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 *   Licensed to the Apache Software Foundation (ASF) under one
 *  or more contributor license agreements.  See the NOTICE file
 *  distributed with this work for additional information
 *  regarding copyright ownership.  The ASF licenses this file
 *  to you 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 org.apache.cayenne.access.util;

import java.io.IOException;
import java.io.PrintWriter;
import java.io.StringWriter;
import java.util.List;

import org.apache.cayenne.CayenneException;
import org.apache.cayenne.CayenneRuntimeException;
import org.apache.cayenne.ResultIterator;
import org.apache.cayenne.query.Query;

/**
 * OperationObserver that is used to track the execution of SelectQueries with
 * results returned as ResultIterator.
 * 
 */
public class IteratedSelectObserver extends DefaultOperationObserver {
    protected ResultIterator resultIterator;

    @Override
    public boolean isIteratedResult() {
        return true;
    }

    @Override
    public void nextRows(Query query, List<?> dataRows) {
        throw new CayenneRuntimeException("Results unexpectedly returned as list.");
    }

    @Override
    public void nextRows(Query q, ResultIterator it) {
        // don't call super - it closes the iterator
        resultIterator = it;
    }

    public ResultIterator getResultIterator() {
        if (super.hasExceptions()) {
            StringWriter str = new StringWriter();
            PrintWriter out = new PrintWriter(str);
            super.printExceptions(out);

            try {
                out.close();
                str.close();
            } catch (IOException ioex) {
                // this should never happen
            }

            throw new CayenneRuntimeException("Error getting ResultIterator: %s", str.getBuffer());
        }

        return resultIterator;
    }

}