/*
 * This file is part of ELKI:
 * Environment for Developing KDD-Applications Supported by Index-Structures
 *
 * Copyright (C) 2022
 * ELKI Development Team
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */
package elki.similarity;

import elki.database.query.similarity.PrimitiveSimilarityQuery;
import elki.database.query.similarity.SimilarityQuery;
import elki.database.relation.Relation;

/**
 * Interface Similarity describes the requirements of any similarity
 * function.
 * 
 * @author Elke Achtert
 * @since 0.1
 * 
 * @opt nodefillcolor LemonChiffon
 * 
 * @param <O> object type
 */
public interface PrimitiveSimilarity<O> extends Similarity<O> {
  /**
   * Computes the similarity between two given DatabaseObjects according to this
   * similarity function.
   * 
   * @param o1 first DatabaseObject
   * @param o2 second DatabaseObject
   * @return the similarity between two given DatabaseObjects according to this
   *         similarity function
   */
  double similarity(O o1, O o2);

  @Override
  default <T extends O> SimilarityQuery<T> instantiate(Relation<T> relation) {
    return new PrimitiveSimilarityQuery<>(relation, this);
  }
}