expression

type Expression interface {
	// Clone clones another Expression.
	Clone() (Expression, error)
	// Eval evaluates expression.
	Eval(ctx context.Context, args map[interface{}]interface{}) (v interface{}, err error)
	// IsStatic returns whether this expression can be evaluated statically or not.
	// A Static expression can be evaluated without ctx and args.
	IsStatic() bool
	// String returns the presentation of the expression.
	String() string
}