Valid password for CNIL (France): at least 8 characters from 3 of the 4 groups: lowercase letters, uppercase letters, digits, other characters

pg_cnil_valid_password.sql

CREATE DOMAIN valid_password
  AS text
  CHECK(7 < char_length(VALUE)
        AND 2 < char_length(   COALESCE(substring(VALUE from '[^a-zA-Z0-9]'), '')
                            || COALESCE(substring(VALUE from  '[0-9]'), '')
                            || COALESCE(substring(VALUE from '[A-Z]'), '')
                            || COALESCE(substring(VALUE from '[a-z]'), '')));