c# - 在原始字符串中获取函数参数值的最佳 c# Regex 模式？

Question

我正在解析 C# 项目中的 html 代码。

假设我们有这个字符串:

<a href="javascript:func('data1','data2'...)">...</a>

或者在必要的 .subtring() 之后:

func('data1','data2'...)

什么是最好的 Regex 模式来检索 func() 的参数，避免依赖定界符(' 和 ,)，因为它们有时可能是参数字符串？

Answer 1

您不应该使用正则表达式来解析编程语言代码，因为它不是常规语言。本文解释了原因:Can regular expressions be used to match nested patterns?

---

为了证明我的观点，请允许我分享一个我认为符合您要求的正则表达式的实际解决方案:

^                               # Start of string
[^()'""]+\(                     # matches `func(`
                                #
(?>                             # START - Iterator (match each parameter)
 (?(param)\s*,(?>\s*))          # if it's not the 1st parameter, start with a `,`
 (?'param'                      # opens 'param' (main group, captures each parameter)
                                #
   (?>                          # Group: matches every char in parameter
      (?'qt'['""])              #  ALTERNATIVE 1: strings (matches ""foo"",'ba\'r','g)o\'o')
      (?:                       #   match anything inside quotes
        [^\\'""]+               #    any char except quotes or escapes
        |(?!\k'qt')['""]        #    or the quotes not used here (ie ""double'quotes"")
        |\\.                    #    or any escaped char
      )*                        #   repeat: *
      \k'qt'                    #   close quotes
   |  (?'parens'\()             #  ALTERNATIVE 2: `(` open nested parens (nested func)
   |  (?'-parens'\))            #  ALTERNATIVE 3: `)` close nested parens
   |  (?'braces'\{)             #  ALTERNATIVE 4: `{` open braces
   |  (?'-braces'})             #  ALTERNATIVE 5: `}` close braces
   |  [^,(){}\\'""]             #  ALTERNATIVE 6: anything else (var, funcName, operator, etc)
   |  (?(parens),)              #  ALTERNATIVE 7: `,` a comma if inside parens
   |  (?(braces),)              #  ALTERNATIVE 8: `,` a comma if inside braces
   )*                           # Repeat: *
                                # CONDITIONS:
  (?(parens)(?!))               #  a. balanced parens
  (?(braces)(?!))               #  b. balanced braces
  (?<!\s)                       #  c. no trailing spaces
                                #
 )                              # closes 'param'
)*                              # Repeat the whole thing once for every parameter
                                #
\s*\)\s*(?:;\s*)?               # matches `)` at the end if func(), maybe with a `;`
$                               # END

一行:

^[^()'""]+\((?>(?(param)\s*,(?>\s*))(?'param'(?>(?'qt'['""])(?:[^\\'""]+|(?!\k'qt')['""]|\\.)*\k'qt'|(?'parens'\()|(?'-parens'\))|(?'braces'\{)|(?'-braces'})|[^,(){}\\'""]|(?(parens),)|(?(braces),))*(?(parens)(?!))(?(braces)(?!))(?<!\s)))*\s*\)\s*(?:;\s*)?$

Test online

正如您现在可以想象的那样(如果您仍在阅读)，即使使用缩进模式并为每个构造添加注释，这个正则表达式也是不可读的，很难维护并且几乎不可能调试......而且我可以猜测会有异常导致它失败。

以防顽固的头脑仍然感兴趣，这是其背后逻辑的链接:Matching Nested Constructs with Balancing Groups (regular-expressions.info)