public bool Parse(string exp)
{
m_tokens.Clear(); //清空语法单元堆栈
if (exp.Trim() == "") //表达式不能为空
{
return(false);
}
else if (!this.IsMatching(exp))//括号、引号、单引号等必须配对
{
return(false);
}
Stack <object> operands = new Stack <object>(); //操作数堆栈
Stack <Operator> operators = new Stack <Operator>(); //运算符堆栈
OperatorType optType = OperatorType.ERR; //运算符类型
string curOpd = ""; //当前操作数
string curOpt = ""; //当前运算符
int curPos = 0; //当前位置
//int funcCount = 0; //函数数量
curPos = FindOperator(exp, "");
exp += "@"; //结束操作符
while (true)
{
curPos = FindOperator(exp, "");
curOpd = exp.Substring(0, curPos).Trim();
curOpt = exp.Substring(curPos, 1);
//////////////测试代码///////////////////////////////////
//System.Diagnostics.Debug.WriteLine("***************");
//System.Diagnostics.Debug.WriteLine("当前读取的操作数：" + curOpd);
//foreach (var item in operands.ToArray())
//{
// if (item is Operand)
// {
// System.Diagnostics.Debug.WriteLine("操作数栈：" + ((Operand)item).Value);
// }
// if (item is Operator)
// {
// System.Diagnostics.Debug.WriteLine("操作数栈：" + ((Operator)item).Value);
// }
//}
//System.Diagnostics.Debug.WriteLine("当前读取的运算符：" + curOpt);
//foreach (var item in operators.ToArray())
//{
// System.Diagnostics.Debug.WriteLine("运算符栈：" + item.Value);
//}
////////////////////////////////////////////////////////
//存储当前操作数到操作数堆栈
if (curOpd != "")
{
operands.Push(new Operand(curOpd, curOpd));
}
//若当前运算符为结束运算符，则停止循环
if (curOpt == "@")
{
break;
}
//若当前运算符为左括号,则直接存入堆栈。
if (curOpt == "(")
{
operators.Push(new Operator(OperatorType.LB, "("));
exp = exp.Substring(curPos + 1).Trim();
continue;
}
//若当前运算符为右括号,则依次弹出运算符堆栈中的运算符并存入到操作数堆栈,直到遇到左括号为止,此时抛弃该左括号.
if (curOpt == ")")
{
while (operators.Count > 0)
{
if (operators.Peek().Type != OperatorType.LB)
{
operands.Push(operators.Pop());
}
else
{
operators.Pop();
break;
}
}
exp = exp.Substring(curPos + 1).Trim();
continue;
}
//调整运算符
curOpt = Operator.AdjustOperator(curOpt, exp, ref curPos);
optType = Operator.ConvertOperator(curOpt);
//若运算符堆栈为空,或者若运算符堆栈栈顶为左括号,则将当前运算符直接存入运算符堆栈.
if (operators.Count == 0 || operators.Peek().Type == OperatorType.LB)
{
operators.Push(new Operator(optType, curOpt));
exp = exp.Substring(curPos + 1).Trim();
continue;
}
//若当前运算符优先级大于运算符栈顶的运算符,则将当前运算符直接存入运算符堆栈.
if (Operator.ComparePriority(optType, operators.Peek().Type) > 0)
{
operators.Push(new Operator(optType, curOpt));
}
else
{
//若当前运算符若比运算符堆栈栈顶的运算符优先级低或相等，则输出栈顶运算符到操作数堆栈，直至运算符栈栈顶运算符低于（不包括等于）该运算符优先级，
//或运算符栈栈顶运算符为左括号
//并将当前运算符压入运算符堆栈。
while (operators.Count > 0)
{
if (Operator.ComparePriority(optType, operators.Peek().Type) <= 0 && operators.Peek().Type != OperatorType.LB)
{
operands.Push(operators.Pop());
if (operators.Count == 0)
{
operators.Push(new Operator(optType, curOpt));
break;
}
}
else
{
operators.Push(new Operator(optType, curOpt));
break;
}
}
}
exp = exp.Substring(curPos + 1).Trim();
}
//转换完成,若运算符堆栈中尚有运算符时,
//则依序取出运算符到操作数堆栈,直到运算符堆栈为空
while (operators.Count > 0)
{
operands.Push(operators.Pop());
}
//调整操作数栈中对象的顺序并输出到最终栈
while (operands.Count > 0)
{
m_tokens.Push(operands.Pop());
}
return(true);
}
