Version 1.8 of gecko-sdk. Downloaded from here:...

gecko-sdk/include/nsISupportsUtils.h

+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* ***** BEGIN LICENSE BLOCK *****
+ * Version: MPL 1.1/GPL 2.0/LGPL 2.1
+ *
+ * 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/
+ *
+ * Software distributed under the License is distributed on an "AS IS" basis,
+ * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
+ * for the specific language governing rights and limitations under the
+ * License.
+ *
+ * The Original Code is mozilla.org code.
+ *
+ * The Initial Developer of the Original Code is
+ * Netscape Communications Corporation.
+ * Portions created by the Initial Developer are Copyright (C) 1998
+ * the Initial Developer. All Rights Reserved.
+ *
+ * Contributor(s):
+ *   Pierre Phaneuf <pp@ludusdesign.com>
+ *   Scott Collins <scc@ScottCollins.net>
+ *   Dan Mosedale <dmose@mozilla.org>
+ *
+ * Alternatively, the contents of this file may be used under the terms of
+ * either of the GNU General Public License Version 2 or later (the "GPL"),
+ * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
+ * in which case the provisions of the GPL or the LGPL are applicable instead
+ * of those above. If you wish to allow use of your version of this file only
+ * under the terms of either the GPL or the LGPL, and not to allow others to
+ * use your version of this file under the terms of the MPL, indicate your
+ * decision by deleting the provisions above and replace them with the notice
+ * and other provisions required by the GPL or the LGPL. If you do not delete
+ * the provisions above, a recipient may use your version of this file under
+ * the terms of any one of the MPL, the GPL or the LGPL.
+ *
+ * ***** END LICENSE BLOCK ***** */
+
+#ifndef nsISupportsUtils_h__
+#define nsISupportsUtils_h__
+
+#ifndef nscore_h___
+#include "nscore.h"
+#endif
+
+#ifndef nsISupportsBase_h__
+#include "nsISupportsBase.h"
+#endif
+
+#ifndef nsError_h__
+#include "nsError.h"
+#endif
+
+#ifndef nsDebug_h___
+#include "nsDebug.h"
+#endif
+
+#ifndef nsISupportsImpl_h__
+#include "nsISupportsImpl.h"
+#endif
+
+/**
+ * Macro for instantiating a new object that implements nsISupports.
+ * Note that you can only use this if you adhere to the no arguments
+ * constructor com policy (which you really should!).
+ * @param _result Where the new instance pointer is stored
+ * @param _type The type of object to call "new" with.
+ */
+#define NS_NEWXPCOM(_result,_type)                                            \
+  PR_BEGIN_MACRO                                                              \
+    _result = new _type();                                                    \
+  PR_END_MACRO
+
+/**
+ * Macro for deleting an object that implements nsISupports.
+ * @param _ptr The object to delete.
+ */
+#define NS_DELETEXPCOM(_ptr)                                                  \
+  PR_BEGIN_MACRO                                                              \
+    delete (_ptr);                                                            \
+  PR_END_MACRO
+
+/**
+ * Macro for adding a reference to an interface.
+ * @param _ptr The interface pointer.
+ */
+#define NS_ADDREF(_ptr) \
+  (_ptr)->AddRef()
+
+/**
+ * Macro for adding a reference to this. This macro should be used
+ * because NS_ADDREF (when tracing) may require an ambiguous cast
+ * from the pointers primary type to nsISupports. This macro sidesteps
+ * that entire problem.
+ */
+#define NS_ADDREF_THIS() \
+  AddRef()
+
+
+extern "C++" {
+// ...because some one is accidentally including this file inside
+// an |extern "C"|
+
+
+// Making this a |inline| |template| allows |expr| to be evaluated only once,
+// yet still denies you the ability to |AddRef()| an |nsCOMPtr|.
+template <class T>
+inline
+nsrefcnt
+ns_if_addref( T expr )
+{
+    return expr ? expr->AddRef() : 0;
+}
+
+} /* extern "C++" */
+
+/**
+ * Macro for adding a reference to an interface that checks for NULL.
+ * @param _expr The interface pointer.
+ */
+#define NS_IF_ADDREF(_expr) ns_if_addref(_expr)
+
+/*
+ * Given these declarations, it explicitly OK and efficient to end a `getter' with:
+ *
+ *    NS_IF_ADDREF(*result = mThing);
+ *
+ * even if |mThing| is an |nsCOMPtr|.  If |mThing| is an |nsCOMPtr|, however, it is still
+ * _illegal_ to say |NS_IF_ADDREF(mThing)|.
+ */
+
+/**
+ * Macro for releasing a reference to an interface.
+ * @param _ptr The interface pointer.
+ */
+#define NS_RELEASE(_ptr)                                                      \
+  PR_BEGIN_MACRO                                                              \
+    (_ptr)->Release();                                                        \
+    (_ptr) = 0;                                                               \
+  PR_END_MACRO
+
+/**
+ * Macro for releasing a reference to an interface.
+ * @param _ptr The interface pointer.
+ */
+#define NS_RELEASE_THIS() \
+    Release()
+
+/**
+ * Macro for releasing a reference to an interface, except that this
+ * macro preserves the return value from the underlying Release call.
+ * The interface pointer argument will only be NULLed if the reference count
+ * goes to zero.
+ *
+ * @param _ptr The interface pointer.
+ */
+#define NS_RELEASE2(_ptr,_rv)                                                 \
+  PR_BEGIN_MACRO                                                              \
+    _rv = (_ptr)->Release();                                                  \
+    if (0 == (_rv)) (_ptr) = 0;                                               \
+  PR_END_MACRO
+
+/**
+ * Macro for releasing a reference to an interface that checks for NULL;
+ * @param _ptr The interface pointer.
+ */
+#define NS_IF_RELEASE(_ptr)                                                   \
+  PR_BEGIN_MACRO                                                              \
+    if (_ptr) {                                                               \
+      (_ptr)->Release();                                                      \
+      (_ptr) = 0;                                                             \
+    }                                                                         \
+  PR_END_MACRO
+
+/*
+ * Often you have to cast an implementation pointer, e.g., |this|, to an
+ * |nsISupports*|, but because you have multiple inheritance, a simple cast
+ * is ambiguous.  One could simply say, e.g., (given a base |nsIBase|),
+ * |NS_STATIC_CAST(nsIBase*, this)|; but that disguises the fact that what
+ * you are really doing is disambiguating the |nsISupports|.  You could make
+ * that more obvious with a double cast, e.g., |NS_STATIC_CAST(nsISupports*,
+ * NS_STATIC_CAST(nsIBase*, this))|, but that is bulky and harder to read...
+ *
+ * The following macro is clean, short, and obvious.  In the example above,
+ * you would use it like this: |NS_ISUPPORTS_CAST(nsIBase*, this)|.
+ */
+
+#define NS_ISUPPORTS_CAST(__unambiguousBase, __expr) \
+  NS_STATIC_CAST(nsISupports*, NS_STATIC_CAST(__unambiguousBase, __expr))
+
+extern "C++" {
+// ...because some one is accidentally including this file inside
+// an |extern "C"|
+
+class nsISupports;
+
+template <class T>
+struct nsCOMTypeInfo
+{
+    static const nsIID& GetIID() { return T::GetIID(); }
+};
+
+NS_SPECIALIZE_TEMPLATE
+struct nsCOMTypeInfo<nsISupports>
+{
+    static const nsIID& GetIID() {
+        static const nsIID iid_NS_ISUPPORTS_IID = NS_ISUPPORTS_IID; return iid_NS_ISUPPORTS_IID;
+    }
+};
+
+#define NS_GET_IID(T) nsCOMTypeInfo<T>::GetIID()
+
+// a type-safe shortcut for calling the |QueryInterface()| member function
+template <class T, class DestinationType>
+inline
+nsresult
+CallQueryInterface( T* aSource, DestinationType** aDestination )
+{
+    NS_PRECONDITION(aSource, "null parameter");
+    NS_PRECONDITION(aDestination, "null parameter");
+    
+    return aSource->QueryInterface(NS_GET_IID(DestinationType),
+                                   NS_REINTERPRET_CAST(void**, aDestination));
+}
+
+} // extern "C++"
+
+#endif /* __nsISupportsUtils_h */