package org.apache.velocity.app.event;
import org.apache.velocity.context.Context;
import org.apache.velocity.util.ContextAware;
/*
* 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.
*/
/**
* Event handler called when the RHS of #set is null. Lets an app approve / veto
* writing a log message based on the specific reference.
*
* @author <a href="mailto:[email protected]">Will Glass-Husain</a>
* @author <a href="mailto:[email protected]">Geir Magnusson Jr.</a>
* @version $Id: NullSetEventHandler.java 685685 2008-08-13 21:43:27Z nbubna $
*/
public interface NullSetEventHandler extends EventHandler
{
/**
* Called when the RHS of a #set() is null, which will result
* in a null LHS. All NullSetEventHandlers
* are called in sequence until a false is returned. If no NullSetEventHandler
* is registered all nulls will be logged.
*
* @param lhs reference literal of left-hand-side of set statement
* @param rhs reference literal of right-hand-side of set statement
* @return true if log message should be written, false otherwise
*/
public boolean shouldLogOnNullSet( String lhs, String rhs );
/**
* Defines the execution strategy for shouldLogOnNullSet
* @since 1.5
*/
static class ShouldLogOnNullSetExecutor implements EventHandlerMethodExecutor
{
private Context context;
private String lhs;
private String rhs;
/**
* when this is false, quit iterating
*/
private boolean result = true;
private boolean executed = false;
ShouldLogOnNullSetExecutor(
Context context,
String lhs,
String rhs)
{
this.context = context;
this.lhs = lhs;
this.rhs = rhs;
}
/**
* Call the method shouldLogOnNullSet()
*
* @param handler call the appropriate method on this handler
*/
public void execute(EventHandler handler)
{
NullSetEventHandler eh = (NullSetEventHandler) handler;
if (eh instanceof ContextAware)
((ContextAware) eh).setContext(context);
executed = true;
result = ((NullSetEventHandler) handler).shouldLogOnNullSet(lhs, rhs);
}
public Object getReturnValue()
{
// return new Boolean(result);
return result ? Boolean.TRUE : Boolean.FALSE;
}
public boolean isDone()
{
return executed && !result;
}
}
}
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