AppsheetEpplus/FormulaParsing/Excel/Functions/Database/DatabaseFunction.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		                2015-04-19
 *******************************************************************************/

using System.Collections.Generic;
using System.Globalization;
using System.Linq;

namespace AppsheetEpplus;

public abstract class DatabaseFunction : ExcelFunction {
  protected RowMatcher RowMatcher { get; private set; }

  public DatabaseFunction()
      : this(new()) {}

  public DatabaseFunction(RowMatcher rowMatcher) {
    RowMatcher = rowMatcher;
  }

  protected IEnumerable<double> GetMatchingValues(
      IEnumerable<FunctionArgument> arguments,
      ParsingContext context) {
    var dbAddress = arguments.ElementAt(0).ValueAsRangeInfo.Address.Address;
    //var field = ArgToString(arguments, 1).ToLower(CultureInfo.InvariantCulture);
    var field = arguments.ElementAt(1).Value;
    var criteriaRange = arguments.ElementAt(2).ValueAsRangeInfo.Address.Address;

    var db = new ExcelDatabase(context.ExcelDataProvider, dbAddress);
    var criteria = new ExcelDatabaseCriteria(context.ExcelDataProvider, criteriaRange);
    var values = new List<double>();

    while (db.HasMoreRows) {
      var dataRow = db.Read();
      if (!RowMatcher.IsMatch(dataRow, criteria)) {
        continue;
      }
      var candidate = ConvertUtil.IsNumeric(field)
          ? dataRow[(int)ConvertUtil.GetValueDouble(field)]
          : dataRow[field.ToString().ToLower(CultureInfo.InvariantCulture)];
      if (ConvertUtil.IsNumeric(candidate)) {
        values.Add(ConvertUtil.GetValueDouble(candidate));
      }
    }
    return values;
  }
}