001// Copyright 2007, 2008, 2010, 2011 The Apache Software Foundation 002// 003// Licensed under the Apache License, Version 2.0 (the "License"); 004// you may not use this file except in compliance with the License. 005// You may obtain a copy of the License at 006// 007// http://www.apache.org/licenses/LICENSE-2.0 008// 009// Unless required by applicable law or agreed to in writing, software 010// distributed under the License is distributed on an "AS IS" BASIS, 011// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 012// See the License for the specific language governing permissions and 013// limitations under the License. 014 015package org.apache.tapestry5.util; 016 017import java.util.Map; 018 019import org.apache.tapestry5.ioc.internal.util.CollectionFactory; 020import org.apache.tapestry5.ioc.internal.util.InternalCommonsUtils; 021import org.apache.tapestry5.ioc.services.Coercion; 022import org.apache.tapestry5.ioc.util.AvailableValues; 023import org.apache.tapestry5.ioc.util.UnknownValueException; 024 025/** 026 * A {@link org.apache.tapestry5.ioc.services.Coercion} for converting strings into an instance of a particular 027 * enumerated type. The {@link Enum#name() name} is used as the key to identify the enum instance, in a case-insensitive 028 * fashion. 029 * <p> 030 * Moved from tapestry-core to tapestry-ioc in release 5.3, but kept in same package for compatibility. 031 * Moved tapestry-ioc to commons in release 5.4, but kept in same package for compatibility. 032 * 033 * @param <T> 034 * the type of enumeration 035 */ 036public final class StringToEnumCoercion<T extends Enum> implements Coercion<String, T> 037{ 038 private final Class<T> enumClass; 039 040 private final Map<String, T> stringToEnum = CollectionFactory.newCaseInsensitiveMap(); 041 042 public StringToEnumCoercion(Class<T> enumClass) 043 { 044 this(enumClass, enumClass.getEnumConstants()); 045 } 046 047 public StringToEnumCoercion(Class<T> enumClass, T... values) 048 { 049 this.enumClass = enumClass; 050 051 for (T value : values) 052 stringToEnum.put(value.name(), value); 053 } 054 055 @Override 056 public T coerce(String input) 057 { 058 if (InternalCommonsUtils.isBlank(input)) 059 return null; 060 061 T result = stringToEnum.get(input); 062 063 if (result == null) 064 { 065 String message = String.format("Input '%s' does not identify a value from enumerated type %s.", input, 066 enumClass.getName()); 067 068 throw new UnknownValueException(message, new AvailableValues(enumClass.getName() + " enum constants", 069 stringToEnum)); 070 } 071 072 return result; 073 } 074 075 /** 076 * Allows an alias value (alternate) string to reference a value. 077 * 078 * @since 5.2.2 079 */ 080 public StringToEnumCoercion<T> addAlias(String alias, T value) 081 { 082 stringToEnum.put(alias, value); 083 084 return this; 085 } 086 087 public static <T extends Enum> StringToEnumCoercion<T> create(Class<T> enumClass) 088 { 089 return new StringToEnumCoercion<T>(enumClass); 090 } 091 092}