EpplusFormulaParser/Excel/Operators/Operator.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.Collections.Frozen;
using System.Collections.Generic;
using System.Diagnostics.CodeAnalysis;

namespace EpplusFormulaParser;

public class Operator : IOperator {
  private const int _precedencePercent = 2;
  private const int _precedenceExp = 4;
  private const int _precedenceMultiplyDivide = 6;
  private const int _precedenceAddSubtract = 12;
  private const int _precedenceConcat = 15;
  private const int _precedenceComparison = 25;

  private Operator(OperatorType type, int precedence) {
    Type = type;
    Precedence = precedence;
  }

  public OperatorType Type { get; }

  public int Precedence { get; }

  public override string ToString() {
    return "Operator: " + Type;
  }

  public static IOperator Plus { get; } = new Operator(OperatorType.Plus, _precedenceAddSubtract);

  public static IOperator Minus { get; } = new Operator(OperatorType.Minus, _precedenceAddSubtract);

  public static IOperator Multiply { get; } =
      new Operator(OperatorType.Multiply, _precedenceMultiplyDivide);

  public static IOperator Divide { get; } =
      new Operator(OperatorType.Divide, _precedenceMultiplyDivide);

  public static IOperator Exp { get; } = new Operator(OperatorType.Exponentiation, _precedenceExp);

  public static IOperator Concat { get; } = new Operator(OperatorType.Concat, _precedenceConcat);

  public static IOperator GreaterThan { get; } =
      new Operator(OperatorType.GreaterThan, _precedenceComparison);

  public static IOperator Eq { get; } = new Operator(OperatorType.Equals, _precedenceComparison);

  public static IOperator NotEqualsTo { get; } =
      new Operator(OperatorType.NotEqualTo, _precedenceComparison);

  public static IOperator GreaterThanOrEqual { get; } =
      new Operator(OperatorType.GreaterThanOrEqual, _precedenceComparison);

  public static IOperator LessThan { get; } =
      new Operator(OperatorType.LessThan, _precedenceComparison);

  public static IOperator LessThanOrEqual { get; } =
      new Operator(OperatorType.LessThanOrEqual, _precedenceComparison);

  public static IOperator Percent { get; } = new Operator(OperatorType.Percent, _precedencePercent);

  private static FrozenDictionary<string, IOperator> _fromString =
      new Dictionary<string, IOperator> {
        { "+", Plus },
        { "-", Minus },
        { "*", Multiply },
        { "/", Divide },
        { "^", Exp },
        { "=", Eq },
        { ">", GreaterThan },
        { ">=", GreaterThanOrEqual },
        { "<", LessThan },
        { "<=", LessThanOrEqual },
        { "<>", NotEqualsTo },
        { "&", Concat },
      }.ToFrozenDictionary();

  public static bool TryParse(string opString, [NotNullWhen(true)] out IOperator? @operator) {
    return _fromString.TryGetValue(opString, out @operator);
  }
}