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Commons JXPath example source code file (RootContext.java)

This example Commons JXPath source code file (RootContext.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Commons JXPath tags/keywords

evalcontext, evalcontext, initialcontext, max_register, nodepointer, nodepointer, nodeset, object, object, rootcontext, rootcontext, string, unknown_value, unsupportedoperationexception

The Commons JXPath RootContext.java source code

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.
 */
package org.apache.commons.jxpath.ri.axes;

import org.apache.commons.jxpath.Function;
import org.apache.commons.jxpath.JXPathContext;
import org.apache.commons.jxpath.NodeSet;
import org.apache.commons.jxpath.ri.EvalContext;
import org.apache.commons.jxpath.ri.JXPathContextReferenceImpl;
import org.apache.commons.jxpath.ri.QName;
import org.apache.commons.jxpath.ri.model.NodePointer;

/**
 * EvalContext that is used to hold the root node for the path traversal.
 *
 * @author Dmitri Plotnikov
 * @version $Revision: 652845 $ $Date: 2008-05-02 12:46:46 -0500 (Fri, 02 May 2008) $
 */
public class RootContext extends EvalContext {
    private JXPathContextReferenceImpl jxpathContext;
    private NodePointer pointer;
    private Object[] registers;
    private int availableRegister = 0;
    public static final Object UNKNOWN_VALUE = new Object();
    private static final int MAX_REGISTER = 4;

    /**
     * Create a new RootContext.
     * @param jxpathContext context
     * @param pointer pointer
     */
    public RootContext(JXPathContextReferenceImpl jxpathContext,
            NodePointer pointer) {
        super(null);
        this.jxpathContext = jxpathContext;
        this.pointer = pointer;
        if (pointer != null) {
            pointer.setNamespaceResolver(jxpathContext.getNamespaceResolver());
        }
    }

    public JXPathContext getJXPathContext() {
        return jxpathContext;
    }

    public RootContext getRootContext() {
        return this;
    }

    /**
     * Get absolute root context
     * @return EvalContext
     */
    public EvalContext getAbsoluteRootContext() {
        return jxpathContext.getAbsoluteRootContext();
    }

    public NodePointer getCurrentNodePointer() {
        return pointer;
    }

    public Object getValue() {
        return pointer;
    }

    public int getCurrentPosition() {
        throw new UnsupportedOperationException();
    }

    public boolean nextNode() {
        throw new UnsupportedOperationException();
    }

    public boolean nextSet() {
        throw new UnsupportedOperationException();
    }

    public boolean setPosition(int position) {
        throw new UnsupportedOperationException();
    }

    /**
     * Get a context that points to the specified object.
     * @param constant object
     * @return EvalContext
     */
    public EvalContext getConstantContext(Object constant) {
        if (constant instanceof NodeSet) {
            return new NodeSetContext(
                new RootContext(jxpathContext, null),
                (NodeSet) constant);
        }

        NodePointer pointer;
        if (constant instanceof NodePointer) {
            pointer = (NodePointer) constant;
        }
        else {
            pointer = NodePointer.newNodePointer(
                    new QName(null, ""),
                    constant,
                    null);
        }
        return new InitialContext(new RootContext(jxpathContext, pointer));
    }

    /**
     * Get variable context.
     * @param variableName variable name
     * @return EvalContext
     */
    public EvalContext getVariableContext(QName variableName) {
        return new InitialContext(
            new RootContext(
                jxpathContext,
                jxpathContext.getVariablePointer(variableName)));
    }

    /**
     * Get the specified function from the context.
     * @param functionName QName
     * @param parameters Object[]
     * @return Function
     */
    public Function getFunction(QName functionName, Object[] parameters) {
        return jxpathContext.getFunction(functionName, parameters);
    }

    /**
     * Get a registered value.
     * @param id int
     * @return Object
     */
    public Object getRegisteredValue(int id) {
        if (registers == null || id >= MAX_REGISTER || id == -1) {
            return UNKNOWN_VALUE;
        }
        return registers[id];
    }

    /**
     * Set the next registered value.
     * @param value Object
     * @return the id that can reclaim value.
     */
    public int setRegisteredValue(Object value) {
        if (registers == null) {
            registers = new Object[MAX_REGISTER];
            for (int i = 0; i < MAX_REGISTER; i++) {
                registers[i] = UNKNOWN_VALUE;
            }
        }
        if (availableRegister >= MAX_REGISTER) {
            return -1;
        }
        registers[availableRegister] = value;
        availableRegister++;
        return availableRegister - 1;
    }

    public String toString() {
        return super.toString() + ":" + pointer.asPath();
    }
}

Other Commons JXPath examples (source code examples)

Here is a short list of links related to this Commons JXPath RootContext.java source code file:

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