scriptella.spi.support.HierarchicalParametersCallback Maven / Gradle / Ivy
/*
* Copyright 2006-2012 The Scriptella Project Team.
*
* Licensed 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 scriptella.spi.support;
import scriptella.spi.ParametersCallback;
/**
* Hierarchical implementation of {@link scriptella.spi.ParametersCallback} interface.
* This class decorates behaviour of a primary callback by obtaining
* absent parameter values from the parent callback.
*
Note: This class is mutable and not thread-safe.
*
* @author Fyodor Kupolov
* @version 1.0
*/
public class HierarchicalParametersCallback implements ParametersCallback {
private ParametersCallback callback;
private ParametersCallback parentCallback;
/**
* Creates a hierarchical parameters callback instance.
*
* @param callback primary callback.
* @param parentCallback secondary (parent) callback. If null - only primary callback is used.
*/
public HierarchicalParametersCallback(ParametersCallback callback, ParametersCallback parentCallback) {
setCallback(callback);
setParentCallback(parentCallback);
}
/**
* Returns primary callback.
*
* @return primary callback.
*/
public ParametersCallback getCallback() {
return callback;
}
/**
* Sets primary callback.
*
* @param callback primary callback. Cannot be null.
*/
public void setCallback(ParametersCallback callback) {
if (callback == null) {
throw new IllegalArgumentException("Parameters callback cannot be null");
}
this.callback = callback;
}
/**
* Returns secondary callback.
*
* @return secondary callback.
*/
public ParametersCallback getParentCallback() {
if (callback == null) {
throw new IllegalArgumentException("Parameters callback cannot be null");
}
return parentCallback;
}
/**
* Sets secondary callback.
*
* @param parentCallback secondary callback. May be null, in this case only primary callback is used.
*/
public void setParentCallback(ParametersCallback parentCallback) {
this.parentCallback = parentCallback;
}
/**
* This method obtains the value of a specified parameter from the primary callback
* . If the returned value is null, the parameter's value is obtained from secondary callback.
*
* @param name parameter name.
* @return value of the specified parameter.
*/
public Object getParameter(final String name) {
Object v = callback.getParameter(name);
if (v != null) {
return v;
}
return parentCallback == null ? null : parentCallback.getParameter(name);
}
}