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46 package groovy.util;
47
48 import java.io.PrintWriter;
49 import java.util.ArrayList;
50 import java.util.Collection;
51 import java.util.Collections;
52 import java.util.Iterator;
53 import java.util.List;
54 import java.util.Map;
55
56 import org.codehaus.groovy.runtime.InvokerHelper;
57
58 /***
59 * Represents an arbitrary tree node which can be used for structured metadata which can be any arbitrary XML-like tree.
60 * A node can have a name, a value and an optional Map of attributes.
61 * Typically the name is a String and a value is either a String or a List of other Nodes.
62 * Though the types are extensible to provide a flexible structure.
63 * e.g. you could use a QName as the name which includes a namespace URI and a local name. Or a JMX ObjectName etc.
64 * So this class can represent metadata like {foo a=1 b="abc"} or nested metadata like {foo a=1 b="123" { bar x=12 text="hello" }}
65 *
66 * @author <a href="mailto:james@coredevelopers.net">James Strachan</a>
67 * @version $Revision: 1.8 $
68 */
69 public class Node {
70
71 private Node parent;
72 private Object name;
73 private Map attributes;
74 private Object value;
75
76 public Node(Node parent, Object name) {
77 this(parent, name, Collections.EMPTY_MAP, Collections.EMPTY_LIST);
78 }
79
80 public Node(Node parent, Object name, Object value) {
81 this(parent, name, Collections.EMPTY_MAP, value);
82 }
83
84 public Node(Node parent, Object name, Map attributes) {
85 this(parent, name, attributes, Collections.EMPTY_LIST);
86 }
87
88 public Node(Node parent, Object name, Map attributes, Object value) {
89 this.parent = parent;
90 this.name = name;
91 this.attributes = attributes;
92 this.value = value;
93
94 if (parent != null) {
95 Object parentValue = parent.value();
96 List parentList = null;
97 if (parentValue instanceof List) {
98 parentList = (List) parentValue;
99 }
100 else {
101 parentList = new ArrayList();
102 parentList.add(parentValue);
103 parent.setValue(parentList);
104 }
105 parentList.add(this);
106 }
107 }
108
109 public String text() {
110 if (value instanceof String) {
111 return (String) value;
112 }
113 else if (value instanceof Collection) {
114 Collection coll = (Collection) value;
115 String previousText = null;
116 StringBuffer buffer = null;
117 for (Iterator iter = coll.iterator(); iter.hasNext();) {
118 Object child = iter.next();
119 if (child instanceof String) {
120 String childText = (String) child;
121 if (previousText == null) {
122 previousText = childText;
123 }
124 else {
125 if (buffer == null) {
126 buffer = new StringBuffer();
127 buffer.append(previousText);
128 }
129 buffer.append(childText);
130 }
131 }
132 }
133 if (buffer != null) {
134 return buffer.toString();
135 }
136 else {
137 if (previousText != null) {
138 return previousText;
139 }
140 }
141 }
142 return "";
143 }
144
145 public Iterator iterator() {
146 return children().iterator();
147 }
148
149 public List children() {
150 if (value == null) {
151 return Collections.EMPTY_LIST;
152 }
153 else if (value instanceof List) {
154 return (List) value;
155 }
156 else {
157
158 return Collections.singletonList(value);
159 }
160 }
161
162 public Map attributes() {
163 return attributes;
164 }
165
166 public Object attribute(Object key) {
167 return (attributes != null) ? attributes.get(key) : null;
168 }
169
170 public Object name() {
171 return name;
172 }
173
174 public Object value() {
175 return value;
176 }
177
178 public void setValue(Object value) {
179 this.value = value;
180 }
181
182 public Node parent() {
183 return parent;
184 }
185
186 public Object get(String key) {
187 if (key.charAt(0) == '@') {
188 String attributeName = key.substring(1);
189 return attributes().get(attributeName);
190 }
191 else {
192
193 List answer = new ArrayList();
194 for (Iterator iter = children().iterator(); iter.hasNext();) {
195 Object child = iter.next();
196 if (child instanceof Node) {
197 Node childNode = (Node) child;
198 if (key.equals(childNode.name())) {
199 answer.add(childNode);
200 }
201 }
202 }
203 return answer;
204 }
205 }
206
207
208
209
210
211
212
213 /***
214 * Provide a collection of all the nodes in the tree
215 * using a depth first traversal
216 */
217 public List depthFirst() {
218 List answer = new ArrayList();
219 answer.add(this);
220 answer.addAll(depthFirstRest());
221 return answer;
222 }
223
224 private List depthFirstRest() {
225 List answer = new ArrayList();
226 for (Iterator iter = InvokerHelper.asIterator(value); iter.hasNext(); ) {
227 Object child = iter.next();
228 if (child instanceof Node) {
229 Node childNode = (Node) child;
230 List children = childNode.depthFirstRest();
231 answer.add(childNode);
232 answer.addAll(children);
233 }
234 }
235 return answer;
236 }
237
238 /***
239 * Provide a collection of all the nodes in the tree
240 * using a bredth first traversal
241 */
242 public List breadthFirst() {
243 List answer = new ArrayList();
244 answer.add(this);
245 answer.addAll(breadthFirstRest());
246 return answer;
247 }
248
249 private List breadthFirstRest() {
250 List answer = new ArrayList();
251 for (Iterator iter = InvokerHelper.asIterator(value); iter.hasNext(); ) {
252 Object child = iter.next();
253 if (child instanceof Node) {
254 Node childNode = (Node) child;
255 answer.add(childNode);
256 }
257 }
258 List copy = new ArrayList(answer);
259 for (Iterator iter = copy.iterator(); iter.hasNext(); ) {
260 Node childNode = (Node) iter.next();
261 List children = childNode.breadthFirstRest();
262 answer.addAll(children);
263 }
264 return answer;
265 }
266
267 public String toString() {
268 return name + "[attributes=" + attributes + "; value=" + value + "]";
269 }
270
271 public void print(PrintWriter out) {
272 new NodePrinter(out).print(this);
273 }
274 }