module ActiveRecord::ConnectionAdapters::MySQL::Quoting::ClassMethods

def column_name_matcher
  /
    \A
    (
      (?:
        # `table_name`.`column_name` | function(one or no argument)
        ((?:\w+\.|`\w+`\.)?(?:\w+|`\w+`) | \w+\((?:|\g<2>)\))
      )
      (?:(?:\s+AS)?\s+(?:\w+|`\w+`))?
    )
    (?:\s*,\s*\g<1>)*
    \z
  /ix
end