Perl的正则表达式mathjax语法

Question

我做一个Perl的正则表达式的问题改变\字符遵循以下规则：

1. 的匹配序列应该用\(
2. 开始它应与\)
3. 任何\结束前一匹配序列中的字符应替换为双反斜杠\\

示例文本参考：

Se la \probabilità dell'evento\ A è \(\frac{3}{4} \) e la 
probabilità dell'evento B è \(\frac{1}{4}\)  
\(\frac{3}{4} +\frac{3}{4}\) . 
\(\frac{1}{4} - \frac{3}{4}\) . 
\(\frac{3}{16}\) . 
\(\frac{1}{2}\) . 

应该改为：

Se la \probabilità dell'evento\ A è \\(\\frac{3}{4} \\) e la 
probabilità dell'evento B è \\(\\frac{1}{4}\\)  
\\(\\frac{3}{4} +\\frac{3}{4}\\) . 
\\(\\frac{1}{4} - \\frac{3}{4}\\) . 
\\(\\frac{3}{16}\\) . 
\\(\\frac{1}{2}\\) . 

到目前为止，这是我最好的选择：

s/(\\\()(.*)(\\)(.*)(\\\))/\\\\\($2\\\\$4\\\\\)/mg 

主要生产：

Se la \probabilità dell'evento\ A è \\(\\frac{3}{4} \\) e la 
probabilità dell'evento B è \\(\\frac{1}{4}\\)  
\\(\frac{3}{4} +\\frac{3}{4}\\) . 
\\(\frac{1}{4} - \\frac{3}{4}\\) . 
\\(\\frac{3}{16}\\) . 
\\(\\frac{1}{2}\\) . 

，你可以见

\\(\frac{3}{4} +\\frac{3}{4}\\) . 
\\(\frac{1}{4} - \\frac{3}{4}\\) . 

是错误的。

如何修改我的正则表达式以适应我的需求？

Answer 1

发布从我原来的一个更新的正则表达式。

原来的验证结果为所有逃脱。
看了之后，它可以通过一次确认
找到开始块来加快速度。

底部是一个比较两种方法的基准。

更新的正则表达式：

$str =~ s/(?s)(?:(?!\A)\G(?!\))[^\\]*\K\\|\\(?=\(.*?\\\)))/\\\\/g;

Formatted and tested:

(?s)    # Dot-All modifier 
(?:    # Cluster start 
     (?! \A)   # Not beginning of string 
     \G     # G anchor - If matched before, start at end of last match 
     (?! \))   # Last was an escape, so ')' ends the block 
     [^\\]*    # Many non-escape's 
     \K     # Previous is not part of match 
     \\     # A lone escape 
    |     # or, 
         # New Block Check - 
     \\     # A lone escape then, 
     (?=    # One time Validation: 
      \(    # an opening '(' 
      .*?    # anything 
      \\ \)    # then a final '\)' 
    )     # ------------- 
)     # Cluster end 

基准：

样品\(\\\\\\\\\\\\\\\\\\\\\\\\\\\\\ \)

个

结果

New Regex: (?s)(?:(?!\A)\G(?!\))[^\\]*\K\\|\\(?=\(.*?\\\))) 
Options: <none> 
Completed iterations: 50/50  (x 1000) 
Matches found per iteration: 31 
Elapsed Time: 1.25 s, 1253.92 ms, 1253924 µs 


Old Regex: (?s)(?:(?!\A)\G[^\\]*\K\\|\\(?=\())(?=.*?(?<=\\)\)) 
Options: <none> 
Completed iterations: 50/50  (x 1000) 
Matches found per iteration: 31 
Elapsed Time: 3.95 s, 3952.31 ms, 3952307 µs 

Answer 2

我测试@sln正则表达式

s/(?x)(?:(?!\A)\G[^\\]*\K\\|\\(?=\())(?=.*?(?<=\\)\))/\\\\/g; 

而且似乎工作，但它仍然是一个神秘的谜给我。

更新与解释

Formatted and tested:

(?s)    # Inline Dot-All modifier 
(?:    # Cluster start 
     (?! \A)   # Not beginning of string 
     \G     # G anchor - If matched before, start at end of last match 
     [^\\]*    # Many non-escape's 
     \K     # Previous is not part of match 
     \\     # A lone escape 
    |     # or, 
         # Start of an opening '\(' 
     \\     # A lone escape 
     (?= \()   # followed by an open parenth 
)     # Cluster end 
(?=    # Lookahead, each match validates a final '\)' 
     .*? 
     (?<= \\) 
     \) 
)