private IEnumerable <ExcelExpressionPart> EvaluateFunctionArguments(ExcelExpression expression, ExpressionScope scope)
{
var args = new List <ExcelExpressionPart>();
ExcelExpression activeArg = null;
foreach (var item in expression)
{
if (item.TokenType == ExcelFormulaTokenType.Argument)
{
if (activeArg == null)
{
// possible optional argument -- consecutive commas
args.Add(new ExcelExpressionPart(ExcelValue.NULL));
}
else
{
args.Add(activeArg.Evaluate(scope));
}
activeArg = null;
}
else
{
if (activeArg == null)
{
activeArg = new ExcelExpression();
}
activeArg.Add(item);
}
}
if (activeArg != null)
{
args.Add(activeArg.Evaluate(scope));
}
return(args);
}
private EvaluationResult Evaluate(string name, string cell, IEnumerable <ExcelFormulaToken> tokens, ExpressionScope scope, ExpressionFormat format)
{
var result = new EvaluationResult()
{
Name = name,
Cell = cell
};
try
{
var queue = new Queue <ExcelFormulaToken>(tokens);
var excelExpression = new ExcelExpression();
TraverseExpression(excelExpression, queue, scope);
var operand = excelExpression.Evaluate(scope);
scope.Set(cell ?? name, operand.Value);
result.Value = operand.Value.InnerValue;
result.Text = operand.Value?.ToString(outputLang, format);
}
catch (Exception ex)
{
result.Error = ex.Message;
}
finally { }
return(result);
}
private void TraverseExpression(ExcelExpression expression, Queue <ExcelFormulaToken> tokens, ExpressionScope scope)
{
while (tokens.Any())
{
var token = tokens.Dequeue();
if (token.Subtype == ExcelFormulaTokenSubtype.Stop)
{
return;
}
else if (token.Subtype == ExcelFormulaTokenSubtype.Start)
{
var childExpression = new ExcelExpression();
TraverseExpression(childExpression, tokens, scope);
switch (token.Type)
{
case ExcelFormulaTokenType.Function:
var name = token.Value.ToUpper();
var args = EvaluateFunctionArguments(childExpression, scope)
.Select(o => o.Value)
.ToList();
var value = Functions.INSTANCE.Evaluate(name, args, scope);
expression.Add(new ExcelExpressionPart(value));
break;
case ExcelFormulaTokenType.Subexpression:
var subExpression = childExpression.Evaluate(scope);
expression.Add(subExpression);
break;
default:
throw new NotImplementedException($"Start TokenType={token.Type}");
}
}
else
{
expression.Add(new ExcelExpressionPart(token, scope));
}
}
}