如何删除包含多个字符串和注释符号的行的行注释

Question

I'd like to parse KConf files which contain single line comments which are introduced by the # character. Below you can find an example of such file.

https://github.com/torvalds/linux/blob/master/arch/x86/Kconfig

I am aware that the single line test string almost looks random though it should contain most if not all variants of nested hashes and strings and quotes in comments which do not introduce a string.

The regex engine that I use currently the one in Groovy which is based Java.

Test string

Lorem "ipsum # \\" dolor" sit amet, 'consectetur # \\' adipiscing' elit. Maecenas 'suscipit #mollis' quam, non #bibendum 'elit # eleifend "in. Duis # convallis" luctus nunc, ac luctus lectus dapibus at.

Desired result

Lorem "ipsum # \\" dolor" sit amet, 'consectetur # \\' adipiscing' elit. Maecenas 'suscipit #mollis' quam, non

or (with the leading space)

#bibendum 'elit # eleifend "in. Duis # convallis" luctus nunc, ac luctus lectus dapibus at.

Answer 1

First of all, I've escaped your string so it can be stored as a variable using JavaScript (since you don't seem to indicate a language, I'll assume JS):

var str = 'Lorem "ipsum # " dolor" sit amet, \\'consectetur # \\' adipiscing\\' elit. Maecenas \\'suscipit#mollis\\' quam, non #bibendum \\'elit # eleifend "in. Duis # convallis" luctus nunc, ac luctus lectus dapibus at.';

To remove everything following a " " followed by a "#" which is not followed by a space:

str.replace(/ #[^ ].*/, '');

Lastly, your second desired result makes absolutely no sense.

All of this would of course be helped by a proper description.

Answer 2

Based on the limited information, this regex might work.
It seems a little extra complex trying to distinquish embedded hashes from coments though.
Didn't have time to test it but cut'n pasted a few regex pieces.
Note that it should be used in Multi-Line Mode . And Everything is geared to a line parse.
Ie nothing in the regex will span lines.

 #  (?-s)^(?:"[^"\\\n]*(?:\\.[^"\\\n]*)*"|'[^'\\\n]*(?:\\.[^'\\\n]*)*'|[^#"'\s]+|(?<=[^\s#])\#+|[^\S\n]+(?!\#))*(?:[^\S\n]+|^)(\#.*)$
 #  "(?-s)^(?:\"[^\"\\\\\\n]*(?:\\\\.[^\"\\\\\\n]*)*\"|'[^'\\\\\\n]*(?:\\\\.[^'\\\\\\n]*)*'|[^#\"'\\s]+|(?<=[^\\s#])\\#+|[^\\S\\n]+(?!\\#))*(?:[^\\S\\n]+|^)(\\#.*)$"

 (?-s)                   # Modifier, No dot all 
 ^                       # Beginning of line
 (?:
      "                       # Double quotes
      [^"\\\n]* 
      (?: \\ . [^"\\\n]* )*
      "
   |                        # or
      '                       # Single quotes
      [^'\\\n]* 
      (?: \\ . [^'\\\n]* )*
      '
   |                        # or
      [^#"'\s]+               # Not hash, quotes, whitespace
   |                        # or
      (?<= [^\s#] )           # Preceded by a character, but not hash or whitespace
      \#+                     # Embeded hashes
   |                        # or
      [^\S\n]+                # Whitespaces (non-newline)
      (?! \# )                # Not folowed by hash
 )*
 (?: [^\S\n]+ | ^ )      # Whitespaces  (non-newline) or BOL
 ( \# .* )               # (1), hash comment
 $                       # End of line

Answer 3

Raw regex:

^((?:\\.|("|')(?:(?!\2|\\|[\r\n]).|\\.)*\2|[^#'"\r\n])+)#.+

Replace with $1 :

Example:

String re = "^((?:\\\\.|(\"|')(?:(?!\\2|\\\\|[\\r\\n]).|\\\\.)*\\2|[^#'\"\\r\\n])+)#.+";
String line = "Lorem \"ipsum # \\\" dolor\" sit amet, 'consectetur # \\' adipiscing' elit. Maecenas 'suscipit #mollis' quam, non #bibendum 'elit # eleifend \"in. Duis # convallis\" luctus nunc, ac luctus lectus dapibus at.";
String uncommented = line.replaceAll(re, "$1");

//=> Lorem "ipsum # \" dolor" sit amet, 'consectetur # \' adipiscing' elit. Maecenas 'suscipit #mollis' quam, non

regex101 demo

ideone demo

Breakdown:

^                         # Beginning of line
  (                       # Beginning of 1st capture group
    (?:                   # Non-capture group 1
      \\.                 # Match an escaped character
    |
      ("|')               # Or, a quote (and capture it in 2nd capture group),
      (?:                 # Non-capture group 2
        (?!\2|\\|[\r\n]). # Followed by any character except relevant quote, \ or newline
      |
        \\.               # Or an escaped character
      )*                  # Close of non-capture group 2 and repeat as many times
      \2                  # Close the quoted part
    |
      [^#'"\r\n]          # Any non-hash, single/double quote, newline characters
    )+                    # Close of non-capture group 1 and repeat as many times
  )                       # Close capture group 1
  #.+                     # Match comments