Method eval

src/expr/src/scalar/func/impls/string.rs:359–383

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

impl LazyUnaryFunc for CastStringToArray {
    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 (datums, dims) = strconv::parse_array(
            a.unwrap_str(),
            || Datum::Null,
            |elem_text| {
                let elem_text = match elem_text {
                    Cow::Owned(s) => temp_storage.push_string(s),
                    Cow::Borrowed(s) => s,
                };
                self.cast_expr
                    .eval(&[Datum::String(elem_text)], temp_storage)
            },
        )?;

        Ok(temp_storage.try_make_datum(|packer| packer.try_push_array(&dims, datums))?)
    }

    /// The output SqlColumnType of this function
    fn output_sql_type(&self, input_type: SqlColumnType) -> SqlColumnType {