001/* TabularType.java -- Type descriptor for TabularData instances.
002   Copyright (C) 2006, 2007 Free Software Foundation, Inc.
003
004This file is part of GNU Classpath.
005
006GNU Classpath is free software; you can redistribute it and/or modify
007it under the terms of the GNU General Public License as published by
008the Free Software Foundation; either version 2, or (at your option)
009any later version.
010
011GNU Classpath is distributed in the hope that it will be useful, but
012WITHOUT ANY WARRANTY; without even the implied warranty of
013MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014General Public License for more details.
015
016You should have received a copy of the GNU General Public License
017along with GNU Classpath; see the file COPYING.  If not, write to the
018Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
01902110-1301 USA.
020
021Linking this library statically or dynamically with other modules is
022making a combined work based on this library.  Thus, the terms and
023conditions of the GNU General Public License cover the whole
024combination.
025
026As a special exception, the copyright holders of this library give you
027permission to link this library with independent modules to produce an
028executable, regardless of the license terms of these independent
029modules, and to copy and distribute the resulting executable under
030terms of your choice, provided that you also meet, for each linked
031independent module, the terms and conditions of the license of that
032module.  An independent module is a module which is not derived from
033or based on this library.  If you modify this library, you may extend
034this exception to your version of the library, but you are not
035obligated to do so.  If you do not wish to do so, delete this
036exception statement from your version. */
037
038package javax.management.openmbean;
039
040import java.util.Arrays;
041import java.util.Collections;
042import java.util.Iterator;
043import java.util.List;
044
045/**
046 * The open type descriptor for instances of the
047 * {@link TabularData} class.
048 * 
049 * @author Andrew John Hughes (gnu_andrew@member.fsf.org)
050 * @since 1.5
051 */
052public class TabularType
053  extends OpenType<TabularData>
054{
055
056  /**
057   * Compatible with JDK 1.5
058   */
059  private static final long serialVersionUID = 6554071860220659261L;
060
061  /**
062   * The composite type used by the rows of the table.
063   */
064  private CompositeType rowType;
065
066  /**
067   * The list of index names, which form the columns of the table.
068   * They are retained in the order given by the user, and is
069   * unmodifiable.
070   */
071  private List<String> indexNames;
072
073  /**
074   * The hash code of this instance.
075   */
076  private transient Integer hashCode;
077
078  /**
079   * The <code>toString()</code> result of this instance.
080   */
081  private transient String string;
082
083  /**
084   * <p>
085   * Constructs a new {@link TabularType} instance for the given
086   * type name, description, row type and index names.  All parameters
087   * (including the individual elements of the array of index names)
088   * must be non-null and those that are of type {@link java.lang.String}
089   * must be non-empty.  The array of index names must also be non-empty.
090   * </p>
091   * <p>
092   * The result of <code>TabularData.class.getName()</code> is adopted
093   * as the class name (see {@link OpenType}).  The ordering of the array
094   * elements is relevant in determining the indicies of the values in the
095   * table, and thus in the use of the 
096   * {@link TabularData#get(java.lang.Object[])} and
097   * {@link TabularData#remove(java.lang.Object[])} methods of the
098   * {@link TabularData} class.
099   * </p>
100   *
101   * @param name the name of this tabular type.
102   * @param desc a description of this tabular type.
103   * @param rowType the type of the rows of the table.
104   * @param indexNames the names used to index the rows within the table.
105   * @throws IllegalArgumentException if any validity constraint listed above
106   *                                  is broken.
107   * @throws OpenDataException if an index name does not match a corresponding
108   *                           name in the given row type.
109   */
110  public TabularType(String name, String desc, CompositeType rowType,
111                     String[] indexNames)
112    throws OpenDataException
113  {
114    super(TabularData.class.getName(), name, desc);
115    if (rowType == null)
116      throw new IllegalArgumentException("A null row type was given.");
117    for (int a = 0; a < indexNames.length; ++a)
118      {
119        if (indexNames[a] == null)
120          throw new IllegalArgumentException("Name " + a +
121                                             " is null.");
122        if (indexNames[a].length() == 0)
123          throw new IllegalArgumentException("Name " + a + 
124                                             " is the empty string.");
125        if (!(rowType.containsKey(indexNames[a])))
126          throw new OpenDataException("No matching key for " +
127                                      indexNames[a] + " was found in " +
128                                      "the supplied row type.");
129      }
130    this.rowType = rowType;
131    this.indexNames = Collections.unmodifiableList(Arrays.asList(indexNames));
132  }
133
134  /**
135   * <p>
136   * Compares this tabular data type with another object
137   * for equality.  The objects are judged to be equal if:
138   * </p>
139   * <ul>
140   * <li><code>obj</code> is not null.</li>
141   * <li><code>obj</code> is an instance of
142   * {@link TabularType}.</li>
143   * <li>The type names are equal.</li>
144   * <li>The row types are equal.</li>
145   * <li>The index names are equal and in the same order.</li>
146   * </ul>
147   * 
148   * @param obj the object to compare with.
149   * @return true if the conditions above hold.
150   */
151  public boolean equals(Object obj)
152  {
153    if (!(obj instanceof TabularType))
154      return false;
155    TabularType ttype = (TabularType) obj;
156    return  (ttype.getTypeName().equals(getTypeName())
157             && (ttype.getRowType().equals(getRowType()))
158             && (ttype.getIndexNames().equals(getIndexNames())));
159  }
160
161  /**
162   * Returns an unmodifiable list containing the index names.
163   * The ordering of these names is used to determine the indicies
164   * of the {@link CompositeData} values, and is retained from that
165   * used in the call to this object's constructor.
166   *
167   * @return an unmodifiable list of the index names used by this
168   *         tabular data structure.
169   */
170  public List<String> getIndexNames()
171  {
172    return indexNames;
173  }
174
175  /**
176   * Returns the type of the rows used by this tabular data structure.
177   *
178   * @return the row type.
179   */
180  public CompositeType getRowType()
181  {
182    return rowType;
183  }
184
185  /**
186   * <p>
187   * Returns the hash code of the tabular data type.
188   * This is computed as the sum of the hash codes of the
189   * index names together with the hash code of the type
190   * name and row type.  These are the same elements
191   * of the type that are compared as part of the
192   * {@link #equals(java.lang.Object)} method, thus ensuring
193   * that the hashcode is compatible with the equality
194   * test.
195   * </p>
196   * <p>
197   * As instances of this class are immutable, the hash code
198   * is computed just once for each instance and reused
199   * throughout its life.
200   * </p>
201   *
202   * @return the hash code of this instance.
203   */
204  public int hashCode()
205  {
206    if (hashCode == null)
207      {
208        int elementTotal = 0;
209        for (String s : indexNames)
210          elementTotal += s.hashCode();
211        hashCode = Integer.valueOf(elementTotal 
212                                   + getTypeName().hashCode()
213                                   + rowType.hashCode());
214      }
215    return hashCode.intValue();
216  }
217                               
218  /**
219   * Returns true if the specified object is a member of this
220   * tabular type.  The object is judged to be so if it is
221   * an instance of {@link TabularData} with an equivalent
222   * type, according to the definition of
223   * {@link #equals(java.lang.Object)} for {@link TabularType}.
224   *
225   * @param obj the object to test for membership.
226   * @return true if the object is a member of this type.
227   */
228  public boolean isValue(Object obj)
229  {
230    if (obj instanceof TabularData)
231      {
232        TabularData data = (TabularData) obj;
233        return equals(data.getTabularType());
234      }
235    return false;
236  }
237
238  /**
239   * <p>
240   * Returns a textual representation of this instance.  This
241   * is constructed using the class name
242   * (<code>javax.management.openmbean.TabularType</code>)
243   * and each element of the instance which is relevant to
244   * the definition of {@link equals(java.lang.Object)} and
245   * {@link hashCode()} (i.e. the type name, the row type
246   * and the index names).
247   * </p>
248   * <p>
249   * As instances of this class are immutable, the return value
250   * is computed just once for each instance and reused
251   * throughout its life.
252   * </p>
253   *
254   * @return a @link{java.lang.String} instance representing
255   *         the instance in textual form.
256   */
257  public String toString()
258  {
259    if (string == null)
260      string = getClass().getName()
261        + "[name=" + getTypeName()
262        + ", rowType=" + rowType
263        + ", indexNames=" + indexNames
264        + "]";
265    return string;
266  }
267
268}