Method parse

src/sql/src/session/vars/value.rs:117–126

(input: VarInput)

    }

    fn parse(input: VarInput) -> Result<Self, VarParseError>
    where
        Self: Sized,
    {
        let s = extract_single_value(input)?;
        match s {
            "" => Ok(None),
            _ => <V as Value>::parse(VarInput::Flat(s)).map(Some),
        }
    }

    fn box_clone(&self) -> Box<dyn Value> {
        Box::new(self.clone())