用除括號外的子字符串分割字符串

Question

我們如何用“和”分割后面的內容。

field = "a > b and b = 0 and (f = 1 and g = 2)"

這樣做， field.Split(" and ")將返回 4 個字符串，其中我們將在其中包含括號

a > b
b = 0
(f = 1 
g = 2)

我只想要 3 個字符串，由外部 "and" 拆分：

a > b
b = 0
(f = 1 and g = 2)

也嘗試了各種 Regex 選項，但沒有運氣。

Answer 1

即使您有嵌套的平衡括號，您也可以使用

\s*\band\b\s* # whole word and enclosed with 0+ whitespaces
(?=           # start of a positive lookahead:   
  (?: 
    [^()]*    # 0 or more chars other than ( and )
    \((?>[^()]+|(?<o>\()|(?<-o>\)))*(?(o)(?!))\)  # a (...) substring with nested parens support
  )*          # repeat the sequence of above two patterns 0 or more times
  [^()]*$     # 0 or more chars other than ( and ) and end of string  
)             # end of the positive lookahead

請參閱正則表達式演示。

查看C# 片段：

var text = "a > b and b = 0 and (f = 1 and (g = 2 and j = 68) and v = 566) and a > b and b = 0 and (f = 1 and g = 2)";
var pattern = @"(?x)
        var pattern = @"(?x)
\s*\band\b\s* # whole word and enclosed with 0+ whitespaces
(?=           # start of a positive lookahead:   
  (?: 
    [^()]*    # 0 or more chars other than ( and )
    \((?>[^()]+|(?<o>\()|(?<-o>\)))*(?(o)(?!))\)  # a (...) substring with nested parens support
  )*          # repeat the sequence of above two patterns 0 or more times
  [^()]*$     # 0 or more chars other than ( and ) and end of string  
)             # end of the positive lookahead";
var results = Regex.Split(text, pattern);

輸出：

a > b
b = 0
(f = 1 and (g = 2 and j = 68) and v = 566)
a > b
b = 0
(f = 1 and g = 2)