// GPars - Groovy Parallel Systems
//
// Copyright © 2008-11  The original author or authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//       http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package groovyx.gpars.dataflow.expression;

import org.codehaus.groovy.runtime.InvokerHelper;

/**
 * A DFE, which evaluates a property when the receiver becomes available
 *
 * @author Alex Tkachman
 */
public class DataflowGetPropertyExpression<T> extends DataflowExpression<T> {
    private static final long serialVersionUID = 2984824057556784227L;
    private final DataflowExpression<T> receiver;
    private final String name;

    public DataflowGetPropertyExpression(final DataflowExpression<T> expression, final String name) {
        this.receiver = expression;
        this.name = name;
        subscribe();
    }

    @Override
    protected void subscribe(final DataflowExpressionsCollector listener) {
        listener.subscribe(receiver);
    }

    /**
     * Retrieves the receiver's property value
     */
    @Override
    @SuppressWarnings("unchecked")
    protected T evaluate() {
        //noinspection unchecked
        return (T) InvokerHelper.getProperty(receiver.value, name);
    }
}
