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package org.hsqldb;

import org.hsqldb.ParserDQL.CompileContext;
import org.hsqldb.lib.OrderedHashSet;
import org.hsqldb.result.Result;

/**
 * Implementation of Statement for PSM and trigger assignment.
 *
 * @author Fred Toussi (fredt@users dot sourceforge.net)
 * @version 2.3.0
 * @since 2.0.1
 */
public class StatementCursor extends StatementQuery {

    public static final StatementCursor[] emptyArray = new StatementCursor[]{};

    StatementCursor(Session session, QueryExpression query,
                    CompileContext compileContext) {
        super(session, query, compileContext);
    }

    Result getResult(Session session) {

        Object[] data    = session.sessionContext.routineArguments;
        Result   current = (Result) data[data.length - 1];
        Result   head    = current;

        while (current != null) {
            if (getCursorName().name.equals(current.getMainString())) {
                current.navigator.release();

                if (head == current) {
                    head = current.getChainedResult();
                }
            }

            if (current.getChainedResult() == null) {
                break;
            }

            current = current.getChainedResult();
        }

        data[data.length - 1] = head;

        Result result = queryExpression.getResult(session, 0);

        result.setStatement(this);

        if (result.isError()) {
            return result;
        }

        result.setMainString(getCursorName().name);

        if (head == null) {
            data[data.length - 1] = result;
        } else {
            ((Result) data[data.length - 1]).addChainedResult(result);
        }

        return Result.updateZeroResult;
    }

    /**
     * always readonly
     */
    void collectTableNamesForWrite(OrderedHashSet set) {}

}
