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Diffstat (limited to 'libjava/classpath/gnu/java/beans/encoder/ArrayPersistenceDelegate.java')
| -rw-r--r-- | libjava/classpath/gnu/java/beans/encoder/ArrayPersistenceDelegate.java | 153 |
1 files changed, 153 insertions, 0 deletions
diff --git a/libjava/classpath/gnu/java/beans/encoder/ArrayPersistenceDelegate.java b/libjava/classpath/gnu/java/beans/encoder/ArrayPersistenceDelegate.java new file mode 100644 index 000000000..52fc45796 --- /dev/null +++ b/libjava/classpath/gnu/java/beans/encoder/ArrayPersistenceDelegate.java @@ -0,0 +1,153 @@ +/* ArrayPersistenceDelegate.java - A PersistenceDelegate that handles arrays. + Copyright (C) 2005 Free Software Foundation, Inc. + + This file is part of GNU Classpath. + + GNU Classpath is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 2, or (at your option) + any later version. + + GNU Classpath is distributed in the hope that it will be useful, but + WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + General Public License for more details. + + You should have received a copy of the GNU General Public License + along with GNU Classpath; see the file COPYING. If not, write to the + Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA + 02110-1301 USA. + + Linking this library statically or dynamically with other modules is + making a combined work based on this library. Thus, the terms and + conditions of the GNU General Public License cover the whole + combination. + + As a special exception, the copyright holders of this library give you + permission to link this library with independent modules to produce an + executable, regardless of the license terms of these independent + modules, and to copy and distribute the resulting executable under + terms of your choice, provided that you also meet, for each linked + independent module, the terms and conditions of the license of that + module. An independent module is a module which is not derived from + or based on this library. If you modify this library, you may extend + this exception to your version of the library, but you are not + obligated to do so. If you do not wish to do so, delete this + exception statement from your version. */ + + +package gnu.java.beans.encoder; + +import java.beans.Encoder; +import java.beans.Expression; +import java.beans.PersistenceDelegate; +import java.beans.Statement; + +import java.lang.reflect.Array; +import java.util.HashMap; + +public class ArrayPersistenceDelegate extends PersistenceDelegate +{ + private static final HashMap NULL_VALUES = new HashMap(); + + static + { + NULL_VALUES.put(Boolean.TYPE, Boolean.FALSE); + NULL_VALUES.put(Byte.TYPE, Byte.valueOf((byte) 0)); + NULL_VALUES.put(Short.TYPE, Short.valueOf((short) 0)); + NULL_VALUES.put(Integer.TYPE, Integer.valueOf(0)); + NULL_VALUES.put(Long.TYPE, Long.valueOf(0)); + NULL_VALUES.put(Float.TYPE, Float.valueOf(0.0f)); + NULL_VALUES.put(Double.TYPE, Double.valueOf(0.0)); + } + + protected Expression instantiate(Object oldInstance, Encoder out) + { + Class type = oldInstance.getClass().getComponentType(); + + // oldInstance is expected to be an array, then + // getClass().getComponentType() should lead + // to its component type. + assert (type != null); + + // Not handling primitive types in a special way here + // causes that Class.forName("int") is built as an Expression + // later which would cause an exception if executed. A special + // handling to avoid the execution for primitive types can be + // java.beans.Encoder.writeExpression() . + return new Expression( + oldInstance, + Array.class, + "newInstance", + new Object[] { + type, + new Integer(Array.getLength(oldInstance)) }); + } + + protected void initialize(Class type, Object oldInstance, Object newInstance, + Encoder out) + { + int length = Array.getLength(oldInstance); + + // Compares the array value against a prototypical + // null value of the array's component type in order to skip + // writing the default values of an array. + + // Note: I have no idea why the persistence delegate for arrays writes + // an Expression that reads the value and then writes a Statement that sets + // the value. However it turned out that object arrays work better with the + // get-Expression and primitive array work fine with the set-Statement. + + type = type.getComponentType(); + if (type.isPrimitive()) + { + Object nullValue = NULL_VALUES.get(type); + + for (int i = 0; i < length; i++) + { + Object oldValue = Array.get(oldInstance, i); + + if (!oldValue.equals(nullValue)) + { + out.writeExpression(new Expression(Array.class, "get", + new Object[] { oldInstance, + Integer.valueOf(i), + })); + + out.writeStatement(new Statement(Array.class, "set", + new Object[] { + oldInstance, + Integer.valueOf(i), + oldValue + })); + } + } + + } + else + { + + for (int i = 0; i < length; i++) + { + Object oldValue = Array.get(oldInstance, i); + + if (oldValue != null) + { + out.writeExpression(new Expression(Array.class, "get", + new Object[] { oldInstance, + Integer.valueOf(i), + })); + + out.writeStatement(new Statement(Array.class, "set", + new Object[] { + oldInstance, + Integer.valueOf(i), + oldValue + })); + } + } + } + + } + +} |