feat: old Firebolt dialect (#31849)

superset/sql/dialects/firebolt.py

@@ -19,6 +19,7 @@ from __future__ import annotations
 
 from sqlglot import exp, generator, parser
 from sqlglot.dialects.dialect import Dialect
+from sqlglot.helper import csv
 from sqlglot.tokens import TokenType
 
 
@@ -73,3 +74,119 @@ class Firebolt(Dialect):
                 return f"NOT ({self.sql(expression, 'this')})"
 
             return super().not_sql(expression)
+
+
+class FireboltOld(Firebolt):
+    """
+    Dialect for the old version of Firebolt (https://old.docs.firebolt.io/).
+
+    The main difference is that `UNNEST` is an operator like `JOIN`, instead of a
+    function.
+    """
+
+    class Parser(Firebolt.Parser):
+        TABLE_ALIAS_TOKENS = Firebolt.Parser.TABLE_ALIAS_TOKENS - {TokenType.UNNEST}
+
+        def _parse_join(
+            self,
+            skip_join_token: bool = False,
+            parse_bracket: bool = False,
+        ) -> exp.Join | None:
+            if unnest := self._parse_unnest():
+                return self.expression(exp.Join, this=unnest)
+
+            return super()._parse_join(skip_join_token, parse_bracket)
+
+        def _parse_unnest(self, with_alias: bool = True) -> exp.Unnest | None:
+            if not self._match(TokenType.UNNEST):
+                return None
+
+            # parse expressions (col1 AS foo), instead of equalities as in the original
+            # dialect
+            expressions = self._parse_wrapped_csv(self._parse_expression)
+            offset = self._match_pair(TokenType.WITH, TokenType.ORDINALITY)
+
+            alias = self._parse_table_alias() if with_alias else None
+
+            if alias:
+                if self.dialect.UNNEST_COLUMN_ONLY:
+                    if alias.args.get("columns"):
+                        self.raise_error("Unexpected extra column alias in unnest.")
+
+                    alias.set("columns", [alias.this])
+                    alias.set("this", None)
+
+                columns = alias.args.get("columns") or []
+                if offset and len(expressions) < len(columns):
+                    offset = columns.pop()
+
+            if not offset and self._match_pair(TokenType.WITH, TokenType.OFFSET):
+                self._match(TokenType.ALIAS)
+                offset = self._parse_id_var(
+                    any_token=False, tokens=self.UNNEST_OFFSET_ALIAS_TOKENS
+                ) or exp.to_identifier("offset")
+
+            return self.expression(
+                exp.Unnest,
+                expressions=expressions,
+                alias=alias,
+                offset=offset,
+            )
+
+    class Generator(Firebolt.Generator):
+        def join_sql(self, expression: exp.Join) -> str:
+            if not self.SEMI_ANTI_JOIN_WITH_SIDE and expression.kind in (
+                "SEMI",
+                "ANTI",
+            ):
+                side = None
+            else:
+                side = expression.side
+
+            op_sql = " ".join(
+                op
+                for op in (
+                    expression.method,
+                    "GLOBAL" if expression.args.get("global") else None,
+                    side,
+                    expression.kind,
+                    expression.hint if self.JOIN_HINTS else None,
+                )
+                if op
+            )
+            match_cond = self.sql(expression, "match_condition")
+            match_cond = f" MATCH_CONDITION ({match_cond})" if match_cond else ""
+            on_sql = self.sql(expression, "on")
+            using = expression.args.get("using")
+
+            if not on_sql and using:
+                on_sql = csv(*(self.sql(column) for column in using))
+
+            this = expression.this
+            this_sql = self.sql(this)
+
+            if exprs := self.expressions(expression):
+                this_sql = f"{this_sql},{self.seg(exprs)}"
+
+            if on_sql:
+                on_sql = self.indent(on_sql, skip_first=True)
+                space = self.seg(" " * self.pad) if self.pretty else " "
+                if using:
+                    on_sql = f"{space}USING ({on_sql})"
+                else:
+                    on_sql = f"{space}ON {on_sql}"
+            elif not op_sql:
+                # the main difference with the base dialect is the lack of comma before
+                # an `UNNEST`
+                if (
+                    isinstance(this, exp.Lateral)
+                    and this.args.get("cross_apply") is not None
+                ) or isinstance(this, exp.Unnest):
+                    return f" {this_sql}"
+
+                return f", {this_sql}"
+
+            if op_sql != "STRAIGHT_JOIN":
+                op_sql = f"{op_sql} JOIN" if op_sql else "JOIN"
+
+            return f"{self.seg(op_sql)} {this_sql}{match_cond}{on_sql}"