Oniguruma regex conditional group capture-CodePudding

I am attempting to capture the word function using Oniguruma regex (for VSCode syntax highlighting) into 2 different groups depending on if :: are the preceding characters. As far as I know Oniguruma does not support conditionals, hence I thought I could capture the regex result into group 1 if the characters are not present and into group 2 if they are

Currently, I have the following:

(?>::\s*\b(function)\b)|\b(function)\b

Some text to test the code on:

  integer function fun_with_func_space(     function    )
    integer, intent(inout) :: function
  end function fun_with_func_space

Intended regex match

Given the text above group $1 should

finds 1st and 2nd "function" in 'integer function fun_with_func_space(     function    )'
finds no match in 'integer, intent(inout) :: function'
finds "function" in 'end function fun_with_func_space'

group $2 on the other hand should

finds no match in 'integer function fun_with_func_space(     function    )'
find "function" in 'integer function fun_with_func_space(     function    )'
finds no match in 'end function fun_with_func_space'

As far as I understand the following should mean: "Capture and exit into group 2 the word function if preceded by :: else capture function in group 1." and according to regex101.com it should work: https://regex101.com/r/VtgeTD/1, yet my syntax highlighting is still failing. Am I doing something wrong?

CodePudding user response：

Try using a look behind:

(?:(?<=::|:: ))\b(function)\b|\b(function)\b

See live demo.

Or use a non-capturing group:

(?:::\s*)(function)\b|\b(function)\b

See live demo.