001// Copyright 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.ioc.internal;
016
017import org.apache.tapestry5.commons.ObjectLocator;
018import org.apache.tapestry5.commons.services.TypeCoercer;
019
020/**
021 * A proxy for the {@link TypeCoercer}
022 * 
023 * @since 5.3
024 */
025public final class TypeCoercerProxyImpl implements TypeCoercerProxy
026{
027    private final ObjectLocator locator;
028
029    private TypeCoercer delegate;
030
031    public TypeCoercerProxyImpl(ObjectLocator locator)
032    {
033        this.locator = locator;
034    }
035
036    private TypeCoercer delegate()
037    {
038        if (delegate == null)
039            delegate = locator.getService(TypeCoercer.class);
040
041        return delegate;
042    }
043
044    @Override
045    public <S, T> T coerce(S input, Class<T> targetType)
046    {
047        if (targetType.isInstance(input))
048            return targetType.cast(input);
049
050        return delegate().coerce(input, targetType);
051    }
052
053}