/*

 * @(#)$Id: DescendantOrSelfStep.java 3619 2008-03-26 07:23:03Z yui $

 *

 * Copyright 2006-2008 Makoto YUI

 *

 * Licensed under the Apache License, Version 2.0 (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.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 * 

 * Contributors:

 *     Makoto YUI - initial implementation

 */

package xbird.xquery.expr.path.axis;



import xbird.xquery.DynamicError;

import xbird.xquery.XQueryException;

import xbird.xquery.dm.value.*;

import xbird.xquery.dm.value.sequence.*;

import xbird.xquery.expr.path.NodeTest;

import xbird.xquery.meta.*;

import xbird.xquery.optim.RewriteInfo;



/**

 * The descendant-or-self axis contains the context node and the descendants 

 * of the context node.

 * <DIV lang="en"></DIV>

 * <DIV lang="ja"></DIV>

 * 

 * @author Makoto YUI (yuin405+xbird@gmail.com)

 */

public class DescendantOrSelfStep extends AxisStep {

    private static final long serialVersionUID = -1036349267969466494L;



    public DescendantOrSelfStep(NodeTest test) {

        this(DESC_OR_SELF, test);

    }



    public DescendantOrSelfStep(int kind, NodeTest test) {

        super(kind, test);

    }



    @Override

    public boolean isPathIndexAccessable(StaticContext statEnv, RewriteInfo info) {

        if(!info.hasPreviousStep()) {

            return false;

        }

        String nt = _nodeTest.toString();

        if(!"*".equals(nt) && !"node()".equals(nt)) {

            return false;

        }

        info.markDescendantOrSelf();

        return true;

    }



    public Sequence<? extends Item> eval(Sequence<? extends Item> contextSeq, DynamicContext dynEnv)

            throws XQueryException {

        if(contextSeq == null) {

            throw new DynamicError("err:XPDY0002", "ContextItem is not set");

        }

        final INodeSequence<XQNode> src = ProxyNodeSequence.wrap(contextSeq, dynEnv);

        final IFocus<XQNode> srcItor = src.iterator();

        if(srcItor.hasNext()) {

            final XQNode n = srcItor.next();

            if(srcItor.hasNext()) {

                srcItor.closeQuietly();

                reportError("err:XPTY0020", "Context item is expected to be a node, but was node sequence.");

            }

            srcItor.closeQuietly();

            // FIXME DMNode

            return new DescendantOrSelfEmurationSequence(n, _nodeTest, dynEnv);

        }

        srcItor.closeQuietly();

        return NodeSequence.<XQNode> emptySequence();

    }



    /** 

     * Represents "/descendant-or-self::node()/"

     */

    public static final class RootDescStep extends DescendantOrSelfStep {

        private static final long serialVersionUID = -8533383126416496506L;



        public static final RootDescStep INSTANCE = new RootDescStep();



        public RootDescStep() {

            super(NodeTest.ANYNODE);

        }

    }



    protected static final class DescendantOrSelfEmurationSequence extends AxisEmurationSequence {

        private static final long serialVersionUID = 3516008834617795445L;



        private final NodeTest _filterNodeTest;

        private final XQNode _stopNode;

        private final long _stopNID;

        private final boolean _excludeSelf;



        public DescendantOrSelfEmurationSequence(XQNode baseNode, NodeTest nodeTest, DynamicContext dynEnv) {

            this(baseNode, nodeTest, dynEnv, false);

        }



        public DescendantOrSelfEmurationSequence(XQNode baseNode, NodeTest nodeTest, DynamicContext dynEnv, boolean excludeSelf) {

            super(baseNode, dynEnv);

            this._filterNodeTest = nodeTest;

            this._stopNode = baseNode.following(true);

            this._stopNID = (_stopNode == null) ? Long.MIN_VALUE : _stopNode.getPosition();

            this._excludeSelf = excludeSelf;

        }



        public boolean next(final IFocus<XQNode> focus) throws XQueryException {

            XQNode curNode = focus.getContextItem();

            for(int pos = focus.getContextPosition(); curNode != null; pos++) {

                if(pos == 0) {

                    if(_excludeSelf) {

                        curNode = curNode.firstChild();

                    }

                } else {

                    curNode = curNode.nextNode();

                    if(curNode == null) {

                        return false;

                    }

                    if(curNode == _stopNode) {// REVIEWME DMNode

                        return false;

                    }

                    final long nid = curNode.getPosition();

                    if(nid == _stopNID) {

                        return false;

                    }

                }

                if(_filterNodeTest.accepts(curNode)) {

                    focus.setContextItem(curNode);

                    return true;

                }

            }

            return false;

        }



    }



}