Repo created

TMessagesProj/jni/rlottie/src/vector/vcowptr.h

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+/* 
+ * Copyright (c) 2018 Samsung Electronics Co., Ltd. All rights reserved.
+ * 
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ * 
+ * This library 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
+ * Lesser General Public License for more details.
+ * 
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+#ifndef VCOWPTR_H
+#define VCOWPTR_H
+
+#include <assert.h>
+#include "vglobal.h"
+
+template <typename T>
+class vcow_ptr {
+    struct model {
+        std::atomic<std::size_t> mRef{1};
+
+        model() = default;
+
+        template <class... Args>
+        explicit model(Args&&... args) : mValue(std::forward<Args>(args)...)
+        {
+        }
+
+        T mValue;
+    };
+    model* mModel;
+
+public:
+    using element_type = T;
+
+    vcow_ptr()
+    {
+        static model default_s;
+        mModel = &default_s;
+        ++mModel->mRef;
+    }
+
+    ~vcow_ptr()
+    {
+        if (mModel && (--mModel->mRef == 0)) delete mModel;
+    }
+
+    template <class... Args>
+    vcow_ptr(Args&&... args) : mModel(new model(std::forward<Args>(args)...))
+    {
+    }
+
+    vcow_ptr(const vcow_ptr& x) noexcept : mModel(x.mModel)
+    {
+        assert(mModel);
+        ++mModel->mRef;
+    }
+    vcow_ptr(vcow_ptr&& x) noexcept : mModel(x.mModel)
+    {
+        assert(mModel);
+        x.mModel = nullptr;
+    }
+
+    auto operator=(const vcow_ptr& x) noexcept -> vcow_ptr&
+    {
+        return *this = vcow_ptr(x);
+    }
+
+    auto operator=(vcow_ptr&& x) noexcept -> vcow_ptr&
+    {
+        auto tmp = std::move(x);
+        swap(*this, tmp);
+        return *this;
+    }
+
+    auto operator*() const noexcept -> const element_type& { return read(); }
+
+    auto operator-> () const noexcept -> const element_type* { return &read(); }
+
+    int refCount() const noexcept
+    {
+        assert(mModel);
+
+        return mModel->mRef;
+    }
+
+    bool unique() const noexcept
+    {
+        assert(mModel);
+
+        return mModel->mRef == 1;
+    }
+
+    auto write() -> element_type&
+    {
+        if (!unique()) *this = vcow_ptr(read());
+
+        return mModel->mValue;
+    }
+
+    auto read() const noexcept -> const element_type&
+    {
+        assert(mModel);
+
+        return mModel->mValue;
+    }
+
+    friend inline void swap(vcow_ptr& x, vcow_ptr& y) noexcept
+    {
+        std::swap(x.mModel, y.mModel);
+    }
+};
+
+#endif  // VCOWPTR_H