Runner.java

/*
 * Copyright 2015 S. Webber
 *
 * 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.
 */
package org.oakgp.util;

import java.util.Collection;
import java.util.function.Predicate;

import org.oakgp.evolve.GenerationEvolver;
import org.oakgp.node.Node;
import org.oakgp.rank.GenerationRanker;
import org.oakgp.rank.RankedCandidates;

/** Performs a Genetic Programming run. */
public final class Runner {
   /** Private constructor as all methods are static. */
   private Runner() {
      // do nothing
   }

   /**
    * Performs a Genetic Programming run.
    *
    * @param generationRanker
    *           ranks a generation by their fitness
    * @param generationEvolver
    *           creates a new generation based on the previous generation
    * @param terminator
    *           a function that determines if the run should finish
    * @param initialPopulation
    *           the initial population that will be used as a basis for generating future generations
    * @return the final generation produced as part of this run - the best candidate of this generation can be retrieved using {@link RankedCandidates#best()}
    */
   public static RankedCandidates process(GenerationRanker generationRanker, GenerationEvolver generationEvolver, Predicate<RankedCandidates> terminator,
         Collection<Node> initialPopulation) {
      RankedCandidates rankedCandidates = generationRanker.rank(initialPopulation);
      while (!terminator.test(rankedCandidates)) {
         Collection<Node> newGeneration = generationEvolver.evolve(rankedCandidates);
         rankedCandidates = generationRanker.rank(newGeneration);
      }
      return rankedCandidates;
   }
}