Method eval

src/expr/src/scalar/func/impls/map.rs:38–51

(
        &'a self,
        datums: &[Datum<'a>],
        temp_storage: &'a RowArena,
        a: &'a impl Eval,
    )

impl LazyUnaryFunc for CastMapToString {
    fn eval<'a>(
        &'a self,
        datums: &[Datum<'a>],
        temp_storage: &'a RowArena,
        a: &'a impl Eval,
    ) -> Result<Datum<'a>, EvalError> {
        let a = a.eval(datums, temp_storage)?;
        if a.is_null() {
            return Ok(Datum::Null);
        }
        let mut buf = String::new();
        stringify_datum(&mut buf, a, &self.ty)?;
        Ok(Datum::String(temp_storage.push_string(buf)))
    }

    fn output_sql_type(&self, input_type: SqlColumnType) -> SqlColumnType {
        SqlScalarType::String.nullable(input_type.nullable)