EPPlus/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;
using System.Collections.Generic;
using System.Globalization;
using System.Linq;
using System.Text;
using OfficeOpenXml.Utils;

namespace OfficeOpenXml.FormulaParsing.Excel.Functions.Database
{
    public abstract class DatabaseFunction : ExcelFunction
    {
        protected RowMatcher RowMatcher { get; private set; }

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

        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;
        }
    }
}