duckdb.rs

// 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::dialect::Dialect;

/// A [`Dialect`] for [DuckDB](https://duckdb.org/)
#[derive(Debug, Default)]
pub struct DuckDbDialect;

// In most cases the redshift dialect is identical to [`PostgresSqlDialect`].
impl Dialect for DuckDbDialect {
    fn supports_trailing_commas(&self) -> bool {
        true
    }

    fn is_identifier_start(&self, ch: char) -> bool {
        ch.is_alphabetic() || ch == '_'
    }

    fn is_identifier_part(&self, ch: char) -> bool {
        ch.is_alphabetic() || ch.is_ascii_digit() || ch == '$' || ch == '_'
    }

    fn supports_filter_during_aggregation(&self) -> bool {
        true
    }

    fn supports_group_by_expr(&self) -> bool {
        true
    }

    fn supports_named_fn_args_with_eq_operator(&self) -> bool {
        true
    }

    // DuckDB uses this syntax for `STRUCT`s.
    //
    // https://duckdb.org/docs/sql/data_types/struct.html#creating-structs
    fn supports_dictionary_syntax(&self) -> bool {
        true
    }

    // DuckDB uses this syntax for `MAP`s.
    //
    // https://duckdb.org/docs/sql/data_types/map.html#creating-maps
    fn support_map_literal_syntax(&self) -> bool {
        true
    }

    /// DuckDB allows this.
    ///
    /// https://duckdb.org/2023/08/23/even-friendlier-sql.html#from-first-in-select-statements
    fn allow_from_first(&self) -> bool {
        true
    }
}