/* -*- 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 Communicator client 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):
 *   Chris Waterson <waterson@netscape.com>
 *
 * 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 nsRDFPropertyTestNode_h__
#define nsRDFPropertyTestNode_h__

#include "nscore.h"
#include "nsRDFTestNode.h"
#include "nsIRDFDataSource.h"
#include "nsIRDFResource.h"
#include "nsXULTemplateQueryProcessorRDF.h"

class nsRDFPropertyTestNode : public nsRDFTestNode
{
public:
    /**
     * Both source and target unbound (?source ^property ?target)
     */
    nsRDFPropertyTestNode(TestNode* aParent,
                          nsXULTemplateQueryProcessorRDF* aProcessor,
                          nsIAtom* aSourceVariable,
                          nsIRDFResource* aProperty,
                          nsIAtom* aTargetVariable);

    /**
     * Source bound, target unbound (source ^property ?target)
     */
    nsRDFPropertyTestNode(TestNode* aParent,
                          nsXULTemplateQueryProcessorRDF* aProcessor,
                          nsIRDFResource* aSource,
                          nsIRDFResource* aProperty,
                          nsIAtom* aTargetVariable);

    /**
     * Source unbound, target bound (?source ^property target)
     */
    nsRDFPropertyTestNode(TestNode* aParent,
                          nsXULTemplateQueryProcessorRDF* aProcessor,
                          nsIAtom* aSourceVariable,
                          nsIRDFResource* aProperty,
                          nsIRDFNode* aTarget);

    virtual nsresult FilterInstantiations(InstantiationSet& aInstantiations,
                                          PRBool* aCantHandleYet) const;

    virtual PRBool
    CanPropagate(nsIRDFResource* aSource,
                 nsIRDFResource* aProperty,
                 nsIRDFNode* aTarget,
                 Instantiation& aInitialBindings) const;

    virtual void
    Retract(nsIRDFResource* aSource,
            nsIRDFResource* aProperty,
            nsIRDFNode* aTarget) const;


    class Element : public MemoryElement {
    protected:
        // Hide so that only Create() and Destroy() can be used to
        // allocate and deallocate from the heap
        static void* operator new(size_t) CPP_THROW_NEW { return 0; }
        static void operator delete(void*, size_t) {}

    public:
        Element(nsIRDFResource* aSource,
                nsIRDFResource* aProperty,
                nsIRDFNode* aTarget)
            : mSource(aSource),
              mProperty(aProperty),
              mTarget(aTarget) {
            MOZ_COUNT_CTOR(nsRDFPropertyTestNode::Element); }

        virtual ~Element() { MOZ_COUNT_DTOR(nsRDFPropertyTestNode::Element); }

        static Element*
        Create(nsIRDFResource* aSource,
               nsIRDFResource* aProperty,
               nsIRDFNode* aTarget) {
            void* place = MemoryElement::gPool.Alloc(sizeof(Element));
            return place ? ::new (place) Element(aSource, aProperty, aTarget) : nsnull; }

        void Destroy() {
            this->~Element();
            MemoryElement::gPool.Free(this, sizeof(Element));
        }

        virtual const char* Type() const {
            return "nsRDFPropertyTestNode::Element"; }

        virtual PLHashNumber Hash() const {
            return PLHashNumber(NS_PTR_TO_INT32(mSource.get())) ^
                (PLHashNumber(NS_PTR_TO_INT32(mProperty.get())) >> 4) ^
                (PLHashNumber(NS_PTR_TO_INT32(mTarget.get())) >> 12); }

        virtual PRBool Equals(const MemoryElement& aElement) const {
            if (aElement.Type() == Type()) {
                const Element& element = static_cast<const Element&>(aElement);
                return mSource == element.mSource
                    && mProperty == element.mProperty
                    && mTarget == element.mTarget;
            }
            return PR_FALSE; }

    protected:
        nsCOMPtr<nsIRDFResource> mSource;
        nsCOMPtr<nsIRDFResource> mProperty;
        nsCOMPtr<nsIRDFNode> mTarget;
    };

protected:
    nsXULTemplateQueryProcessorRDF* mProcessor;
    nsCOMPtr<nsIAtom>        mSourceVariable;
    nsCOMPtr<nsIRDFResource> mSource;
    nsCOMPtr<nsIRDFResource> mProperty;
    nsCOMPtr<nsIAtom>        mTargetVariable;
    nsCOMPtr<nsIRDFNode>     mTarget;
};

#endif // nsRDFPropertyTestNode_h__