EPPlus/FormulaParsing/Excel/Functions/RefAndLookup/Offset.cs

/* Copyright (C) 2011  Jan Källman
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.

 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU Lesser General Public License for more details.
 *
 * The GNU Lesser General Public License can be viewed at http://www.opensource.org/licenses/lgpl-license.php
 * If you unfamiliar with this license or have questions about it, here is an http://www.gnu.org/licenses/gpl-faq.html
 *
 * All code and executables are provided "as is" with no warranty either express or implied.
 * The author accepts no liability for any damage or loss of business that this product may cause.
 *
 * Code change notes:
 *
 * Author							Change						Date
 *******************************************************************************
 * Mats Alm   		                Added		                2015-01-11
 *******************************************************************************/

using System.Collections.Generic;
using System.Linq;
using OfficeOpenXml.FormulaParsing.ExpressionGraph;

namespace OfficeOpenXml.FormulaParsing.Excel.Functions.RefAndLookup;

public class Offset : LookupFunction {
  public override CompileResult Execute(
      IEnumerable<FunctionArgument> arguments,
      ParsingContext context) {
    var functionArguments = arguments as FunctionArgument[] ?? arguments.ToArray();
    ValidateArguments(functionArguments, 3);
    var startRange = ArgToString(functionArguments, 0);
    var rowOffset = ArgToInt(functionArguments, 1);
    var colOffset = ArgToInt(functionArguments, 2);
    int width = 0,
        height = 0;
    if (functionArguments.Length > 3) {
      height = ArgToInt(functionArguments, 3);
      ThrowExcelErrorValueExceptionIf(() => height == 0, eErrorType.Ref);
    }
    if (functionArguments.Length > 4) {
      width = ArgToInt(functionArguments, 4);
      ThrowExcelErrorValueExceptionIf(() => width == 0, eErrorType.Ref);
    }

    var adr = new ExcelAddress(startRange);
    var ws = adr.WorkSheet;

    var fromRow = adr._fromRow + rowOffset;
    var fromCol = adr._fromCol + colOffset;
    var toRow = (height != 0 ? height : adr._toRow) + rowOffset;
    var toCol = (width != 0 ? width : adr._toCol) + colOffset;

    var newRange = context.ExcelDataProvider.GetRange(ws, fromRow, fromCol, toRow, toCol);
    if (!newRange.IsMulti) {
      if (newRange.IsEmpty) {
        return CompileResult.Empty;
      }
      var val = newRange.GetValue(fromRow, fromCol);
      if (IsNumeric(val)) {
        return CreateResult(val, DataType.Decimal);
      }
      if (val is ExcelErrorValue) {
        return CreateResult(val, DataType.ExcelError);
      }
      return CreateResult(val, DataType.String);
    }
    return CreateResult(newRange, DataType.Enumerable);
  }
}