/// <summary>
/// 計算
/// </summary>
/// <param name="Parameters">參數陣列</param>
/// <returns></returns>
public double Calculate(string[] Parameters)
{
double ret = default(double);
Queue <FormulaElement> postfixQueue = new Queue <FormulaElement>(_postfixQueue); // 取得一個複製的後序佇列副本
Stack <FormulaElement> stack = new Stack <FormulaElement>();
while (postfixQueue.Count > 0)
{
FormulaElement element = postfixQueue.Dequeue();
if (element.ElementType != FormulaElementType.Operator) // 若是運算元
{
if (element.ElementType != FormulaElementType.Constant)
{
element.Constant = Convert.ToDouble(Parameters[element.Variable]);
}
stack.Push(element);
}
else // 若為運算子
{
double operand1 = stack.Pop().Constant;
double operand2 = stack.Pop().Constant;
switch (element.Operator)
{
case '+':
stack.Push(new FormulaElement(FormulaElementType.Constant, operand2 + operand1));
break;
case '-':
stack.Push(new FormulaElement(FormulaElementType.Constant, operand2 - operand1));
break;
case '*':
stack.Push(new FormulaElement(FormulaElementType.Constant, operand2 * operand1));
break;
case '/':
stack.Push(new FormulaElement(FormulaElementType.Constant, operand2 / operand1));
break;
}
}
}
ret = stack.Pop().Constant;
return(ret);
}
/// <summary>
/// 將中序佇列轉換成後序佇列
/// </summary>
/// <param name="infixQueue"></param>
/// <returns></returns>
private Queue <FormulaElement> ConvertToPostfixQueue(Queue <FormulaElement> infixQueue)
{
Stack <FormulaElement> stack = new Stack <FormulaElement>(); // 暫存堆疊
Queue <FormulaElement> postfixQueue = new Queue <FormulaElement>(); // 存放後序運算式的佇列
string number = string.Empty;
// 依序處理中序運算式的佇列的每一個元素
while (infixQueue.Count > 0)
{
FormulaElement element = infixQueue.Dequeue();
if (element.ElementType == FormulaElementType.Constant || element.ElementType == FormulaElementType.Variable)
{
postfixQueue.Enqueue(element);
}
else
{
switch (element.Operator)
{
case '(':
stack.Push(element);
break;
case ')':
while (stack.Count > 0)
{
if (stack.Peek().Operator != '(')
{
postfixQueue.Enqueue(stack.Pop());
}
else
{
stack.Pop();
//break; // Bug 就在這裡 請移除註解，增加break; 即可修復Bug
}
}
break;
default:
if (stack.Count == 0) // 堆疊為空時
{
stack.Push(element);
}
else
{
while (stack.Count > 0)
{
if (element.IsGreaterThan(stack.Peek()))
{
break;
}
else
{
postfixQueue.Enqueue(stack.Pop());
}
}
stack.Push(element);
}
break;
}
}
}
// 將運算子堆疊
while (stack.Count > 0)
{
postfixQueue.Enqueue(stack.Pop());
}
return(postfixQueue);
}