1 ///////////////////////////////////////////////////////////////////////////////////////////////
2 // checkstyle: Checks Java source code and other text files for adherence to a set of rules.
3 // Copyright (C) 2001-2025 the original author or authors.
4 //
5 // This library is free software; you can redistribute it and/or
6 // modify it under the terms of the GNU Lesser General Public
7 // License as published by the Free Software Foundation; either
8 // version 2.1 of the License, or (at your option) any later version.
9 //
10 // This library is distributed in the hope that it will be useful,
11 // but WITHOUT ANY WARRANTY; without even the implied warranty of
12 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 // Lesser General Public License for more details.
14 //
15 // You should have received a copy of the GNU Lesser General Public
16 // License along with this library; if not, write to the Free Software
17 // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
18 ///////////////////////////////////////////////////////////////////////////////////////////////
19
20 package com.puppycrawl.tools.checkstyle.xpath;
21
22 import com.puppycrawl.tools.checkstyle.xpath.iterators.DescendantIterator;
23 import net.sf.saxon.Configuration;
24 import net.sf.saxon.om.AxisInfo;
25 import net.sf.saxon.om.GenericTreeInfo;
26 import net.sf.saxon.om.NamespaceUri;
27 import net.sf.saxon.om.NodeInfo;
28 import net.sf.saxon.tree.iter.ArrayIterator;
29 import net.sf.saxon.tree.iter.AxisIterator;
30 import net.sf.saxon.tree.iter.EmptyIterator;
31 import net.sf.saxon.tree.iter.SingleNodeIterator;
32 import net.sf.saxon.type.Type;
33
34 /**
35 * Represents root node of Xpath-tree.
36 */
37 public abstract class AbstractRootNode extends AbstractNode {
38
39 /** Name of the root element. */
40 private static final String ROOT_NAME = "ROOT";
41
42 /** Constant for optimization. */
43 private static final AbstractNode[] EMPTY_ABSTRACT_NODE_ARRAY = new AbstractNode[0];
44
45 /**
46 * Creates a new {@code AbstractRootNode} instance.
47 */
48 protected AbstractRootNode() {
49 super(new GenericTreeInfo(Configuration.newConfiguration()));
50 }
51
52 /**
53 * Compares current object with specified for order.
54 * Throws {@code UnsupportedOperationException} because functionality not required here.
55 *
56 * @param nodeInfo another {@code NodeInfo} object
57 * @return number representing order of current object to specified one
58 */
59 @Override
60 public int compareOrder(NodeInfo nodeInfo) {
61 throw throwUnsupportedOperationException();
62 }
63
64 /**
65 * Returns attribute value. Throws {@code UnsupportedOperationException} because root node
66 * has no attributes.
67 *
68 * @param namespace namespace
69 * @param localPart actual name of the attribute
70 * @return attribute value
71 */
72 @Override
73 public String getAttributeValue(NamespaceUri namespace, String localPart) {
74 throw throwUnsupportedOperationException();
75 }
76
77 /**
78 * Returns local part.
79 *
80 * @return local part
81 */
82 @Override
83 public String getLocalPart() {
84 return ROOT_NAME;
85 }
86
87 /**
88 * Returns type of the node.
89 *
90 * @return node kind
91 */
92 @Override
93 public int getNodeKind() {
94 return Type.DOCUMENT;
95 }
96
97 /**
98 * Returns parent.
99 *
100 * @return parent
101 */
102 @Override
103 public NodeInfo getParent() {
104 return null;
105 }
106
107 /**
108 * Returns root of the tree.
109 *
110 * @return root of the tree
111 */
112 @Override
113 public NodeInfo getRoot() {
114 return this;
115 }
116
117 /**
118 * Determines axis iteration algorithm. Throws {@code UnsupportedOperationException} in case,
119 * when there is no axis iterator for given axisNumber.
120 *
121 * @param axisNumber element from {@code AxisInfo}
122 * @return {@code AxisIterator} object
123 */
124 @Override
125 public AxisIterator iterateAxis(int axisNumber) {
126 return switch (axisNumber) {
127 case AxisInfo.ANCESTOR,
128 AxisInfo.PARENT,
129 AxisInfo.FOLLOWING,
130 AxisInfo.FOLLOWING_SIBLING,
131 AxisInfo.PRECEDING,
132 AxisInfo.PRECEDING_SIBLING -> EmptyIterator.ofNodes();
133
134 case AxisInfo.ANCESTOR_OR_SELF,
135 AxisInfo.SELF -> SingleNodeIterator.makeIterator(this);
136
137 case AxisInfo.CHILD -> {
138 if (hasChildNodes()) {
139 yield new ArrayIterator.OfNodes<>(
140 getChildren().toArray(EMPTY_ABSTRACT_NODE_ARRAY));
141 }
142 yield EmptyIterator.ofNodes();
143 }
144
145 case AxisInfo.DESCENDANT -> {
146 if (hasChildNodes()) {
147 yield new DescendantIterator(this, DescendantIterator.StartWith.CHILDREN);
148 }
149 yield EmptyIterator.ofNodes();
150 }
151
152 case AxisInfo.DESCENDANT_OR_SELF ->
153 new DescendantIterator(this, DescendantIterator.StartWith.CURRENT_NODE);
154
155 default -> throw throwUnsupportedOperationException();
156 };
157 }
158
159 /**
160 * Getter method for node depth.
161 *
162 * @return always {@code 0}
163 */
164 @Override
165 public int getDepth() {
166 return 0;
167 }
168
169 /**
170 * Returns UnsupportedOperationException exception.
171 *
172 * @return UnsupportedOperationException exception
173 */
174 private static UnsupportedOperationException throwUnsupportedOperationException() {
175 return new UnsupportedOperationException("Operation is not supported");
176 }
177
178 }