return clause.Expr{SQL: "DEFAULT"}
}

func (DummyDialector) Migrator(*gorm.DB) gorm.Migrator {
	return nil
}

func (DummyDialector) BindVarTo(writer clause.Writer, stmt *gorm.Statement, v interface{}) {
	writer.WriteByte('?')
}

func (DummyDialector) QuoteTo(writer clause.Writer, str string) {
	var (
		underQuoted, selfQuoted bool
		continuousBacktick      int8
		shiftDelimiter          int8
	)

		}

		if v.Alias != "" {
			writer.WriteString(" AS ")
			write(v.Raw, v.Alias)
		}
	case []clause.Column:
		writer.WriteByte('(')
		for idx, d := range v {
			if idx > 0 {
				writer.WriteByte(',')
			}
			stmt.QuoteTo(writer, d)
		}
		writer.WriteByte(')')
	case clause.Expr:
		v.Build(stmt)
	case string:
		stmt.DB.Dialector.QuoteTo(writer, v)
	case []string:
		writer.WriteByte('(')

type Dialector interface {
	Name() string
	Initialize(*DB) error
	Migrator(db *DB) Migrator
	DataTypeOf(*schema.Field) string
	DefaultValueOf(*schema.Field) clause.Expression
	BindVarTo(writer clause.Writer, stmt *Statement, v interface{})
	QuoteTo(clause.Writer, string)
	Explain(sql string, vars ...interface{}) string
}

// Plugin GORM plugin interface
type Plugin interface {
	Name() string
	Initialize(*DB) error
}

const (
	// Silent silent log level
	Silent LogLevel = iota + 1
	// Error error log level
	Error
	// Warn warn log level
	Warn
	// Info info log level
	Info
)

// Writer log writer interface
type Writer interface {
	Printf(string, ...interface{})
}

// Config logger config
type Config struct {
	SlowThreshold             time.Duration
	Colorful                  bool

// ClauseBuilder clause builder, allows to customize how to build clause
type ClauseBuilder func(Clause, Builder)

type Writer interface {
	WriteByte(byte) error
	WriteString(string) (int, error)
}

// Builder builder interface
type Builder interface {
	Writer
	WriteQuoted(field interface{})
	AddVar(Writer, ...interface{})
	AddError(error) error
}

// Clause
type Clause struct {
	Name                string // WHERE