third_party/WebKit/Source/bindings/core/v8/WrapperTypeInfo.h

/*
 * Copyright (C) 2010 Google 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:
 *
 *     * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above
 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
 * distribution.
 *     * Neither the name of Google Inc. nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef WrapperTypeInfo_h
#define WrapperTypeInfo_h

#include "gin/public/wrapper_info.h"
#include "platform/heap/Handle.h"
#include "wtf/Allocator.h"
#include "wtf/Assertions.h"
#include <v8.h>

namespace blink {

class ActiveDOMObject;
class EventTarget;
class ScriptWrappable;

ScriptWrappable* toScriptWrappable(const v8::PersistentBase<v8::Object>& wrapper);

static const int v8DOMWrapperTypeIndex = static_cast<int>(gin::kWrapperInfoIndex);
static const int v8DOMWrapperObjectIndex = static_cast<int>(gin::kEncodedValueIndex);
static const int v8DefaultWrapperInternalFieldCount = static_cast<int>(gin::kNumberOfInternalFields);
static const int v8PrototypeTypeIndex = 0;
static const int v8PrototypeInternalFieldcount = 1;

typedef v8::Local<v8::FunctionTemplate> (*DomTemplateFunction)(v8::Isolate*);
typedef void (*RefObjectFunction)(ScriptWrappable*);
typedef void (*DerefObjectFunction)(ScriptWrappable*);
typedef void (*TraceFunction)(Visitor*, ScriptWrappable*);
typedef ActiveDOMObject* (*ToActiveDOMObjectFunction)(v8::Local<v8::Object>);
typedef void (*ResolveWrapperReachabilityFunction)(v8::Isolate*, ScriptWrappable*, const v8::Persistent<v8::Object>&);
typedef void (*PreparePrototypeAndInterfaceObjectFunction)(v8::Isolate*, v8::Local<v8::Object>, v8::Local<v8::Function>, v8::Local<v8::FunctionTemplate>);
typedef void (*InstallConditionallyEnabledPropertiesFunction)(v8::Local<v8::Object>, v8::Isolate*);

inline void setObjectGroup(v8::Isolate* isolate, ScriptWrappable* scriptWrappable, const v8::Persistent<v8::Object>& wrapper)
{
    isolate->SetObjectGroupId(wrapper, v8::UniqueId(reinterpret_cast<intptr_t>(scriptWrappable)));
}

// This struct provides a way to store a bunch of information that is helpful when unwrapping
// v8 objects. Each v8 bindings class has exactly one static WrapperTypeInfo member, so
// comparing pointers is a safe way to determine if types match.
struct WrapperTypeInfo {
    DISALLOW_ALLOCATION();
    enum WrapperTypePrototype {
        WrapperTypeObjectPrototype,
        WrapperTypeExceptionPrototype,
    };

    enum WrapperClassId {
        NodeClassId = 1, // NodeClassId must be smaller than ObjectClassId.
        ObjectClassId,
    };

    enum EventTargetInheritance {
        NotInheritFromEventTarget,
        InheritFromEventTarget,
    };

    enum Lifetime {
        Dependent,
        Independent,
    };

    enum GCType {
        GarbageCollectedObject,
        WillBeGarbageCollectedObject,
        RefCountedObject,
    };

    static const WrapperTypeInfo* unwrap(v8::Local<v8::Value> typeInfoWrapper)
    {
        return reinterpret_cast<const WrapperTypeInfo*>(v8::External::Cast(*typeInfoWrapper)->Value());
    }

    bool equals(const WrapperTypeInfo* that) const
    {
        return this == that;
    }

    bool isSubclass(const WrapperTypeInfo* that) const
    {
        for (const WrapperTypeInfo* current = this; current; current = current->parentClass) {
            if (current == that)
                return true;
        }

        return false;
    }

    void configureWrapper(v8::PersistentBase<v8::Object>* wrapper) const
    {
        wrapper->SetWrapperClassId(wrapperClassId);
        if (lifetime == Independent)
            wrapper->MarkIndependent();
    }

    v8::Local<v8::FunctionTemplate> domTemplate(v8::Isolate* isolate) const
    {
        return domTemplateFunction(isolate);
    }

    bool isGarbageCollected() const
    {
        return (gcType == GarbageCollectedObject
#if ENABLE(OILPAN)
                || gcType == WillBeGarbageCollectedObject
#endif
                );
    }

    void refObject(ScriptWrappable* scriptWrappable) const
    {
        if (isGarbageCollected()) {
            Heap::increaseWrapperCount(1);
        } else {
            ASSERT(refObjectFunction);
            refObjectFunction(scriptWrappable);
        }
    }

    void derefObject(ScriptWrappable* scriptWrappable) const
    {
        if (isGarbageCollected()) {
            Heap::decreaseWrapperCount(1);
            Heap::increaseCollectedWrapperCount(1);
        } else {
            ASSERT(derefObjectFunction);
            derefObjectFunction(scriptWrappable);
        }
    }

    void derefObject() const
    {
        ASSERT(isGarbageCollected());
        Heap::decreaseWrapperCount(1);
        Heap::increaseCollectedWrapperCount(1);
    }

    void trace(Visitor* visitor, ScriptWrappable* scriptWrappable) const
    {
        ASSERT(traceFunction);
        return traceFunction(visitor, scriptWrappable);
    }

    void preparePrototypeAndInterfaceObject(v8::Isolate* isolate, v8::Local<v8::Object> prototypeObject, v8::Local<v8::Function> interfaceObject, v8::Local<v8::FunctionTemplate> interfaceTemplate) const
    {
        if (preparePrototypeAndInterfaceObjectFunction)
            preparePrototypeAndInterfaceObjectFunction(isolate, prototypeObject, interfaceObject, interfaceTemplate);
    }

    void installConditionallyEnabledProperties(v8::Local<v8::Object> prototypeObject, v8::Isolate* isolate) const
    {
        if (installConditionallyEnabledPropertiesFunction)
            installConditionallyEnabledPropertiesFunction(prototypeObject, isolate);
    }

    ActiveDOMObject* toActiveDOMObject(v8::Local<v8::Object> object) const
    {
        if (!toActiveDOMObjectFunction)
            return 0;
        return toActiveDOMObjectFunction(object);
    }

    EventTarget* toEventTarget(v8::Local<v8::Object>) const;

    void visitDOMWrapper(v8::Isolate* isolate, ScriptWrappable* scriptWrappable, const v8::Persistent<v8::Object>& wrapper) const
    {
        if (!visitDOMWrapperFunction)
            setObjectGroup(isolate, scriptWrappable, wrapper);
        else
            visitDOMWrapperFunction(isolate, scriptWrappable, wrapper);
    }

    // This field must be the first member of the struct WrapperTypeInfo. This is also checked by a static_assert() below.
    const gin::GinEmbedder ginEmbedder;

    DomTemplateFunction domTemplateFunction;
    const RefObjectFunction refObjectFunction;
    const DerefObjectFunction derefObjectFunction;
    const TraceFunction traceFunction;
    const ToActiveDOMObjectFunction toActiveDOMObjectFunction;
    const ResolveWrapperReachabilityFunction visitDOMWrapperFunction;
    PreparePrototypeAndInterfaceObjectFunction preparePrototypeAndInterfaceObjectFunction;
    const InstallConditionallyEnabledPropertiesFunction installConditionallyEnabledPropertiesFunction;
    const char* const interfaceName;
    const WrapperTypeInfo* parentClass;
    const unsigned wrapperTypePrototype : 1; // WrapperTypePrototype
    const unsigned wrapperClassId : 2; // WrapperClassId
    const unsigned eventTargetInheritance : 1; // EventTargetInheritance
    const unsigned lifetime : 1; // Lifetime
    const unsigned gcType : 2; // GCType
};

template<typename T, int offset>
inline T* getInternalField(const v8::PersistentBase<v8::Object>& persistent)
{
    ASSERT(offset < v8::Object::InternalFieldCount(persistent));
    return reinterpret_cast<T*>(v8::Object::GetAlignedPointerFromInternalField(persistent, offset));
}

template<typename T, int offset>
inline T* getInternalField(v8::Local<v8::Object> wrapper)
{
    ASSERT(offset < wrapper->InternalFieldCount());
    return reinterpret_cast<T*>(wrapper->GetAlignedPointerFromInternalField(offset));
}

inline ScriptWrappable* toScriptWrappable(const v8::PersistentBase<v8::Object>& wrapper)
{
    return getInternalField<ScriptWrappable, v8DOMWrapperObjectIndex>(wrapper);
}

inline ScriptWrappable* toScriptWrappable(v8::Local<v8::Object> wrapper)
{
    return getInternalField<ScriptWrappable, v8DOMWrapperObjectIndex>(wrapper);
}

inline const WrapperTypeInfo* toWrapperTypeInfo(const v8::PersistentBase<v8::Object>& wrapper)
{
    return getInternalField<WrapperTypeInfo, v8DOMWrapperTypeIndex>(wrapper);
}

inline const WrapperTypeInfo* toWrapperTypeInfo(v8::Local<v8::Object> wrapper)
{
    return getInternalField<WrapperTypeInfo, v8DOMWrapperTypeIndex>(wrapper);
}

} // namespace blink

#endif // WrapperTypeInfo_h