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The XPath engine used by HtmlUnit.
/*
* 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.htmlunit.xpath.objects;
import org.htmlunit.xpath.Expression;
import org.htmlunit.xpath.NodeSetDTM;
import org.htmlunit.xpath.XPathContext;
import org.htmlunit.xpath.XPathException;
import org.htmlunit.xpath.XPathVisitor;
import org.htmlunit.xpath.res.XPATHErrorResources;
import org.htmlunit.xpath.res.XPATHMessages;
import org.htmlunit.xpath.xml.dtm.DTMIterator;
import org.w3c.dom.NodeList;
import org.w3c.dom.traversal.NodeIterator;
/**
* This class represents an XPath object, and is capable of converting the object to various types,
* such as a string. This class acts as the base class to other XPath type objects, such as XString,
* and provides polymorphic casting capabilities.
*/
public class XObject extends Expression {
/**
* The java object which this object wraps.
*
* @serial
*/
protected Object m_obj; // This may be NULL!!!
/** Create an XObject. */
public XObject() {
}
/**
* Create an XObject.
*
* @param obj Can be any object, should be a specific type for derived classes, or null.
*/
public XObject(final Object obj) {
setObject(obj);
}
protected void setObject(final Object obj) {
m_obj = obj;
}
/** {@inheritDoc} */
@Override
public XObject execute(final XPathContext xctxt) throws javax.xml.transform.TransformerException {
return this;
}
/**
* Detaches the DTMIterator from the set which it iterated over, releasing any
* computational resources and placing the iterator in the INVALID state. After detach
* has been invoked, calls to nextNode or previousNode will
* raise a runtime exception.
*/
public void detach() {
}
/** Constant for NULL object type */
public static final int CLASS_NULL = -1;
/** Constant for UNKNOWN object type */
public static final int CLASS_UNKNOWN = 0;
/** Constant for BOOLEAN object type */
public static final int CLASS_BOOLEAN = 1;
/** Constant for NUMBER object type */
public static final int CLASS_NUMBER = 2;
/** Constant for STRING object type */
public static final int CLASS_STRING = 3;
/** Constant for NODESET object type */
public static final int CLASS_NODESET = 4;
/** Constant for RESULT TREE FRAGMENT object type */
public static final int CLASS_RTREEFRAG = 5;
/**
* Tell what kind of class this is.
*
* @return CLASS_UNKNOWN
*/
public int getType() {
return CLASS_UNKNOWN;
}
/**
* Given a request type, return the equivalent string. For diagnostic purposes.
*
* @return type string "#UNKNOWN" + object class name
*/
public String getTypeString() {
return "#UNKNOWN (" + object().getClass().getName() + ")";
}
/**
* Cast result object to a number. Always issues an error.
*
* @return 0.0
* @throws javax.xml.transform.TransformerException in case of error
*/
public double num() throws javax.xml.transform.TransformerException {
error(XPATHErrorResources.ER_CANT_CONVERT_TO_NUMBER, new Object[] {getTypeString()});
return 0.0;
}
/**
* Cast result object to a number, but allow side effects, such as the incrementing of an
* iterator.
*
* @return numeric value of the string conversion from the next node in the NodeSetDTM, or NAN if
* no node was found
*/
public double numWithSideEffects() throws javax.xml.transform.TransformerException {
return num();
}
/**
* Cast result object to a boolean. Always issues an error.
*
* @return false
* @throws javax.xml.transform.TransformerException in case of error
*/
public boolean bool() throws javax.xml.transform.TransformerException {
error(XPATHErrorResources.ER_CANT_CONVERT_TO_NUMBER, new Object[] {getTypeString()});
return false;
}
/**
* Cast result object to a boolean, but allow side effects, such as the incrementing of an
* iterator.
*
* @return True if there is a next node in the nodeset
*/
public boolean boolWithSideEffects() throws javax.xml.transform.TransformerException {
return bool();
}
/**
* Cast result object to a string.
*
* @return The string this wraps or the empty string if null
*/
public XString xstr() {
return new XString(str());
}
/**
* Cast result object to a string.
*
* @return The object as a string
*/
public String str() {
return (m_obj != null) ? m_obj.toString() : "";
}
/** {@inheritDoc} */
@Override
public String toString() {
return str();
}
/**
* Return a java object that's closest to the representation that should be handed to an
* extension.
*
* @return The object that this class wraps
*/
public Object object() {
return m_obj;
}
/**
* Cast result object to a nodelist. Always issues an error.
*
* @return null
* @throws javax.xml.transform.TransformerException in case of error
*/
public DTMIterator iter() throws javax.xml.transform.TransformerException {
error(XPATHErrorResources.ER_CANT_CONVERT_TO_NODELIST, new Object[] {getTypeString()});
return null;
}
/**
* Cast result object to a nodelist. Always issues an error.
*
* @return null
* @throws javax.xml.transform.TransformerException in case of error
*/
public NodeIterator nodeset() throws javax.xml.transform.TransformerException {
error(XPATHErrorResources.ER_CANT_CONVERT_TO_NODELIST, new Object[] {getTypeString()});
return null;
}
/**
* Cast result object to a nodelist. Always issues an error.
*
* @return null
* @throws javax.xml.transform.TransformerException in case of error
*/
public NodeList nodelist() throws javax.xml.transform.TransformerException {
error(XPATHErrorResources.ER_CANT_CONVERT_TO_NODELIST, new Object[] {getTypeString()});
return null;
}
/**
* Cast result object to a nodelist. Always issues an error.
*
* @return The object as a NodeSetDTM.
* @throws javax.xml.transform.TransformerException in case of error
*/
public NodeSetDTM mutableNodeset() throws javax.xml.transform.TransformerException {
error(XPATHErrorResources.ER_CANT_CONVERT_TO_MUTABLENODELIST, new Object[] {getTypeString()});
return (NodeSetDTM) m_obj;
}
/**
* Tell if one object is less than the other.
*
* @param obj2 Object to compare this to
* @return True if this object is less than the given object
* @throws javax.xml.transform.TransformerException in case of error
*/
public boolean lessThan(final XObject obj2) throws javax.xml.transform.TransformerException {
// In order to handle the 'all' semantics of
// nodeset comparisons, we always call the
// nodeset function. Because the arguments
// are backwards, we call the opposite comparison
// function.
if (obj2.getType() == XObject.CLASS_NODESET) {
return obj2.greaterThan(this);
}
return this.num() < obj2.num();
}
/**
* Tell if one object is less than or equal to the other.
*
* @param obj2 Object to compare this to
* @return True if this object is less than or equal to the given object
* @throws javax.xml.transform.TransformerException in case of error
*/
public boolean lessThanOrEqual(final XObject obj2)
throws javax.xml.transform.TransformerException {
// In order to handle the 'all' semantics of
// nodeset comparisons, we always call the
// nodeset function. Because the arguments
// are backwards, we call the opposite comparison
// function.
if (obj2.getType() == XObject.CLASS_NODESET) {
return obj2.greaterThanOrEqual(this);
}
return this.num() <= obj2.num();
}
/**
* Tell if one object is greater than the other.
*
* @param obj2 Object to compare this to
* @return True if this object is greater than the given object
* @throws javax.xml.transform.TransformerException in case of error
*/
public boolean greaterThan(final XObject obj2) throws javax.xml.transform.TransformerException {
// In order to handle the 'all' semantics of
// nodeset comparisons, we always call the
// nodeset function. Because the arguments
// are backwards, we call the opposite comparison
// function.
if (obj2.getType() == XObject.CLASS_NODESET) {
return obj2.lessThan(this);
}
return this.num() > obj2.num();
}
/**
* Tell if one object is greater than or equal to the other.
*
* @param obj2 Object to compare this to
* @return True if this object is greater than or equal to the given object
* @throws javax.xml.transform.TransformerException in case of error
*/
public boolean greaterThanOrEqual(final XObject obj2)
throws javax.xml.transform.TransformerException {
// In order to handle the 'all' semantics of
// nodeset comparisons, we always call the
// nodeset function. Because the arguments
// are backwards, we call the opposite comparison
// function.
if (obj2.getType() == XObject.CLASS_NODESET) {
return obj2.lessThanOrEqual(this);
}
return this.num() >= obj2.num();
}
/**
* Tell if two objects are functionally equal.
*
* @param obj2 Object to compare this to
* @return True if this object is equal to the given object
*/
public boolean equals(final XObject obj2) {
// In order to handle the 'all' semantics of
// nodeset comparisons, we always call the
// nodeset function.
if (obj2.getType() == XObject.CLASS_NODESET) {
return obj2.equals(this);
}
if (null != m_obj) {
return m_obj.equals(obj2.m_obj);
}
return obj2.m_obj == null;
}
/**
* Tell if two objects are functionally not equal.
*
* @param obj2 Object to compare this to
* @return True if this object is not equal to the given object
* @throws javax.xml.transform.TransformerException in case of error
*/
public boolean notEquals(final XObject obj2) throws javax.xml.transform.TransformerException {
// In order to handle the 'all' semantics of
// nodeset comparisons, we always call the
// nodeset function.
if (obj2.getType() == XObject.CLASS_NODESET) {
return obj2.notEquals(this);
}
return !equals(obj2);
}
/**
* Tell the user of an error, and probably throw an exception.
*
* @param msg Error message to issue
* @throws javax.xml.transform.TransformerException in case of error
*/
protected void error(final String msg) throws javax.xml.transform.TransformerException {
error(msg, null);
}
/**
* Tell the user of an error, and probably throw an exception.
*
* @param msg Error message to issue
* @param args Arguments to use in the message
* @throws javax.xml.transform.TransformerException in case of error
*/
protected void error(final String msg, final Object[] args)
throws javax.xml.transform.TransformerException {
final String fmsg = XPATHMessages.createXPATHMessage(msg, args);
throw new XPathException(fmsg, this);
}
/** {@inheritDoc} */
@Override
public void callVisitors(final XPathVisitor visitor) {
assertion(false, "callVisitors should not be called for this object!!!");
}
/** {@inheritDoc} */
@Override
public boolean deepEquals(final Expression expr) {
// If equals at the expression level calls deepEquals, I think we're
// still safe from infinite recursion since this object overrides
// equals. I hope.
if (!isSameClass(expr) || !this.equals((XObject) expr)) {
return false;
}
return true;
}
}
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