adding a tree interface to datasources. Not yet in build system

rdf/base/public/nsIRDFTree.h

@@ -0,0 +1,60 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ *
+ * The contents of this file are subject to the Netscape Public License
+ * Version 1.0 (the "NPL"); you may not use this file except in
+ * compliance with the NPL.  You may obtain a copy of the NPL at
+ * http://www.mozilla.org/NPL/
+ *
+ * Software distributed under the NPL is distributed on an "AS IS" basis,
+ * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the NPL
+ * for the specific language governing rights and limitations under the
+ * NPL.
+ *
+ * The Initial Developer of this code under the NPL is Netscape
+ * Communications Corporation.  Portions created by Netscape are
+ * Copyright (C) 1998 Netscape Communications Corporation.  All Rights
+ * Reserved.
+ */
+
+#ifndef nsIRDFTree_h__
+#define nsIRDFTree_h__
+
+#include "nscore.h"
+#include "nsISupports.h"
+#include "prtypes.h"
+#include "rdf.h" // for error codes
+
+/*
+  An interface for presenting a tree view of an rdf datasource (or
+  database).
+
+  Any datasource can also support nsIRDFTree. The interface is purely
+  syntactic sugar for traversing simple tree where the child relation
+  corresponds to the property type nc:child (nc = http://home.netscape.com/NC-rdf#).
+  Each leaf is assumed to have a certain predefined set of properties
+  such as creationDate, size, lastModificationDate, lastVisitDate, etc.
+
+  This interface is substantially less general than nsIRDFDataSource,
+  but is adequate for bookmarks, the file system, history and a few
+  other very commonly used data sources.
+
+ */
+
+// {7D7EEBD1-AA41-11d2-80B7-006097B76B8E}
+#define NS_IRDFTREE_IID \
+{ 0x7d7eebd1, 0xaa41, 0x11d2, { 0x80, 0xb7, 0x0, 0x60, 0x97, 0xb7, 0x6b, 0x8e } };
+
+class nsIRDFTree : public nsISupports {
+public:
+
+  NS_IMETHOD ListChildren (nsIRDFResource* folder, nsVoidArray** result);
+ // XXX should define something called nsResourceArray and use that
+
+  NS_IMETHOD IsFolder (nsIRDFResource* node, PRBool* result);
+
+  NS_IMETHOD GetProperty (nsIRDFResource* node, nsIRDFResource* property, 
+			  nsIRDFNode** result);
+
+}
+
+#endif