1 ///////////////////////////////////////////////////////////////////////////////////////////////
2 // checkstyle: Checks Java source code and other text files for adherence to a set of rules.
3 // Copyright (C) 2001-2024 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 final AxisIterator result;
127 switch (axisNumber) {
128 case AxisInfo.ANCESTOR:
129 case AxisInfo.PARENT:
130 case AxisInfo.FOLLOWING:
131 case AxisInfo.FOLLOWING_SIBLING:
132 case AxisInfo.PRECEDING:
133 case AxisInfo.PRECEDING_SIBLING:
134 result = EmptyIterator.ofNodes();
135 break;
136 case AxisInfo.ANCESTOR_OR_SELF:
137 case AxisInfo.SELF:
138 result = SingleNodeIterator.makeIterator(this);
139 break;
140 case AxisInfo.CHILD:
141 if (hasChildNodes()) {
142 result = new ArrayIterator.OfNodes<>(
143 getChildren().toArray(EMPTY_ABSTRACT_NODE_ARRAY));
144 }
145 else {
146 result = EmptyIterator.ofNodes();
147 }
148 break;
149 case AxisInfo.DESCENDANT:
150 if (hasChildNodes()) {
151 result = new DescendantIterator(this, DescendantIterator.StartWith.CHILDREN);
152 }
153 else {
154 result = EmptyIterator.ofNodes();
155 }
156 break;
157 case AxisInfo.DESCENDANT_OR_SELF:
158 result = new DescendantIterator(this, DescendantIterator.StartWith.CURRENT_NODE);
159 break;
160 default:
161 throw throwUnsupportedOperationException();
162 }
163 return result;
164 }
165
166 /**
167 * Getter method for node depth.
168 *
169 * @return always {@code 0}
170 */
171 @Override
172 public int getDepth() {
173 return 0;
174 }
175
176 /**
177 * Returns UnsupportedOperationException exception.
178 *
179 * @return UnsupportedOperationException exception
180 */
181 private static UnsupportedOperationException throwUnsupportedOperationException() {
182 return new UnsupportedOperationException("Operation is not supported");
183 }
184
185 }