffer& args, CallbackType callbackType, JSC::PropertyName functionName, NakedPtr<JSC::Exception>& returnedException)
    {
        return JSCallbackData::invokeCallback(callback(), args, callbackType, functionName, returnedException);
    }

private:
    JSC::Strong<JSC::JSObject> m_callback;
};

class JSCallbackDataWeak : public JSCallbackData {
public:
    JSCallbackDataWeak(JSC::JSObject* callback, void* owner)
        : m_callback(callback, &m_weakOwner, owner)
    {
    }

    JSC::JSObject* callback() { return m_callback.get(); }
    JSDOMGlobalObject* globalObject() { return JSC::jsCast<JSDOMGlobalObject*>(m_callback->globalObject()); }

    JSC::JSValue invokeCallback(JSC::MarkedArgumentBuffer& args, CallbackType callbackType, JSC::PropertyName functionName, NakedPtr<JSC::Exception>& returnedException)
    {
        return JSCallbackData::invokeCallback(callback(), args, callbackType, functionName, returnedException);
    }

private:
    class WeakOwner : public JSC::WeakHandleOwner {
        virtual bool isReachableFromOpaqueRoots(JSC::Handle<JSC::Unknown>, void* context, JSC::SlotVisitor&);
    };
    WeakOwner m_weakOwner;
    JSC::Weak<JSC::JSObject> m_callback;
};

class DeleteCallbackDataTask : public ScriptExecutionContext::Task {
public:
    template <typename CallbackDataType>
    explicit DeleteCallbackDataTask(CallbackDataType* data)
        : ScriptExecutionContext::Task(ScriptExecutionContext::Task::CleanupTask, [data = std::unique_ptr<CallbackDataType>(data)] (ScriptExecutionContext&) {
        })
    {
    }
};

} // namespace WebCore

#endif // JSCallbackData_h