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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.patterns;
import org.htmlunit.xpath.Expression;
import org.htmlunit.xpath.XPathContext;
import org.htmlunit.xpath.XPathVisitor;
import org.htmlunit.xpath.axes.SubContextList;
import org.htmlunit.xpath.compiler.PseudoNames;
import org.htmlunit.xpath.objects.XObject;
import org.htmlunit.xpath.xml.dtm.Axis;
import org.htmlunit.xpath.xml.dtm.DTM;
import org.htmlunit.xpath.xml.dtm.DTMAxisTraverser;
import org.htmlunit.xpath.xml.dtm.DTMFilter;
/** This class represents a single pattern match step. */
public class StepPattern extends NodeTest implements SubContextList {
/** The axis for this test. */
protected int m_axis;
/**
* Construct a StepPattern that tests for namespaces and node names.
*
* @param whatToShow Bit set defined mainly by {@link org.w3c.dom.traversal.NodeFilter}.
* @param namespace The namespace to be tested.
* @param name The local name to be tested.
* @param axis The Axis for this test, one of of Axes.ANCESTORORSELF, etc.
*/
public StepPattern(int whatToShow, String namespace, String name, int axis) {
super(whatToShow, namespace, name);
m_axis = axis;
}
/**
* Construct a StepPattern that doesn't test for node names.
*
* @param whatToShow Bit set defined mainly by {@link org.w3c.dom.traversal.NodeFilter}.
* @param axis The Axis for this test, one of of Axes.ANCESTORORSELF, etc.
*/
public StepPattern(int whatToShow, int axis) {
super(whatToShow);
m_axis = axis;
}
/**
* The target local name or psuedo name, for hash table lookup optimization.
*
* @serial
*/
String m_targetString; // only calculate on head
/**
* Calculate the local name or psuedo name of the node that this pattern will test, for hash table
* lookup optimization.
*
* @see org.htmlunit.xpath.compiler.PseudoNames
*/
public void calcTargetString() {
int whatToShow = getWhatToShow();
switch (whatToShow) {
case DTMFilter.SHOW_COMMENT:
m_targetString = PseudoNames.PSEUDONAME_COMMENT;
break;
case DTMFilter.SHOW_TEXT:
case DTMFilter.SHOW_CDATA_SECTION:
case DTMFilter.SHOW_TEXT | DTMFilter.SHOW_CDATA_SECTION:
m_targetString = PseudoNames.PSEUDONAME_TEXT;
break;
case DTMFilter.SHOW_ALL:
m_targetString = PseudoNames.PSEUDONAME_ANY;
break;
case DTMFilter.SHOW_DOCUMENT:
case DTMFilter.SHOW_DOCUMENT | DTMFilter.SHOW_DOCUMENT_FRAGMENT:
m_targetString = PseudoNames.PSEUDONAME_ROOT;
break;
case DTMFilter.SHOW_ELEMENT:
if (WILD == m_name) m_targetString = PseudoNames.PSEUDONAME_ANY;
else m_targetString = m_name;
break;
default:
m_targetString = PseudoNames.PSEUDONAME_ANY;
break;
}
}
/**
* Reference to nodetest and predicate for parent or ancestor.
*
* @serial
*/
StepPattern m_relativePathPattern;
/**
* Set the reference to nodetest and predicate for parent or ancestor.
*
* @param expr The relative pattern expression.
*/
public void setRelativePathPattern(StepPattern expr) {
m_relativePathPattern = expr;
expr.exprSetParent(this);
calcScore();
}
/**
* Get the reference to nodetest and predicate for parent or ancestor.
*
* @return The relative pattern expression.
*/
public StepPattern getRelativePathPattern() {
return m_relativePathPattern;
}
/**
* Set the list of predicate expressions for this pattern step.
*
* @return List of expression objects.
*/
public Expression[] getPredicates() {
return m_predicates;
}
/**
* The list of predicate expressions for this pattern step.
*
* @serial
*/
Expression[] m_predicates;
/** {@inheritDoc} */
@Override
public boolean canTraverseOutsideSubtree() {
int n = getPredicateCount();
for (int i = 0; i < n; i++) {
if (getPredicate(i).canTraverseOutsideSubtree()) return true;
}
return false;
}
/**
* Get a predicate expression.
*
* @param i The index of the predicate.
* @return A predicate expression.
*/
public Expression getPredicate(int i) {
return m_predicates[i];
}
/**
* Get the number of predicates for this match pattern step.
*
* @return the number of predicates for this match pattern step.
*/
public final int getPredicateCount() {
return (null == m_predicates) ? 0 : m_predicates.length;
}
/**
* Set the predicates for this match pattern step.
*
* @param predicates An array of expressions that define predicates for this step.
*/
public void setPredicates(Expression[] predicates) {
m_predicates = predicates;
if (null != predicates) {
for (Expression predicate : predicates) {
predicate.exprSetParent(this);
}
}
calcScore();
}
/** {@inheritDoc} */
@Override
public void calcScore() {
if ((getPredicateCount() > 0) || (null != m_relativePathPattern)) {
m_score = SCORE_OTHER;
} else super.calcScore();
if (null == m_targetString) calcTargetString();
}
/** {@inheritDoc} */
@Override
public XObject execute(XPathContext xctxt, int currentNode)
throws javax.xml.transform.TransformerException {
DTM dtm = xctxt.getDTM(currentNode);
if (dtm != null) {
int expType = dtm.getExpandedTypeID(currentNode);
return execute(xctxt, currentNode, dtm, expType);
}
return NodeTest.SCORE_NONE;
}
/** {@inheritDoc} */
@Override
public XObject execute(XPathContext xctxt) throws javax.xml.transform.TransformerException {
return execute(xctxt, xctxt.getCurrentNode());
}
/** {@inheritDoc} */
@Override
public XObject execute(XPathContext xctxt, int currentNode, DTM dtm, int expType)
throws javax.xml.transform.TransformerException {
if (m_whatToShow == NodeTest.SHOW_BYFUNCTION) {
if (null != m_relativePathPattern) {
return m_relativePathPattern.execute(xctxt);
}
return NodeTest.SCORE_NONE;
}
XObject score;
score = super.execute(xctxt, currentNode, dtm, expType);
if (score == NodeTest.SCORE_NONE) return NodeTest.SCORE_NONE;
if (getPredicateCount() != 0) {
if (!executePredicates(xctxt, dtm, currentNode)) return NodeTest.SCORE_NONE;
}
if (null != m_relativePathPattern)
return m_relativePathPattern.executeRelativePathPattern(xctxt, dtm, currentNode);
return score;
}
/**
* New Method to check whether the current node satisfies a position predicate
*
* @param xctxt The XPath runtime context.
* @param predPos Which predicate we're evaluating of foo[1][2][3].
* @param dtm The DTM of the current node.
* @param context The currentNode.
* @param pos The position being requested, i.e. the value returned by
* m_predicates[predPos].execute(xctxt).
* @return true of the position of the context matches pos, false otherwise.
*/
private boolean checkProximityPosition(
XPathContext xctxt, int predPos, DTM dtm, int context, int pos) {
try {
DTMAxisTraverser traverser = dtm.getAxisTraverser(Axis.PRECEDINGSIBLING);
for (int child = traverser.first(context);
DTM.NULL != child;
child = traverser.next(context, child)) {
try {
xctxt.pushCurrentNode(child);
if (NodeTest.SCORE_NONE != super.execute(xctxt, child)) {
boolean pass = true;
try {
xctxt.pushSubContextList(this);
for (int i = 0; i < predPos; i++) {
xctxt.pushPredicatePos(i);
try {
XObject pred = m_predicates[i].execute(xctxt);
try {
if (XObject.CLASS_NUMBER == pred.getType()) {
throw new Error("Why: Should never have been called");
} else if (!pred.boolWithSideEffects()) {
pass = false;
break;
}
} finally {
pred.detach();
}
} finally {
xctxt.popPredicatePos();
}
}
} finally {
xctxt.popSubContextList();
}
if (pass) pos--;
if (pos < 1) return false;
}
} finally {
xctxt.popCurrentNode();
}
}
} catch (javax.xml.transform.TransformerException se) {
// TODO: should keep throw sax exception...
throw new java.lang.RuntimeException(se.getMessage());
}
return pos == 1;
}
/**
* Get the proximity position index of the current node based on this node test.
*
* @param xctxt XPath runtime context.
* @param predPos Which predicate we're evaluating of foo[1][2][3].
* @param findLast If true, don't terminate when the context node is found.
* @return the proximity position index of the current node based on the node test.
*/
private int getProximityPosition(XPathContext xctxt, int predPos, boolean findLast) {
int pos = 0;
int context = xctxt.getCurrentNode();
DTM dtm = xctxt.getDTM(context);
int parent = dtm.getParent(context);
try {
DTMAxisTraverser traverser = dtm.getAxisTraverser(Axis.CHILD);
for (int child = traverser.first(parent);
DTM.NULL != child;
child = traverser.next(parent, child)) {
try {
xctxt.pushCurrentNode(child);
if (NodeTest.SCORE_NONE != super.execute(xctxt, child)) {
boolean pass = true;
try {
xctxt.pushSubContextList(this);
for (int i = 0; i < predPos; i++) {
xctxt.pushPredicatePos(i);
try {
XObject pred = m_predicates[i].execute(xctxt);
try {
if (XObject.CLASS_NUMBER == pred.getType()) {
if ((pos + 1) != (int) pred.numWithSideEffects()) {
pass = false;
break;
}
} else if (!pred.boolWithSideEffects()) {
pass = false;
break;
}
} finally {
pred.detach();
}
} finally {
xctxt.popPredicatePos();
}
}
} finally {
xctxt.popSubContextList();
}
if (pass) pos++;
if (!findLast && child == context) {
return pos;
}
}
} finally {
xctxt.popCurrentNode();
}
}
} catch (javax.xml.transform.TransformerException se) {
// TODO: should keep throw sax exception...
throw new java.lang.RuntimeException(se.getMessage());
}
return pos;
}
/** {@inheritDoc} */
@Override
public int getProximityPosition(XPathContext xctxt) {
return getProximityPosition(xctxt, xctxt.getPredicatePos(), false);
}
/** {@inheritDoc} */
@Override
public int getLastPos(XPathContext xctxt) {
return getProximityPosition(xctxt, xctxt.getPredicatePos(), true);
}
/**
* Execute the match pattern step relative to another step.
*
* @param xctxt The XPath runtime context.
* @param dtm The DTM of the current node.
* @param currentNode The current node context.
* @return {@link org.htmlunit.xpath.patterns.NodeTest#SCORE_NODETEST}, {@link
* org.htmlunit.xpath.patterns.NodeTest#SCORE_NONE}, {@link
* org.htmlunit.xpath.patterns.NodeTest#SCORE_NSWILD}, {@link
* org.htmlunit.xpath.patterns.NodeTest#SCORE_QNAME}, or {@link
* org.htmlunit.xpath.patterns.NodeTest#SCORE_OTHER}.
* @throws javax.xml.transform.TransformerException in case of error
*/
protected final XObject executeRelativePathPattern(XPathContext xctxt, DTM dtm, int currentNode)
throws javax.xml.transform.TransformerException {
XObject score = NodeTest.SCORE_NONE;
DTMAxisTraverser traverser;
traverser = dtm.getAxisTraverser(m_axis);
for (int relative = traverser.first(currentNode);
DTM.NULL != relative;
relative = traverser.next(currentNode, relative)) {
try {
xctxt.pushCurrentNode(relative);
score = execute(xctxt);
if (score != NodeTest.SCORE_NONE) break;
} finally {
xctxt.popCurrentNode();
}
}
return score;
}
/**
* Execute the predicates on this step to determine if the current node should be filtered or
* accepted.
*
* @param xctxt The XPath runtime context.
* @param dtm The DTM of the current node.
* @param currentNode The current node context.
* @return true if the node should be accepted, false otherwise.
* @throws javax.xml.transform.TransformerException in case of error
*/
protected final boolean executePredicates(XPathContext xctxt, DTM dtm, int currentNode)
throws javax.xml.transform.TransformerException {
boolean result = true;
boolean positionAlreadySeen = false;
int n = getPredicateCount();
try {
xctxt.pushSubContextList(this);
for (int i = 0; i < n; i++) {
xctxt.pushPredicatePos(i);
try {
XObject pred = m_predicates[i].execute(xctxt);
try {
if (XObject.CLASS_NUMBER == pred.getType()) {
int pos = (int) pred.num();
if (positionAlreadySeen) {
result = pos == 1;
break;
} else {
positionAlreadySeen = true;
if (!checkProximityPosition(xctxt, i, dtm, currentNode, pos)) {
result = false;
break;
}
}
} else if (!pred.boolWithSideEffects()) {
result = false;
break;
}
} finally {
pred.detach();
}
} finally {
xctxt.popPredicatePos();
}
}
} finally {
xctxt.popSubContextList();
}
return result;
}
/** {@inheritDoc} */
@Override
public String toString() {
StringBuilder buf = new StringBuilder();
for (StepPattern pat = this; pat != null; pat = pat.m_relativePathPattern) {
if (pat != this) buf.append("/");
buf.append(Axis.getNames(pat.m_axis));
buf.append("::");
if (0x000005000 == pat.m_whatToShow) {
buf.append("doc()");
} else if (DTMFilter.SHOW_BYFUNCTION == pat.m_whatToShow) {
buf.append("function()");
} else if (DTMFilter.SHOW_ALL == pat.m_whatToShow) {
buf.append("node()");
} else if (DTMFilter.SHOW_TEXT == pat.m_whatToShow) {
buf.append("text()");
} else if (DTMFilter.SHOW_PROCESSING_INSTRUCTION == pat.m_whatToShow) {
buf.append("processing-instruction(");
if (null != pat.m_name) {
buf.append(pat.m_name);
}
buf.append(")");
} else if (DTMFilter.SHOW_COMMENT == pat.m_whatToShow) {
buf.append("comment()");
} else if (null != pat.m_name) {
if (DTMFilter.SHOW_ATTRIBUTE == pat.m_whatToShow) {
buf.append("@");
}
if (null != pat.m_namespace) {
buf.append("{");
buf.append(pat.m_namespace);
buf.append("}");
}
buf.append(pat.m_name);
} else if (DTMFilter.SHOW_ATTRIBUTE == pat.m_whatToShow) {
buf.append("@");
} else if ((DTMFilter.SHOW_DOCUMENT | DTMFilter.SHOW_DOCUMENT_FRAGMENT) == pat.m_whatToShow) {
buf.append("doc-root()");
} else {
buf.append("?").append(Integer.toHexString(pat.m_whatToShow));
}
if (null != pat.m_predicates) {
for (int i = 0; i < pat.m_predicates.length; i++) {
buf.append("[");
buf.append(pat.m_predicates[i]);
buf.append("]");
}
}
}
return buf.toString();
}
/**
* Set the axis that this step should follow.
*
* @param axis The Axis for this test, one of of Axes.ANCESTORORSELF, etc.
*/
public void setAxis(int axis) {
m_axis = axis;
}
/**
* Get the axis that this step follows.
*
* @return The Axis for this test, one of of Axes.ANCESTORORSELF, etc.
*/
public int getAxis() {
return m_axis;
}
/** {@inheritDoc} */
@Override
public void callVisitors(XPathVisitor visitor) {
if (visitor.visitMatchPattern()) {
callSubtreeVisitors(visitor);
}
}
/**
* Call the visitors on the subtree. Factored out from callVisitors so it may be called by derived
* classes.
*/
protected void callSubtreeVisitors(XPathVisitor visitor) {
if (null != m_predicates) {
for (Expression m_predicate : m_predicates) {
if (visitor.visitPredicate(m_predicate)) {
m_predicate.callVisitors(visitor);
}
}
}
if (null != m_relativePathPattern) {
m_relativePathPattern.callVisitors(visitor);
}
}
/** {@inheritDoc} */
@Override
public boolean deepEquals(Expression expr) {
if (!super.deepEquals(expr)) return false;
StepPattern sp = (StepPattern) expr;
if (null != m_predicates) {
int n = m_predicates.length;
if ((null == sp.m_predicates) || (sp.m_predicates.length != n)) return false;
for (int i = 0; i < n; i++) {
if (!m_predicates[i].deepEquals(sp.m_predicates[i])) return false;
}
} else if (null != sp.m_predicates) return false;
if (null != m_relativePathPattern) {
if (!m_relativePathPattern.deepEquals(sp.m_relativePathPattern)) return false;
} else if (sp.m_relativePathPattern != null) return false;
return true;
}
}
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