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Stricter parsing for subqueries (3/4)

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This makes the parser more strict when handling SELECTs nested
somewhere in the main statement:

1) instead of accepting SELECT anywhere in the expression where an
   operand was expected, we only accept it inside parens. (I've added a
   test for the currently supported syntax, <scalar subquery> in ANSI
   SQL terms)

2) instead of accepting any expression in the derived table context:
   `FROM ( ... )` - we only look for a SELECT subquery there.

Due to #1, I had to swith the 'ansi' test from invoking the expression
parser to the statement parser.
This commit is contained in:
Nickolay Ponomarev 2019-01-31 00:10:10 +03:00
parent 82dc581639
commit 215820ef66
4 changed files with 48 additions and 21 deletions
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15
src/sqlparser.rs
View file

@ -158,7 +158,6 @@ impl Parser {
match self.next_token() {
Some(t) => match t {
Token::SQLWord(w) => match w.keyword.as_ref() {
"SELECT" => Ok(ASTNode::SQLSelect(self.parse_select()?)),
"TRUE" | "FALSE" | "NULL" => {
self.prev_token();
self.parse_sql_value()
@ -197,9 +196,13 @@ impl Parser {
self.parse_sql_value()
}
Token::LParen => {
let expr = self.parse_expr()?;
let expr = if self.parse_keyword("SELECT") {
ASTNode::SQLSubquery(self.parse_select()?)
} else {
ASTNode::SQLNested(Box::new(self.parse_expr()?))
};
self.expect_token(&Token::RParen)?;
Ok(ASTNode::SQLNested(Box::new(expr)))
Ok(expr)
}
_ => parser_err!(format!(
"Prefix parser expected a keyword but found {:?}",
@ -1184,8 +1187,10 @@ impl Parser {
/// A table name or a parenthesized subquery, followed by optional `[AS] alias`
pub fn parse_table_factor(&mut self) -> Result<ASTNode, ParserError> {
let relation = if self.consume_token(&Token::LParen) {
self.prev_token();
self.parse_subexpr(0)? /* TBD (3) */
self.expect_keyword("SELECT")?;
let subquery = self.parse_select()?;
self.expect_token(&Token::RParen)?;
ASTNode::SQLSubquery(subquery)
} else {
self.parse_compound_identifier(&Token::Period)?
};