Fix: windowspec generator

sqlglot/__init__.py

@@ -21,10 +21,12 @@
     Expression as Expression,
     alias_ as alias,
     and_ as and_,
+    cast as cast,
     column as column,
     condition as condition,
     except_ as except_,
     from_ as from_,
+    func as func,
     intersect as intersect,
     maybe_parse as maybe_parse,
     not_ as not_,
@@ -33,6 +35,7 @@
     subquery as subquery,
     table_ as table,
     to_column as to_column,
+    to_identifier as to_identifier,
     to_table as to_table,
     union as union,
 )

sqlglot/generator.py

@@ -1550,7 +1550,7 @@ def window_sql(self, expression: exp.Window) -> str:
         partition_sql = partition + " " if partition and order else partition
 
         spec = expression.args.get("spec")
-        spec_sql = " " + self.window_spec_sql(spec) if spec else ""
+        spec_sql = " " + self.windowspec_sql(spec) if spec else ""
 
         alias = self.sql(expression, "alias")
         over = self.sql(expression, "over") or "OVER"
@@ -1572,7 +1572,7 @@ def partition_by_sql(self, expression: exp.Window | exp.MatchRecognize) -> str:
         partition = self.expressions(expression, key="partition_by", flat=True)
         return f"PARTITION BY {partition}" if partition else ""
 
-    def window_spec_sql(self, expression: exp.WindowSpec) -> str:
+    def windowspec_sql(self, expression: exp.WindowSpec) -> str:
         kind = self.sql(expression, "kind")
         start = csv(self.sql(expression, "start"), self.sql(expression, "start_side"), sep=" ")
         end = (