1 files changed, 43 insertions, 25 deletions

diff --git a/sqlglot/expressions.py b/sqlglot/expressions.py
index 599c7db..8cdacce 100644
--- a/sqlglot/expressions.py
+++ b/sqlglot/expressions.py
@@ -213,21 +213,23 @@ class Expression(metaclass=_Expression):
         """
         return self.find_ancestor(Select)
 
-    def walk(self, bfs=True):
+    def walk(self, bfs=True, prune=None):
         """
         Returns a generator object which visits all nodes in this tree.
 
         Args:
             bfs (bool): if set to True the BFS traversal order will be applied,
                 otherwise the DFS traversal will be used instead.
+            prune ((node, parent, arg_key) -> bool): callable that returns True if
+                the generator should stop traversing this branch of the tree.
 
         Returns:
             the generator object.
         """
         if bfs:
-            yield from self.bfs()
+            yield from self.bfs(prune=prune)
         else:
-            yield from self.dfs()
+            yield from self.dfs(prune=prune)
 
     def dfs(self, parent=None, key=None, prune=None):
         """
@@ -506,6 +508,10 @@ class DerivedTable(Expression):
         return [select.alias_or_name for select in self.selects]
 
 
+class UDTF(DerivedTable):
+    pass
+
+
 class Annotation(Expression):
     arg_types = {
         "this": True,
@@ -652,7 +658,13 @@ class Delete(Expression):
 
 
 class Drop(Expression):
-    arg_types = {"this": False, "kind": False, "exists": False}
+    arg_types = {
+        "this": False,
+        "kind": False,
+        "exists": False,
+        "temporary": False,
+        "materialized": False,
+    }
 
 
 class Filter(Expression):
@@ -827,7 +839,7 @@ class Join(Expression):
         return join
 
 
-class Lateral(DerivedTable):
+class Lateral(UDTF):
     arg_types = {"this": True, "outer": False, "alias": False}
 
 
@@ -915,6 +927,14 @@ class LanguageProperty(Property):
     pass
 
 
+class ExecuteAsProperty(Property):
+    pass
+
+
+class VolatilityProperty(Property):
+    arg_types = {"this": True}
+
+
 class Properties(Expression):
     arg_types = {"expressions": True}
 
@@ -1098,7 +1118,7 @@ class Intersect(Union):
     pass
 
 
-class Unnest(DerivedTable):
+class Unnest(UDTF):
     arg_types = {
         "expressions": True,
         "ordinality": False,
@@ -1116,8 +1136,12 @@ class Update(Expression):
     }
 
 
-class Values(Expression):
-    arg_types = {"expressions": True}
+class Values(UDTF):
+    arg_types = {
+        "expressions": True,
+        "ordinality": False,
+        "alias": False,
+    }
 
 
 class Var(Expression):
@@ -2033,23 +2057,17 @@ class Func(Condition):
 
     @classmethod
     def from_arg_list(cls, args):
-        args_num = len(args)
-
-        all_arg_keys = list(cls.arg_types)
-        # If this function supports variable length argument treat the last argument as such.
-        non_var_len_arg_keys = all_arg_keys[:-1] if cls.is_var_len_args else all_arg_keys
-
-        args_dict = {}
-        arg_idx = 0
-        for arg_key in non_var_len_arg_keys:
-            if arg_idx >= args_num:
-                break
-            if args[arg_idx] is not None:
-                args_dict[arg_key] = args[arg_idx]
-            arg_idx += 1
-
-        if arg_idx < args_num and cls.is_var_len_args:
-            args_dict[all_arg_keys[-1]] = args[arg_idx:]
+        if cls.is_var_len_args:
+            all_arg_keys = list(cls.arg_types)
+            # If this function supports variable length argument treat the last argument as such.
+            non_var_len_arg_keys = all_arg_keys[:-1] if cls.is_var_len_args else all_arg_keys
+            num_non_var = len(non_var_len_arg_keys)
+
+            args_dict = {arg_key: arg for arg, arg_key in zip(args, non_var_len_arg_keys)}
+            args_dict[all_arg_keys[-1]] = args[num_non_var:]
+        else:
+            args_dict = {arg_key: arg for arg, arg_key in zip(args, cls.arg_types)}
+
         return cls(**args_dict)
 
     @classmethod