EPPlus/FormulaParsing/Excel/Operators/OperatorsDict.cs

/*******************************************************************************
 * You may amend and distribute as you like, but don't remove this header!
 *
 * EPPlus provides server-side generation of Excel 2007/2010 spreadsheets.
 * See http://www.codeplex.com/EPPlus for details.
 *
 * 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       		        2013-03-01 (Prior file history on https://github.com/swmal/ExcelFormulaParser)
 *******************************************************************************/
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace OfficeOpenXml.FormulaParsing.Excel.Operators
{
    public class OperatorsDict : Dictionary<string, IOperator>
    {
        public OperatorsDict()
        {
            Add("+", Operator.Plus);
            Add("-", Operator.Minus);
            Add("*", Operator.Multiply);
            Add("/", Operator.Divide);
            Add("^", Operator.Exp);
            Add("=", Operator.Eq);
            Add(">", Operator.GreaterThan);
            Add(">=", Operator.GreaterThanOrEqual);
            Add("<", Operator.LessThan);
            Add("<=", Operator.LessThanOrEqual);
            Add("<>", Operator.NotEqualsTo);
            Add("&", Operator.Concat);
        }

        private static IDictionary<string, IOperator> _instance;

        public static IDictionary<string, IOperator> Instance
        {
            get 
            {
                if (_instance == null)
                {
                    _instance = new OperatorsDict();
                }
                return _instance;
            }
        }
    }
}