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

   1 /* gnu.java.beans.decoder.VoidHandler
   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.beans.ExceptionListener;
  41
  42 import org.xml.sax.Attributes;
  43
  44 public class VoidHandler extends AbstractElementHandler
  45 {
  46     /**
  47      * @param PersistenceParser
  48      */
  49     VoidHandler(ElementHandler parent)
  50     {
  51         super(parent, true);
  52     }
  53
  54     protected Context startElement(
  55         Attributes attributes,
  56         ExceptionListener exceptionListener)
  57         throws AssemblyException
  58     {
  59         Context ctx = startElementImpl(attributes);
  60         ctx.setStatement(true);
  61
  62         return ctx;
  63     }
  64
  65     private Context startElementImpl(Attributes attributes)
  66         throws AssemblyException
  67     {
  68         String id = attributes.getValue("id");
  69         String className = attributes.getValue("class");
  70         String methodName = attributes.getValue("method");
  71         String propertyName = attributes.getValue("property");
  72         String index = attributes.getValue("index");
  73
  74         if (className != null)
  75         {
  76             try
  77             {
  78                 Class klass = instantiateClass(className);
  79
  80                 // class name exists which means that we are in a static context.
  81                 // so we may want to ...
  82                 // run a constructor if methodName is "new" or null
  83                 if (methodName == null || methodName.equals("new"))
  84                     // if the id is null the result cannot be by the decoder accessed but the
  85                     // constructor may have side effects (e.g. registering itself in a global registry)
  86                     return new ConstructorContext(id, klass);
  87
  88                 // (falling through is important!)
  89                 // run a static method on the given class (if methodName exists, which is implied already)
  90                 return new StaticMethodContext(id, klass, methodName);
  91             }
  92             catch (ClassNotFoundException cnfe)
  93             {
  94                 throw new AssemblyException(cnfe);
  95             }
  96         }
  97         else
  98         {
  99             // className does not exist which means we are in the context of
 100             // some object and want to ...
 101             // access an element by index
 102             if (index != null)
 103             {
 104                 // note: whether this resolves into get(i) or set(i, o) depends on the
 105                 // number of arguments and is decided by the ObjectAssembler
 106                 try
 107                 {
 108                     return new IndexContext(id, Integer.parseInt(index));
 109                 }
 110                 catch (NumberFormatException nfe)
 111                 {
 112                     throw new AssemblyException(nfe);
 113                 }
 114             }
 115
 116             // access a method if methodName exists
 117             if (methodName != null)
 118                 return new MethodContext(id, methodName);
 119
 120             // (falling through is important!)
 121             // access a property if a propertyName exists
 122             if (propertyName != null && propertyName.length() > 0)
 123                 // this is reported as an ordinary method invocation where the propertyName is
 124                 // converted into a 'setter'-method name: convert first character of property name
 125                 // to upper case and prepend 'set'
 126                 // Note: This will be a setter-method because the <void> tag implies that no return
 127                 // value is expected (but a side effect)
 128                 return new PropertyContext(id, propertyName);
 129         }
 130
 131         // if code reaches this point the tag has wrong attributes. The following test
 132         // does not make it better but can provide are more specific error message for
 133         // a common mistake: <void> tags are not allowed to have an idref attribute
 134         throw new AssemblyException(
 135             new IllegalArgumentException(
 136                 (attributes.getValue("idref") == null)
 137                     ? "Missing attributes for <void> tag"
 138                     : "<void> does not support 'idref' attribute."));
 139     }
 140 }