public static Queue <Symbol> ToInfixQueue(string expression)
{
if (tokenizer_regex == null)
{
Queue <string> skipped = new Queue <string>();
StringBuilder expr = new StringBuilder();
expr.Append("([\\,");
foreach (OperatorSymbol op in OperatorSymbol.Operators)
{
if (op.Name.Length > 1)
{
skipped.Enqueue(op.Name);
continue;
}
expr.Append("\\");
expr.Append(op.Name);
}
foreach (GroupSymbol gp in GroupSymbol.GroupSymbols)
{
expr.Append("\\");
expr.Append(gp.Name);
}
expr.Append("]{1}");
while (skipped.Count > 0)
{
expr.Append("|");
expr.Append(skipped.Dequeue());
}
expr.Append(")");
tokenizer_regex = new Regex(expr.ToString(), RegexOptions.IgnorePatternWhitespace);
}
string [] tokens = tokenizer_regex.Split(expression);
List <Symbol> symbol_list = new List <Symbol>();
for (int i = 0; i < tokens.Length; i++)
{
string token = tokens[i].Trim();
string next_token = null;
if (token == String.Empty)
{
continue;
}
if (i < tokens.Length - 1)
{
next_token = tokens[i + 1].Trim();
}
Symbol symbol = Symbol.FromString(token, next_token);
symbol_list.Add(symbol);
// I'm too tired to fix this at the stack/execution level right now;
// injecting void at the parsing level for zero-arg functions
if (symbol_list.Count >= 3 && GroupSymbol.IsRight(symbol) &&
GroupSymbol.IsLeft(symbol_list[symbol_list.Count - 2]) &&
symbol_list[symbol_list.Count - 3] is FunctionSymbol)
{
symbol_list.Insert(symbol_list.Count - 1, new VoidSymbol());
}
}
Queue <Symbol> queue = new Queue <Symbol>();
foreach (Symbol symbol in symbol_list)
{
queue.Enqueue(symbol);
}
return(queue);
}
public static Queue <Symbol> ToPostfixQueue(Queue <Symbol> infix)
{
Stack <Symbol> stack = new Stack <Symbol>();
Queue <Symbol> postfix = new Queue <Symbol>();
Symbol temp_symbol;
foreach (Symbol symbol in infix)
{
if (symbol is ValueSymbol)
{
postfix.Enqueue(symbol);
}
else if (GroupSymbol.IsLeft(symbol))
{
stack.Push(symbol);
}
else if (GroupSymbol.IsRight(symbol))
{
while (stack.Count > 0)
{
temp_symbol = stack.Pop();
if (GroupSymbol.IsLeft(temp_symbol))
{
break;
}
postfix.Enqueue(temp_symbol);
}
}
else
{
if (stack.Count > 0)
{
temp_symbol = stack.Pop();
while (stack.Count != 0 && OperationSymbol.Compare(temp_symbol, symbol))
{
postfix.Enqueue(temp_symbol);
temp_symbol = stack.Pop();
}
if (OperationSymbol.Compare(temp_symbol, symbol))
{
postfix.Enqueue(temp_symbol);
}
else
{
stack.Push(temp_symbol);
}
}
stack.Push(symbol);
}
}
while (stack.Count > 0)
{
postfix.Enqueue(stack.Pop());
}
return(postfix);
}