Feat: add the ability to set meta in sql comments (#2351)

sqlglot/expressions.py

@@ -52,6 +52,9 @@ def __new__(cls, clsname, bases, attrs):
         return klass
 
 
+SQLGLOT_META = "sqlglot.meta"
+
+
 class Expression(metaclass=_Expression):
     """
     The base class for all expressions in a syntax tree. Each Expression encapsulates any necessary
@@ -266,7 +269,14 @@ def add_comments(self, comments: t.Optional[t.List[str]]) -> None:
         if self.comments is None:
             self.comments = []
         if comments:
-            self.comments.extend(comments)
+            for comment in comments:
+                _, *meta = comment.split(SQLGLOT_META)
+                if meta:
+                    for kv in "".join(meta).split(","):
+                        k, *v = kv.split("=")
+                        value = v[0].strip() if v else True
+                        self.meta[k.strip()] = value
+                self.comments.append(comment)
 
     def append(self, arg_key: str, value: t.Any) -> None:
         """

tests/test_expressions.py

@@ -951,3 +951,8 @@ def test_is_type(self):
 
         with self.assertRaises(ParseError):
             exp.DataType.build("foo")
+
+    def test_set_meta(self):
+        query = parse_one("SELECT * FROM foo /* sqlglot.meta x = 1, y = a, z */")
+        self.assertEqual(query.find(exp.Table).meta, {"x": "1", "y": "a", "z": True})
+        self.assertEqual(query.sql(), "SELECT * FROM foo /* sqlglot.meta x = 1, y = a, z */")