code: /*
   * #%L
   * Simmetrics Core
   * %%
   * Copyright (C) 2014 - 2016 Simmetrics Authors
   * %%
   * 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%
   */
  package org.simmetrics.metrics.functions;
  
  import static com.google.common.base.Preconditions.checkArgument;
  
  /**
   * A substitution function that assigns one value to equal characters, another
   * value to unequal characters.
   * 
   * <p>
   * This class is immutable and thread-safe.
   *
   */
  public class MatchMismatch implements Substitution {
  
  	private final float matchValue;
  	private final float mismatchValue;
  
  	/**
  	 * Constructs a new match-mismatch substitution function. When two
  	 * characters are equal a score of <code>matchValue</code> is assigned. In
  	 * case of a mismatch a score of <code>mismatchValue</code>. The
  	 * <code>matchValue</code> must be strictly greater then
  	 * <code>mismatchValue</code>
  	 * 
  	 * @param matchValue
  	 *            value when characters are equal
  	 * @param mismatchValue
  	 *            value when characters are not equal
  	 */
  	public MatchMismatch(float matchValue, float mismatchValue) {
  		super();
  		checkArgument(matchValue > mismatchValue);
  
  		this.matchValue = matchValue;
  		this.mismatchValue = mismatchValue;
  	}
  
  	@Override
  	public float compare(String a, int aIndex, String b, int bIndex) {
  		return a.charAt(aIndex) == b.charAt(bIndex) ? matchValue
  				: mismatchValue;
  	}
  
  	@Override
  	public float max() {
  		return matchValue;
  	}
  
  	@Override
  	public float min() {
  		return mismatchValue;
  	}
  
  	@Override
  	public String toString() {
  		return "MatchMismatch [matchCost=" + matchValue + ", mismatchCost="
  				+ mismatchValue + "]";
  	}
  
  }
  