📄 evaluator.cs
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tokenEvalTime = evalTime.Elapsed.TotalMilliseconds;
token.LastEvaluationTime = tokenEvalTime; // set this evaluation time in the token object.
return true;
*/
#endregion
}
#endregion
#region Private Methods
private bool EvaluateTokens(Parser.TokenItem LeftOperand, Parser.TokenItem RightOperand, Parser.TokenItem Operator, out Parser.TokenItem Result, out string ErrorMsg)
{
// intitialize the outgoing variables
Result = null;
ErrorMsg = "";
// local variables
double dResult = 0;
bool boolResult = false;
// validate the parameters
if (LeftOperand == null)
{
ErrorMsg = "Failed to evaluate the operator: The left token is null.";
return false;
}
if (RightOperand == null)
{
ErrorMsg = "Failed to evaluate the operator: The right token is null.";
return false;
}
if (Operator == null)
{
ErrorMsg = "Failed to evaluate the operator: The operator token is null.";
return false;
}
switch (Operator.TokenName.Trim().ToLower())
{
case "^":
#region Exponents
// Exponents require that both operands can be converted to doubles
try
{
if ((Support.DataTypeCheck.IsDouble(LeftOperand.TokenName) == true) && (Support.DataTypeCheck.IsDouble(RightOperand.TokenName) == true))
{
dResult = Math.Pow(LeftOperand.TokenName_Double, RightOperand.TokenName_Double);
Result = new Parser.TokenItem(dResult.ToString(), Parser.TokenType.Token_Operand, EvaluationEngine.Parser.TokenDataType.Token_DataType_Double, LeftOperand.InOperandFunction);
}
else
{
ErrorMsg = "Syntax Error: Expecting numeric values for exponents.";
return false;
}
}
catch (Exception err)
{
ErrorMsg = "Failed to evaluate the Exponent operator: " + err.Message;
return false;
}
break;
#endregion
case "*":
#region Multiplication
// multiplication expects that the operands can be converted to doubles
try
{
if ((Support.DataTypeCheck.IsDouble(LeftOperand.TokenName) == true) && (Support.DataTypeCheck.IsDouble(RightOperand.TokenName) == true))
{
dResult = LeftOperand.TokenName_Double * RightOperand.TokenName_Double;
Result = new Parser.TokenItem(dResult.ToString(), Parser.TokenType.Token_Operand, EvaluationEngine.Parser.TokenDataType.Token_DataType_Double, LeftOperand.InOperandFunction);
}
else
{
ErrorMsg = "Syntax Error: Expecting numeric values to multiply.";
return false;
}
}
catch (Exception err)
{
ErrorMsg = "Failed to evaluate the Multiplication operator: " + err.Message;
return false;
}
break;
#endregion
case "/":
#region Division
// divison requires that both operators can be converted to doubles and the denominator is not 0
try
{
if ((Support.DataTypeCheck.IsDouble(LeftOperand.TokenName) == true) && (Support.DataTypeCheck.IsDouble(RightOperand.TokenName) == true))
{
double denominator = RightOperand.TokenName_Double;
if (denominator != 0)
{
dResult = LeftOperand.TokenName_Double / denominator;
Result = new Parser.TokenItem(dResult.ToString(), Parser.TokenType.Token_Operand, EvaluationEngine.Parser.TokenDataType.Token_DataType_Double, LeftOperand.InOperandFunction);
}
else
{
ErrorMsg = "Syntax Error: Division by zero.";
return false;
}
}
else
{
ErrorMsg = "Syntax Error: Expecting numeric values to divide.";
return false;
}
}
catch (Exception err)
{
ErrorMsg = "Failed to evaluate the Division operator: " + err.Message;
return false;
}
break;
#endregion
case "%":
#region Modulus
try
{
// modulus expects that both operators are numeric and the right operand is not zero
if ((Support.DataTypeCheck.IsDouble(LeftOperand.TokenName) == true) && (Support.DataTypeCheck.IsDouble(RightOperand.TokenName) == true))
{
double denominator = RightOperand.TokenName_Double;
if (denominator != 0)
{
dResult = LeftOperand.TokenName_Double % RightOperand.TokenName_Double;
Result = new Parser.TokenItem(dResult.ToString(), Parser.TokenType.Token_Operand, EvaluationEngine.Parser.TokenDataType.Token_DataType_Double, LeftOperand.InOperandFunction);
}
else
{
ErrorMsg = "Syntax Error: Modulus by zero.";
return false;
}
}
else
{
ErrorMsg = "Syntax Error: Expecting numeric values to modulus.";
return false;
}
}
catch (Exception err)
{
ErrorMsg = "Failed to evaluate the Modulus operator: " + err.Message;
return false;
}
break;
#endregion
case "+":
#region Addition
try
{
// addition only works on numeric operands
if ((Support.DataTypeCheck.IsDouble(LeftOperand.TokenName) == true) && (Support.DataTypeCheck.IsDouble(RightOperand.TokenName) == true))
{
dResult = LeftOperand.TokenName_Double + RightOperand.TokenName_Double;
Result = new Parser.TokenItem(dResult.ToString(), Parser.TokenType.Token_Operand, EvaluationEngine.Parser.TokenDataType.Token_DataType_Double, LeftOperand.InOperandFunction);
}
else
{
ErrorMsg = "Syntax Error: Expecting numeric values to add.";
return false;
}
}
catch (Exception err)
{
ErrorMsg = "Failed to evaluate the Addition operator: " + err.Message;
return false;
}
break;
#endregion
case "-":
#region Subtraction
try
{
// subtraction only works on numeric operands
if ((Support.DataTypeCheck.IsDouble(LeftOperand.TokenName) == true) && (Support.DataTypeCheck.IsDouble(RightOperand.TokenName) == true))
{
dResult = LeftOperand.TokenName_Double - RightOperand.TokenName_Double;
Result = new Parser.TokenItem(dResult.ToString(), Parser.TokenType.Token_Operand, EvaluationEngine.Parser.TokenDataType.Token_DataType_Double, LeftOperand.InOperandFunction);
}
else
{
ErrorMsg = "Syntax Error: Expecting numeric values to subtract.";
return false;
}
}
catch (Exception err)
{
ErrorMsg = "Failed to evaluate the Subtraction operator: " + err.Message;
return false;
}
break;
#endregion
case "<":
#region Less Than
if ((Support.DataTypeCheck.IsDouble(LeftOperand.TokenName) == true) && (Support.DataTypeCheck.IsDouble(RightOperand.TokenName) == true))
{
try
{
// do a numeric comparison
boolResult = (LeftOperand.TokenName_Double < RightOperand.TokenName_Double);
Result = new Parser.TokenItem(boolResult.ToString().ToLower(), Parser.TokenType.Token_Operand, EvaluationEngine.Parser.TokenDataType.Token_DataType_Boolean, LeftOperand.InOperandFunction);
}
catch (Exception err)
{
ErrorMsg = "Failed to evaluate the Less Than operator on double operands: " + err.Message;
return false;
}
}
else if ((Support.DataTypeCheck.IsDate(LeftOperand.TokenName) == true) && (Support.DataTypeCheck.IsDate(RightOperand.TokenName) == true))
{
try
{
// do a date comparison
TimeSpan ts = LeftOperand.TokenName_DateTime.Subtract(RightOperand.TokenName_DateTime);
boolResult = (ts.TotalDays < 0);
Result = new Parser.TokenItem(boolResult.ToString().ToLower(), Parser.TokenType.Token_Operand, EvaluationEngine.Parser.TokenDataType.Token_DataType_Boolean, LeftOperand.InOperandFunction);
}
catch (Exception err)
{
ErrorMsg = "Failed to evaluate the Less Than operator on date operands: " + err.Message;
return false;
}
}
else
{
try
{
// do a string comparison
string lText = Support.DataTypeCheck.RemoveTextQuotes(LeftOperand.TokenName);
string rText = Support.DataTypeCheck.RemoveTextQuotes(RightOperand.TokenName);
boolResult = (lText.CompareTo(rText) < 0);
Result = new Parser.TokenItem(boolResult.ToString().ToLower(), Parser.TokenType.Token_Operand, EvaluationEngine.Parser.TokenDataType.Token_DataType_Boolean, LeftOperand.InOperandFunction);
}
catch (Exception err)
{
ErrorMsg = "Failed to evaluate the Less Than operator on string operands: " + err.Message;
return false;
}
}
break;
#endregion
case "<=":
#region Less Than Equal To
if ((Support.DataTypeCheck.IsDouble(LeftOperand.TokenName) == true) && (Support.DataTypeCheck.IsDouble(RightOperand.TokenName) == true))
{
try
{
// do a numeric comparison
boolResult = (LeftOperand.TokenName_Double <= RightOperand.TokenName_Double);
Result = new Parser.TokenItem(boolResult.ToString().ToLower(), Parser.TokenType.Token_Operand, EvaluationEngine.Parser.TokenDataType.Token_DataType_Boolean, LeftOperand.InOperandFunction);
}
catch (Exception err)
{
ErrorMsg = "Failed to evaluate the Less Than or Equal to operator on double operands: " + err.Message;
return false;
}
}
else if ((Support.DataTypeCheck.IsDate(LeftOperand.TokenName) == true) && (Support.DataTypeCheck.IsDate(RightOperand.TokenName) == true))
{
try
{
// do a date comparison
TimeSpan ts = LeftOperand.TokenName_DateTime.Subtract(RightOperand.TokenName_DateTime);
boolResult = (ts.TotalDays <= 0);
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