public IToken CreateTree(Stack <IToken> postfix)
{
postfix = Reverse(postfix);
Stack <IToken> stack = new Stack <IToken>();
IToken token;
while (postfix.Count > 0)
{
token = postfix.Pop();
if (token is IOperandToken || token == ControlToken.FuncParamStart)
{
stack.Push(token);
}
else if (token is InfixOperationToken)
{
InfixOperationToken infixOp = (InfixOperationToken)token;
infixOp.Operand2 = stack.Pop();
infixOp.Operand1 = stack.Pop();
stack.Push(infixOp);
}
else if (token is PrefixOperationToken)
{
PrefixOperationToken prefixOp = (PrefixOperationToken)token;
for (IToken t = stack.Pop(); t != ControlToken.FuncParamStart; t = stack.Pop())
{
prefixOp.Operands.Insert(0, t);
}
stack.Push(prefixOp);
}
}
return(stack.Pop());
}
public Stack <IToken> BuildStack(Queue <IToken> queue)
{
IToken token;
Stack <IToken> postfix = new Stack <IToken>();
Stack <IToken> stack = new Stack <IToken>();
while (queue.Count > 0)
{
token = queue.Dequeue();
if (token == ControlToken.Comma)
{
//pop stack to postfix until we see left parenthesis
while (stack.Count > 0 && stack.Peek() != ControlToken.LeftParenthesis)
{
postfix.Push(stack.Pop());
}
if (stack.Count == 0)
{
throw new StackException("misplace comma or missing left parenthesis");
}
else
{
continue;
}
}
// if it is an operand, put it on the postfix stack
if (token is IOperandToken)
{
postfix.Push(token);
}
if (token == ControlToken.LeftParenthesis)
{
stack.Push(token);
}
else if (token == ControlToken.RightParenthesis)
{
while (stack.Count > 0 && stack.Peek() != ControlToken.LeftParenthesis)
{
postfix.Push(stack.Pop());
}
if (stack.Count == 0)
{
throw new StackException("missing left parenthesis");
}
else
{
stack.Pop();
}
}
else if (token is PrefixOperationToken)
{
stack.Push(token);
postfix.Push(ControlToken.FuncParamStart);
}
else if (token is InfixOperationToken)
{
if (stack.Count == 0 || stack.Peek() == ControlToken.LeftParenthesis)
{
stack.Push(token);
}
else
{
InfixOperationToken infix = (InfixOperationToken)token;
while (stack.Count > 0 &&
stack.Peek() != ControlToken.LeftParenthesis &&
(stack.Peek() is PrefixOperationToken ||
stack.Peek() is InfixOperationToken &&
infix.Precedence <= ((InfixOperationToken)stack.Peek()).Precedence))
{
postfix.Push(stack.Pop());
}
stack.Push(token);
}
}
}
while (stack.Count > 0)
{
token = stack.Pop();
if (token == ControlToken.LeftParenthesis)
{
throw new TokenParsingException("unbalance paranthesis");
}
else
{
postfix.Push(token);
}
}
return(postfix);
}
