/* ====================================================================
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Licensed to the Apache Software Foundation (ASF) Under one or more
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contributor license agreements. See the NOTICE file distributed with
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this work for Additional information regarding copyright ownership.
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The ASF licenses this file to You Under the Apache License, Version 2.0
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(the "License"); you may not use this file except in compliance with
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the License. You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed Under the License is distributed on an "AS Is" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations Under the License.
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==================================================================== */
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namespace HH.WMS.Utils.NPOI.SS.Formula.Functions
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{
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using System;
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using HH.WMS.Utils.NPOI.SS.Formula.Eval;
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using HH.WMS.Utils.NPOI.SS.Formula;
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/**
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* For most Excel functions, involving references ((cell, area), (2d, 3d)), the references are
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* passed in as arguments, and the exact location remains fixed. However, a select few Excel
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* functions have the ability to access cells that were not part of any reference passed as an
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* argument.<br/>
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* Two important functions with this feature are <b>INDIRECT</b> and <b>OFFSet</b><p/>
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*
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* In POI, the <c>HSSFFormulaEvaluator</c> Evaluates every cell in each reference argument before
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* calling the function. This means that functions using fixed references do not need access to
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* the rest of the workbook to execute. Hence the <c>Evaluate()</c> method on the common
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* interface <c>Function</c> does not take a workbook parameter.
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*
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* This interface recognises the requirement of some functions to freely Create and Evaluate
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* references beyond those passed in as arguments.
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*
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* @author Josh Micich
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*/
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public interface FreeRefFunction
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{
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/**
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* @param args the pre-Evaluated arguments for this function. args is never <code>null</code>,
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* nor are any of its elements.
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* @param ec primarily used to identify the source cell Containing the formula being Evaluated.
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* may also be used to dynamically create reference evals.
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* @return never <code>null</code>. Possibly an instance of <c>ErrorEval</c> in the case of
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* a specified Excel error (Exceptions are never thrown to represent Excel errors).
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*/
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ValueEval Evaluate(ValueEval[] args, OperationEvaluationContext ec);
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}
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}
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