Commons JXPath example source code file (VariablePointer.java)

This example Commons JXPath source code file (VariablePointer.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

factory, jxpathabstractfactoryexception, jxpathcontext, jxpathexception, nodeiterator, nodepointer, nodepointer, object, object, qname, variablepointer, variablepointer, whole_collection, whole_collection

The Commons JXPath VariablePointer.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.model;

import org.apache.commons.jxpath.AbstractFactory;
import org.apache.commons.jxpath.JXPathAbstractFactoryException;
import org.apache.commons.jxpath.JXPathContext;
import org.apache.commons.jxpath.JXPathException;
import org.apache.commons.jxpath.JXPathIntrospector;
import org.apache.commons.jxpath.JXPathInvalidAccessException;
import org.apache.commons.jxpath.Variables;
import org.apache.commons.jxpath.ri.QName;
import org.apache.commons.jxpath.ri.compiler.NodeTest;
import org.apache.commons.jxpath.ri.model.beans.NullPointer;
import org.apache.commons.jxpath.util.ValueUtils;

/**
 * Pointer to a context variable.
 *
 * @author Dmitri Plotnikov
 * @version $Revision: 652884 $ $Date: 2008-05-02 15:02:00 -0500 (Fri, 02 May 2008) $
 */
public class VariablePointer extends NodePointer {
    private Variables variables;
    private QName name;
    private NodePointer valuePointer;
    private boolean actual;

    private static final long serialVersionUID = -454731297397189293L;

    /**
     * Create a new VariablePointer.
     * @param variables Variables instance
     * @param name variable name
     */
    public VariablePointer(Variables variables, QName name) {
        super(null);
        this.variables = variables;
        this.name = name;
        actual = true;
    }

    /**
     * Create a new (non-actual) VariablePointer.
     * @param name variable name
     */
    public VariablePointer(QName name) {
        super(null);
        this.name = name;
        actual = false;
    }

    public boolean isContainer() {
        return true;
    }

    public QName getName() {
        return name;
    }

    public Object getBaseValue() {
        if (!actual) {
            throw new JXPathException("Undefined variable: " + name);
        }
        return variables.getVariable(name.toString());
    }

    public boolean isLeaf() {
        Object value = getNode();
        return value == null || JXPathIntrospector.getBeanInfo(value.getClass()).isAtomic();
    }

    public boolean isCollection() {
        Object value = getBaseValue();
        return value != null && ValueUtils.isCollection(value);
    }

    public Object getImmediateNode() {
        Object value = getBaseValue();
        return index == WHOLE_COLLECTION ? ValueUtils.getValue(value)
                : ValueUtils.getValue(value, index);
    }

    public void setValue(Object value) {
        if (!actual) {
            throw new JXPathException("Cannot set undefined variable: " + name);
        }
        valuePointer = null;
        if (index != WHOLE_COLLECTION) {
            Object collection = getBaseValue();
            ValueUtils.setValue(collection, index, value);
        }
        else {
            variables.declareVariable(name.toString(), value);
        }
    }

    public boolean isActual() {
        return actual;
    }

    public void setIndex(int index) {
        super.setIndex(index);
        valuePointer = null;
    }

    public NodePointer getImmediateValuePointer() {
        if (valuePointer == null) {
            Object value = null;
            if (actual) {
                value = getImmediateNode();
                valuePointer =
                    NodePointer.newChildNodePointer(this, null, value);
            }
            else {
                return new NullPointer(this, getName()) {
                    public Object getImmediateNode() {
                        throw new JXPathException(
                            "Undefined variable: " + name);
                    }
                };
            }
        }
        return valuePointer;
    }

    public int getLength() {
        if (actual) {
            Object value = getBaseValue();
            return value == null ? 1 : ValueUtils.getLength(value);
        }
        return 0;
    }

    public NodePointer createPath(JXPathContext context, Object value) {
        if (actual) {
            setValue(value);
            return this;
        }
        NodePointer ptr = createPath(context);
        ptr.setValue(value);
        return ptr;
    }

    public NodePointer createPath(JXPathContext context) {
        if (!actual) {
            AbstractFactory factory = getAbstractFactory(context);
            if (!factory.declareVariable(context, name.toString())) {
                throw new JXPathAbstractFactoryException(
                        "Factory cannot define variable '" + name
                                + "' for path: " + asPath());
            }
            findVariables(context);
            // Assert: actual == true
        }
        return this;
    }

    public NodePointer createChild(
        JXPathContext context,
        QName name,
        int index) {
        Object collection = createCollection(context, index);
        if (!isActual() || (index != 0 && index != WHOLE_COLLECTION)) {
            AbstractFactory factory = getAbstractFactory(context);
            boolean success =
                factory.createObject(
                    context,
                    this,
                    collection,
                    getName().toString(),
                    index);
            if (!success) {
                throw new JXPathAbstractFactoryException(
                        "Factory could not create object path: " + asPath());
            }
            NodePointer cln = (NodePointer) clone();
            cln.setIndex(index);
            return cln;
        }
        return this;
    }

    public NodePointer createChild(
            JXPathContext context,
            QName name,
            int index,
            Object value) {
        Object collection = createCollection(context, index);
        ValueUtils.setValue(collection, index, value);
        NodePointer cl = (NodePointer) clone();
        cl.setIndex(index);
        return cl;
    }

    /**
     * Create a collection.
     * @param context JXPathContext
     * @param index collection index
     * @return Object
     */
    private Object createCollection(JXPathContext context, int index) {
        createPath(context);

        Object collection = getBaseValue();
        if (collection == null) {
            throw new JXPathAbstractFactoryException(
                "Factory did not assign a collection to variable '"
                    + name
                    + "' for path: "
                    + asPath());
        }

        if (index == WHOLE_COLLECTION) {
            index = 0;
        }
        else if (index < 0) {
            throw new JXPathInvalidAccessException("Index is less than 1: "
                    + asPath());
        }

        if (index >= getLength()) {
            collection = ValueUtils.expandCollection(collection, index + 1);
            variables.declareVariable(name.toString(), collection);
        }

        return collection;
    }

    public void remove() {
        if (actual) {
            if (index == WHOLE_COLLECTION) {
                variables.undeclareVariable(name.toString());
            }
            else {
                if (index < 0) {
                    throw new JXPathInvalidAccessException(
                        "Index is less than 1: " + asPath());
                }

                Object collection = getBaseValue();
                if (collection != null && index < getLength()) {
                    collection = ValueUtils.remove(collection, index);
                    variables.declareVariable(name.toString(), collection);
                }
            }
        }
    }

    /**
     * Assimilate the Variables instance associated with the specified context.
     * @param context JXPathContext to search
     */
    protected void findVariables(JXPathContext context) {
        valuePointer = null;
        JXPathContext varCtx = context;
        while (varCtx != null) {
            variables = varCtx.getVariables();
            if (variables.isDeclaredVariable(name.toString())) {
                actual = true;
                break;
            }
            varCtx = varCtx.getParentContext();
            variables = null;
        }
    }

    public int hashCode() {
        return (actual ? System.identityHashCode(variables) : 0)
            + name.hashCode()
            + index;
    }

    public boolean equals(Object object) {
        if (object == this) {
            return true;
        }

        if (!(object instanceof VariablePointer)) {
            return false;
        }

        VariablePointer other = (VariablePointer) object;
        return variables == other.variables
            && name.equals(other.name)
            && index == other.index;
    }

    public String asPath() {
        StringBuffer buffer = new StringBuffer();
        buffer.append('$');
        buffer.append(name);
        if (!actual) {
            if (index != WHOLE_COLLECTION) {
                buffer.append('[').append(index + 1).append(']');
            }
        }
        else if (
            index != WHOLE_COLLECTION
                && (getNode() == null || isCollection())) {
            buffer.append('[').append(index + 1).append(']');
        }
        return buffer.toString();
    }

    public NodeIterator childIterator(
        NodeTest test,
        boolean reverse,
        NodePointer startWith) {
        return getValuePointer().childIterator(test, reverse, startWith);
    }

    public NodeIterator attributeIterator(QName name) {
        return getValuePointer().attributeIterator(name);
    }

    public NodeIterator namespaceIterator() {
        return getValuePointer().namespaceIterator();
    }

    public NodePointer namespacePointer(String name) {
        return getValuePointer().namespacePointer(name);
    }

    public boolean testNode(NodeTest nodeTest) {
        return getValuePointer().testNode(nodeTest);
    }

    public int compareChildNodePointers(
        NodePointer pointer1,
        NodePointer pointer2) {
        return pointer1.getIndex() - pointer2.getIndex();
    }
}