public override DCExpressionItem Clone()
{
DCOperatorExpressionItem result = (DCOperatorExpressionItem)this.MemberwiseClone();
if (this._Left != null)
{
result._Left = this._Left.Clone();
}
if (this._Right != null)
{
result._Right = this._Right.Clone();
}
return(result);
}
/// <summary>
/// 表达式元素列表的收缩
/// </summary>
/// <param name="items"></param>
/// <returns></returns>
private DCExpressionItem CollpaseItems(List <DCExpressionItem> items)
{
if (items.Count == 1)
{
return(items[0]);
}
if (items.Count == 0)
{
return(null);
}
// 特别处理减法操作
for (int iCount = 0; iCount < items.Count; iCount++)
{
if (items[iCount] is DCOperatorExpressionItem && iCount < items.Count - 1)
{
DCOperatorExpressionItem item = (DCOperatorExpressionItem)items[iCount];
if (item.Operator == DCOperatorType.Minus)
{
bool isNegative = false;
if (iCount == 0)
{
// 处于第一的位置，必然是负数操作。
isNegative = true;
}
else
{
DCExpressionItem preItem = items[iCount - 1];
if (preItem is DCOperatorExpressionItem)
{
DCOperatorExpressionItem preOper = (DCOperatorExpressionItem)preItem;
if (preOper.IsLogicExpression)
{
// 前面的元素是逻辑判断元素，是负数操作。
isNegative = true;
}
}
else if (preItem is DCGroupExpressionItem)
{
// 前面的是表达式组元素，为负数操作。
isNegative = true;
}
}
if (isNegative)
{
// 将减法转换为负数运算
item.Operator = DCOperatorType.Negative;
item.Rigth = items[iCount + 1];
items.RemoveAt(iCount + 1);
item.Priority = 0;
item.Collapsed = true;
//iCount--;
}
} //if
} //if
} //for
// 此处进行多次循环，每次循环将优先级最高的操作符元素提升层次。
// 一般来说到最后只剩下一个操作符元素。
while (items.Count > 1)
{
DCOperatorExpressionItem maxPriorityItem = null;
int maxIndex = -1;
int len = items.Count;
// 首先找到优先级最高的操作符。
for (int iCount = 0; iCount < len; iCount++)
{
DCExpressionItem item = items[iCount];
if (item.Collapsed == false && item is DCOperatorExpressionItem)
{
if (maxPriorityItem == null || maxPriorityItem.Priority < item.Priority)
{
maxPriorityItem = (DCOperatorExpressionItem)item;
maxIndex = iCount;
}
}
}//for
if (maxPriorityItem == null)
{
// 没找到要操作的运算符，则退出循环.
break;
}
if (maxIndex < items.Count - 1)
{
// 吞并右边的项目
maxPriorityItem.Rigth = items[maxIndex + 1];
items.RemoveAt(maxIndex + 1);
}
if (maxIndex > 0)
{
// 吞并左边的项目
maxPriorityItem.Left = items[maxIndex - 1];
items.RemoveAt(maxIndex - 1);
}
//if (maxPriorityItem.Operator == DCOperatorType.Minus
// && maxPriorityItem.Left == null
// && maxPriorityItem.Rigth != null)
//{
// // 将减法操作转换为负数操作
// maxPriorityItem.Operator = DCOperatorType.Negative;
//}
// 设置运算符已经被处理过了。
maxPriorityItem.Collapsed = true;
}//while
if (items.Count > 0)
{
return(items[0]);
}
return(null);
}
/// <summary>
/// 解析表达式项目
/// </summary>
/// <param name="rootItem"></param>
/// <param name="tokens"></param>
private void ParseItem(DCExpressionItem rootItem, DCTokenList tokens)
{
List <DCExpressionItem> items = new List <DCExpressionItem>();
while (tokens.MoveNext())
{
DCExpressionItem newItem = null;
DCToken token = tokens.Current;
if (token.Type == CharType.Symbol)
{
// 根据关键字 And Or 进行修复。
if (string.Equals(token.Text, "And", StringComparison.CurrentCultureIgnoreCase))
{
token.Type = CharType.MathOperator;
token.Text = "&&";
}
else if (string.Equals(token.Text, "or", StringComparison.CurrentCultureIgnoreCase))
{
token.Type = CharType.MathOperator;
token.Text = "||";
}
}
if (token.Type == CharType.Symbol)
{
// 标识符
DCToken next = tokens.NextItem;
if (next != null && next.Type == CharType.CurLeft)
{
// 函数调用
tokens.MoveNext();
DCFunctionExpressionItem func = new DCFunctionExpressionItem();
func.Name = token.Text;
ParseItem(func, tokens);
newItem = func;
newItem.Priority = 0;
}
else
{
if (string.Compare(token.Text, "true", true) == 0)
{
// 布尔值常量
newItem = new DCConstExpressionItem(true, DCValueType.Boolean);
}
else if (string.Compare(token.Text, "false", true) == 0)
{
// 布尔值常量
newItem = new DCConstExpressionItem(false, DCValueType.Boolean);
}
else
{
double dbl = 0;
if (double.TryParse(token.Text, out dbl))
{
// 数字常量
newItem = new DCConstExpressionItem(dbl, DCValueType.Number);
}
else
{
// 引用的变量
DCVariableExpressionItem var = new DCVariableExpressionItem();
var.Name = token.Text;
newItem = var;
}
}
newItem.Priority = 0;
}
}
else if (token.Type == CharType.StringConst)
{
// 字符串常量
var strV = token.Text;
if (strV != null && strV.Length >= 2)
{
if (strV[0] == '\'' || strV[0] == '"')
{
strV = strV.Substring(1, strV.Length - 2);
}
}
newItem = new DCConstExpressionItem(strV, DCValueType.String);
}
else if (token.Type == CharType.CurLeft)
{
// 左圆括号，则进行分组
DCGroupExpressionItem group = new DCGroupExpressionItem();
newItem = group;
newItem.Priority = 0;
ParseItem(group, tokens);
}
else if (token.Type == CharType.Spliter ||
token.Type == CharType.CurRight)
{
// 分隔符号或者右圆括号则退出分组
if (items == null || items.Count == 0)
{
throw new System.Exception("项目分组无效:" + this.Text);
}
if (items != null && items.Count > 0)
{
DCExpressionItem item = CollpaseItems(items);
rootItem.AddSubItem(item);
}
items = new List <DCExpressionItem>();
if (token.Type == CharType.CurRight)
{
//退出分组
break;
}
else
{
continue;
}
}
else if (token.Type == CharType.MathOperator ||
token.Type == CharType.LogicOperator)
{
// 操作符号
DCOperatorExpressionItem math = new DCOperatorExpressionItem();
math.Text = token.Text;
switch (token.Text)
{
case "+":
math.Operator = DCOperatorType.Plus;
math.Priority = 1;
break;
case "-":
math.Operator = DCOperatorType.Minus;
math.Priority = 1;
break;
case "*":
math.Operator = DCOperatorType.Multi;
math.Priority = 2;
break;
case "/":
math.Operator = DCOperatorType.Division;
math.Priority = 2;
break;
case ">":
math.Operator = DCOperatorType.Bigger;
math.Priority = 0;
math.IsLogicExpression = true;
break;
case ">=":
math.Operator = DCOperatorType.BiggerOrEqual;
math.Priority = 0;
math.IsLogicExpression = true;
break;
case "=":
math.Operator = DCOperatorType.Equal;
math.Priority = 0;
math.IsLogicExpression = true;
break;
case "==":
math.Operator = DCOperatorType.Equal;
math.Priority = 0;
math.IsLogicExpression = true;
break;
case "<":
math.Operator = DCOperatorType.Less;
math.Priority = 0;
math.IsLogicExpression = true;
break;
case "<=":
math.Operator = DCOperatorType.LessOrEqual;
math.Priority = 0;
math.IsLogicExpression = true;
break;
case "%":
math.Operator = DCOperatorType.Mod;
math.Priority = 2;
break;
case "||":
math.Operator = DCOperatorType.Or;
math.Priority = -1;
math.IsLogicExpression = true;
break;
case "&&":
math.Operator = DCOperatorType.And;
math.Priority = -1;
math.IsLogicExpression = true;
break;
case "!=":
math.Operator = DCOperatorType.Unequal;
math.Priority = 0;
math.IsLogicExpression = true;
break;
default:
throw new NotSupportedException("无效操作符:" + token.Text);
}
newItem = math;
}
else
{
throw new NotSupportedException(token.Type + ":" + token.Text);
}
items.Add(newItem);
}//while
DCExpressionItem item2 = CollpaseItems(items);
if (item2 != null)
{
rootItem.AddSubItem(item2);
}
}