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    1   /*
    2    $Id: Node.java,v 1.8 2004/06/01 15:55:48 tug Exp $
    3
    4    Copyright 2003 (C) James Strachan and Bob Mcwhirter. All Rights Reserved.
    5
    6    Redistribution and use of this software and associated documentation
    7    ("Software"), with or without modification, are permitted provided
    8    that the following conditions are met:
    9
    10   1. Redistributions of source code must retain copyright
    11      statements and notices.  Redistributions must also contain a
    12      copy of this document.
    13
    14   2. Redistributions in binary form must reproduce the
    15      above copyright notice, this list of conditions and the
    16      following disclaimer in the documentation and/or other
    17      materials provided with the distribution.
    18
    19   3. The name "groovy" must not be used to endorse or promote
    20      products derived from this Software without prior written
    21      permission of The Codehaus.  For written permission,
    22      please contact info@codehaus.org.
    23
    24   4. Products derived from this Software may not be called "groovy"
    25      nor may "groovy" appear in their names without prior written
    26      permission of The Codehaus. "groovy" is a registered
    27      trademark of The Codehaus.
    28
    29   5. Due credit should be given to The Codehaus -
    30      http://groovy.codehaus.org/
    31
    32   THIS SOFTWARE IS PROVIDED BY THE CODEHAUS AND CONTRIBUTORS
    33   ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT
    34   NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
    35   FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL
    36   THE CODEHAUS OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
    37   INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
    38   (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
    39   SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
    40   HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
    41   STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
    42   ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
    43   OF THE POSSIBILITY OF SUCH DAMAGE.
    44
    45   */
    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             // we're probably just a String
    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             // iterate through list looking for node with name 'key'
    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 //    public Object get(int idx) {
    208 //        return children().get(idx);
    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 }