Enum Doc 

pub enum Doc<'a> {
    Missing,
    NoResult,
    Doc(&'a Value),
}

doc 语义（用于 creator 伪角色）： Missing → 新插入（无已有文档，creator 自动通过） NoResult → 查询无结果（creator 不通过） Doc → 已有文档

Variants

Missing

NoResult

Doc(&'a Value)

Trait Implementations

impl<'a> Clone for Doc<'a>

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<'a> Copy for Doc<'a>

impl<'a> Debug for Doc<'a>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.