001//
002// Copyright 2011 The Apache Software Foundation
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.internal.transform;
016
017import org.apache.tapestry5.ioc.Invokable;
018import org.apache.tapestry5.ioc.OperationTracker;
019import org.apache.tapestry5.runtime.ComponentEvent;
020
021/**
022 * Used  to encapsulate the list of {@link EventHandlerMethodParameterProvider}s for a particular
023 * method of a particular component, providing {@link OperationTracker} behavior as parameter values
024 * are obtained/computed/coerced.
025 *
026 * @since 5.3
027 */
028public class EventHandlerMethodParameterSource
029{
030    private final String methodIdentifier;
031
032    private final OperationTracker operationTracker;
033
034    private final EventHandlerMethodParameterProvider[] providers;
035
036    public EventHandlerMethodParameterSource(String methodIdentifier, OperationTracker operationTracker, EventHandlerMethodParameterProvider[] providers)
037    {
038
039        this.methodIdentifier = methodIdentifier;
040        this.operationTracker = operationTracker;
041        this.providers = providers;
042    }
043
044    public Object get(final ComponentEvent event, final int index)
045    {
046        // Hopefully this will not be too much overhead; it's really nice to be able to track what parameter
047        // caused a failure.
048
049        return operationTracker.invoke(String.format("Obtaining value for parameter #%d of %s", index + 1, methodIdentifier),
050                new Invokable<Object>()
051                {
052                    public Object invoke()
053                    {
054                        return providers[index].valueForEventHandlerMethodParameter(event);
055                    }
056                });
057    }
058}