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// Copyright 2017 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef UI_BASE_GLIB_SCOPED_GOBJECT_H_
#define UI_BASE_GLIB_SCOPED_GOBJECT_H_
#include <glib-object.h>
#include <cstddef>
#include "base/check.h"
#include "base/memory/raw_ptr.h"
// Similar to a scoped_refptr for GObject types.
template <typename T>
class ScopedGObject {
public:
ScopedGObject() = default;
// Deliberately implicit to allow returning nullptrs.
// NOLINTNEXTLINE(google-explicit-constructor)
ScopedGObject(std::nullptr_t ptr) {}
ScopedGObject(const ScopedGObject<T>& other) : obj_(other.obj_) { Ref(); }
ScopedGObject(ScopedGObject<T>&& other) : obj_(other.obj_) {
other.obj_ = nullptr;
}
~ScopedGObject() { Reset(); }
ScopedGObject<T>& operator=(const ScopedGObject<T>& other) {
Reset();
obj_ = other.obj_;
Ref();
return *this;
}
ScopedGObject<T>& operator=(ScopedGObject<T>&& other) {
Reset();
obj_ = other.obj_;
other.obj_ = nullptr;
return *this;
}
void Reset() {
if (obj_) {
g_object_unref(obj_.ExtractAsDangling());
}
}
T* release() {
T* obj = obj_;
obj_ = nullptr;
return obj;
}
T* get() const { return obj_; }
// Deliberately implicit to allow easier interaction with C APIs.
// NOLINTNEXTLINE(google-explicit-constructor)
operator T*() const { return obj_; }
private:
template <typename U>
friend ScopedGObject<U> TakeGObject(U* obj);
template <typename U>
friend ScopedGObject<U> WrapGObject(U* obj);
explicit ScopedGObject(T* obj) : obj_(obj) {}
void RefSink() {
// Remove the floating reference from |obj_| if it has one.
if (obj_ && g_object_is_floating(obj_)) {
g_object_ref_sink(obj_);
}
}
void Ref() {
if (obj_) {
DCHECK(!g_object_is_floating(obj_));
g_object_ref(obj_);
}
}
raw_ptr<T> obj_ = nullptr;
};
// Create a ScopedGObject and do not increase the GObject's reference count.
// This is usually used to reference a newly-created GObject, which are created
// with a reference count of 1 by default.
template <typename T>
ScopedGObject<T> TakeGObject(T* obj) {
ScopedGObject<T> scoped(obj);
scoped.RefSink();
return scoped;
}
// Create a ScopedGObject and increase the GObject's reference count by 1.
// This is usually used to reference an existing GObject.
template <typename T>
ScopedGObject<T> WrapGObject(T* obj) {
ScopedGObject<T> scoped(obj);
scoped.Ref();
return scoped;
}
#endif // UI_BASE_GLIB_SCOPED_GOBJECT_H_
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