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// 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 java.util.Arrays;
/**
* A converter superclass for converters that parse enums.
*
* <p>Just subclass this class, creating a zero aro argument constructor that
* calls {@link #EnumConverter(Class, String)}.
*
* <p>This class compares the input string to the string returned by the toString()
* method of each enum member in a case-insensitive way. Usually, this is the
* name of the symbol, but beware if you override toString()!
*/
public abstract class EnumConverter<T extends Enum<T>>
implements Converter<T> {
private final Class<T> enumType;
private final String typeName;
/**
* Creates a new enum converter. You *must* implement a zero-argument
* constructor that delegates to this constructor, passing in the appropriate
* parameters.
*
* @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".
*/
protected EnumConverter(Class<T> enumType, String typeName) {
this.enumType = enumType;
this.typeName = typeName;
}
/**
* Implements {@link #convert(String)}.
*/
@Override
public T convert(String input) throws OptionsParsingException {
for (T value : enumType.getEnumConstants()) {
if (value.toString().equalsIgnoreCase(input)) {
return value;
}
}
throw new OptionsParsingException("Not a valid " + typeName + ": '"
+ input + "' (should be "
+ getTypeDescription() + ")");
}
/**
* Implements {@link #getTypeDescription()}.
*/
@Override
public final String getTypeDescription() {
return Converters.joinEnglishList(
Arrays.asList(enumType.getEnumConstants())).toLowerCase();
}
}
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