public Expression2(string stExp)
{
this.stExp = Normalize(stExp);
lstSymbol = Str2SymbolList();
PrioritizeOperators();
expTree = SymbolLst2ExpTree(0, lstSymbol.Count() - 1);
}
private ExpNode SymbolLst2ExpTree(int start, int end)
{
if (start > end)
{
return(null);
}
while (RemoveOutestBracketPari(ref start, ref end))
{
; //use while to handle the case like (((...))), we need to remove all the 3 pairs
}
int idx = FindLowestPriOperator(start, end);
if (idx < 0)
{
//no operators, return the first symbol, should be a operand for a valid expression
return(new ExpNode(lstSymbol[start]));
}
else
{
ExpNode rootOp = new ExpNode(lstSymbol[idx]);
switch (rootOp.Value.Op)
{
case Operator.ADD:
case Operator.MINUS:
case Operator.MUL:
case Operator.DIV:
case Operator.POW:
// operator in middle, and 2 operands operators
rootOp.SubExps = new List <ExpNode>();
if (start <= idx - 1)
{
rootOp.SubExps.Add(SymbolLst2ExpTree(start, idx - 1));
}
if (idx + 1 <= end)
{
rootOp.SubExps.Add(SymbolLst2ExpTree(idx + 1, end));
}
break;
default:
// others are function like operators, i.e. func(p1, p2, ..., pn)
rootOp.SubExps = ReadFuncParameters(start, end);
break;
}
return(rootOp);
}
}
