EPPlus/FormulaParsing/ExpressionGraph/FunctionCompilers/IfFunctionCompiler.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       		        2014-01-27
 *******************************************************************************/

using System;
using System.Collections.Generic;
using System.Linq;
using OfficeOpenXml.FormulaParsing.Excel.Functions;
using OfficeOpenXml.FormulaParsing.Excel.Functions.Logical;
using OfficeOpenXml.FormulaParsing.Exceptions;
using OfficeOpenXml.FormulaParsing.Utilities;
using OfficeOpenXml.Utils;
using Require = OfficeOpenXml.FormulaParsing.Utilities.Require;

namespace OfficeOpenXml.FormulaParsing.ExpressionGraph.FunctionCompilers;

/// <summary>
/// Why do the If function require a compiler of its own you might ask;)
///
/// It is because it only needs to evaluate one of the two last expressions. This
/// compiler handles this - it ignores the irrelevant expression.
/// </summary>
public class IfFunctionCompiler : FunctionCompiler {
  public IfFunctionCompiler(ExcelFunction function)
      : base(function) {
    Require.That(function).Named("function").IsNotNull();
    if (!(function is If)) {
      throw new ArgumentException("function must be of type If");
    }
  }

  public override CompileResult Compile(IEnumerable<Expression> children, ParsingContext context) {
    if (children.Count() < 3) {
      throw new ExcelErrorValueException(eErrorType.Value);
    }
    var args = new List<FunctionArgument>();
    Function.BeforeInvoke(context);
    var firstChild = children.ElementAt(0);
    var v = firstChild.Compile().Result;

    /****  Handle names and ranges ****/
    if (v is ExcelDataProvider.INameInfo) {
      v = ((ExcelDataProvider.INameInfo)v).Value;
    }

    if (v is ExcelDataProvider.IRangeInfo) {
      var r = ((ExcelDataProvider.IRangeInfo)v);
      if (r.GetNCells() > 1) {
        throw (new ArgumentException("Logical can't be more than one cell"));
      }
      v = r.GetOffset(0, 0);
    }
    bool boolVal;
    if (v is bool) {
      boolVal = (bool)v;
    } else {
      if (ConvertUtil.IsNumeric(v)) {
        boolVal = ConvertUtil.GetValueDouble(v) != 0;
      } else {
        throw (new ArgumentException("Invalid logical test"));
      }
    }
    /****  End Handle names and ranges ****/

    args.Add(new(boolVal));
    if (boolVal) {
      var val = children.ElementAt(1).Compile().Result;
      args.Add(new(val));
      args.Add(new(null));
    } else {
      var val = children.ElementAt(2).Compile().Result;
      args.Add(new(null));
      args.Add(new(val));
    }
    return Function.Execute(args, context);
  }
}