PHP Regex expression to validate a name input

Question

As part of my validation I have the following regex expression:

    ^
# Prevent 3+ consecutive letters: 'wheee'
(?!\w*([a-zA-Z])\g{-1}{2,})

[a-zA-Z](?:[a-zA-Z]|'(?!')){0,}

# Words or '&' are space or hyphen separated
(?:
  [ -]

  # Prevent 3+ consecutive letters: 'wheee' (for rest of words)
  (?!\w*([a-zA-Z])\g{-1}{2,})
  (?:[a-zA-Z]|'(?!')){1,}
|
  [ -]
  &
)*$

I was wondering the effectiveness of the expression and/or possible pitfalls?

Answer 1

One possible pitfall is that several celebrities cannot pass your "validation" code. Do you really want Renée Zellweger and Goran Ivanišević being mad at you?

Answer 2

[a-zA-Z]

You use both lowercase and uppercase everywhere. This can possibly be symplified with (inline) modifiers:

(?i)[a-z]

Personally I use quantifiers as a "sugar" instead of explicit interval specifying:

{0,} ==> *
{1,} ==> +