/// <summary>
/// 获取下一个计算节点
/// </summary>
/// <returns></returns>
public CalculateNode GetNextNode()
{
char ch;
switch (1)
{
case 1:
if (_currentIndex == _expressionStr.Length)
{
return(new CalculateNode(CalculationSymbol.EOF));
}
ch = _expressionStr[_currentIndex++];
if (ch == ' ')
{
goto case 1;
}
else if (ch == '(')
{
return(new CalculateNode(CalculationSymbol.OpenBracket));
}
else if (ch == ')')
{
return(new CalculateNode(CalculationSymbol.CloseBracket));
}
else if (ch == '+')
{
return(new CalculateNode(CalculationSymbol.Add));
}
else if (ch == '-')
{
return(new CalculateNode(CalculationSymbol.Sub));
}
else if (ch == '*')
{
return(new CalculateNode(CalculationSymbol.Mul));
}
else if (ch == '/')
{
return(new CalculateNode(CalculationSymbol.Div));
}
else if (char.IsDigit(ch))
{
_currentIndex--;
goto case 2;
}
else
{
throw new MathEvaluatorException();
}
case 2:
var node = new CalculateNode(CalculationSymbol.Number);
var dotIndex = _currentIndex + 1;
while (dotIndex < _expressionStr.Length && char.IsDigit(_expressionStr[dotIndex]))
{
dotIndex++;
}
while (_currentIndex < _expressionStr.Length && char.IsDigit(ch = _expressionStr[_currentIndex]))
{
var digit = ch - 48;
if (digit > 0)
{
node.Value += _m1[digit - 1, dotIndex - _currentIndex - 1];
}
_currentIndex++;
}
if (ch == ',' || ch == '.')
{
_currentIndex++;
while (_currentIndex < _expressionStr.Length && char.IsDigit(ch = _expressionStr[_currentIndex]))
{
var digit = ch - 48;
if (digit > 0)
{
node.Value += _m2[digit - 1, _currentIndex - dotIndex - 1];
}
_currentIndex++;
}
}
return(node);
}
}
/// <summary> /// 获取下一个计算节点 /// </summary> private void NextNode() => _node = _parser.GetNextNode();
