    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
    015    package org.apache.tapestry5.internal.transform;
    016
    017    import org.apache.tapestry5.ioc.Invokable;
    018    import org.apache.tapestry5.ioc.OperationTracker;
    019    import 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     */
    028    public 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    }