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 * Licensed to the Apache Software Foundation (ASF) under one
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 * 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
 * 
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package com.sun.star.report;

/**
 * Expressions are simple computation components.
 *
 * Expressions are always assumed to be immutable. They are not allowed to
 * change their state and it is not guaranteed, in which order they get called.
 * If the expression has been called before, the last computed value will be
 * available from the datarow.
 *
 * This construct allows us to write expressions in the form
 * "Sum := Sum + Column".
 *
 * Multiple calls to getValue on the same expression instance must return the
 * same value (assuming that the datarow passed in is the same).
 */
public interface ReportExpression
{

    void setParameters(Object[] parameters);

    Object getParameters();

    Object getValue(DataRow row);
}