add support to nested join_without parentheses snowflake

Author: barsela1

src/parser/mod.rs

@@ -11695,6 +11695,11 @@ impl<'a> Parser<'a> {
         // Note that for keywords to be properly handled here, they need to be
         // added to `RESERVED_FOR_TABLE_ALIAS`, otherwise they may be parsed as
         // a table alias.
+        let joins = self.parse_joins()?;
+        Ok(TableWithJoins { relation, joins })
+    }
+
+    fn parse_joins(&mut self) -> Result<Vec<Join>, ParserError> {
         let mut joins = vec![];
         loop {
             let global = self.parse_keyword(Keyword::GLOBAL);
@@ -11823,7 +11828,16 @@ impl<'a> Parser<'a> {
                     }
                     _ => break,
                 };
-                let relation = self.parse_table_factor()?;
+                let mut relation = self.parse_table_factor()?;
+
+                if self.is_next_token_a_join() {
+                    let joins = self.parse_joins()?;
+                    relation = TableFactor::NestedJoin {
+                        table_with_joins: Box::new(TableWithJoins { relation, joins }),
+                        alias: None,
+                    };
+                }
+
                 let join_constraint = self.parse_join_constraint(natural)?;
                 Join {
                     relation,
@@ -11833,7 +11847,21 @@ impl<'a> Parser<'a> {
             };
             joins.push(join);
         }
-        Ok(TableWithJoins { relation, joins })
+        Ok(joins)
+    }
+
+    fn is_next_token_a_join(&self) -> bool {
+        matches!(
+            self.peek_token().token,
+            Token::Word(Word {
+                keyword: Keyword::JOIN
+                    | Keyword::INNER
+                    | Keyword::LEFT
+                    | Keyword::RIGHT
+                    | Keyword::FULL,
+                ..
+            })
+        )
     }
 
     /// A table name or a parenthesized subquery, followed by optional `[AS] alias`

tests/sqlparser_snowflake.rs

@@ -3516,3 +3516,87 @@ fn test_alter_session_followed_by_statement() {
         _ => panic!("Unexpected statements: {:?}", stmts),
     }
 }
+
+#[test]
+fn test_nested_join_without_parentheses() {
+    let query = "SELECT DISTINCT p.product_id FROM orders AS o INNER JOIN customers AS c INNER JOIN products AS p ON p.customer_id = c.customer_id ON c.order_id = o.order_id";
+    assert_eq!(
+        only(
+            snowflake()
+                .verified_only_select_with_canonical(query, "")
+                .from
+        )
+        .joins,
+        vec![Join {
+            relation: TableFactor::NestedJoin {
+                table_with_joins: Box::new(TableWithJoins {
+                    relation: TableFactor::Table {
+                        name: ObjectName::from(vec![Ident::new("customers".to_string())]),
+                        alias: Some(TableAlias {
+                            name: Ident {
+                                value: "c".to_string(),
+                                quote_style: None,
+                                span: Span::empty(),
+                            },
+                            columns: vec![],
+                        }),
+                        args: None,
+                        with_hints: vec![],
+                        version: None,
+                        partitions: vec![],
+                        with_ordinality: false,
+                        json_path: None,
+                        sample: None,
+                        index_hints: vec![],
+                    },
+                    joins: vec![Join {
+                        relation: TableFactor::Table {
+                            name: ObjectName::from(vec![Ident::new("products".to_string())]),
+                            alias: Some(TableAlias {
+                                name: Ident {
+                                    value: "p".to_string(),
+                                    quote_style: None,
+                                    span: Span::empty(),
+                                },
+                                columns: vec![],
+                            }),
+                            args: None,
+                            with_hints: vec![],
+                            version: None,
+                            partitions: vec![],
+                            with_ordinality: false,
+                            json_path: None,
+                            sample: None,
+                            index_hints: vec![],
+                        },
+                        global: false,
+                        join_operator: JoinOperator::Inner(JoinConstraint::On(Expr::BinaryOp {
+                            left: Box::new(Expr::CompoundIdentifier(vec![
+                                Ident::new("p".to_string()),
+                                Ident::new("customer_id".to_string())
+                            ])),
+                            op: BinaryOperator::Eq,
+                            right: Box::new(Expr::CompoundIdentifier(vec![
+                                Ident::new("c".to_string()),
+                                Ident::new("customer_id".to_string())
+                            ])),
+                        })),
+                    }]
+                }),
+                alias: None
+            },
+            global: false,
+            join_operator: JoinOperator::Inner(JoinConstraint::On(Expr::BinaryOp {
+                left: Box::new(Expr::CompoundIdentifier(vec![
+                    Ident::new("c".to_string()),
+                    Ident::new("order_id".to_string())
+                ])),
+                op: BinaryOperator::Eq,
+                right: Box::new(Expr::CompoundIdentifier(vec![
+                    Ident::new("o".to_string()),
+                    Ident::new("order_id".to_string())
+                ])),
+            }))
+        }],
+    );
+}