godot/core/reference.h

/*************************************************************************/
/*  reference.h                                                          */
/*************************************************************************/
/*                       This file is part of:                           */
/*                           GODOT ENGINE                                */
/*                      https://godotengine.org                          */
/*************************************************************************/
/* Copyright (c) 2007-2020 Juan Linietsky, Ariel Manzur.                 */
/* Copyright (c) 2014-2020 Godot Engine contributors (cf. AUTHORS.md).   */
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/* "Software"), to deal in the Software without restriction, including   */
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/* permit persons to whom the Software is furnished to do so, subject to */
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/* included in all copies or substantial portions of the Software.       */
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/*************************************************************************/

#ifndef REFERENCE_H
#define REFERENCE_H

#include "object.h"
#include "object_type_db.h"
#include "ref_ptr.h"
#include "safe_refcount.h"

/**
	@author Juan Linietsky <reduzio@gmail.com>
*/
class Reference : public Object {

	OBJ_TYPE(Reference, Object);
	friend class RefBase;
	SafeRefCount refcount;
	SafeRefCount refcount_init;

protected:
	static void _bind_methods();

public:
	_FORCE_INLINE_ bool is_referenced() const { return refcount_init.get() < 1; }
	bool init_ref();
	void reference();
	bool unreference();
	int reference_get_count() const;

	Reference();
	~Reference();
};

#if 0
class RefBase {
protected:
	void ref_inc(Reference *p_reference);
	bool ref_dec(Reference *p_reference);
	Reference *first_ref(Reference *p_reference);
	Reference * get_reference_from_ref(const RefBase &p_base);
	virtual Reference * get_reference() const=0;
	char * get_refptr_data(const RefPtr &p_refptr) const;
public:

	virtual ~RefBase() {}
};
#endif

template <class T>
class Ref {

	T *reference;

	void ref(const Ref &p_from) {

		if (p_from.reference == reference)
			return;

		unref();

		reference = p_from.reference;
		if (reference)
			reference->reference();
	}

	void ref_pointer(T *p_ref) {

		ERR_FAIL_COND(!p_ref);

		if (p_ref->init_ref())
			reference = p_ref;
	}

	//virtual Reference * get_reference() const { return reference; }
public:
	_FORCE_INLINE_ bool operator<(const Ref<T> &p_r) const {

		return reference < p_r.reference;
	}
	_FORCE_INLINE_ bool operator==(const Ref<T> &p_r) const {

		return reference == p_r.reference;
	}
	_FORCE_INLINE_ bool operator!=(const Ref<T> &p_r) const {

		return reference != p_r.reference;
	}

	_FORCE_INLINE_ T *operator->() {

		return reference;
	}

	_FORCE_INLINE_ T *operator*() {

		return reference;
	}

	_FORCE_INLINE_ const T *operator->() const {

		return reference;
	}

	_FORCE_INLINE_ const T *ptr() const {

		return reference;
	}
	_FORCE_INLINE_ T *ptr() {

		return reference;
	}

	_FORCE_INLINE_ const T *operator*() const {

		return reference;
	}

	RefPtr get_ref_ptr() const {

		RefPtr refptr;
		Ref<Reference> *irr = reinterpret_cast<Ref<Reference> *>(refptr.get_data());
		*irr = *this;
		return refptr;
	};

#if 0
	// go to RefPtr
	operator RefPtr() const {

		return get_ref_ptr();
	}
#endif

#if 1
	operator Variant() const {

		return Variant(get_ref_ptr());
	}
#endif

	void operator=(const Ref &p_from) {

		ref(p_from);
	}

	template <class T_Other>
	void operator=(const Ref<T_Other> &p_from) {

		Reference *refb = const_cast<Reference *>(static_cast<const Reference *>(p_from.ptr()));
		if (!refb) {
			unref();
			return;
		}
		Ref r;
		r.reference = refb->cast_to<T>();
		ref(r);
		r.reference = NULL;
	}

	void operator=(const RefPtr &p_refptr) {

		Ref<Reference> *irr = reinterpret_cast<Ref<Reference> *>(p_refptr.get_data());
		Reference *refb = irr->ptr();
		if (!refb) {
			unref();
			return;
		}
		Ref r;
		r.reference = refb->cast_to<T>();
		ref(r);
		r.reference = NULL;
	}

	void operator=(const Variant &p_variant) {

		RefPtr refptr = p_variant;
		Ref<Reference> *irr = reinterpret_cast<Ref<Reference> *>(refptr.get_data());
		Reference *refb = irr->ptr();
		if (!refb) {
			unref();
			return;
		}
		Ref r;
		r.reference = refb->cast_to<T>();
		ref(r);
		r.reference = NULL;
	}

	Ref(const Ref &p_from) {

		reference = NULL;
		ref(p_from);
	}

	template <class T_Other>
	Ref(const Ref<T_Other> &p_from) {

		reference = NULL;
		Reference *refb = const_cast<Reference *>(static_cast<const Reference *>(p_from.ptr()));
		if (!refb) {
			unref();
			return;
		}
		Ref r;
		r.reference = refb->cast_to<T>();
		ref(r);
		r.reference = NULL;
	}

	Ref(T *p_reference) {

		if (p_reference)
			ref_pointer(p_reference);
		else
			reference = NULL;
	}

	Ref(const Variant &p_variant) {

		RefPtr refptr = p_variant;
		Ref<Reference> *irr = reinterpret_cast<Ref<Reference> *>(refptr.get_data());
		reference = NULL;
		Reference *refb = irr->ptr();
		if (!refb) {
			unref();
			return;
		}
		Ref r;
		r.reference = refb->cast_to<T>();
		ref(r);
		r.reference = NULL;
	}

	Ref(const RefPtr &p_refptr) {

		Ref<Reference> *irr = reinterpret_cast<Ref<Reference> *>(p_refptr.get_data());
		reference = NULL;
		Reference *refb = irr->ptr();
		if (!refb) {
			unref();
			return;
		}
		Ref r;
		r.reference = refb->cast_to<T>();
		ref(r);
		r.reference = NULL;
	}

	inline bool is_valid() const { return reference != NULL; }
	inline bool is_null() const { return reference == NULL; }

	void unref() {
		//TODO this should be moved to mutexes, since this engine does not really
		// do a lot of referencing on references and stuff
		// mutexes will avoid more crashes?

		if (reference && reference->unreference()) {

			memdelete(reference);
		}
		reference = NULL;
	}

	void instance() {
		ref(memnew(T));
	}

	Ref() {

		reference = NULL;
	}

	~Ref() {

		unref();
	}
};

typedef Ref<Reference> REF;

class WeakRef : public Reference {

	OBJ_TYPE(WeakRef, Reference);

	ObjectID ref;

protected:
	static void _bind_methods();

public:
	Variant get_ref() const;
	void set_obj(Object *p_object);
	void set_ref(const REF &p_ref);

	WeakRef();
};

#ifdef PTRCALL_ENABLED

template <class T>
struct PtrToArg<Ref<T> > {

	_FORCE_INLINE_ static Ref<T> convert(const void *p_ptr) {

		return Ref<T>(reinterpret_cast<const T *>(p_ptr));
	}

	_FORCE_INLINE_ static void encode(Ref<T> p_val, const void *p_ptr) {

		*(Ref<Reference> *)p_ptr = p_val;
	}
};

template <class T>
struct PtrToArg<const Ref<T> &> {

	_FORCE_INLINE_ static Ref<T> convert(const void *p_ptr) {

		return Ref<T>(reinterpret_cast<const T *>(p_ptr));
	}
};

//this is for RefPtr

template <>
struct PtrToArg<RefPtr> {

	_FORCE_INLINE_ static RefPtr convert(const void *p_ptr) {

		return Ref<Reference>(reinterpret_cast<const Reference *>(p_ptr)).get_ref_ptr();
	}

	_FORCE_INLINE_ static void encode(RefPtr p_val, const void *p_ptr) {

		Ref<Reference> r = p_val;
		*(Ref<Reference> *)p_ptr = r;
	}
};

template <>
struct PtrToArg<const RefPtr &> {

	_FORCE_INLINE_ static RefPtr convert(const void *p_ptr) {

		return Ref<Reference>(reinterpret_cast<const Reference *>(p_ptr)).get_ref_ptr();
	}
};

#endif
#endif // REFERENCE_H