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/*
* 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 org.apache.commons.functor.adapter;
import org.apache.commons.functor.NullaryFunction;
import org.apache.commons.functor.NullaryProcedure;
import org.apache.commons.lang3.Validate;
/**
* Adapts a
* {@link NullaryProcedure NullaryProcedure}
* to the
* {@link NullaryFunction NullaryFunction} interface
* by always returning <code>null</code>.
*
* @param <T> the returned value type.
* @version $Revision: 1365377 $ $Date: 2012-07-24 21:59:23 -0300 (Tue, 24 Jul 2012) $
*/
public final class NullaryProcedureNullaryFunction<T> implements NullaryFunction<T> {
/** The {@link NullaryProcedure NullaryProcedure} I'm wrapping. */
private final NullaryProcedure procedure;
/**
* Create a new NullaryProcedureNullaryFunction.
* @param procedure to adapt
*/
public NullaryProcedureNullaryFunction(NullaryProcedure procedure) {
this.procedure = Validate.notNull(procedure, "NullaryProcedure argument was null");
}
/**
* {@inheritDoc}
*/
public T evaluate() {
procedure.run();
return null;
}
/**
* {@inheritDoc}
*/
@Override
public boolean equals(Object obj) {
if (obj == this) {
return true;
}
if (!(obj instanceof NullaryProcedureNullaryFunction<?>)) {
return false;
}
NullaryProcedureNullaryFunction<?> that = (NullaryProcedureNullaryFunction<?>) obj;
return this.procedure.equals(that.procedure);
}
/**
* {@inheritDoc}
*/
@Override
public int hashCode() {
int hash = "NullaryProcedureNullaryFunction".hashCode();
hash ^= procedure.hashCode();
return hash;
}
/**
* {@inheritDoc}
*/
@Override
public String toString() {
return "NullaryProcedureNullaryFunction<" + procedure + ">";
}
/**
* Adapt a NullaryProcedure as a NullaryFunction.
* @param <T> the returned value type.
* @param procedure to adapt
* @return NullaryProcedureNullaryFunction<T>
*/
public static <T> NullaryProcedureNullaryFunction<T> adapt(NullaryProcedure procedure) {
return null == procedure ? null : new NullaryProcedureNullaryFunction<T>(procedure);
}
}