src/main/java/com/google/devtools/common/options/BoolOrEnumConverter.java

// Copyright 2014 The Bazel Authors. All rights reserved.
//
// 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 com.google.devtools.common.options;

import com.google.devtools.common.options.Converters.BooleanConverter;

/**
 * Converter that can also convert from booleans and enumerations.
 *
 * <p> This is able to additionally convert from the standard set of
 * boolean string values. If there is an overlap in values, those from
 * the underlying enumeration will be taken.
 */
public abstract class BoolOrEnumConverter<T extends Enum<T>> extends EnumConverter<T>{
  private T falseValue;
  private T trueValue;

  /**
   * You *must* implement a zero-argument constructor that delegates
   * to this constructor, passing in the appropriate parameters. This
   * comes from the base {@link EnumConverter} class.
   *
   * @param enumType The type of your enumeration; usually a class literal
   *                 like MyEnum.class
   * @param typeName The intuitive name of your enumeration, for example, the
   *                 type name for CompilationMode might be "compilation mode".
   * @param trueValue The enumeration value to associate with {@code true}.
   * @param falseValue The enumeration value to associate with {@code false}.
   */
  protected BoolOrEnumConverter(Class<T> enumType, String typeName, T trueValue, T falseValue) {
    super(enumType, typeName);
    this.trueValue = trueValue;
    this.falseValue = falseValue;
  }

  @Override
  public T convert(String input) throws OptionsParsingException {
    try {
      return super.convert(input);
    } catch (OptionsParsingException eEnum) {
      try {
        BooleanConverter booleanConverter = new BooleanConverter();
        boolean value = booleanConverter.convert(input);
        return value ? trueValue : falseValue;
      } catch (OptionsParsingException eBoolean) {
        throw eEnum;
      }
    }
  }
}