    001    /*
    002     * Licensed to the Apache Software Foundation (ASF) under one or more
    003     * contributor license agreements.  See the NOTICE file distributed with
    004     * this work for additional information regarding copyright ownership.
    005     * The ASF licenses this file to You under the Apache License, Version 2.0
    006     * (the "License"); you may not use this file except in compliance with
    007     * the License.  You may obtain a copy of the License at
    008     *
    009     *     http://www.apache.org/licenses/LICENSE-2.0
    010     *
    011     * Unless required by applicable law or agreed to in writing, software
    012     * distributed under the License is distributed on an "AS IS" BASIS,
    013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014     * See the License for the specific language governing permissions and
    015     * limitations under the License.
    016     */
    017    package org.apache.commons.jxpath.ri.axes;
    018
    019    import org.apache.commons.jxpath.Function;
    020    import org.apache.commons.jxpath.JXPathContext;
    021    import org.apache.commons.jxpath.NodeSet;
    022    import org.apache.commons.jxpath.ri.EvalContext;
    023    import org.apache.commons.jxpath.ri.JXPathContextReferenceImpl;
    024    import org.apache.commons.jxpath.ri.QName;
    025    import org.apache.commons.jxpath.ri.model.NodePointer;
    026
    027    /**
    028     * EvalContext that is used to hold the root node for the path traversal.
    029     *
    030     * @author Dmitri Plotnikov
    031     * @version $Revision: 652845 $ $Date: 2008-05-02 12:46:46 -0500 (Fri, 02 May 2008) $
    032     */
    033    public class RootContext extends EvalContext {
    034        private JXPathContextReferenceImpl jxpathContext;
    035        private NodePointer pointer;
    036        private Object[] registers;
    037        private int availableRegister = 0;
    038        public static final Object UNKNOWN_VALUE = new Object();
    039        private static final int MAX_REGISTER = 4;
    040
    041        /**
    042         * Create a new RootContext.
    043         * @param jxpathContext context
    044         * @param pointer pointer
    045         */
    046        public RootContext(JXPathContextReferenceImpl jxpathContext,
    047                NodePointer pointer) {
    048            super(null);
    049            this.jxpathContext = jxpathContext;
    050            this.pointer = pointer;
    051            if (pointer != null) {
    052                pointer.setNamespaceResolver(jxpathContext.getNamespaceResolver());
    053            }
    054        }
    055
    056        public JXPathContext getJXPathContext() {
    057            return jxpathContext;
    058        }
    059
    060        public RootContext getRootContext() {
    061            return this;
    062        }
    063
    064        /**
    065         * Get absolute root context
    066         * @return EvalContext
    067         */
    068        public EvalContext getAbsoluteRootContext() {
    069            return jxpathContext.getAbsoluteRootContext();
    070        }
    071
    072        public NodePointer getCurrentNodePointer() {
    073            return pointer;
    074        }
    075
    076        public Object getValue() {
    077            return pointer;
    078        }
    079
    080        public int getCurrentPosition() {
    081            throw new UnsupportedOperationException();
    082        }
    083
    084        public boolean nextNode() {
    085            throw new UnsupportedOperationException();
    086        }
    087
    088        public boolean nextSet() {
    089            throw new UnsupportedOperationException();
    090        }
    091
    092        public boolean setPosition(int position) {
    093            throw new UnsupportedOperationException();
    094        }
    095
    096        /**
    097         * Get a context that points to the specified object.
    098         * @param constant object
    099         * @return EvalContext
    100         */
    101        public EvalContext getConstantContext(Object constant) {
    102            if (constant instanceof NodeSet) {
    103                return new NodeSetContext(
    104                    new RootContext(jxpathContext, null),
    105                    (NodeSet) constant);
    106            }
    107
    108            NodePointer pointer;
    109            if (constant instanceof NodePointer) {
    110                pointer = (NodePointer) constant;
    111            }
    112            else {
    113                pointer = NodePointer.newNodePointer(
    114                        new QName(null, ""),
    115                        constant,
    116                        null);
    117            }
    118            return new InitialContext(new RootContext(jxpathContext, pointer));
    119        }
    120
    121        /**
    122         * Get variable context.
    123         * @param variableName variable name
    124         * @return EvalContext
    125         */
    126        public EvalContext getVariableContext(QName variableName) {
    127            return new InitialContext(
    128                new RootContext(
    129                    jxpathContext,
    130                    jxpathContext.getVariablePointer(variableName)));
    131        }
    132
    133        /**
    134         * Get the specified function from the context.
    135         * @param functionName QName
    136         * @param parameters Object[]
    137         * @return Function
    138         */
    139        public Function getFunction(QName functionName, Object[] parameters) {
    140            return jxpathContext.getFunction(functionName, parameters);
    141        }
    142
    143        /**
    144         * Get a registered value.
    145         * @param id int
    146         * @return Object
    147         */
    148        public Object getRegisteredValue(int id) {
    149            if (registers == null || id >= MAX_REGISTER || id == -1) {
    150                return UNKNOWN_VALUE;
    151            }
    152            return registers[id];
    153        }
    154
    155        /**
    156         * Set the next registered value.
    157         * @param value Object
    158         * @return the id that can reclaim value.
    159         */
    160        public int setRegisteredValue(Object value) {
    161            if (registers == null) {
    162                registers = new Object[MAX_REGISTER];
    163                for (int i = 0; i < MAX_REGISTER; i++) {
    164                    registers[i] = UNKNOWN_VALUE;
    165                }
    166            }
    167            if (availableRegister >= MAX_REGISTER) {
    168                return -1;
    169            }
    170            registers[availableRegister] = value;
    171            availableRegister++;
    172            return availableRegister - 1;
    173        }
    174
    175        public String toString() {
    176            return super.toString() + ":" + pointer.asPath();
    177        }
    178    }