Bug 550475 - Part 1: Add a RefPtr template class to Cairo. r=jrmuizel

gfx/cairo/cairo/src/cairo-win32-refptr.h

@@ -0,0 +1,156 @@
+/* -*- Mode: c; tab-width: 8; c-basic-offset: 4; indent-tabs-mode: t; -*- */
+/* Cairo - a vector graphics library with display and print output
+ *
+ * Copyright © 2010 Mozilla Foundation
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it either under the terms of the GNU Lesser General Public
+ * License version 2.1 as published by the Free Software Foundation
+ * (the "LGPL") or, at your option, under the terms of the Mozilla
+ * Public License Version 1.1 (the "MPL"). If you do not alter this
+ * notice, a recipient may use your version of this file under either
+ * the MPL or the LGPL.
+ *
+ * You should have received a copy of the LGPL along with this library
+ * in the file COPYING-LGPL-2.1; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ * You should have received a copy of the MPL along with this library
+ * in the file COPYING-MPL-1.1
+ *
+ * The contents of this file are subject to the Mozilla Public License
+ * Version 1.1 (the "License"); you may not use this file except in
+ * compliance with the License. You may obtain a copy of the License at
+ * http://www.mozilla.org/MPL/
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY
+ * OF ANY KIND, either express or implied. See the LGPL or the MPL for
+ * the specific language governing rights and limitations.
+ *
+ * The Original Code is the cairo graphics library.
+ *
+ * The Initial Developer of the Original Code is the Mozilla Foundation
+ *
+ * Contributor(s):
+ *	Bas Schouten <bschouten@mozilla.com>
+ */
+#ifndef CAIRO_WIN32_REFPTR_H
+#define CAIRO_WIN32_REFPTR_H
+
+template<class T>
+class RefPtr
+{
+public:
+    RefPtr() : mPtr(NULL)
+    { }
+
+    RefPtr(T *aPtr) : mPtr(aPtr)
+    {
+	if (mPtr) {
+	    mPtr->AddRef();
+	}
+    }
+
+    RefPtr(const RefPtr<T> &aRefPtr)
+    {
+	mPtr = aRefPtr.mPtr;
+	if (mPtr) {
+	    mPtr->AddRef();
+	}
+    }
+
+    template <class newType>
+    explicit RefPtr(const RefPtr<newType> &aRefPtr)
+    {
+	mPtr = aRefPtr.get();
+	if (mPtr) {
+	    mPtr->AddRef();
+	}
+    }
+
+    ~RefPtr()
+    {
+	if (mPtr) {
+	    mPtr->Release();
+	}
+    }
+
+    RefPtr<T> &operator =(const RefPtr<T> aPtr)
+    {
+	assignPtr(aPtr.mPtr);
+	return *this;
+    }
+    
+    RefPtr<T> &operator =(T* aPtr)
+    {
+	assignPtr(aPtr);
+	return *this;
+    }
+
+    /** 
+     * WARNING for ease of use, passing a reference will release/clear out ptr!
+     * We null out the ptr before returning its address so people passing byref
+     * as input will most likely get functions returning errors rather than accessing
+     * freed memory. Further more accessing it after this point if it hasn't
+     * been set will produce a null pointer dereference.
+     */
+    T** operator&()
+    {
+	if (mPtr) {
+	    mPtr->Release();
+	    mPtr = NULL;
+	}
+	return &mPtr;
+    }
+
+    T* operator->()
+    {
+	return mPtr;
+    }
+
+    operator bool()
+    {
+	return (mPtr ? true : false);
+    }
+
+    operator T*()
+    {
+	return mPtr;
+    }
+
+    template <class newType>
+    operator RefPtr<newType>()
+    {
+	RefPtr<newType> newPtr;
+	newPtr = mPtr;
+	return newPtr;
+    }
+
+    T* get() const
+    {
+	return mPtr;
+    }
+
+    T* forget()
+    {
+	T* ptr = mPtr;
+	mPtr = NULL;
+	return ptr;
+    }
+
+private:
+    void assignPtr(T* aPtr)
+    {
+	T *oldPtr = mPtr;
+	mPtr = aPtr;
+	if (mPtr) {
+	    mPtr->AddRef();
+	}
+	if (oldPtr) {
+	    oldPtr->Release();
+	}
+    }
+
+    T *mPtr;
+};
+
+#endif