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 *  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
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package org.apache.cayenne;

import java.util.List;

/**
 * Defines API of an iterator over the records returned as a result of
 * Select queries execution. Usually a ResultIterator is supported by an open
 * java.sql.ResultSet, therefore ResultIterators must be explicitly closed when
 * the user is done working with them. An alternative to that is
 * {@link ObjectContext#iterate(org.apache.cayenne.query.Select, ResultIteratorCallback)}
 * method that handles resource management.
 *
 * @since 3.0
 */
public interface ResultIterator<T> extends Iterable<T>, AutoCloseable {

    /**
     * Returns all yet unread rows from ResultSet without closing it.
     * 
     * @since 3.0
     */
    List<T> allRows();

    /**
     * Returns true if there is at least one more record that can be read from
     * the iterator.
     */
    boolean hasNextRow();

    /**
     * Returns the next result row that is, depending on the query, may be a
     * scalar value, a DataRow, or an Object[] array containing a mix of scalars
     * and DataRows.
     * 
     * @since 3.0
     */
    T nextRow();

    /**
     * Goes past current row. If the row is not needed, this may save some time
     * on data conversion.
     * 
     * @since 3.0
     */
    void skipRow();

    /**
     * Closes ResultIterator and associated ResultSet. This method must be
     * called explicitly when the user is finished processing the records.
     * Otherwise unused database resources will not be released properly.
     */
    void close();
}