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.InternalUtils; 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 is release 5.3, but kept in same package for compatibility. 031 * 032 * @param <T> 033 * the type of enumeration 034 */ 035public final class StringToEnumCoercion<T extends Enum> implements Coercion<String, T> 036{ 037 private final Class<T> enumClass; 038 039 private final Map<String, T> stringToEnum = CollectionFactory.newCaseInsensitiveMap(); 040 041 public StringToEnumCoercion(Class<T> enumClass) 042 { 043 this(enumClass, enumClass.getEnumConstants()); 044 } 045 046 public StringToEnumCoercion(Class<T> enumClass, T... values) 047 { 048 this.enumClass = enumClass; 049 050 for (T value : values) 051 stringToEnum.put(value.name(), value); 052 } 053 054 public T coerce(String input) 055 { 056 if (InternalUtils.isBlank(input)) 057 return null; 058 059 T result = stringToEnum.get(input); 060 061 if (result == null) 062 { 063 String message = String.format("Input '%s' does not identify a value from enumerated type %s.", input, 064 enumClass.getName()); 065 066 throw new UnknownValueException(message, new AvailableValues(enumClass.getName() + " enum constants", 067 stringToEnum)); 068 } 069 070 return result; 071 } 072 073 /** 074 * Allows an alias value (alternate) string to reference a value. 075 * 076 * @since 5.2.2 077 */ 078 public StringToEnumCoercion<T> addAlias(String alias, T value) 079 { 080 stringToEnum.put(alias, value); 081 082 return this; 083 } 084 085 public static <T extends Enum> StringToEnumCoercion<T> create(Class<T> enumClass) 086 { 087 return new StringToEnumCoercion<T>(enumClass); 088 } 089 090}