Ticket #16759: 16759_where_clone.diff

django/db/models/sql/query.py

@@ -254 +254 @@
         obj.dupe_avoidance = self.dupe_avoidance.copy()
         obj.select = self.select[:]
         obj.tables = self.tables[:]
-        obj.where = copy.deepcopy(self.where, memo=memo)
+        try:
+            obj.where = self.where.clone()
+        except AttributeError:
+            obj.where = copy.deepcopy(self.where, memo=memo)
         obj.where_class = self.where_class
         if self.group_by is None:
             obj.group_by = None
         else:
             obj.group_by = self.group_by[:]
-        obj.having = copy.deepcopy(self.having, memo=memo)
+        try:
+            obj.having = self.having.clone()
+        except AttributeError:
+            obj.having = copy.deepcopy(self.having, memo=memo)
         obj.order_by = self.order_by[:]
         obj.low_mark, obj.high_mark = self.low_mark, self.high_mark
         obj.distinct = self.distinct

django/db/models/sql/where.py

@@ -260 +260 @@
     def relabel_aliases(self, change_map, node=None):
         return
 
+    def clone(self):
+        return self
+
 class NothingNode(object):
     """
     A node that matches nothing.
@@ -270 +273 @@
     def relabel_aliases(self, change_map, node=None):
         return
 
+    def clone(self):
+        return self
+
 class ExtraWhere(object):
     def __init__(self, sqls, params):
         self.sqls = sqls
@@ -278 +284 @@
     def as_sql(self, qn=None, connection=None):
         return " AND ".join(self.sqls), tuple(self.params or ())
 
+    def clone(self):
+        return self
+
 class Constraint(object):
     """
     An object that can be passed to WhereNode.add() and knows how to
@@ -342 +351 @@
     def relabel_aliases(self, change_map):
         if self.alias in change_map:
             self.alias = change_map[self.alias]
+
+    def clone(self):
+        return Constraint(self.alias, self.col, self.field)

django/utils/tree.py

@@ -45 +45 @@
         return obj
     _new_instance = classmethod(_new_instance)
 
+    def clone(self):
+        clone = self.__class__._new_instance(
+            children=[], connector=self.connector, negated=self.negated)
+        for child in self.children:
+            if isinstance(child, tuple):
+                clone.children.append(
+                    (child[0].clone(), child[1], child[2], child[3]))
+            else:
+                try:
+                    clone.children.append(child.clone())
+                except AttributeError:
+                    # backwards compatibility - raise deprecation warning?
+                    clone.children.append(copy.deepcopy(child))
+        for parent in self.subtree_parents:
+             try:
+                 clone.subtree_parents.append(parent.clone())
+             except AttributeError:
+                 clone.subtree_parents.append(copy.deepcopy(parent))
+        return clone
+
     def __str__(self):
         if self.negated:
             return '(NOT (%s: %s))' % (self.connector, ', '.join([str(c) for c