I’m adding a text input formatter as extension, What is the regex for this case:

1. Allow english/arabic characters and numbers.

2. Block all special characters except DOT. DASH- SINGLEQUOTE’

here is my regex:

static final RegExp  _allowFewSpecialCharacters = RegExp(r"[a-zA-Z0-9u0600-u06FFp{L}p{Nd}s!.-']");

Method:

 static TextInputFormatter filterSpecialCharacters() {
  return FilteringTextInputFormatter.deny(_allowFewSpecialCharacters);
 }

usage:

TextField(
          decoration: const InputDecoration(labelText: 'Allow few characters'),
          inputFormatters: [AppTextInputFormatters.filterSpecialCharacters()],
        ),

My approach is not working, what is wrong and how this task can be accomplished ?