/// <summary>
/// 计算表达式
/// </summary>
public CSymbol Evaluate(){
Stack operandStack = new Stack();
foreach(CSymbol s in m_postfix)
{
if (s.type == CSymbol.Type.Value)
{
operandStack.Push(s);
}
else if (s.type == CSymbol.Type.Operator)
{
CSymbol op3 = new CSymbol(); //结果标识符
CSymbol op1, op2; //操作数
switch (s.name)
{
case "+":
op2 = (CSymbol)operandStack.Pop();
op1 = (CSymbol)operandStack.Pop();
op3 = EvaluateAddition(op1, op2);
break;
case "-":
op2 = (CSymbol)operandStack.Pop();
op1 = (CSymbol)operandStack.Pop();
op3 = EvaluateSubtraction(op1, op2);
break;
case "*":
op2 = (CSymbol)operandStack.Pop();
op1 = (CSymbol)operandStack.Pop();
op3 = EvaluateMultiplication(op1, op2);
break;
case "/":
op2 = (CSymbol)operandStack.Pop();
op1 = (CSymbol)operandStack.Pop();
op3 = EvaluateDivision(op1, op2);
break;
case "==":
op2 = (CSymbol)operandStack.Pop();
op1 = (CSymbol)operandStack.Pop();
op3 = EvaluateEquals(op1, op2);
break;
case "!=":
op2 = (CSymbol)operandStack.Pop();
op1 = (CSymbol)operandStack.Pop();
op3 = EvaluateNEquals(op1, op2);
break;
case ">":
op2 = (CSymbol)operandStack.Pop();
op1 = (CSymbol)operandStack.Pop();
op3 = EvaluateGreaterThan(op1, op2);
break;
case "<":
op2 = (CSymbol)operandStack.Pop();
op1 = (CSymbol)operandStack.Pop();
op3 = EvaluateLessThan(op1, op2);
break;
case ">=":
op2 = (CSymbol)operandStack.Pop();
op1 = (CSymbol)operandStack.Pop();
op3 = EvaluateGreaterThanEqual(op1, op2);
break;
case "<=":
op2 = (CSymbol)operandStack.Pop();
op1 = (CSymbol)operandStack.Pop();
op3 = EvaluateLessThanEqual(op1, op2);
break;
case "AND":
op2 = (CSymbol)operandStack.Pop();
op1 = (CSymbol)operandStack.Pop();
op3 = EvaluateAnd(op1, op2);
break;
case "OR":
op2 = (CSymbol)operandStack.Pop();
op1 = (CSymbol)operandStack.Pop();
op3 = EvaluateOr(op1, op2);
break;
case "NOT":
op1 = (CSymbol)operandStack.Pop();
op3 = EvaluateNot(op1);
break;
default:
throw new Exception("Invalid operator:" + s.name);
}
operandStack.Push(op3);
}
else if (s.type == CSymbol.Type.Param)
{
CSymbol op3 = new CSymbol();
op3.type = CSymbol.Type.Value;
//读取变量的值
op3.value = ParseToSymbol(m_params[s.name].value1.ToString()).value;
operandStack.Push(op3);
continue;
}
}
CSymbol returnValue = (CSymbol)operandStack.Pop();
if (operandStack.Count > 0)
throw new Exception("Invalid Expression");
return returnValue;
}
/// <summary>
/// 计算流（Flow）表达式的值
/// 返回值：真假
/// </summary>
public bool Evaluate(){
CSymbol v = m_ExpressionEvaluator.Evaluate();
return Convert.ToBoolean(v.value);
}
