//setup and evaluate the lexedTokens, then set PreviousAnswer
public string Compute()
{
List <Token> processedTokens = ProcessBrackets(ProcessNegatives(lexedTokens));
Expression expression = new Expression(processedTokens);
Token computedValue = expression.EvaluateExpression();
PreviousAnswer.value = computedValue;
PreviousAnswer.hasBeenSet = true;
return(computedValue.NumValue.ToString());
}
//Evaluates any expression inside of brackets, then replaces the
//bracket set with that value.
List <Token> ProcessBrackets(List <Token> tokens)
{
if (HasBrackets(tokens))
{
int innerBracketStart = FindStartingBracket(tokens);
int innerBracketEnd = FindEndingBracket(tokens, innerBracketStart);
//build a list of the tokens inside ( )
List <Token> insideTokens = new List <Token>();
for (int i = innerBracketStart + 1; i < innerBracketEnd; i++)
{
insideTokens.Add(tokens[i]);
}
//evaluate, then replace with a single num token
Expression insideExpression = new Expression(insideTokens);
tokens.RemoveRange(innerBracketStart, innerBracketEnd - innerBracketStart + 1);
tokens.Insert(innerBracketStart, insideExpression.EvaluateExpression());
ProcessBrackets(tokens); //recursive call, repeat until no more bracket sets found
}
return(tokens);
}