AbstractElementNode.java
///////////////////////////////////////////////////////////////////////////////////////////////
// checkstyle: Checks Java source code and other text files for adherence to a set of rules.
// Copyright (C) 2001-2024 the original author or authors.
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
///////////////////////////////////////////////////////////////////////////////////////////////
package com.puppycrawl.tools.checkstyle.xpath;
import java.util.Collections;
import java.util.List;
import java.util.Optional;
import com.puppycrawl.tools.checkstyle.xpath.iterators.DescendantIterator;
import com.puppycrawl.tools.checkstyle.xpath.iterators.FollowingIterator;
import com.puppycrawl.tools.checkstyle.xpath.iterators.PrecedingIterator;
import com.puppycrawl.tools.checkstyle.xpath.iterators.ReverseListIterator;
import net.sf.saxon.om.AxisInfo;
import net.sf.saxon.om.NamespaceUri;
import net.sf.saxon.om.NodeInfo;
import net.sf.saxon.tree.iter.ArrayIterator;
import net.sf.saxon.tree.iter.AxisIterator;
import net.sf.saxon.tree.iter.EmptyIterator;
import net.sf.saxon.tree.iter.SingleNodeIterator;
import net.sf.saxon.tree.util.Navigator;
import net.sf.saxon.type.Type;
/**
* Represents element node of Xpath-tree.
*/
public abstract class AbstractElementNode extends AbstractNode {
/** String literal for text attribute. */
protected static final String TEXT_ATTRIBUTE_NAME = "text";
/** Constant for optimization. */
private static final AbstractNode[] EMPTY_ABSTRACT_NODE_ARRAY = new AbstractNode[0];
/** Holder value for lazy creation of attribute node. */
private static final AttributeNode ATTRIBUTE_NODE_UNINITIALIZED = new AttributeNode(null, null);
/** The root node. */
private final AbstractNode root;
/** The parent of the current node. */
private final AbstractNode parent;
/** Depth of the node. */
private final int depth;
/** Represents index among siblings. */
private final int indexAmongSiblings;
/** The text attribute node. */
private AttributeNode attributeNode = ATTRIBUTE_NODE_UNINITIALIZED;
/**
* Creates a new {@code AbstractElementNode} instance.
*
* @param root {@code Node} root of the tree
* @param parent {@code Node} parent of the current node
* @param depth the current node depth in the hierarchy
* @param indexAmongSiblings the current node index among the parent children nodes
*/
protected AbstractElementNode(AbstractNode root, AbstractNode parent,
int depth, int indexAmongSiblings) {
super(root.getTreeInfo());
this.parent = parent;
this.root = root;
this.depth = depth;
this.indexAmongSiblings = indexAmongSiblings;
}
/**
* Creates {@code AttributeNode} object and returns it.
*
* @return attribute node if possible, otherwise the {@code null} value
*/
protected abstract AttributeNode createAttributeNode();
/**
* Compares current object with specified for order.
*
* @param other another {@code NodeInfo} object
* @return number representing order of current object to specified one
*/
@Override
public int compareOrder(NodeInfo other) {
int result = 0;
if (other instanceof AbstractNode) {
result = Integer.compare(depth, ((AbstractNode) other).getDepth());
if (result == 0) {
result = compareCommonAncestorChildrenOrder(this, other);
}
}
return result;
}
/**
* Walks up the hierarchy until a common ancestor is found.
* Then compares topmost sibling nodes.
*
* @param first {@code NodeInfo} to compare
* @param second {@code NodeInfo} to compare
* @return the value {@code 0} if {@code first == second};
* a value less than {@code 0} if {@code first} should be first;
* a value greater than {@code 0} if {@code second} should be first.
*/
private static int compareCommonAncestorChildrenOrder(NodeInfo first, NodeInfo second) {
NodeInfo child1 = first;
NodeInfo child2 = second;
while (!child1.getParent().equals(child2.getParent())) {
child1 = child1.getParent();
child2 = child2.getParent();
}
final int index1 = ((AbstractElementNode) child1).indexAmongSiblings;
final int index2 = ((AbstractElementNode) child2).indexAmongSiblings;
return Integer.compare(index1, index2);
}
/**
* Getter method for node depth.
*
* @return depth
*/
@Override
public int getDepth() {
return depth;
}
/**
* Returns attribute value.
*
* @param namespace namespace
* @param localPart actual name of the attribute
* @return attribute value or null if the attribute was not found
*/
@Override
public String getAttributeValue(NamespaceUri namespace, String localPart) {
final String result;
if (TEXT_ATTRIBUTE_NAME.equals(localPart)) {
result = Optional.ofNullable(getAttributeNode())
.map(AttributeNode::getStringValue)
.orElse(null);
}
else {
result = null;
}
return result;
}
/**
* Returns type of the node.
*
* @return node kind
*/
@Override
public int getNodeKind() {
return Type.ELEMENT;
}
/**
* Returns parent.
*
* @return parent
*/
@Override
public NodeInfo getParent() {
return parent;
}
/**
* Returns root.
*
* @return root
*/
@Override
public AbstractNode getRoot() {
return root;
}
/**
* Determines axis iteration algorithm. Throws {@code UnsupportedOperationException} in case,
* when there is no axis iterator for given axisNumber.
*
* <p>Reason of suppression for resource, IOResourceOpenedButNotSafelyClosed:
* {@link AxisIterator} implements {@link java.io.Closeable} interface,
* but none of the subclasses of the {@link AxisIterator}
* class has non-empty {@code close()} method.
*
* @param axisNumber element from {@code AxisInfo}
* @return {@code AxisIterator} object
*/
@Override
public AxisIterator iterateAxis(int axisNumber) {
final AxisIterator result;
switch (axisNumber) {
case AxisInfo.ANCESTOR:
result = new Navigator.AncestorEnumeration(this, false);
break;
case AxisInfo.ANCESTOR_OR_SELF:
result = new Navigator.AncestorEnumeration(this, true);
break;
case AxisInfo.ATTRIBUTE:
result = SingleNodeIterator.makeIterator(getAttributeNode());
break;
case AxisInfo.CHILD:
if (hasChildNodes()) {
result = new ArrayIterator.OfNodes<>(
getChildren().toArray(EMPTY_ABSTRACT_NODE_ARRAY));
}
else {
result = EmptyIterator.ofNodes();
}
break;
case AxisInfo.DESCENDANT:
if (hasChildNodes()) {
result = new DescendantIterator(this, DescendantIterator.StartWith.CHILDREN);
}
else {
result = EmptyIterator.ofNodes();
}
break;
case AxisInfo.DESCENDANT_OR_SELF:
result = new DescendantIterator(this, DescendantIterator.StartWith.CURRENT_NODE);
break;
case AxisInfo.PARENT:
result = SingleNodeIterator.makeIterator(parent);
break;
case AxisInfo.SELF:
result = SingleNodeIterator.makeIterator(this);
break;
case AxisInfo.FOLLOWING_SIBLING:
result = getFollowingSiblingsIterator();
break;
case AxisInfo.PRECEDING_SIBLING:
result = getPrecedingSiblingsIterator();
break;
case AxisInfo.FOLLOWING:
result = new FollowingIterator(this);
break;
case AxisInfo.PRECEDING:
result = new PrecedingIterator(this);
break;
default:
throw throwUnsupportedOperationException();
}
return result;
}
/**
* Returns preceding sibling axis iterator.
*
* <p>Reason of suppression for resource, IOResourceOpenedButNotSafelyClosed:
* {@link AxisIterator} implements {@link java.io.Closeable} interface,
* but none of the subclasses of the {@link AxisIterator}
* class has non-empty {@code close()} method.
*
* @return iterator
*/
private AxisIterator getPrecedingSiblingsIterator() {
final AxisIterator result;
if (indexAmongSiblings == 0) {
result = EmptyIterator.ofNodes();
}
else {
result = new ReverseListIterator(getPrecedingSiblings());
}
return result;
}
/**
* Returns following sibling axis iterator.
*
* <p>Reason of suppression for resource, IOResourceOpenedButNotSafelyClosed:
* {@link AxisIterator} implements {@link java.io.Closeable} interface,
* but none of the subclasses of the {@link AxisIterator}
* class has non-empty {@code close()} method.
*
* @return iterator
*/
private AxisIterator getFollowingSiblingsIterator() {
final AxisIterator result;
if (indexAmongSiblings == parent.getChildren().size() - 1) {
result = EmptyIterator.ofNodes();
}
else {
result = new ArrayIterator.OfNodes<>(
getFollowingSiblings().toArray(EMPTY_ABSTRACT_NODE_ARRAY));
}
return result;
}
/**
* Returns following siblings of the current node.
*
* @return siblings
*/
private List<AbstractNode> getFollowingSiblings() {
final List<AbstractNode> siblings = parent.getChildren();
return siblings.subList(indexAmongSiblings + 1, siblings.size());
}
/**
* Returns preceding siblings of the current node.
*
* @return siblings
*/
private List<AbstractNode> getPrecedingSiblings() {
final List<AbstractNode> siblings = parent.getChildren();
return Collections.unmodifiableList(siblings.subList(0, indexAmongSiblings));
}
/**
* Checks if token type supports {@code @text} attribute,
* extracts its value, creates {@code AttributeNode} object and returns it.
* Value can be accessed using {@code @text} attribute.
*
* @return attribute node if possible, otherwise the {@code null} value
*/
private AttributeNode getAttributeNode() {
if (attributeNode == ATTRIBUTE_NODE_UNINITIALIZED) {
attributeNode = createAttributeNode();
}
return attributeNode;
}
/**
* Returns UnsupportedOperationException exception.
*
* @return UnsupportedOperationException exception
*/
private static UnsupportedOperationException throwUnsupportedOperationException() {
return new UnsupportedOperationException("Operation is not supported");
}
}