From 147337c53f4427a2fb12f73c536dad27a04c2344 Mon Sep 17 00:00:00 2001
From: Samer Afach <info@afach.de>
Date: Thu, 6 Apr 2017 11:36:17 +0200
Subject: [PATCH] Add SmartPtr.h

---
 SmartPtr.h | 205 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 205 insertions(+)
 create mode 100644 SmartPtr.h

diff --git a/SmartPtr.h b/SmartPtr.h
new file mode 100644
index 0000000..25b0f6c
--- /dev/null
+++ b/SmartPtr.h
@@ -0,0 +1,205 @@
+#ifndef SMARTPTR_H
+#define SMARTPTR_H
+
+#include <map>
+#include <string>
+#include <stdexcept>
+
+/**
+ * Simple shared pointer class with NO thread safety (not even the counter is thread-safe)
+ */
+template <typename T>
+class SmartPtr
+{
+    //Rule 1: tracker is always NULL when ptr == NULL
+    //Rule 2: ID is only assigned in constructors
+
+    typedef std::map<unsigned long,SmartPtr<T>*> IDMap;
+    typedef std::pair<unsigned long,SmartPtr<T>*> IDPair;
+
+    T* ptr;
+    IDMap *tracker; //track pointers to same object
+    unsigned long ID;
+    static unsigned long __IDCounter;
+
+public:
+    typedef T element_type;
+    SmartPtr(const SmartPtr& other);
+    SmartPtr<T>& operator=(const SmartPtr& other);
+    SmartPtr(T* new_ptr = NULL);
+    T& operator*();
+    const T& operator*() const;
+    ~SmartPtr();
+    unsigned long use_count() const;
+    operator bool();
+    T* get();
+    const T* const get() const;
+    T* release();
+    void reset(T* new_ptr = NULL);
+    inline bool isNull();
+    template <template <typename _T, typename = std::allocator<_T> > class Container>
+    static Container<T*> GetRawPtrContainer(const Container<SmartPtr<T> >& input_container);
+};
+
+template <typename T>
+unsigned long SmartPtr<T>::__IDCounter = 0;
+
+
+template<typename T>
+template <template <typename _T, typename = std::allocator<_T> > class Container>
+Container<T*> SmartPtr<T>::GetRawPtrContainer(const Container<SmartPtr<T> >& input_container)
+{
+    Container<T*> container;
+    for(typename Container<SmartPtr<T> >::const_iterator it = input_container.begin();
+        it != input_container.end();
+        it++)
+    {
+        container.push_back(it->ptr);
+    }
+    return container;
+}
+
+template<typename T>
+SmartPtr<T>::SmartPtr(const SmartPtr &other)
+{
+    this->tracker = other.tracker;
+    this->ptr = other.ptr;
+    this->ID = __IDCounter++;
+    if(!isNull())
+        tracker->insert(IDPair(ID,this));
+}
+
+template<typename T>
+SmartPtr<T> &SmartPtr<T>::operator=(const SmartPtr &other)
+{
+    this->tracker = other.tracker;
+    this->ptr = other.ptr;
+    this->ID = __IDCounter++;
+    if(!isNull())
+        tracker->insert(IDPair(ID,this));
+    return *this;
+}
+
+template<typename T>
+SmartPtr<T>::SmartPtr(T *new_ptr)
+{
+    ptr = NULL;
+    tracker = NULL;
+    ID = __IDCounter++;
+    reset(new_ptr);
+}
+
+template<typename T>
+T& SmartPtr<T>::operator*()
+{
+    if(this->get() != NULL)
+        return *this->get();
+    else
+        throw std::runtime_error("Null pointer exception. Tried to dereference a NULL in SmartPtr");
+}
+
+template<typename T>
+const T& SmartPtr<T>::operator*() const
+{
+    if(this->get() != NULL)
+        return *this->get();
+    else
+        throw std::runtime_error("Null pointer exception. Tried to dereference a NULL in SmartPtr");
+}
+
+template<typename T>
+SmartPtr<T>::~SmartPtr()
+{
+    reset();
+}
+
+template<typename T>
+unsigned long SmartPtr<T>::use_count() const
+{
+    if(isNull())
+        return 0;
+    else
+        return tracker->size();
+}
+
+template<typename T>
+SmartPtr<T>::operator bool()
+{
+    return !isNull();
+}
+
+template<typename T>
+T *SmartPtr<T>::get()
+{
+    return ptr;
+}
+
+template<typename T>
+const T * const SmartPtr<T>::get() const
+{
+    return ptr;
+}
+
+template<typename T>
+T *SmartPtr<T>::release()
+{
+    T* ret_ptr = ptr;
+    if(!isNull()) {
+        IDMap* trackerHolder = tracker;
+        for(typename IDMap::iterator it = trackerHolder->begin(); it != trackerHolder->end(); it++)
+        {
+            it->second->ptr = NULL;
+            it->second->tracker = NULL;
+        }
+        delete trackerHolder;
+    }
+    return ret_ptr;
+}
+
+template<typename T>
+void SmartPtr<T>::reset(T *new_ptr) {
+    if(!isNull())
+    {
+        //ptr and tracker are not NULL, guaranteed
+        if(tracker->size() == 1) //this is the last reference
+        {
+            delete ptr;
+            ptr = NULL;
+            delete tracker;
+            tracker = NULL;
+        }
+        else
+        {
+            tracker->erase(ID);
+            if(new_ptr != NULL)
+            {
+                tracker = new IDMap;
+                tracker->insert(IDPair(ID,this));
+            }
+            else
+            {
+                tracker = NULL;
+                ptr = NULL;
+            }
+        }
+    }
+    else //if this is NULL
+    {
+        if(new_ptr != NULL)
+        {
+            if(tracker == NULL) {
+                tracker = new IDMap;
+                tracker->insert(IDPair(ID,this));
+                ptr = new_ptr;
+            }
+        }
+    }
+}
+
+template<typename T>
+bool SmartPtr<T>::isNull()
+{
+    return (ptr == NULL);
+}
+
+#endif // SMARTPTR_H