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// 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.

#[cfg(not(feature = "std"))]
use alloc::boxed::Box;

use crate::{
    ast::{BinaryOperator, Expr},
    dialect::Dialect,
    keywords::Keyword,
};

/// [MySQL](https://www.mysql.com/)
#[derive(Debug)]
pub struct MySqlDialect {}

impl Dialect for MySqlDialect {
    fn is_identifier_start(&self, ch: char) -> bool {
        // See https://dev.mysql.com/doc/refman/8.0/en/identifiers.html.
        // Identifiers which begin with a digit are recognized while tokenizing numbers,
        // so they can be distinguished from exponent numeric literals.
        ch.is_alphabetic()
            || ch == '_'
            || ch == '$'
            || ch == '@'
            || ('\u{0080}'..='\u{ffff}').contains(&ch)
    }

    fn is_identifier_part(&self, ch: char) -> bool {
        self.is_identifier_start(ch) || ch.is_ascii_digit()
    }

    fn is_delimited_identifier_start(&self, ch: char) -> bool {
        ch == '`'
    }

    fn parse_infix(
        &self,
        parser: &mut crate::parser::Parser,
        expr: &crate::ast::Expr,
        _precedence: u8,
    ) -> Option<Result<crate::ast::Expr, crate::parser::ParserError>> {
        // Parse DIV as an operator
        if parser.parse_keyword(Keyword::DIV) {
            Some(Ok(Expr::BinaryOp {
                left: Box::new(expr.clone()),
                op: BinaryOperator::MyIntegerDivide,
                right: Box::new(parser.parse_expr().unwrap()),
            }))
        } else {
            None
        }
    }
}