extract_value_from_default

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 82
      def self.extract_value_from_default(default)
        # This is a performance optimization for Ruby 1.9.2 in development.
        # If the value is nil, we return nil straight away without checking
        # the regular expressions. If we check each regular expression,
        # Regexp#=== will call NilClass#to_str, which will trigger
        # method_missing (defined by whiny nil in ActiveSupport) which
        # makes this method very very slow.
        return default unless default

        case default
          when /\A'(.*)'::(num|date|tstz|ts|int4|int8)range\z/
            $1
          # Numeric types
          when /\A\(?(-?\d+(\.\d*)?\)?(::bigint)?)\z/
            $1
          # Character types
          when /\A\(?'(.*)'::.*\b(?:character varying|bpchar|text)\z/
            $1.gsub(/''/, "'")
          # Binary data types
          when /\A'(.*)'::bytea\z/
            $1
          # Date/time types
          when /\A'(.+)'::(?:time(?:stamp)? with(?:out)? time zone|date)\z/
            $1
          when /\A'(.*)'::interval\z/
            $1
          # Boolean type
          when 'true'
            true
          when 'false'
            false
          # Geometric types
          when /\A'(.*)'::(?:point|line|lseg|box|"?path"?|polygon|circle)\z/
            $1
          # Network address types
          when /\A'(.*)'::(?:cidr|inet|macaddr)\z/
            $1
          # Bit string types
          when /\AB'(.*)'::"?bit(?: varying)?"?\z/
            $1
          # XML type
          when /\A'(.*)'::xml\z/
            $1
          # Arrays
          when /\A'(.*)'::"?\D+"?\[\]\z/
            $1
          # Hstore
          when /\A'(.*)'::hstore\z/
            $1
          # JSON
          when /\A'(.*)'::json\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