Squashed 'kiwi/' content from commit 268028e

git-subtree-dir: kiwi
git-subtree-split: 268028ee4a694dcd89e4b1e683bf2f9ac48c08d9

kiwi/shareddata.h

@@ -0,0 +1,181 @@
+/*-----------------------------------------------------------------------------
+| Copyright (c) 2013-2017, Nucleic Development Team.
+|
+| Distributed under the terms of the Modified BSD License.
+|
+| The full license is in the file LICENSE, distributed with this software.
+|----------------------------------------------------------------------------*/
+#pragma once
+
+/*
+Implementation note
+===================
+SharedDataPtr/SharedData offer the same basic functionality as std::shared_ptr,
+but do not use atomic counters under the hood.
+Since kiwi operates within a single thread context, atomic counters are not necessary,
+especially given the extra CPU cost.
+Therefore the use of SharedDataPtr/SharedData is preferred over std::shared_ptr.
+*/
+
+namespace kiwi
+{
+
+class SharedData
+{
+
+public:
+    SharedData() : m_refcount(0) {}
+
+    SharedData(const SharedData &other) = delete;
+
+    SharedData(SharedData&& other) = delete;
+
+    int m_refcount;
+
+    SharedData &operator=(const SharedData &other) = delete;
+    
+    SharedData &operator=(SharedData&& other) = delete;
+};
+
+template <typename T>
+class SharedDataPtr
+{
+
+public:
+    using Type = T;
+
+    SharedDataPtr() : m_data(nullptr) {}
+
+    explicit SharedDataPtr(T *data) : m_data(data)
+    {
+        incref(m_data);
+    }
+
+    ~SharedDataPtr()
+    {
+        decref(m_data);
+    }
+
+    T *data()
+    {
+        return m_data;
+    }
+
+    const T *data() const
+    {
+        return m_data;
+    }
+
+    operator T *()
+    {
+        return m_data;
+    }
+
+    operator const T *() const
+    {
+        return m_data;
+    }
+
+    T *operator->()
+    {
+        return m_data;
+    }
+
+    const T *operator->() const
+    {
+        return m_data;
+    }
+
+    T &operator*()
+    {
+        return *m_data;
+    }
+
+    const T &operator*() const
+    {
+        return *m_data;
+    }
+
+    bool operator!() const
+    {
+        return !m_data;
+    }
+
+    bool operator<(const SharedDataPtr<T> &other) const
+    {
+        return m_data < other.m_data;
+    }
+
+    bool operator==(const SharedDataPtr<T> &other) const
+    {
+        return m_data == other.m_data;
+    }
+
+    bool operator!=(const SharedDataPtr<T> &other) const
+    {
+        return m_data != other.m_data;
+    }
+
+    SharedDataPtr(const SharedDataPtr<T> &other) : m_data(other.m_data)
+    {
+        incref(m_data);
+    }
+
+    SharedDataPtr(SharedDataPtr&& other) noexcept : m_data(other.m_data)
+    {
+        other.m_data = nullptr;
+    }
+
+    SharedDataPtr<T> &operator=(const SharedDataPtr<T> &other)
+    {
+        if (m_data != other.m_data)
+        {
+            T *temp = m_data;
+            m_data = other.m_data;
+            incref(m_data);
+            decref(temp);
+        }
+        return *this;
+    }
+
+    SharedDataPtr<T>& operator=(SharedDataPtr<T>&& other) noexcept
+    {
+        if (m_data != other.m_data)
+        {
+            T *temp = m_data;
+            m_data = other.m_data;
+            other.m_data = nullptr;
+            decref(temp);
+        }
+        return *this;
+    }
+
+    SharedDataPtr<T> &operator=(T *other)
+    {
+        if (m_data != other)
+        {
+            T *temp = m_data;
+            m_data = other;
+            incref(m_data);
+            decref(temp);
+        }
+        return *this;
+    }
+
+private:
+    static void incref(T *data)
+    {
+        if (data)
+            ++data->m_refcount;
+    }
+
+    static void decref(T *data)
+    {
+        if (data && --data->m_refcount == 0)
+            delete data;
+    }
+
+    T *m_data;
+};
+
+} // namespace kiwi