Golang正则表达式替换不包括带引号的字符串

Question

I'm trying to implement the removeComments function in Golang from this Javascript implementation. I'm hoping to remove any comments from the text. For example:

/* this is comments, and should be removed */

However, "/* this is quoted, so it should not be removed*/"

In the Javascript implementation, quoted matching are not captured in groups, so I can easily filter them out. However, in Golang, it seems it's not easy to tell whether the matched part is captured in a group or not. So how can I implement the same removeComments logic in Golang as the same in the Javascript version?

Answer 1

These do not preserve formatting

---

Preferred way (produces a NULL if group 1 is not matched)
works in golang playground -

     # https://play.golang.org/p/yKtPk5QCQV
     # fmt.Println(reg.ReplaceAllString(txt, "$1"))
     # (?:/\*[^*]*\*+(?:[^/*][^*]*\*+)*/|//[^
]*(?:
|$))|("[^"\\]*(?:\\[\S\s][^"\\]*)*"|'[^'\\]*(?:\\[\S\s][^'\\]*)*'|[\S\s][^/"'\\]*)

     (?:                              # Comments 
          /\*                              # Start /* .. */ comment
          [^*]* \*+
          (?: [^/*] [^*]* \*+ )*
          /                                # End /* .. */ comment
       |  
          //  [^
]*                       # Start // comment
          (?: 
 | $ )                     # End // comment
     )
  |  
     (                                # (1 start), Non - comments 
          "
          [^"\\]*                          # Double quoted text
          (?: \\ [\S\s] [^"\\]* )*
          "
       |  
          '
          [^'\\]*                          # Single quoted text
          (?: \\ [\S\s] [^'\\]* )*
          ' 
       |  [\S\s]                           # Any other char
          [^/"'\\]*                        # Chars which doesn't start a comment, string, escape, or line continuation (escape + newline)
     )                                # (1 end)

Alternative way (group 1 is always matched, but could be empty)
works in golang playground -

 # https://play.golang.org/p/7FDGZSmMtP
 # fmt.Println(reg.ReplaceAllString(txt, "$1"))
 # (?:/\*[^*]*\*+(?:[^/*][^*]*\*+)*/|//[^
]*(?:
|$))?((?:"[^"\\]*(?:\\[\S\s][^"\\]*)*"|'[^'\\]*(?:\\[\S\s][^'\\]*)*'|[\S\s][^/"'\\]*)?)     

 (?:                              # Comments 
      /\*                              # Start /* .. */ comment
      [^*]* \*+
      (?: [^/*] [^*]* \*+ )*
      /                                # End /* .. */ comment
   |  
      //  [^
]*                       # Start // comment
      (?: 
 | $ )                     # End // comment
 )?
 (                                # (1 start), Non - comments 
      (?:
           "
           [^"\\]*                          # Double quoted text
           (?: \\ [\S\s] [^"\\]* )*
           "
        |  
           '
           [^'\\]*                          # Single quoted text
           (?: \\ [\S\s] [^'\\]* )*
           ' 
        |  [\S\s]                           # Any other char
           [^/"'\\]*                        # Chars which doesn't start a comment, string, escape, or line continuation (escape + newline)
      )?
 )                                # (1 end)

---

The Cadilac - Preserves Formatting

(Unfortunately, this can't be done in Golang because Golang cannot do Assertions)
Posted incase you move to a different regex engine.

     # raw:   ((?:(?:^[ \t]*)?(?:/\*[^*]*\*+(?:[^/*][^*]*\*+)*/(?:[ \t]*?
(?=[ \t]*(?:?
|/\*|//)))?|//(?:[^\\]|\\(?:?
)?)*?(?:?
(?=[ \t]*(?:?
|/\*|//))|(?=?
))))+)|("[^"\\]*(?:\\[\S\s][^"\\]*)*"|'[^'\\]*(?:\\[\S\s][^'\\]*)*'|(?:?
|[\S\s])[^/"'\\\s]*)
     # delimited:  /((?:(?:^[ \t]*)?(?:\/\*[^*]*\*+(?:[^\/*][^*]*\*+)*\/(?:[ \t]*?
(?=[ \t]*(?:?
|\/\*|\/\/)))?|\/\/(?:[^\\]|\\(?:?
)?)*?(?:?
(?=[ \t]*(?:?
|\/\*|\/\/))|(?=?
))))+)|("[^"\\]*(?:\\[\S\s][^"\\]*)*"|'[^'\\]*(?:\\[\S\s][^'\\]*)*'|(?:?
|[\S\s])[^\/"'\\\s]*)/

     (                                # (1 start), Comments 
          (?:
               (?: ^ [ \t]* )?                  # <- To preserve formatting
               (?:
                    /\*                              # Start /* .. */ comment
                    [^*]* \*+
                    (?: [^/*] [^*]* \*+ )*
                    /                                # End /* .. */ comment
                    (?:                              # <- To preserve formatting 
                         [ \t]* ? 
                                      
                         (?=
                              [ \t]*                  
                              (?: ? 
 | /\* | // )
                         )
                    )?
                 |  
                    //                               # Start // comment
                    (?:                              # Possible line-continuation
                         [^\\] 
                      |  \\ 
                         (?: ? 
 )?
                    )*?
                    (?:                              # End // comment
                         ? 
                               
                         (?=                              # <- To preserve formatting
                              [ \t]*                          
                              (?: ? 
 | /\* | // )
                         )
                      |  (?= ? 
 )
                    )
               )
          )+                               # Grab multiple comment blocks if need be
     )                                # (1 end)

  |                                 ## OR

     (                                # (2 start), Non - comments 
          "
          [^"\\]*                          # Double quoted text
          (?: \\ [\S\s] [^"\\]* )*
          "
       |  
          '
          [^'\\]*                          # Single quoted text
          (?: \\ [\S\s] [^'\\]* )*
          ' 
       |  
          (?: ? 
 | [\S\s] )            # Linebreak or Any other char
          [^/"'\\\s]*                      # Chars which doesn't start a comment, string, escape,
                                           # or line continuation (escape + newline)
     )                                # (2 end)