1 files changed, 175 insertions, 0 deletions
diff --git a/kdecore/ksharedptr.h b/kdecore/ksharedptr.h
new file mode 100644
index 000000000..ada08413b
--- /dev/null
+++ b/kdecore/ksharedptr.h
@@ -0,0 +1,175 @@
+/* This file is part of the KDE libraries
+   Copyright (c) 1999 Waldo Bastian <bastian@kde.org>
+
+   This library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Library General Public
+   License version 2 as published by the Free Software Foundation.
+
+   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
+   Library General Public License for more details.
+
+   You should have received a copy of the GNU Library General Public License
+   along with this library; see the file COPYING.LIB.  If not, write to
+   the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+   Boston, MA 02110-1301, USA.
+*/
+#ifndef KSharedPTR_H
+#define KSharedPTR_H
+
+#include "kdelibs_export.h"
+
+/**
+ * Reference counting for shared objects.  If you derive your object
+ * from this class, then you may use it in conjunction with
+ * KSharedPtr to control the lifetime of your object.
+ *
+ * Specifically, all classes that derive from KShared have an internal
+ * counter keeping track of how many other objects have a reference to
+ * their object.  If used with KSharedPtr, then your object will
+ * not be deleted until all references to the object have been
+ * released.
+ *
+ * You should probably not ever use any of the methods in this class
+ * directly -- let the KSharedPtr take care of that.  Just derive
+ * your class from KShared and forget about it.
+ *
+ * @author Waldo Bastian <bastian@kde.org>
+ */
+class KDECORE_EXPORT KShared {
+public:
+   /**
+    * Standard constructor.  This will initialize the reference count
+    * on this object to 0.
+    */
+   KShared() : count(0) { }
+
+   /**
+    * Copy constructor.  This will @em not actually copy the objects
+    * but it will initialize the reference count on this object to 0.
+    */
+   KShared( const KShared & ) : count(0) { }
+
+   /**
+    * Overloaded assignment operator.
+    */
+   KShared &operator=(const KShared & ) { return *this; }
+
+   /**
+    * Increases the reference count by one.
+    */
+   void _KShared_ref() const { count++; }
+
+   /**
+    * Releases a reference (decreases the reference count by one).  If
+    * the count goes to 0, this object will delete itself.
+    */
+   void _KShared_unref() const { if (!--count) delete this; }
+
+   /**
+    * Return the current number of references held.
+    *
+    * @return Number of references
+    */
+   int _KShared_count() const { return count; }
+
+protected:
+   virtual ~KShared() { }
+private:
+   mutable int count;
+};
+
+/**
+ * Can be used to control the lifetime of an object that has derived
+ * KShared. As long a someone holds a KSharedPtr on some KShared
+ * object it won't become deleted but is deleted once its reference
+ * count is 0.  This struct emulates C++ pointers virtually perfectly.
+ * So just use it like a simple C++ pointer.
+ *
+ * KShared and KSharedPtr are preferred over QShared / QSharedPtr
+ * since they are more safe.
+ *
+ * WARNING: Please note that this class template provides an implicit
+ * conversion to T*. Do *not* change this pointer or the pointee (don't
+ * call delete on it, for instance) behind KSharedPtr's back.
+ *
+ * @author Waldo Bastian <bastian@kde.org>
+ */
+template< class T >
+class KSharedPtr
+{
+public:
+/**
+ * Creates a null pointer.
+ */
+  KSharedPtr()
+    : ptr(0) { }
+  /**
+   * Creates a new pointer.
+   * @param t the pointer
+   */
+  KSharedPtr( T* t )
+    : ptr(t) { if ( ptr ) ptr->_KShared_ref(); }
+
+  /**
+   * Copies a pointer.
+   * @param p the pointer to copy
+   */
+  KSharedPtr( const KSharedPtr& p )
+    : ptr(p.ptr) { if ( ptr ) ptr->_KShared_ref(); }
+
+  /**
+   * Unreferences the object that this pointer points to. If it was
+   * the last reference, the object will be deleted.
+   */
+  ~KSharedPtr() { if ( ptr ) ptr->_KShared_unref(); }
+
+  KSharedPtr<T>& operator= ( const KSharedPtr<T>& p ) {
+    if ( ptr == p.ptr ) return *this;
+    if ( ptr ) ptr->_KShared_unref();
+    ptr = p.ptr;
+    if ( ptr ) ptr->_KShared_ref();
+    return *this;
+  }
+  KSharedPtr<T>& operator= ( T* p ) {
+    if ( ptr == p ) return *this;
+    if ( ptr ) ptr->_KShared_unref();
+    ptr = p;
+    if ( ptr ) ptr->_KShared_ref();
+    return *this;
+  }
+  bool operator== ( const KSharedPtr<T>& p ) const { return ( ptr == p.ptr ); }
+  bool operator!= ( const KSharedPtr<T>& p ) const { return ( ptr != p.ptr ); }
+  bool operator== ( const T* p ) const { return ( ptr == p ); }
+  bool operator!= ( const T* p ) const { return ( ptr != p ); }
+  bool operator!() const { return ( ptr == 0 ); }
+  operator T*() const { return ptr; }
+
+  /**
+   * Returns the pointer.
+   * @return the pointer
+   */
+  T* data() { return ptr; }
+
+  /**
+   * Returns the pointer.
+   * @return the pointer
+   */
+  const T* data() const { return ptr; }
+
+  const T& operator*() const { return *ptr; }
+  T& operator*() { return *ptr; }
+  const T* operator->() const { return ptr; }
+  T* operator->() { return ptr; }
+
+  /**
+   * Returns the number of references.
+   * @return the number of references
+   */
+  int count() const { return ptr->_KShared_count(); } // for debugging purposes
+private:
+  T* ptr;
+};
+
+#endif