How to exclude "<? ... ?>" fragments in php code (gulp-htmlmin)?

Question

To ignore php code in gulp-htmlmin I use
ignoreCustomFragments: [/<\?(php|=)[\s\S]*?(?:\?>|$)/]

But in my php code there is a string which contains the following fragment - "<?xml ... ?>". This string gives a mistake of gulp-htmlmin. I think it is because the string has "?>" which "closes" php code before its actual end.
How to set regex of ignoreCustomFragments to avoid the mistake?

Answer 1

/
<\?(php|=)
(?:
  # match any symbol except ? or ' or "
  [^?'"]
  # or ? not followed by >
  | \?(?!>)
  # or match '...' substring
  | '(?:
        # match any symbol except '
        [^']
        # or ' preceded by \
        | (?<=\\)'
     )*'
  # or match "..." substring
  | "(?: [^"] | (?<=\\)" )*"
)*
(?:\?>|$)
/gmx

---

Update

For handling comments:

<\?(php|=)
(?:
  # match any symbol except ? or ' or " or /
  [^?'"\/]
  # or ? not followed by >
  | \? (?!>)
  # or / not followed by [*/]
  | \/ (?![*\/])
  # or match comment //
  | \/\/ [^\r\n]+
  # or match comment /* */
  | \/\* (?: [^*] | \*(?!\/) )+ \*\/
  # or match '...' substring
  | '(?:
        # match any symbol except '
        [^']
        # or ' preceded by \
        | (?<=\\)'
     )*'
  # or match "..." substring
  | "(?: [^"] | (?<=\\)" )*"
)*
(?:\?>|$)