use crate::ast::{CommentObject, Statement};
use crate::dialect::Dialect;
use crate::keywords::Keyword;
use crate::parser::{Parser, ParserError};
use crate::tokenizer::Token;
#[derive(Debug)]
pub struct PostgreSqlDialect {}
impl Dialect for PostgreSqlDialect {
fn identifier_quote_style(&self, _identifier: &str) -> Option<char> {
Some('"')
}
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 parse_statement(&self, parser: &mut Parser) -> Option<Result<Statement, ParserError>> {
if parser.parse_keyword(Keyword::COMMENT) {
Some(parse_comment(parser))
} else {
None
}
}
fn supports_filter_during_aggregation(&self) -> bool {
true
}
fn supports_group_by_expr(&self) -> bool {
true
}
}
pub fn parse_comment(parser: &mut Parser) -> Result<Statement, ParserError> {
let if_exists = parser.parse_keywords(&[Keyword::IF, Keyword::EXISTS]);
parser.expect_keyword(Keyword::ON)?;
let token = parser.next_token();
let (object_type, object_name) = match token.token {
Token::Word(w) if w.keyword == Keyword::COLUMN => {
let object_name = parser.parse_object_name(false)?;
(CommentObject::Column, object_name)
}
Token::Word(w) if w.keyword == Keyword::TABLE => {
let object_name = parser.parse_object_name(false)?;
(CommentObject::Table, object_name)
}
_ => parser.expected("comment object_type", token)?,
};
parser.expect_keyword(Keyword::IS)?;
let comment = if parser.parse_keyword(Keyword::NULL) {
None
} else {
Some(parser.parse_literal_string()?)
};
Ok(Statement::Comment {
object_type,
object_name,
comment,
if_exists,
})
}