gomp-20050608-branch/libjava/classpath/gnu/java/beans/decoder/PropertyContext.java

   1 /* gnu.java.beans.decoder.PropertyContext
   2    Copyright (C) 2004 Free Software Foundation, Inc.
   3
   4 This file is part of GNU Classpath.
   5
   6 GNU Classpath is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 2, or (at your option)
   9 any later version.
  10
  11 GNU Classpath is distributed in the hope that it will be useful, but
  12 WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GNU Classpath; see the file COPYING.  If not, write to the
  18 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  19 02110-1301 USA.
  20
  21 Linking this library statically or dynamically with other modules is
  22 making a combined work based on this library.  Thus, the terms and
  23 conditions of the GNU General Public License cover the whole
  24 combination.
  25
  26 As a special exception, the copyright holders of this library give you
  27 permission to link this library with independent modules to produce an
  28 executable, regardless of the license terms of these independent
  29 modules, and to copy and distribute the resulting executable under
  30 terms of your choice, provided that you also meet, for each linked
  31 independent module, the terms and conditions of the license of that
  32 module.  An independent module is a module which is not derived from
  33 or based on this library.  If you modify this library, you may extend
  34 this exception to your version of the library, but you are not
  35 obligated to do so.  If you do not wish to do so, delete this
  36 exception statement from your version. */
  37
  38 package gnu.java.beans.decoder;
  39
  40 import java.lang.reflect.InvocationTargetException;
  41 import java.lang.reflect.Method;
  42
  43 /** PropertyContext is a Context implementation that is very similar to MethodContext
  44  * and IndexContext. The sole purpose of PropertyContext to find out whether it should
  45  * 'set' or 'get' a certain property. This decision is made using the number of
  46  * arguments.
  47  * <p>When the method call has to be made and there is no argument we 'get' the property.
  48  * With one argument it is 'set'.</p>
  49  *
  50  * @author Robert Schuster
  51  */
  52 class PropertyContext extends AbstractObjectContext
  53 {
  54   private Object argument;
  55   private String propertyName;
  56   private String prefix = "get";
  57   private boolean methodCalled;
  58
  59   PropertyContext(String id, String newPropertyName)
  60   {
  61     setId(id);
  62     propertyName = newPropertyName;
  63   }
  64
  65   /* (non-Javadoc)
  66    * @see gnu.java.beans.decoder.Context#addObject(java.lang.Object)
  67    */
  68   public void addParameterObject(Object o) throws AssemblyException
  69   {
  70     if (methodCalled)
  71       throw new AssemblyException(new IllegalArgumentException("Cannot add parameter object when method was already called."));
  72
  73     if (argument != null)
  74       throw new AssemblyException(new IllegalArgumentException("Property attribut allows zero or one argument only."));
  75
  76     argument = o;
  77         setStatement(true);
  78     prefix = "set";
  79   }
  80
  81   /* (non-Javadoc)
  82    * @see gnu.java.beans.decoder.Context#endContext(gnu.java.beans.decoder.Context)
  83    */
  84   public void notifyStatement(Context outerContext) throws AssemblyException
  85   {
  86     if (methodCalled)
  87       return;
  88     methodCalled = true;
  89
  90     Object outerObject = outerContext.getResult();
  91
  92     if (outerObject == null)
  93       throw new AssemblyException(new NullPointerException("No object to access property "
  94           + propertyName));
  95
  96
  97     // converts property name into a method name
  98     String methodName = prefix + propertyName.substring(0, 1).toUpperCase()
  99                         + propertyName.substring(1);
 100
 101     // prepares the argument
 102     Object[] args = (argument != null) ? new Object[] { argument } : null;
 103
 104     try
 105       {
 106         Method method = MethodFinder.getMethod(outerObject.getClass(),
 107                                                methodName, args);
 108
 109         // stores the result whether it is available or not
 110         setObject(method.invoke(outerObject, args));
 111       }
 112     catch (NoSuchMethodException nsme)
 113       {
 114         throw new AssemblyException(nsme);
 115       }
 116     catch (InvocationTargetException ite)
 117       {
 118         throw new AssemblyException(ite.getCause());
 119       }
 120     catch (IllegalAccessException iae)
 121       {
 122         throw new AssemblyException(iae);
 123       }
 124   }
 125
 126   public Object endContext(Context outerContext) throws AssemblyException
 127   {
 128     notifyStatement(outerContext);
 129
 130     return getResult();
 131   }
 132
 133   public boolean subContextFailed()
 134   {
 135     return ! methodCalled;
 136   }
 137 }