Repo created

libs/base/ref_counted.hpp

@@ -0,0 +1,107 @@
+#pragma once
+
+#include "base/macros.hpp"
+
+#include <cstdint>
+#include <memory>
+
+namespace base
+{
+class RefCounted
+{
+public:
+  virtual ~RefCounted() = default;
+
+  void IncRef() noexcept { ++m_refs; }
+  uint64_t DecRef() noexcept { return --m_refs; }
+  uint64_t NumRefs() const noexcept { return m_refs; }
+
+protected:
+  RefCounted() noexcept = default;
+
+  uint64_t m_refs = 0;
+
+  DISALLOW_COPY_AND_MOVE(RefCounted);
+};
+
+template <typename T>
+class RefCountPtr
+{
+public:
+  RefCountPtr() noexcept = default;
+
+  explicit RefCountPtr(T * p) noexcept : m_p(p)
+  {
+    if (m_p)
+      m_p->IncRef();
+  }
+
+  explicit RefCountPtr(std::unique_ptr<T> p) noexcept : RefCountPtr(p.release()) {}
+
+  RefCountPtr(RefCountPtr const & rhs) { *this = rhs; }
+
+  RefCountPtr(RefCountPtr && rhs) { *this = std::move(rhs); }
+
+  ~RefCountPtr() { Reset(); }
+
+  RefCountPtr & operator=(std::unique_ptr<T> p)
+  {
+    Reset();
+
+    m_p = p.release();
+    if (m_p)
+      m_p->IncRef();
+
+    return *this;
+  }
+
+  RefCountPtr & operator=(RefCountPtr const & rhs)
+  {
+    if (this == &rhs)
+      return *this;
+
+    Reset();
+    m_p = rhs.m_p;
+    if (m_p)
+      m_p->IncRef();
+
+    return *this;
+  }
+
+  RefCountPtr & operator=(RefCountPtr && rhs)
+  {
+    if (this == &rhs)
+      return *this;
+
+    Reset();
+    m_p = rhs.m_p;
+    rhs.m_p = nullptr;
+
+    return *this;
+  }
+
+  void Reset()
+  {
+    if (!m_p)
+      return;
+
+    if (m_p->DecRef() == 0)
+      delete m_p;
+    m_p = nullptr;
+  }
+
+  T * Get() noexcept { return m_p; }
+  T const * Get() const noexcept { return m_p; }
+
+  T & operator*() { return *m_p; }
+  T const & operator*() const { return *m_p; }
+
+  T * operator->() noexcept { return m_p; }
+  T const * operator->() const noexcept { return m_p; }
+
+  operator bool() const noexcept { return m_p != nullptr; }
+
+private:
+  T * m_p = nullptr;
+};
+}  // namespace base