src/dialect/duckdb.rs

// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements.  See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership.  The ASF licenses this file
// to you 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
    }

    fn supports_named_fn_args_with_assignment_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
    }

    /// See <https://duckdb.org/docs/stable/sql/functions/lambda>
    fn supports_lambda_functions(&self) -> bool {
        true
    }

    /// Returns true if this dialect allows the `EXTRACT` function to use single quotes in the part being extracted.
    fn allow_extract_single_quotes(&self) -> bool {
        true
    }

    // DuckDB is compatible with PostgreSQL syntax for this statement,
    // although not all features may be implemented.
    fn supports_explain_with_utility_options(&self) -> bool {
        true
    }

    /// See DuckDB <https://duckdb.org/docs/sql/statements/load_and_install.html#load>
    fn supports_load_extension(&self) -> bool {
        true
    }

    // See DuckDB <https://duckdb.org/docs/sql/data_types/array.html#defining-an-array-field>
    fn supports_array_typedef_with_brackets(&self) -> bool {
        true
    }

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

    /// See DuckDB <https://duckdb.org/docs/sql/query_syntax/orderby.html#order-by-all-examples>
    fn supports_order_by_all(&self) -> bool {
        true
    }

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

    /// DuckDB supports `NOTNULL` as an alias for `IS NOT NULL`,
    /// see DuckDB Comparisons <https://duckdb.org/docs/stable/sql/expressions/comparison_operators#between-and-is-not-null>
    fn supports_notnull_operator(&self) -> bool {
        true
    }
}