core/src/main/java/flex/messaging/io/amf/translator/decoder/ActionScriptDecoder.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package flex.messaging.io.amf.translator.decoder;

import flex.messaging.io.SerializationContext;

import java.util.Calendar;
import java.util.Date;

/**
 * Decode an ActionScript object (of some type) to a Java object (of some type).
 */
public abstract class ActionScriptDecoder {
    /**
     * Does this type have a placeholder shell?
     *
     * @return boolean true if there is a placeholder shell
     */
    public boolean hasShell() {
        return false;
    }

    /**
     * Used for calls only interested in creating a placeholder shell for a type.
     *
     * @param encodedObject the encoded object
     * @param desiredClass  the desired class for the decoded object
     * @return Object the shell placeholder object
     */
    public Object createShell(Object encodedObject, Class desiredClass) {
        return null;
    }

    /**
     * Used by calls to decode an object has a shell placeholder.
     *
     * @param shell         the placeholder shell
     * @param encodedObject the encoded object
     * @param desiredClass  the desired class for the decoded object
     * @return Object the decoded object
     */
    public abstract Object decodeObject(Object shell, Object encodedObject, Class desiredClass);

    /**
     * Used by calls wanted to decode an object. If the decoder requires a place holder shell one is created
     * and then the encodedObject is decoded to fill the object shell.
     *
     * @param encodedObject the encoded object
     * @param desiredClass  the desire class for the decoded object
     * @return Object the decoded object
     */
    public Object decodeObject(Object encodedObject, Class desiredClass) {
        Object shell = null;

        if (hasShell()) {
            shell = createShell(encodedObject, desiredClass);
        }

        return decodeObject(shell, encodedObject, desiredClass);
    }

    protected boolean canUseByReference(Object o) {
        if (o == null)
            return false;

        else if (o instanceof String)
            return false;

        else if (o instanceof Number)
            return false;

        else if (o instanceof Boolean)
            return false;

        else if (o instanceof Date) {
            return SerializationContext.getSerializationContext().supportDatesByReference;
        } else if (o instanceof Calendar)
            return false;

        else if (o instanceof Character)
            return false;

        return true;
    }

    protected static Object getDefaultPrimitiveValue(Class type) {
        if (type == Boolean.TYPE)
            return Boolean.FALSE;
        else if (type == Integer.TYPE)
            return new Integer(0);
        else if (type == Double.TYPE)
            return new Double(0);
        else if (type == Long.TYPE)
            return new Long(0);
        else if (type == Float.TYPE)
            return new Float(0);
        else if (type == Character.TYPE)
            return new Character(Character.MIN_VALUE);
        else if (type == Short.TYPE)
            return new Short((short) 0);
        else if (type == Byte.TYPE)
            return new Byte((byte) 0);

        return null;
    }
}