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;
  
  /**
   * A gap function assigns penalty to the creation of a gap in a string when
   * matching against another string.
   * <p>
   * The penalty returned must be non-positive value to be consistent with the
   * results of the substitution function.
   * 
   * <p>
   * This class is immutable and thread-safe.
   * 
   * 
   * @see Substitution
   * @see <a href="https://en.wikipedia.org/wiki/Gap_penalty">Wikipedia - Gap
   *      Penalty</a>
   *
   */
  public interface Gap {
  
  	/**
  	 * Returns the penalty for creating a gap from <code>fromIndex</code> to
  	 * <code>toIndex -1</code>. The value must be non-positive.
  	 * 
  	 * @param fromIndex
  	 *            index at which the gap starts
  	 * @param toIndex
  	 *            index after the last gap entry
  	 * @return a gap penalty
  	 */
  	public float value(int fromIndex, int toIndex);
  
  	/**
  	 * Returns the minimum value a gap can have.
  	 * 
  	 * @return the minimum value a gap can have
  	 */
  	public float max();
  
  	/**
  	 * Returns the maximum value a gap can have.
  	 * 
  	 * @return the maximum value a gap can have
  	 */
  	public float min();
  }
  