ReplaceByIfEqualTo.java

/*
 * Copyright (c) 2013, SRI International
 * All rights reserved.
 * Licensed under the The BSD 3-Clause License;
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at:
 * 
 * http://opensource.org/licenses/BSD-3-Clause
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 
 * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 * 
 * Redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution.
 * 
 * Neither the name of the aic-util nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, 
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package com.sri.ai.util.base;

import com.google.common.annotations.Beta;
import com.google.common.base.Function;

/**
 * A {@link Function} constructed on two objects, <code>replaced</code> and
 * <code>replacement</code>. When evaluates, this function returns
 * <code>replacement</code> if the argument equals <code>replaced</code>, or the
 * argument itself otherwise. This is useful for libraries that use generic
 * search-and-replace methods parameterized by a replacement function.
 * 
 * @author braz
 */
@Beta
public class ReplaceByIfEqualTo<T> implements Function<T, T> {

	private T replaced;
	private T replacement;
	
	public ReplaceByIfEqualTo(T replacement, T replaced) {
		this.replaced    = replaced;
		this.replacement = replacement;
	}

	@Override
	public T apply(T obj) {
		if (obj.equals(replaced)) {
			return replacement;
		}
		return obj;
	}
}