content: /**
   * 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.apache.aurora.scheduler.resources;
  
  import com.google.common.primitives.Longs;
  
  /**
   * Converts Aurora resource values to/from generic (String) representation.
   * @param <T> Resource value type to convert.
   */
  public interface AuroraResourceConverter<T> {
    /**
     * Parses resource value from the string representation.
     *
     * @param value String value to parse.
     * @return Resource value of type {@code T}.
     */
    T parseFrom(String value);
  
    /**
     * Converts resource of type {@code T} to its string representation.
     *
     * @param value Resource value to stringify.
     * @return String representation of the resource value.
     */
    default String stringify(Object value) {
      return value.toString();
    }
  
    /**
     * Gets resource quantity.
     *
     * @param value Value to quantify.
     * @return Resource quantity.
     */
    Double quantify(Object value);
  
    /**
     * Converts resource quantity to matching resource value type (if such conversion exists).
     *
     * @param value Resource quantity.
     * @return Value of type T.
     */
    T valueOf(Double value);
  
    LongConverter LONG = new LongConverter();
    DoubleConverter DOUBLE = new DoubleConverter();
    StringConverter STRING = new StringConverter();
  
    class LongConverter implements AuroraResourceConverter<Long> {
      @Override
      public Long parseFrom(String value) {
        return Longs.tryParse(value);
      }
  
      @Override
      public Double quantify(Object value) {
        return (double) (long) value;
      }
  
      @Override
      public Long valueOf(Double value) {
        return value.longValue();
      }
    }
  
    class DoubleConverter implements AuroraResourceConverter<Double> {
      @Override
      public Double parseFrom(String value) {
        return Double.parseDouble(value);
      }
  
      @Override
      public Double quantify(Object value) {
        return (Double) value;
      }
  
      @Override
      public Double valueOf(Double value) {
        return value;
      }
    }
  
    class StringConverter implements AuroraResourceConverter<String> {
      @Override
      public String parseFrom(String value) {
        return value;
      }
  
      @Override
      public Double quantify(Object value) {
        return 1.0;
      }
  
      @Override
      public String valueOf(Double value) {
        throw new UnsupportedOperationException("Unsupported for string resource types");
      }
    }
  }
  