private static IElementValue EvaluateExpression(IList <Element> data, IObjectResolver dc)
{
if (data.Count == 0)
{
return(null);
}
Stack <IElementValue> output = new Stack <IElementValue>();
for (int j = 0; j < data.Count; j++)
{
Element element = data[j];
switch (element.Type)
{
case TokenType.BinaryOperator:
ElementBinaryOperator binaryElement = (ElementBinaryOperator)element;
BinaryOperator binaryOperator = (BinaryOperator)binaryElement.Operator;
IElementValue b2 = output.Pop();
IElementValue b1 = output.Pop();
IElementValue binaryOutput = binaryOperator.Apply(b1, b2);
output.Push(binaryOutput);
break;
case TokenType.UnitaryOperator:
ElementUnitaryOperator unitaryElement = (ElementUnitaryOperator)element;
UnitaryOperator unitaryOperator = (UnitaryOperator)unitaryElement.Operator;
IElementValue u1 = output.Pop();
IElementValue unitaryOutput = unitaryOperator.Apply(u1);
output.Push(unitaryOutput);
break;
case TokenType.Function:
ElementFunction functionElement = (ElementFunction)element;
FunctionOperator functionOperator = (FunctionOperator)functionElement.Operator;
IElementValue[] paramVals = new IElementValue[functionElement.Parameters.Count];
for (int paramIndex = 0; paramIndex < functionElement.Parameters.Count; paramIndex++)
{
paramVals[paramIndex] = EvaluateExpression(functionElement.Parameters[paramIndex], dc);
}
IElementValue functionOutput = functionOperator.Apply(paramVals);
output.Push(functionOutput);
break;
case TokenType.DecimalLiteral:
case TokenType.IntegerLiteral:
case TokenType.StringLiteral:
case TokenType.BooleanLiteral:
case TokenType.Selector:
output.Push((IElementValue)element);
break;
case TokenType.OpenParenthesis:
int parenthesis = 1;
IList <Element> parenthesisElements = new List <Element>();
for (j = j + 1; j < data.Count; j++)
{
Element parenthesisElement = data[j];
if (parenthesisElement.Type == TokenType.OpenParenthesis)
{
parenthesis++;
}
else if (parenthesisElement.Type == TokenType.CloseParenthesis)
{
parenthesis--;
if (parenthesis == 0)
{
IElementValue parenthesisOutput = EvaluateExpression(parenthesisElements, dc);
output.Push(parenthesisOutput);
break;
}
}
else
{
parenthesisElements.Add(parenthesisElement);
}
}
break;
case TokenType.TernaryIf:
IElementValue ternaryIfValue = output.Pop();
if (ternaryIfValue.Type != TokenType.BooleanLiteral)
{
throw new ELException("Condition is not boolean.");
}
bool condition = (bool)ternaryIfValue.Value;
IList <Element> ternaryElements = new List <Element>();
bool elseReached = false;
for (j = j + 1; j < data.Count; j++)
{
Element conditionValue = data[j];
if (conditionValue.Type == TokenType.TernaryElse)
{
elseReached = true;
}
if (condition == true)
{
if (elseReached == true)
{
j = data.Count;
break;
}
ternaryElements.Add(conditionValue);
}
else
{
if (elseReached == true)
{
ternaryElements.Add(conditionValue);
}
}
}
IElementValue ternaryOutput = EvaluateExpression(ternaryElements, dc);
output.Push(ternaryOutput);
break;
case TokenType.Variable:
StringBuilder variableStr = new StringBuilder();
string expression;
expression = ((ElementVariable)element).Expression;
variableStr.Append(expression);
bool variableBoundryHit = false;
bool end = false;
while (j + 1 < data.Count && end == false)
{
switch (data[j + 1].Type)
{
case TokenType.Variable:
if (!variableBoundryHit)
{
end = true;
break;
}
j++;
variableStr.Append(((ElementVariable)data[j]).Expression);
variableBoundryHit = false;
break;
case TokenType.OpenBracket:
j++;
int brackets = 1;
variableBoundryHit = true;
IList <Element> bracketElements = new List <Element>();
for (j = j + 1; j < data.Count; j++)
{
Element bracketElement = data[j];
if (bracketElement.Type == TokenType.OpenBracket)
{
brackets++;
}
else if (bracketElement.Type == TokenType.CloseBracket)
{
brackets--;
if (brackets == 0)
{
IElementValue bracketOutput = EvaluateExpression(bracketElements, dc);
if (bracketOutput.Type != TokenType.IntegerLiteral &&
bracketOutput.Type != TokenType.Selector)
{
throw new ELException("Integers and Selectors can only be used as brackets indexes.");
}
variableStr.Append("[").Append(bracketOutput.Value).Append("]");
break;
}
}
else
{
bracketElements.Add(bracketElement);
}
}
break;
case TokenType.Dot:
j++;
variableBoundryHit = true;
variableStr.Append(".");
break;
default:
end = true;
break;
}
}
object value = dc.GetVariableObject(variableStr.ToString());
IElementValue elementValue;
if (value is string)
{
elementValue = new ElementLiteral(TokenType.StringLiteral, value);
}
else if (value is bool)
{
elementValue = new ElementLiteral(TokenType.BooleanLiteral, value);
}
else if (value is int)
{
elementValue = new ElementLiteral(TokenType.IntegerLiteral, value);
}
else if (value is double || value is float || value is decimal)
{
elementValue = new ElementLiteral(TokenType.DecimalLiteral, Convert.ToDouble(value));
}
else
{
elementValue = new ElementLiteral(TokenType.Object, value);
}
output.Push(elementValue);
break;
}
}
if (output.Count != 1)
{
throw new ELException("Error evaluating expression");
}
return((IElementValue)output.Pop());
}