extract_value_from_default

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 765
        def extract_value_from_default(default)
          case default
            # Quoted types
          when /\A[(B]?'(.*)'.*::"?([\w. ]+)"?(?:\[\])?\z/
            # The default 'now'::date is CURRENT_DATE
            if $1 == "now" && $2 == "date"
              nil
            else
              $1.gsub("''", "'")
            end
            # Boolean types
          when "true", "false"
            default
            # Numeric types
          when /\A\(?(-?\d+(\.\d*)?)\)?(::bigint)?\z/
            $1
            # Object identifier types
          when /\A-?\d+\z/
            $1
          else
            # Anything else is blank, some user type, or some function
            # and we can't know the value of that, so return nil.
            nil
          end
        end