用于匹配嵌套括号内的特定文本的 C# 正则表达式

问题描述：

我有这些代码行用于括号之间的运算符:

I have these code lines for take to operators between parentheses:

string filtered = Regex.Replace(input, "\\(.*?\\)", string.Empty);
var result = filtered.Split(new[] { ' ' }, 
            StringSplitOptions.RemoveEmptyEntries)
            .Where(element => element == "OR" || element == "AND");    
string temp = string.Join(" ", result);

这些行不适用于嵌套括号.

These lines do not work for nested parentheses.

例如；它适用于此输入:

X1 OR ( X2 AND X3 AND X4 AND X5 ) OR X6

它给了我这个结果:OR OR

但是，当我的输入有多个嵌套括号时，它会出错.

But, when my input has more than one nested parentheses, it works wrongly.

对于这个输入:

X1 OR ( X2 AND( X3 AND X4 ) AND X5 ) OR X6

我想取结果 OR OR 但它打印 OR AND OR.

I want to take for result OR OR but it prints OR AND OR.

虽然字符串中有两个(字符，但匹配第一个)字符后结束处理.

Although there are two ( characters in string, when it ends processing after matching the first ) character.

如何调整我的正则表达式模式?

How can I adjust my regex pattern?

答

你的 \(.*?\) 正则表达式包含 3 个部分:1) \( 匹配一个文字 (, 2) .*? lazy 点匹配模式(匹配 0+ 除换行符以外的任何字符，尽可能少，直到 first ) 和 3) 匹配文字 ) 的 \).

Your \(.*?\) regex contains 3 parts: 1) \( matching a literal (, 2) .*? lazy dot matching pattern (that matches 0+ any characters other than a newline, as few as possible, up to the first ), and 3) a \) matching a literal ).

使用平衡结构 如果您字符串不能有转义序列:

@"\((?>[^()]|(?<o>)\(|(?<-o>)\))*\)(?(o)(?!))"

这里的重点是表达式不应包含任何锚点(如 什么是正则表达式平衡组).

The point here is that the expression should not be enclosed with any anchors (as in What are regular expression Balancing Groups).

详情:

\( - 文字 (
(?> - 原子组的开始以防止回溯到它
- [^()] - 除了 ( 和 )
- | - 或
- (?<o>)\( - 匹配文字 ( 并将空值压入堆栈 "o"
- | - 或
- (?<-o>)\) - 匹配文字 ) 并从堆栈 "o" 中删除一个值
- \( - a literal (
- (?> - start of an atomic group to prevent backtracking into it
  - [^()] - any char other than ( and )
  - | - or
  - (?<o>)\( - matches a literal ( and pushes an empty value into stack "o"
  - | - or
  - (?<-o>)\) - matches a literal ) and removes one value from stack "o"
  见正则表达式演示.
```
var input = "X1 OR ( X2 AND( X3 AND X4 ) AND X5 ) OR X6";
var filtered = Regex.Replace(input, @"\((?>[^()]|(?<o>)\(|(?<-o>)\))*\)(?(o)(?!))", string.Empty);
var result = filtered.Split(new[] { ' ' }, 
    StringSplitOptions.RemoveEmptyEntries)
    .Where(element => element == "OR" || element == "AND");    
var temp = string.Join(" ", result);
```
  参见 C# 演示

用于匹配嵌套括号内的特定文本的 C# 正则表达式

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