1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133

// 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, LockTable, LockTableType, Statement},
    dialect::Dialect,
    keywords::Keyword,
    parser::{Parser, ParserError},
};

/// A [`Dialect`] for [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 identifier_quote_style(&self, _identifier: &str) -> Option<char> {
        Some('`')
    }

    // See https://dev.mysql.com/doc/refman/8.0/en/string-literals.html#character-escape-sequences
    fn supports_string_literal_backslash_escape(&self) -> bool {
        true
    }

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

    fn parse_infix(
        &self,
        parser: &mut crate::parser::Parser,
        expr: &crate::ast::Expr,
        _precedence: u8,
    ) -> Option<Result<crate::ast::Expr, 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
        }
    }

    fn parse_statement(&self, parser: &mut Parser) -> Option<Result<Statement, ParserError>> {
        if parser.parse_keywords(&[Keyword::LOCK, Keyword::TABLES]) {
            Some(parse_lock_tables(parser))
        } else if parser.parse_keywords(&[Keyword::UNLOCK, Keyword::TABLES]) {
            Some(parse_unlock_tables(parser))
        } else {
            None
        }
    }
}

/// `LOCK TABLES`
/// <https://dev.mysql.com/doc/refman/8.0/en/lock-tables.html>
fn parse_lock_tables(parser: &mut Parser) -> Result<Statement, ParserError> {
    let tables = parser.parse_comma_separated(parse_lock_table)?;
    Ok(Statement::LockTables { tables })
}

// tbl_name [[AS] alias] lock_type
fn parse_lock_table(parser: &mut Parser) -> Result<LockTable, ParserError> {
    let table = parser.parse_identifier(false)?;
    let alias =
        parser.parse_optional_alias(&[Keyword::READ, Keyword::WRITE, Keyword::LOW_PRIORITY])?;
    let lock_type = parse_lock_tables_type(parser)?;

    Ok(LockTable {
        table,
        alias,
        lock_type,
    })
}

// READ [LOCAL] | [LOW_PRIORITY] WRITE
fn parse_lock_tables_type(parser: &mut Parser) -> Result<LockTableType, ParserError> {
    if parser.parse_keyword(Keyword::READ) {
        if parser.parse_keyword(Keyword::LOCAL) {
            Ok(LockTableType::Read { local: true })
        } else {
            Ok(LockTableType::Read { local: false })
        }
    } else if parser.parse_keyword(Keyword::WRITE) {
        Ok(LockTableType::Write {
            low_priority: false,
        })
    } else if parser.parse_keywords(&[Keyword::LOW_PRIORITY, Keyword::WRITE]) {
        Ok(LockTableType::Write { low_priority: true })
    } else {
        parser.expected("an lock type in LOCK TABLES", parser.peek_token())
    }
}

/// UNLOCK TABLES
/// <https://dev.mysql.com/doc/refman/8.0/en/lock-tables.html>
fn parse_unlock_tables(_parser: &mut Parser) -> Result<Statement, ParserError> {
    Ok(Statement::UnlockTables)
}