/// <summary>
/// modified method that implements part of Shunting Yard
/// Algorithm.
///
/// //Pseudo Code
/// If token is an operator, o1 , then use pushSpew.
///
/// ===Spew part=====
/// while there is an operator token, o2, at the top of stack and :
/// either o1 is left-associative (-,+,*,/) and its priority is less
/// than or equal to o2,
/// or o1 is right-associative ( ^ ), and priority is less than o2
///
/// pop o2 off stack onto output Queue
/// end while
///
/// ====Push part====
/// push o1 onto stack
///
/// </summary>
/// <param name="output">The Queue that holds the tokens in
/// post fix notation</param>
/// <param name="tokenToPush">Incoming token to be compared with
/// stack</param>
public void pushSpew(Queue<Token> output, Token tokenToPush_o1)
{
//deals with right-associative
Token stackToken_o2 ;
if (tokenToPush_o1.Type == tokenType.POST)
{
while (stack.Count != 0 &&
((stackToken_o2 = stack.Peek()).Precedence > tokenToPush_o1.Precedence))
{
output.Enqueue(stack.Pop());
}
}
//deals with left-associative
else
{
while (stack.Count != 0 &&
((stackToken_o2 = stack.Peek()).Precedence >= tokenToPush_o1.Precedence))
{
output.Enqueue(stack.Pop());
}
}
stack.Push(tokenToPush_o1);
}
Token getNextToken(string input)
{
input = input.Trim();
Token nextTok = new Token();
//Create Regexes for each string value
Regex ARG_NUM_Regex = new Regex(@"^[0-9]*\.?[0-9]+");
//For now , variables can be any combination of letters and numbers
Regex ARG_VAR_Regex = new Regex(@"^[a-zA-Z0-9]+");
Regex DI_OP_Regex = new Regex(@"^[+|\-|\/|*]");
Regex OPEN_Regex = new Regex(@"^\(");
Regex CLOSE_Regex = new Regex(@"^\)");
Regex POST_Regex = new Regex(@"^[\^]");
//Case out matches
if (ARG_NUM_Regex.IsMatch(input))
{
nextTok.Type = tokenType.ARG_NUM;
nextTok.TokenValue = ARG_NUM_Regex.Match(input).Value;
nextTok.Precedence = 1;
}else if(ARG_VAR_Regex.IsMatch(input)){
nextTok.Type = tokenType.ARG_VAR;
nextTok.TokenValue = ARG_VAR_Regex.Match(input).Value;
nextTok.Precedence = 1;
}
else if (DI_OP_Regex.IsMatch(input))
{
nextTok.Type = tokenType.DI_OP;
nextTok.TokenValue = DI_OP_Regex.Match(input).Value;
switch (nextTok.TokenValue)
{
case "+":
case "-": nextTok.Precedence = 2; break;
case "*":
case "/": nextTok.Precedence = 3; break;
}
}
else if (OPEN_Regex.IsMatch(input))
{
nextTok.Type = tokenType.OPEN;
nextTok.Precedence = -2;
nextTok.TokenValue = "(";
}
else if (CLOSE_Regex.IsMatch(input))
{
nextTok.Type = tokenType.CLOSE;
nextTok.Precedence = -1;
nextTok.TokenValue = ")";
}else if (POST_Regex.IsMatch(input))
{
nextTok.Type = tokenType.POST;
nextTok.TokenValue = POST_Regex.Match(input).Value;
nextTok.Precedence = 4;
}
else{
Console.WriteLine("Could not regex match next token,");
nextTok.Type = tokenType.UNRECOGNIZED;
}
//set values and return token
return nextTok;
}
public void push(Token tokenToPush)
{
this.stack.Push(tokenToPush);
}
private string consume(string input, Token t)
{
return input.Substring(t.TokenValue.Length);
}
