/// <summary>
/// 二元计算
/// </summary>
/// <param name="left"></param>
/// <param name="right"></param>
/// <param name="op"></param>
/// <returns></returns>
public object DyadicOperation(ExpNode left, ExpNode right, string symbol)
{
IOperator iOp = OperatorFactory.GetOperator(symbol);
iOp.LeftOperand = OperandOperation(left).ToString();
iOp.RightOperand = OperandOperation(right).ToString();
return(iOp.Eval());
// return iOp.Eval(;
}
private int ReadOperator(string readStr, List <ExpNode> infixList, string operand)
{
ExpNode node = OperatorFactory.CheckOperatorSing(readStr);
if (node != null)
{
operand = operand.Trim();
if (!string.IsNullOrEmpty(operand))
{
infixList.Add(new ExpNode(operand, ExpNodeType.Operand, 0));
}
infixList.Add(node);
return(node.Text.Length);
}
return(0);
}
/// <summary>
/// 计算后缀表达式的值
/// </summary>
/// <param name="postfixList"></param>
/// <returns></returns>
public object Eval(List <ExpNode> postfixList)
{
ExpNode num1, num2;
Stack <ExpNode> num = new Stack <ExpNode>();
object result = null;
foreach (ExpNode node in postfixList)
{
if (node.NodeType == ExpNodeType.Operator)
{
num2 = num.Pop();
num1 = num.Pop();
try
{
result = DyadicOperation(num1, num2, node.Text);
ExpNode resultNode = new ExpNode(result.ToString(), ExpNodeType.Operand, 0);
num.Push(resultNode);
}
catch (Exception e)
{
throw new EExpressException("在计算" + num1.Text + node.Text + num2.Text + "时发生错误," + e.Message);
}
}
else
{
num.Push(node);
}
}
if (result == null)
{
ExpNode node = num.Pop();
if (node == null)
{
return(null);
}
result = OperandOperation(node);
}
return(result);
}
/// <summary>
/// 将操作数节点处理为操作数
/// </summary>
/// <param name="node"></param>
/// <returns></returns>
private object OperandOperation(ExpNode node)
{
object result = null;
switch (node.NodeType)
{
case ExpNodeType.Operand:
result = node.Text.ToString();
break;
case ExpNodeType.Method:
result = FunctionOperation(node.Text);
break;
default:
result = 0;
break;
}
return(result);
}
private bool IsPop(ExpNode op, Stack <ExpNode> operators)
{
if (operators.Count == 0)
{
return(false);
}
ExpNode stackTop = operators.Peek();
if (stackTop.NodeType == ExpNodeType.LeftBracket)
{
return(false);
}
if (stackTop.Level >= op.Level)
{
return(true);
}
return(false);
}
/// <summary>
/// 检查表达式首个字符开始的位置是否是运算符，是则返回这个运算符，否则返回空
/// </summary>
/// <param name="exp"></param>
/// <returns></returns>
public static ExpNode CheckOperatorSing(string exp)
{
ExpNode expNode = null;
foreach (OperatorSchema opReg in _operatorRegList.Operators)
{
string sign = opReg.Id;
if (exp.StartsWith(sign))
{
if (expNode == null)
{
expNode = new ExpNode(sign, ExpNodeType.Operator, opReg.Level);
}
else if (sign.Length > expNode.Text.Length)
{
expNode = new ExpNode(sign, ExpNodeType.Operator, opReg.Level);
}
}
}
return(expNode);
}
