org.bndly.common.velocity.impl.NullTool Maven / Gradle / Ivy
package org.bndly.common.velocity.impl;
/*-
* #%L
* Velocity
* %%
* Copyright (C) 2013 - 2020 Cybercon GmbH
* %%
* 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.
* #L%
*/
import org.apache.velocity.context.Context;
/**
* The code of this class is taken from http://wiki.apache.org/velocity/NullTool because it
* is not part of the velocity core release. It is a useful utility to work with
* null in templates.
* @author cybercon <[email protected]>
*/
public final class NullTool {
public static final NullTool INSTANCE = new NullTool();
private NullTool() {
}
/**
* Sets the given VTL reference back to null.
*
* @param context the current Context
* @param key the VTL reference to set back to null.
*/
public void setNull(Context context, String key) {
if (this.isNull(context)) {
return;
}
context.remove(key);
}
/**
* Sets the given VTL reference to the given value. If the value is null, the VTL reference is set to null.
*
* @param context the current Context
* @param key the VTL reference to set.
* @param value the value to set the VTL reference to.
*/
public void set(Context context, String key, Object value) {
if (this.isNull(context)) {
return;
}
if (this.isNull(value)) {
this.setNull(context, key);
return;
}
context.put(key, value);
}
/**
* Checks if a VTL reference is null.
*
* @param object the VTL reference to check.
* @return true if the VTL reference is null, false if otherwise.
*/
public boolean isNull(Object object) {
return object == null;
}
/**
* Checks if a VTL reference is not null.
*
* @param object the VTL reference to check.
* @return true if the VTL reference is not null, false if otherwise.
*/
public boolean isNotNull(Object object) {
return !this.isNull(object);
}
/**
* A convinient method which returns null. Actually, this tool will work the same without this method, because Velocity treats non-existing methods as null. :)
*
* @return null
*/
public Object getNull() {
return null;
}
}