Replace multiple occurences of character after zero-length assertion

I would like to replace every _ with a - on lines starting with #| label: using PCRE2 regex within my text editor.

Example:

#| label: my_chunk_label
my_function_name <- function(x)

Should become:

#| label: my-chunk-label
my_function_name <- function(x)

In contrast to .NET regex, where one could substitute (?<=^#\| label: .+)_ with - (regex101 example), PCRE2 does not support infinite lookbehind so the regex is invalid. So far, the only way I found was to repeatedly substitute ^#[^_]+\K_ with - (regex101 example) but I was curious if there is a single-pass solution.

>Solution :

If you are using pcre, you could make use of \G and \K

Then in the replacement use -

(?:^#|\h+label:\h+|\G(?!^))[^\r\n_]*\K_

The pattern matches:

• (?: Non capture group for the alternatives
  • ^#|\h+label:\h+ Match the pattern that should be at the start of the string, where \h matches a horizontal whitespace character
  • | Or
  • \G(?!^) Assert the current position at the end of the previous match, not at the start
• ) Close the non capture group
• [^\r\n_]* Match optional characters except for newlines or _
• \K Forget what is matched so far
• _ Match the underscore

Regex demo