From 19b2dfd1bfe7fd716dd3d8bfa5f972070d83b42f Mon Sep 17 00:00:00 2001
From: Ian Foote <python@ian.feete.org>
Date: Sat, 5 Nov 2016 15:49:29 +0000
Subject: Refs #11964, #26167 -- Made Expressions deconstructible.

---
 django/db/models/expressions.py | 36 ++++++++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)

(limited to 'django')

diff --git a/django/db/models/expressions.py b/django/db/models/expressions.py
index cfa23ccd2d..2528da2249 100644
--- a/django/db/models/expressions.py
+++ b/django/db/models/expressions.py
@@ -5,6 +5,7 @@ from django.core.exceptions import EmptyResultSet, FieldError
 from django.db.backends import utils as backend_utils
 from django.db.models import fields
 from django.db.models.query_utils import Q
+from django.utils.deconstruct import deconstructible
 from django.utils.functional import cached_property
 
 
@@ -117,6 +118,7 @@ class Combinable:
         )
 
 
+@deconstructible
 class BaseExpression:
     """
     Base class for all query expressions.
@@ -339,6 +341,27 @@ class BaseExpression:
             if expr:
                 yield from expr.flatten()
 
+    def __eq__(self, other):
+        if self.__class__ != other.__class__:
+            return False
+        path, args, kwargs = self.deconstruct()
+        other_path, other_args, other_kwargs = other.deconstruct()
+        if (path, args) == (other_path, other_args):
+            kwargs = kwargs.copy()
+            other_kwargs = other_kwargs.copy()
+            output_field = type(kwargs.pop('output_field', None))
+            other_output_field = type(other_kwargs.pop('output_field', None))
+            if output_field == other_output_field:
+                return kwargs == other_kwargs
+        return False
+
+    def __hash__(self):
+        path, args, kwargs = self.deconstruct()
+        h = hash(path) ^ hash(args)
+        for kwarg in kwargs.items():
+            h ^= hash(kwarg)
+        return h
+
 
 class Expression(BaseExpression, Combinable):
     """
@@ -445,6 +468,7 @@ class TemporalSubtraction(CombinedExpression):
         return connection.ops.subtract_temporals(self.lhs.output_field.get_internal_type(), lhs, rhs)
 
 
+@deconstructible
 class F(Combinable):
     """
     An object capable of resolving references to existing query objects.
@@ -468,6 +492,12 @@ class F(Combinable):
     def desc(self, **kwargs):
         return OrderBy(self, descending=True, **kwargs)
 
+    def __eq__(self, other):
+        return self.__class__ == other.__class__ and self.name == other.name
+
+    def __hash__(self):
+        return hash(self.name)
+
 
 class ResolvedOuterRef(F):
     """
@@ -647,6 +677,12 @@ class RawSQL(Expression):
     def get_group_by_cols(self):
         return [self]
 
+    def __hash__(self):
+        h = hash(self.sql) ^ hash(self._output_field)
+        for param in self.params:
+            h ^= hash(param)
+        return h
+
 
 class Star(Expression):
     def __repr__(self):
-- 
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