// Copyright Joyent, Inc. and other Node contributors.

//

// Permission is hereby granted, free of charge, to any person obtaining a

// copy of this software and associated documentation files (the

// "Software"), to deal in the Software without restriction, including

// without limitation the rights to use, copy, modify, merge, publish,

// distribute, sublicense, and/or sell copies of the Software, and to permit

// persons to whom the Software is furnished to do so, subject to the

// following conditions:

//

// The above copyright notice and this permission notice shall be included

// in all copies or substantial portions of the Software.

//

// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS

// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF

// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN

// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,

// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR

// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE

// USE OR OTHER DEALINGS IN THE SOFTWARE.

#ifndef SRC_BASE_OBJECT_H_

#define SRC_BASE_OBJECT_H_

#if defined(NODE_WANT_INTERNALS) && NODE_WANT_INTERNALS

#include "node_persistent.h"

#include "memory_tracker-inl.h"

#include "v8.h"

#include <type_traits> // std::remove_reference

namespace node {

class Environment;

class BaseObject : public MemoryRetainer {

public:

// Associates this object with `object`. It uses the 0th internal field for

// that, and in particular aborts if there is no such field.

inline BaseObject(Environment* env, v8::Local<v8::Object> object);

virtual inline ~BaseObject();

// Returns the wrapped object. Returns an empty handle when

// persistent.IsEmpty() is true.

inline v8::Local<v8::Object> object() const;

// Same as the above, except it additionally verifies that this object

// is associated with the passed Isolate in debug mode.

inline v8::Local<v8::Object> object(v8::Isolate* isolate) const;

inline Persistent<v8::Object>& persistent();

inline Environment* env() const;

// Get a BaseObject* pointer, or subclass pointer, for the JS object that

// was also passed to the `BaseObject()` constructor initially.

// This may return `nullptr` if the C++ object has not been constructed yet,

// e.g. when the JS object used `MakeLazilyInitializedJSTemplate`.

static inline BaseObject* FromJSObject(v8::Local<v8::Object> object);

template <typename T>

static inline T* FromJSObject(v8::Local<v8::Object> object);

// Make the `Persistent` a weak reference and, `delete` this object once

// the JS object has been garbage collected.

inline void MakeWeak();

// Undo `MakeWeak()`, i.e. turn this into a strong reference.

inline void ClearWeak();

// Utility to create a FunctionTemplate with one internal field (used for

// the `BaseObject*` pointer) and a constructor that initializes that field

// to `nullptr`.

static inline v8::Local<v8::FunctionTemplate> MakeLazilyInitializedJSTemplate(

Environment* env);

private:

BaseObject();

v8::Local<v8::Object> WrappedObject() const override;

bool IsRootNode() const override;

static void DeleteMe(void* data);

// persistent_handle_ needs to be at a fixed offset from the start of the

// class because it is used by src/node_postmortem_metadata.cc to calculate

// offsets and generate debug symbols for BaseObject, which assumes that the

// position of members in memory are predictable. For more information please

// refer to `doc/guides/node-postmortem-support.md`

friend int GenDebugSymbols();

friend class Environment;

Persistent<v8::Object> persistent_handle_;

Environment* env_;

};

// Global alias for FromJSObject() to avoid churn.

template <typename T>

inline T* Unwrap(v8::Local<v8::Object> obj) {

return BaseObject::FromJSObject<T>(obj);

}

#define ASSIGN_OR_RETURN_UNWRAP(ptr, obj, ...) \

do { \

*ptr = static_cast<typename std::remove_reference<decltype(*ptr)>::type>( \

BaseObject::FromJSObject(obj)); \

if (*ptr == nullptr) \

return __VA_ARGS__; \

} while (0)

} // namespace node

#endif // defined(NODE_WANT_INTERNALS) && NODE_WANT_INTERNALS

#endif // SRC_BASE_OBJECT_H_