1 // Copyright 2014 The Bazel Authors. All rights reserved. 2 // 3 // Licensed under the Apache License, Version 2.0 (the "License"); 4 // you may not use this file except in compliance with the License. 5 // You may obtain a copy of the License at 6 // 7 // http://www.apache.org/licenses/LICENSE-2.0 8 // 9 // Unless required by applicable law or agreed to in writing, software 10 // distributed under the License is distributed on an "AS IS" BASIS, 11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 // See the License for the specific language governing permissions and 13 // limitations under the License. 14 15 package com.google.devtools.common.options; 16 17 import java.util.Arrays; 18 19 /** 20 * A converter superclass for converters that parse enums. 21 * 22 * <p>Just subclass this class, creating a zero argument constructor that 23 * calls {@link #EnumConverter(Class, String)}. 24 * 25 * <p>This class compares the input string to the string returned by the toString() 26 * method of each enum member in a case-insensitive way. Usually, this is the 27 * name of the symbol, but beware if you override toString()! 28 */ 29 public abstract class EnumConverter<T extends Enum<T>> 30 implements Converter<T> { 31 32 private final Class<T> enumType; 33 private final String typeName; 34 35 /** 36 * Creates a new enum converter. You *must* implement a zero-argument 37 * constructor that delegates to this constructor, passing in the appropriate 38 * parameters. 39 * 40 * @param enumType The type of your enumeration; usually a class literal 41 * like MyEnum.class 42 * @param typeName The intuitive name of your enumeration, for example, the 43 * type name for CompilationMode might be "compilation mode". 44 */ 45 protected EnumConverter(Class<T> enumType, String typeName) { 46 this.enumType = enumType; 47 this.typeName = typeName; 48 } 49 50 /** 51 * Implements {@link #convert(String)}. 52 */ 53 @Override 54 public T convert(String input) throws OptionsParsingException { 55 for (T value : enumType.getEnumConstants()) { 56 if (value.toString().equalsIgnoreCase(input)) { 57 return value; 58 } 59 } 60 throw new OptionsParsingException("Not a valid " + typeName + ": '" 61 + input + "' (should be " 62 + getTypeDescription() + ")"); 63 } 64 65 /** 66 * Implements {@link #getTypeDescription()}. 67 */ 68 @Override 69 public final String getTypeDescription() { 70 return Converters.joinEnglishList( 71 Arrays.asList(enumType.getEnumConstants())).toLowerCase(); 72 } 73 74 } 75
