AppsheetEpplus/FormulaParsing/ExpressionGraph/ExpressionGraph.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.Generic;

namespace AppsheetEpplus;

public class ExpressionGraph {
  private readonly List<Expression> _expressions = new();

  public IEnumerable<Expression> Expressions => _expressions;

  public Expression Current { get; private set; }

  public Expression Add(Expression expression) {
    _expressions.Add(expression);
    if (Current != null) {
      Current.Next = expression;
      expression.Prev = Current;
    }
    Current = expression;
    return expression;
  }

  public void Reset() {
    _expressions.Clear();
    Current = null;
  }

  public void Remove(Expression item) {
    if (item == Current) {
      Current = item.Prev ?? item.Next;
    }
    _expressions.Remove(item);
  }
}