AppsheetEpplus/FormulaParsing/ExpressionGraph/FunctionExpression.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.Linq;

namespace AppsheetEpplus;

/// <summary>
/// Expression that handles execution of a function.
/// </summary>
public class FunctionExpression : AtomicExpression {
  /// <summary>
  /// Constructor
  /// </summary>
  /// <param name="expression">should be the of the function</param>
  /// <param name="parsingContext"></param>
  /// <param name="isNegated">True if the numeric result of the function should be negated.</param>
  public FunctionExpression(string expression, ParsingContext parsingContext, bool isNegated)
      : base(expression) {
    _parsingContext = parsingContext;
    _functionCompilerFactory = new(parsingContext.Configuration.FunctionRepository);
    _isNegated = isNegated;
    base.AddChild(new FunctionArgumentExpression(this));
  }

  private readonly ParsingContext _parsingContext;
  private readonly FunctionCompilerFactory _functionCompilerFactory;
  private readonly bool _isNegated;

  public override CompileResult Compile() {
    try {
      var function = _parsingContext.Configuration.FunctionRepository.GetFunction(ExpressionString);
      if (function == null) {
        if (_parsingContext.Debug) {
          _parsingContext.Configuration.Logger.Log(
              _parsingContext,
              string.Format("'{0}' is not a supported function", ExpressionString));
        }
        return new(ExcelErrorValue.Create(eErrorType.Name), DataType.ExcelError);
      }
      if (_parsingContext.Debug) {
        _parsingContext.Configuration.Logger.LogFunction(ExpressionString);
      }
      var compiler = _functionCompilerFactory.Create(function);
      var result = compiler.Compile(HasChildren ? Children : [], _parsingContext);
      if (_isNegated) {
        if (!result.IsNumeric) {
          if (_parsingContext.Debug) {
            var msg = string.Format(
                "Trying to negate a non-numeric value ({0}) in function '{1}'",
                result.Result,
                ExpressionString);
            _parsingContext.Configuration.Logger.Log(_parsingContext, msg);
          }
          return new(ExcelErrorValue.Create(eErrorType.Value), DataType.ExcelError);
        }
        return new(result.ResultNumeric * -1, result.DataType);
      }
      return result;
    } catch (ExcelErrorValueException e) {
      if (_parsingContext.Debug) {
        _parsingContext.Configuration.Logger.Log(_parsingContext, e);
      }
      return new(e.ErrorValue, DataType.ExcelError);
    }
  }

  public override Expression PrepareForNextChild() {
    return base.AddChild(new FunctionArgumentExpression(this));
  }

  public override bool HasChildren => (Children.Any() && Children.First().Children.Any());

  public override Expression AddChild(Expression child) {
    Children.Last().AddChild(child);
    return child;
  }
}