001    /*
002     $Id: Node.java,v 1.12 2005/09/27 12:32:51 hmeling Exp $
003    
004     Copyright 2003 (C) James Strachan and Bob Mcwhirter. All Rights Reserved.
005    
006     Redistribution and use of this software and associated documentation
007     ("Software"), with or without modification, are permitted provided
008     that the following conditions are met:
009    
010     1. Redistributions of source code must retain copyright
011        statements and notices.  Redistributions must also contain a
012        copy of this document.
013    
014     2. Redistributions in binary form must reproduce the
015        above copyright notice, this list of conditions and the
016        following disclaimer in the documentation and/or other
017        materials provided with the distribution.
018    
019     3. The name "groovy" must not be used to endorse or promote
020        products derived from this Software without prior written
021        permission of The Codehaus.  For written permission,
022        please contact info@codehaus.org.
023    
024     4. Products derived from this Software may not be called "groovy"
025        nor may "groovy" appear in their names without prior written
026        permission of The Codehaus. "groovy" is a registered
027        trademark of The Codehaus.
028    
029     5. Due credit should be given to The Codehaus -
030        http://groovy.codehaus.org/
031    
032     THIS SOFTWARE IS PROVIDED BY THE CODEHAUS AND CONTRIBUTORS
033     ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT
034     NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
035     FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL
036     THE CODEHAUS OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
037     INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
038     (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
039     SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
040     HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
041     STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
042     ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
043     OF THE POSSIBILITY OF SUCH DAMAGE.
044    
045     */
046    package groovy.util;
047    
048    import org.codehaus.groovy.runtime.InvokerHelper;
049    
050    import groovy.xml.QName;
051    
052    import java.io.PrintWriter;
053    import java.util.Collection;
054    import java.util.Collections;
055    import java.util.Iterator;
056    import java.util.List;
057    import java.util.Map;
058    
059    /**
060     * Represents an arbitrary tree node which can be used for structured  metadata which can be any arbitrary XML-like tree.
061     * A node can have a name, a value and an optional Map of attributes.
062     * Typically the name is a String and a value is either a String or a List of other Nodes.
063     * Though the types are extensible to provide a flexible structure. 
064     * e.g. you could use a QName as the name which includes a namespace URI and a local name. Or a JMX ObjectName etc.
065     * 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" }}
066     * 
067     * @author <a href="mailto:james@coredevelopers.net">James Strachan</a>
068     * @version $Revision: 1.12 $
069     */
070    public class Node implements java.io.Serializable {
071    
072        private static final long serialVersionUID = 4121134753270542643L;
073        private Node parent;
074        private Object name;
075        private Map attributes;
076        private Object value;
077    
078        public Node(Node parent, Object name) {
079            this(parent, name, Collections.EMPTY_MAP, Collections.EMPTY_LIST);
080        }
081    
082        public Node(Node parent, Object name, Object value) {
083            this(parent, name, Collections.EMPTY_MAP, value);
084        }
085    
086        public Node(Node parent, Object name, Map attributes) {
087            this(parent, name, attributes, Collections.EMPTY_LIST);
088        }
089    
090        public Node(Node parent, Object name, Map attributes, Object value) {
091            this.parent = parent;
092            this.name = name;
093            this.attributes = attributes;
094            this.value = value;
095            
096            if (parent != null) {
097                Object parentValue = parent.value();
098                List parentList = null;
099                if (parentValue instanceof List) {
100                    parentList = (List) parentValue;
101                }
102                else {
103                    parentList = new NodeList();
104                    parentList.add(parentValue);
105                    parent.setValue(parentList);
106                }
107                parentList.add(this);
108            }
109        }
110    
111        public String text() {
112            if (value instanceof String) {
113                return (String) value;
114            }
115            else if (value instanceof Collection) {
116                Collection coll = (Collection) value;
117                String previousText = null;
118                StringBuffer buffer = null;
119                for (Iterator iter = coll.iterator(); iter.hasNext();) {
120                    Object child = iter.next();
121                    if (child instanceof String) {
122                        String childText = (String) child;
123                        if (previousText == null) {
124                            previousText = childText;
125                        }
126                        else {
127                            if (buffer == null) {
128                                buffer = new StringBuffer();
129                                buffer.append(previousText);
130                            }
131                            buffer.append(childText);
132                        }
133                    }
134                }
135                if (buffer != null) {
136                    return buffer.toString();
137                }
138                else {
139                    if (previousText != null) {
140                        return previousText;
141                    }
142                }
143            }
144            return "";
145        }
146    
147        
148        public Iterator iterator() {
149            return children().iterator();
150        }
151        
152        public List children() {
153            if (value == null) {
154                return Collections.EMPTY_LIST;
155            }
156            else if (value instanceof List) {
157                return (List) value;
158            }
159            else {
160                // we're probably just a String
161                return Collections.singletonList(value);
162            }
163        }
164    
165        public Map attributes() {
166            return attributes;
167        }
168    
169        public Object attribute(Object key) {
170            return (attributes != null) ? attributes.get(key) : null;
171        }
172        
173        public Object name() {
174            return name;
175        }
176    
177        public Object value() {
178            return value;
179        }
180    
181        public void setValue(Object value) {
182            this.value = value;
183        }
184    
185        public Node parent() {
186            return parent;
187        }
188    
189        /**
190         * Provides lookup of elements by non-namespaced name
191         */
192        public Object get(String key) {
193            if (key.charAt(0) == '@') {
194                String attributeName = key.substring(1);
195                return attributes().get(attributeName);
196            }
197            else {
198                // iterate through list looking for node with name 'key'
199                List answer = new NodeList();
200                for (Iterator iter = children().iterator(); iter.hasNext();) {
201                    Object child = iter.next();
202                    if (child instanceof Node) {
203                        Node childNode = (Node) child;
204                        Object childNodeName = childNode.name();
205                        if (childNodeName != null && childNodeName.equals(key)) {
206                            answer.add(childNode);
207                        }
208                    }
209                }
210                return answer;
211            }
212        }
213        
214        /**
215         * Provides lookup of elements by QName
216         */
217        public NodeList getAt(QName name) {
218            NodeList answer = new NodeList();
219            for (Iterator iter = children().iterator(); iter.hasNext();) {
220                Object child = iter.next();
221                if (child instanceof Node) {
222                    Node childNode = (Node) child;
223                    Object childNodeName = childNode.name();
224                    if (childNodeName != null && childNodeName.equals(name)) {
225                        answer.add(childNode);
226                    }
227                }
228            }
229            return answer;
230        }
231    
232    //    public Object get(int idx) {
233    //        return children().get(idx);
234    //    }
235    
236    
237    
238        /**
239         * Provide a collection of all the nodes in the tree
240         * using a depth first traversal
241         */
242        public List depthFirst() {
243            List answer = new NodeList();
244            answer.add(this);
245            answer.addAll(depthFirstRest());
246            return answer;
247        }
248        
249        private  List depthFirstRest() {
250            List answer = new NodeList();
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                    List children = childNode.depthFirstRest();
256                    answer.add(childNode);
257                    answer.addAll(children);
258                }
259            }
260            return answer;
261        }
262    
263        /**
264         * Provide a collection of all the nodes in the tree
265         * using a bredth first traversal
266         */
267        public List breadthFirst() {
268            List answer = new NodeList();
269            answer.add(this);
270            answer.addAll(breadthFirstRest());
271            return answer;
272        }
273        
274        private  List breadthFirstRest() {
275            List answer = new NodeList();
276            for (Iterator iter = InvokerHelper.asIterator(value); iter.hasNext(); ) {
277                Object child = iter.next();
278                if (child instanceof Node) {
279                    Node childNode = (Node) child;
280                    answer.add(childNode);
281                }
282            }
283            List copy = new NodeList(answer);
284            for (Iterator iter = copy.iterator(); iter.hasNext(); ) {
285                Node childNode = (Node) iter.next();
286                List children = childNode.breadthFirstRest();
287                answer.addAll(children);
288            }
289            return answer;
290        }
291    
292        public String toString() {
293            return name + "[attributes=" + attributes + "; value=" + value + "]";
294        }
295    
296        public void print(PrintWriter out) {
297            new NodePrinter(out).print(this);
298        }
299    }