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// Copyright 2021 Datafuse Labs
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

use crate::error::Result;
use crate::rows::Row;
use crate::value::Value;

macro_rules! replace_expr {
    ($_t:tt $sub:expr) => {
        $sub
    };
}

// This macro implements TryFrom for tuple of types
macro_rules! impl_tuple_from_row {
    ( $($Ti:tt),+ ) => {
        impl<$($Ti),+> TryFrom<Row> for ($($Ti,)+)
        where
            $($Ti: TryFrom<Value>),+
        {
            type Error = String;
            fn try_from(row: Row) -> Result<Self, String> {
                // It is not possible yet to get the number of metavariable repetitions
                // ref: https://github.com/rust-lang/lang-team/issues/28#issue-644523674
                // This is a workaround
                let expected_len = <[()]>::len(&[$(replace_expr!(($Ti) ())),*]);

                if expected_len != row.len() {
                    return Err(format!("row size mismatch: expected {} columns, got {}", expected_len, row.len()));
                }
                let mut vals_iter = row.into_iter().enumerate();

                Ok((
                    $(
                        {
                            let (col_ix, col_value) = vals_iter
                                .next()
                                .unwrap(); // vals_iter size is checked before this code is reached,
                                           // so it is safe to unwrap
                            let t = col_value.get_type();
                            $Ti::try_from(col_value)
                                .map_err(|_| format!("failed converting column {} from type({:?}) to type({})", col_ix, t, std::any::type_name::<$Ti>()))?
                        }
                    ,)+
                ))
            }
        }
    }
}

// Implement FromRow for tuples of size up to 16
impl_tuple_from_row!(T1);
impl_tuple_from_row!(T1, T2);
impl_tuple_from_row!(T1, T2, T3);
impl_tuple_from_row!(T1, T2, T3, T4);
impl_tuple_from_row!(T1, T2, T3, T4, T5);
impl_tuple_from_row!(T1, T2, T3, T4, T5, T6);
impl_tuple_from_row!(T1, T2, T3, T4, T5, T6, T7);
impl_tuple_from_row!(T1, T2, T3, T4, T5, T6, T7, T8);
impl_tuple_from_row!(T1, T2, T3, T4, T5, T6, T7, T8, T9);
impl_tuple_from_row!(T1, T2, T3, T4, T5, T6, T7, T8, T9, T10);
impl_tuple_from_row!(T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11);
impl_tuple_from_row!(T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12);
impl_tuple_from_row!(T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13);
impl_tuple_from_row!(T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14);
impl_tuple_from_row!(T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15);
impl_tuple_from_row!(T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16);