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/*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software Foundation,
* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
#pragma once
/** \file
* \ingroup bke
*/
#include <atomic>
#include <iostream>
#include "BLI_hash.hh"
struct Mesh;
namespace blender::bke {
/**
* Geometry can contain geometry of different types, such as meshes and curves (although currently
* only meshes are supported).
*
* Geometries are reference counted. This allows them to be shared without making unnecessary
* copies. A geometry that is shared is immutable. If some code wants to change it,
* #make_geometry_mutable should be called first.
*/
class Geometry {
private:
/* Number of users of this geometry. If this number goes to zero, the geometry is freed. If it is
* above 1, the geometry is immutable. */
std::atomic<int> users_ = 1;
/* Only contains a mesh for now. */
Mesh *mesh_ = nullptr;
/* Determines if the mesh is freed when the geometry does not want to reference it anymore. */
bool mesh_owned_ = false;
public:
Geometry() = default;
Geometry(const Geometry &other);
Geometry(Geometry &&other) = delete;
~Geometry();
/* Disable copy and move assignment operators. */
Geometry &operator=(const Geometry &other) = delete;
Geometry &operator=(Geometry &&other) = delete;
void user_add();
void user_remove();
bool is_mutable() const;
void mesh_set_and_keep_ownership(Mesh *mesh);
void mesh_set_and_transfer_ownership(Mesh *mesh);
void mesh_reset();
Mesh *mesh_get_for_read();
Mesh *mesh_get_for_write();
Mesh *mesh_release();
};
/**
* A simple automatic reference counter. This should probably be moved to another file eventually.
* It is similar to std::shared_ptr, but expects that the reference count is inside the object.
*/
template<typename T> class UserCounter {
private:
T *data_ = nullptr;
public:
UserCounter() = default;
UserCounter(T *data) : data_(data)
{
}
UserCounter(const UserCounter &other) : data_(other.data_)
{
this->user_add(data_);
}
UserCounter(UserCounter &&other) : data_(other.data_)
{
other.data_ = nullptr;
}
~UserCounter()
{
this->user_remove(data_);
}
UserCounter &operator=(const UserCounter &other)
{
if (this == &other) {
return *this;
}
this->user_remove(data_);
data_ = other.data_;
this->user_add(data_);
return *this;
}
UserCounter &operator=(UserCounter &&other)
{
if (this == &other) {
return *this;
}
this->user_remove(data_);
data_ = other.data_;
other.data_ = nullptr;
return *this;
}
T *operator->()
{
BLI_assert(data_ != nullptr);
return data_;
}
T &operator*()
{
BLI_assert(data_ != nullptr);
return *data_;
}
operator bool() const
{
return data_ != nullptr;
}
T *get()
{
return data_;
}
T *release()
{
T *data = data_;
data_ = nullptr;
return data;
}
void reset()
{
this->user_remove(data_);
data_ = nullptr;
}
bool has_value() const
{
return data_ != nullptr;
}
uint64_t hash() const
{
return DefaultHash<T *>{}(data_);
}
friend bool operator==(const UserCounter &a, const UserCounter &b)
{
return a.data_ == b.data_;
}
friend std::ostream &operator<<(std::ostream &stream, const UserCounter &value)
{
stream << value.data_;
return stream;
}
private:
static void user_add(T *data)
{
if (data != nullptr) {
data->user_add();
}
}
static void user_remove(T *data)
{
if (data != nullptr) {
data->user_remove();
}
}
};
/* An automatically reference counted geometry. */
using GeometryPtr = UserCounter<class Geometry>;
void make_geometry_mutable(GeometryPtr &geometry);
} // namespace blender::bke
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