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 org.apache.tapestry5.ValueEncoder;
018import org.apache.tapestry5.ioc.internal.util.InternalUtils;
019import org.apache.tapestry5.ioc.services.TypeCoercer;
020
021/**
022 * A value encoder that can be used for arbitrary Enum types. The enum name is stored as the client side value.
023 */
024public class EnumValueEncoder<E extends Enum<E>> implements ValueEncoder<E>
025{
026    private final TypeCoercer typeCoercer;
027
028    private final Class<E> enumType;
029
030    public EnumValueEncoder(TypeCoercer typeCoercer, final Class<E> enumType)
031    {
032        assert enumType != null;
033
034        this.typeCoercer = typeCoercer;
035        this.enumType = enumType;
036    }
037
038    public String toClient(E value)
039    {
040        if (value == null)
041            return null;
042
043        return value.name();
044    }
045
046    public E toValue(String clientValue)
047    {
048        if (InternalUtils.isBlank(clientValue))
049            return null;
050
051        return typeCoercer.coerce(clientValue, enumType);
052    }
053
054}