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Functional Reactive with Core Java
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/**
 * Copyright © 2017 Sven Ruppert ([email protected])
 *
 * 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.rapidpm.frp.matcher;

import java.util.function.Supplier;
import java.util.stream.Stream;

import org.rapidpm.frp.model.Pair;
import org.rapidpm.frp.model.Result;

public class Case extends Pair, Supplier>> {

  /**
   * Constructor for Case.
   *
   * @param booleanSupplier a {@link java.util.function.Supplier} object.
   * @param resultSupplier a {@link java.util.function.Supplier} object.
   */
  public Case(final Supplier booleanSupplier , final Supplier> resultSupplier) {
    super(booleanSupplier , resultSupplier);
  }

  /**
   * matchCase.
   *
   * @param condition a {@link java.util.function.Supplier} object.
   * @param value a {@link java.util.function.Supplier} object.
   * @param  a T object.
   * @return a {@link org.rapidpm.frp.matcher.Case} object.
   */
  public static  Case matchCase(Supplier condition ,
                                      Supplier> value) {
    return new Case<>(condition , value);
  }

  /**
   * matchCase.
   *
   * @param value a {@link java.util.function.Supplier} object.
   * @param  a T object.
   * @return a {@link org.rapidpm.frp.matcher.Case.DefaultCase} object.
   */
  public static  DefaultCase matchCase(Supplier> value) {
    return new DefaultCase<>(() -> true , value);
  }

  /**
   * isMatching.
   *
   * @return a boolean.
   */
  private boolean isMatching() {
    return getT1().get();
  }

  /**
   * result.
   *
   * @return a {@link org.rapidpm.frp.model.Result} object.
   */
  public Result result() {
    return getT2().get();
  }

  /**
   * match.
   *
   * @param defaultCase a {@link org.rapidpm.frp.matcher.Case.DefaultCase} object.
   * @param matchers a {@link org.rapidpm.frp.matcher.Case} object.
   * @param  a T object.
   * @return a {@link org.rapidpm.frp.model.Result} object.
   */
  @SafeVarargs
  public static  Result match(DefaultCase defaultCase , Case... matchers) {
    return Stream
        .of(matchers)
        .filter(Case::isMatching)
        .map(Case::result)
        .findFirst()
        .orElseGet(defaultCase::result);
  }

  public static class DefaultCase extends Case {
    public DefaultCase(final Supplier booleanSupplier , final Supplier> resultSupplier) {
      super(booleanSupplier , resultSupplier);
    }
  }
}