From 31fe5681a49cbcf291abf755ee5f2f2fb1e4a582 Mon Sep 17 00:00:00 2001
From: alwin <alwin>
Date: Thu, 11 Mar 2004 22:23:49 +0000
Subject: added a (clean-room) smart-pointer implementation to the OPIE project.

Its an implementation I had made in 1999 for some other GPL projects and is
clean-room, so would be fine someone takes a look on it.
---
(limited to 'libopie2/opiecore/osmart_pointer.h')

diff --git a/libopie2/opiecore/osmart_pointer.h b/libopie2/opiecore/osmart_pointer.h
new file mode 100644
index 0000000..a362a60
--- a/dev/null
+++ b/libopie2/opiecore/osmart_pointer.h
@@ -0,0 +1,144 @@
+// -*- Mode: C++; -*-
+/*
+                            This file is part of the Opie Project
+                            Copyright (C) 2004 Rajko Albrecht <alwin@handhelds.org>
+                            Copyright (C) The Opie Team <opie-devel@handhelds.org>
+             =.             
+           .=l.
+          .>+-=
+_;:,     .>    :=|.         This program is free software; you can
+.> <`_,   >  .   <=         redistribute it and/or  modify it under
+:`=1 )Y*s>-.--   :          the terms of the GNU Library General Public
+.="- .-=="i,     .._        License as published by the Free Software
+- .   .-<_>     .<>         Foundation; either version 2 of the License,
+    ._= =}       :          or (at your option) any later version.
+   .%`+i>       _;_.
+   .i_,=:_.      -<s.       This program 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., 59 Temple Place - Suite 330,
+                            Boston, MA 02111-1307, USA.
+*/
+
+#ifndef _osmart_pointer_h
+#define _osmart_pointer_h
+
+/*!
+ * \file osmart_pointer.h
+ * \brief smart pointer and reference counter
+ * \author Rajko Albrecht
+ *
+ */
+
+namespace Opie {
+
+//! simple reference counter class
+class oref_count {
+protected:
+    //! reference count member
+    long m_RefCount;
+public:
+    //! first reference must be added after "new" via Pointer()
+    oref_count() : m_RefCount(0)
+    {}
+    virtual ~oref_count() {}
+    //! add a reference
+    void Incr() {
+        ++m_RefCount;
+    }
+    //! delete a reference
+    void Decr() {
+        --m_RefCount;
+    }
+    //! is it referenced
+    bool Shared() { return (m_RefCount > 0); }
+};
+
+//! reference counting wrapper class
+template<class T> class osmart_pointer {
+    //! pointer to object
+    /*!
+     * this object must contain Incr(), Decr() and Shared() 
+     * methode as public members. The best way is, that it will be a child
+     * class of RefCount
+     */
+    T *ptr;
+public:
+    //! standart constructor
+    osmart_pointer() { ptr = NULL; }
+    //! standart destructor
+    /*!
+     * release the reference, if it were the last reference, destroys
+     * ptr
+     */
+    ~osmart_pointer()
+    {
+        if (ptr){
+            ptr->Decr();
+            if (!ptr->Shared())
+                delete ptr;
+        }
+    }
+    //! construction
+    osmart_pointer(T* t) { if (ptr = t) ptr->Incr(); }
+    //! Pointer copy
+    osmart_pointer(const smart_pointer<T>& p) 
+    { if (ptr = p.ptr) ptr->Incr(); }
+    //! pointer copy by assignment
+    osmart_pointer<T>& operator= (const smart_pointer<T>& p) 
+    {
+        // already same: nothing to do
+        if (ptr == p.ptr) return *this;
+        // decouple reference
+        if (ptr) { ptr->Decr(); if (!ptr->Shared()) delete ptr; } 
+        // establish new reference
+        if (ptr = p.ptr) ptr->Incr();
+        return *this;
+    }
+    osmart_pointer<T>& operator= (T*p)
+    {
+        if (ptr==p)return *this;
+        if (ptr) {
+            ptr->Decr();
+            if (!ptr->Shared()) delete ptr;
+        }
+        if (ptr=p) ptr->Incr();
+        return *this;
+    }
+
+    //! cast to conventional pointer
+    operator T* () const { return ptr; }
+    
+    //! deref: fails for NULL pointer
+    T& operator* () {return *ptr; }
+    //! deref: fails for NULL pointer
+    const T& operator* ()const {return *ptr; }
+
+    //! deref with method call
+    T* operator-> () {return ptr; }
+    //! deref with const method call
+    const T* operator-> ()const {return ptr; }
+    
+    //! supports "if (pointer)"
+    operator bool () const { return (ptr != NULL); }
+    //! "if (pointer)" as non const
+    operator bool () { return ptr != NULL;}
+    
+    //! support if (!pointer)"
+    bool operator! () const { return (ptr == NULL); }
+    //! support if (!pointer)" as non const
+    bool operator! () { return (ptr == NULL); }
+};
+
+}
+
+#endif
--
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