//Methods
public ITokenable Parse()
{
while (indexString < input.Length - 1)
{
ReadNextChar();
if (double.TryParse(currentChar.ToString(), out _) || currentChar == '.')
{
//this is a number, use a while loop to build the token, storing the value as a string for now
string numberString = "";
//numbers can optionally contain a single decimal point, but no more than that, use a bool to track
bool isDecimal = false;
//if the number input started with a period
if (currentChar == '.')
{
numberString = "0";
isDecimal = true;
}
while ((int.TryParse(currentChar.ToString(), out _) || currentChar == '.') && indexString < input.Length - 1)
{
numberString += currentChar;
ReadNextChar();
if (currentChar == '.')
{
//the user is attempting to add a decilmal, which might be acceptable
if (!isDecimal)
{
//this is the first decimal, that's ok
numberString += currentChar;
isDecimal = true;
if (indexString < input.Length - 1)
{
ReadNextChar();
}
}
else
{
//the user is attempting to add a second decimal to the number, throw an error
throw new Exception("You can only have one decimal point in the same number.");
}
}
}
//the current character isn't a number, so the numberToken's value is now complete.
double.TryParse(numberString, out double value);
numToken = new NumberToken(value);
AddTokenToChain(numToken);
}
switch (currentChar)
{
case '+':
//This an addition opperator
token = new OperatorToken(Expression.Add);
AddTokenToChain(token);
break;
case 'π':
case 'p':
//This is adding pi, it will add three token, including open and close parentheses
openToken = new OperatorToken(Expression.OpenParenthesis);
numToken = new NumberToken(3.1416d);
closeToken = new OperatorToken(Expression.CloseParenthesis);
AddTokenToChain(openToken);
AddTokenToChain(numToken);
AddTokenToChain(closeToken);
break;
case 'e':
//This is adding e, it will add three token, including open and close parentheses
openToken = new OperatorToken(Expression.OpenParenthesis);
numToken = new NumberToken(2.71828d);
closeToken = new OperatorToken(Expression.CloseParenthesis);
AddTokenToChain(openToken);
AddTokenToChain(numToken);
AddTokenToChain(closeToken);
break;
case 'α':
case 'a':
//This is adding alpha, it will add three token, including open and close parentheses
openToken = new OperatorToken(Expression.OpenParenthesis);
numToken = new NumberToken(2.5029d);
closeToken = new OperatorToken(Expression.CloseParenthesis);
AddTokenToChain(openToken);
AddTokenToChain(numToken);
AddTokenToChain(closeToken);
break;
case 'δ':
case 'd':
//This is adding delta, it will add three token, including open and close parentheses
openToken = new OperatorToken(Expression.OpenParenthesis);
numToken = new NumberToken(4.6692d);
closeToken = new OperatorToken(Expression.CloseParenthesis);
AddTokenToChain(openToken);
AddTokenToChain(numToken);
AddTokenToChain(closeToken);
break;
case 'ζ':
case 'z':
//This is adding zeta, it will add three token, including open and close parentheses
openToken = new OperatorToken(Expression.OpenParenthesis);
numToken = new NumberToken(1.20206d);
closeToken = new OperatorToken(Expression.CloseParenthesis);
AddTokenToChain(openToken);
AddTokenToChain(numToken);
AddTokenToChain(closeToken);
break;
case 'φ':
case 'f':
//This is adding phi, it will add three token, including open and close parentheses
openToken = new OperatorToken(Expression.OpenParenthesis);
numToken = new NumberToken(1.618d);
closeToken = new OperatorToken(Expression.CloseParenthesis);
AddTokenToChain(openToken);
AddTokenToChain(numToken);
AddTokenToChain(closeToken);
break;
case 'γ':
case 'g':
//This is adding phi, it will add three token, including open and close parentheses
openToken = new OperatorToken(Expression.OpenParenthesis);
numToken = new NumberToken(0.57721d);
closeToken = new OperatorToken(Expression.CloseParenthesis);
AddTokenToChain(openToken);
AddTokenToChain(numToken);
AddTokenToChain(closeToken);
break;
case '-':
//This a subtraction opperator
token = new OperatorToken(Expression.Subtract);
AddTokenToChain(token);
break;
case '*':
//This a multiply opperator
token = new OperatorToken(Expression.Multiply);
AddTokenToChain(token);
break;
case '/':
//This a division opperator
token = new OperatorToken(Expression.Divide);
AddTokenToChain(token);
break;
case '^':
//This an exponent opperator
token = new OperatorToken(Expression.Exponent);
AddTokenToChain(token);
break;
case '(':
//This an openParenthesis token, but not really an operator
token = new OperatorToken(Expression.OpenParenthesis);
AddTokenToChain(token);
parenthesesBalance++;
break;
case ')':
//This ac closeParenthesis token
token = new OperatorToken(Expression.CloseParenthesis);
AddTokenToChain(token);
parenthesesBalance--;
if (parenthesesBalance < 0)
{
throw new Exception("You must close all parentheses.");
}
break;
case '=':
//Error for bad input
if (parenthesesBalance != 0)
{
throw new Exception("You must close all parentheses.");
}
//this is the end of the equation
Executor executor = new Executor(FirstToken);
executor.SimplifyExpression();
Value = executor.Value;
IsComplete = true;
break;
default:
if (!Int32.TryParse(currentChar.ToString(), out _) && currentChar != '.')
{
throw new SyntaxError("Invalid input: " + currentChar);
}
break;
}
}
return(CurrentToken);
}
public ITokenable SimplifyExpression()
{
currentToken = firstToken;
//Since the order of operations are stored as enums we can use this value to track which expressions
//need to be worked on now. The max value is the last operator on the enum list.
int orderOfOperations = 0;
int maxOperation = (int)Enum.GetValues(typeof(Expression)).Cast <Expression>().Max() - 3;
//A first pass must be made to check for open parenthesis
while (currentToken != null && currentToken.Expression != Expression.CloseParenthesis)
{
if (currentToken.Expression == Expression.OpenParenthesis)
{
//A new open parenthesis has been found, send the next token to avoid infinite method calls
Executor executor = new Executor(currentToken.NextToken);
ITokenable newToken = executor.SimplifyExpression();
if (newToken.PreviousToken == null)
{
firstToken = newToken;
}
currentToken = newToken;
//If this is true we just came out of parentheses, they should have been removed from the chain so this resets the chain
if (firstToken.Expression == Expression.OpenParenthesis)
{
firstToken = currentToken;
}
}
currentToken = currentToken.NextToken;
}
//Now we will loop through the order of operations.
do
{
currentToken = firstToken;
while (currentToken != null && currentToken.Expression != Expression.CloseParenthesis)
{
//Check each token to see if the expression equals the current order of operation
if ((int)currentToken.Expression == orderOfOperations)
{
//The operator matches the current operator that we are looking for.
//Binary and unary operations are handled differently
if (orderOfOperations > 1)
{
//A binary operation acts on the two numbers before and after it, changing the value of the
//previous number and then removing the operator and the second number from the link list of nodes.
NumberToken firstOperand = (NumberToken)currentToken.PreviousToken;
firstOperand.Value = currentToken.Evaluation();
firstOperand.NextToken = currentToken.NextToken.NextToken;
if (firstOperand.NextToken != null)
{
firstOperand.NextToken.PreviousToken = firstOperand;
}
currentToken = firstOperand;
}
else
{
//This is a unary operation, the operand will be updated and this token removed from the link list
NumberToken operand = (NumberToken)currentToken.NextToken;
operand.Value = currentToken.Evaluation();
operand.PreviousToken = currentToken.PreviousToken;
if (operand.PreviousToken != null)
{
operand.PreviousToken.NextToken = operand;
}
//If the unary operator was the first token in the chain we need to update that
if (firstToken == currentToken)
{
firstToken = operand;
}
currentToken = operand;
}
}
currentToken = currentToken.NextToken;
}
//Iterate to the next order of operation
orderOfOperations++;
} while (orderOfOperations <= maxOperation);
//At this point there is either only one token in the link chain or we have parentheses that need cleaning up
if (firstToken.Expression == Expression.OpenParenthesis && firstToken.PreviousToken == null)
{
firstToken = firstToken.NextToken;
firstToken.PreviousToken = null;
}
if (firstToken.PreviousToken != null && firstToken.PreviousToken.Expression == Expression.OpenParenthesis)
{
//This code cleans up the open parenthesis
//If a number is next to a parenthesis then the parenthesis needs to be converted into a multiply operator,
//if an operator is there then just delete this parenthesis from the chain, if it is null then delete this token.
if (firstToken.PreviousToken.PreviousToken != null)
{
if (firstToken.PreviousToken.PreviousToken.Expression != Expression.Number)
{
//Delete parenthesis token, linking the next number token into the chain.
firstToken.PreviousToken = firstToken.PreviousToken.PreviousToken;
firstToken.PreviousToken.NextToken = firstToken;
}
else
{
//The previous token is a number, convert the parenthesis token into a multiply token
firstToken.PreviousToken.Expression = Expression.Multiply;
}
}
else
{
//Delete parenthesis token, there is nothing before it.
firstToken.PreviousToken = null;
}
//Clean up the close parenthesis
//Now find the close parenthesis (either the second or third token in the sub-chain we are working on) and apply similar logic
currentToken = firstToken;
while (currentToken.Expression != Expression.CloseParenthesis)
{
currentToken = currentToken.NextToken;
}
if (currentToken.NextToken != null)
{
if (currentToken.NextToken.Expression == Expression.Number || currentToken.NextToken.Expression == Expression.OpenParenthesis)
{
currentToken.Expression = Expression.Multiply;
}
else
{
//The next token is an operator, just delete this
currentToken.PreviousToken.NextToken = currentToken.NextToken;
currentToken.NextToken.PreviousToken = currentToken.PreviousToken;
currentToken.NextToken = null;
currentToken.PreviousToken = null;
}
}
else
{
//This is the end of the chain
currentToken.PreviousToken.NextToken = null;
}
}
Value = firstToken.Evaluation();
return(firstToken);
}
