IndexedVector


1   package persistence.antlr.collections.impl;
2   
3   /* ANTLR Translator Generator
4    * Project led by Terence Parr at http://www.jGuru.com
5    * Software rights: http://www.antlr.org/license.html
6    *
7    */
8   
9   import java.util.Hashtable  ;
10  import java.util.Enumeration  ;
11  
12  import persistence.antlr.collections.impl.Vector;
13  
14  /**
15   * A simple indexed vector: a normal vector except that you must
16   * specify a key when adding an element.  This allows fast lookup
17   * and allows the order of specification to be preserved.
18   */
19  public class IndexedVector {
20      protected Vector elements;
21      protected Hashtable   index;
22  
23  
24      /**
25       * IndexedVector constructor comment.
26       */
27      public IndexedVector() {
28          elements = new Vector(10);
29          index = new Hashtable  (10);
30      }
31  
32      /**
33       * IndexedVector constructor comment.
34       * @param size int
35       */
36      public IndexedVector(int size) {
37          elements = new Vector(size);
38          index = new Hashtable  (size);
39      }
40  
41      public synchronized void appendElement(Object   key, Object   value) {
42          elements.appendElement(value);
43          index.put(key, value);
44      }
45  
46      /**
47       * Returns the element at the specified index.
48       * @param index the index of the desired element
49       * @exception ArrayIndexOutOfBoundsException If an invalid
50       * index was given.
51       */
52      public Object   elementAt(int i) {
53          return elements.elementAt(i);
54      }
55  
56      public Enumeration   elements() {
57          return elements.elements();
58      }
59  
60      public Object   getElement(Object   key) {
61          Object   o = index.get(key);
62          return o;
63      }
64  
65      /** remove element referred to by key NOT value; return false if not found. */
66      public synchronized boolean removeElement(Object   key) {
67          Object   value = index.get(key);
68          if (value == null) {
69              return false;
70          }
71          index.remove(key);
72          elements.removeElement(value);
73          return false;
74      }
75  
76      public int size() {
77          return elements.size();
78      }
79  }
80
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