Internal refactoring; moving LOOKUP_SEP up one level.

In an ideal world, nothing except django.db.models.query should have to
import stuff from django.models.sql.*. A few things were needing to get
hold of sql.constants.LOOKUP_SEP, so this commit moves it up to
django.db.models.constants.LOOKUP_SEP.

There are still a couple of places (admin) poking into sql.* to get
QUERY_TERMS, which is unfortunate, but a slightly different issue and
harder to adjust.

5 files changed, 14 insertions, 8 deletions

diff --git a/django/db/models/sql/compiler.py b/django/db/models/sql/compiler.py
index caf2330bd1..28d2404858 100644
--- a/django/db/models/sql/compiler.py
+++ b/django/db/models/sql/compiler.py
@@ -3,9 +3,10 @@ from django.utils.six.moves import zip
 from django.core.exceptions import FieldError
 from django.db import transaction
 from django.db.backends.util import truncate_name
+from django.db.models.constants import LOOKUP_SEP
 from django.db.models.query_utils import select_related_descend
 from django.db.models.sql.constants import (SINGLE, MULTI, ORDER_DIR,
-    LOOKUP_SEP, GET_ITERATOR_CHUNK_SIZE)
+        GET_ITERATOR_CHUNK_SIZE)
 from django.db.models.sql.datastructures import EmptyResultSet
 from django.db.models.sql.expressions import SQLEvaluator
 from django.db.models.sql.query import get_order_dir, Query
diff --git a/django/db/models/sql/constants.py b/django/db/models/sql/constants.py
index b9cf2c96fd..f750310624 100644
--- a/django/db/models/sql/constants.py
+++ b/django/db/models/sql/constants.py
@@ -1,7 +1,13 @@
+"""
+Constants specific to the SQL storage portion of the ORM.
+"""
+
 from collections import namedtuple
 import re
 
-# Valid query types (a set is used for speedy lookups).
+# Valid query types (a set is used for speedy lookups). These are (currently)
+# considered SQL-specific; other storage systems may choose to use different
+# lookup types.
 QUERY_TERMS = set([
     'exact', 'iexact', 'contains', 'icontains', 'gt', 'gte', 'lt', 'lte', 'in',
     'startswith', 'istartswith', 'endswith', 'iendswith', 'range', 'year',
@@ -12,9 +18,6 @@ QUERY_TERMS = set([
 # Larger values are slightly faster at the expense of more storage space.
 GET_ITERATOR_CHUNK_SIZE = 100
 
-# Separator used to split filter strings apart.
-LOOKUP_SEP = '__'
-
 # Constants to make looking up tuple values clearer.
 # Join lists (indexes into the tuples that are values in the alias_map
 # dictionary in the Query class).
diff --git a/django/db/models/sql/expressions.py b/django/db/models/sql/expressions.py
index 1bbf742b5c..ac8fea6da3 100644
--- a/django/db/models/sql/expressions.py
+++ b/django/db/models/sql/expressions.py
@@ -1,6 +1,6 @@
 from django.core.exceptions import FieldError
+from django.db.models.constants import LOOKUP_SEP
 from django.db.models.fields import FieldDoesNotExist
-from django.db.models.sql.constants import LOOKUP_SEP
 
 class SQLEvaluator(object):
     def __init__(self, expression, query, allow_joins=True):
diff --git a/django/db/models/sql/query.py b/django/db/models/sql/query.py
index f259a2c7d5..77f24fcf24 100644
--- a/django/db/models/sql/query.py
+++ b/django/db/models/sql/query.py
@@ -15,11 +15,12 @@ from django.utils.tree import Node
 from django.utils import six
 from django.db import connections, DEFAULT_DB_ALIAS
 from django.db.models import signals
+from django.db.models.constants import LOOKUP_SEP
 from django.db.models.expressions import ExpressionNode
 from django.db.models.fields import FieldDoesNotExist
 from django.db.models.sql import aggregates as base_aggregates_module
-from django.db.models.sql.constants import (QUERY_TERMS, LOOKUP_SEP, ORDER_DIR,
-    SINGLE, ORDER_PATTERN, JoinInfo)
+from django.db.models.sql.constants import (QUERY_TERMS, ORDER_DIR, SINGLE,
+        ORDER_PATTERN, JoinInfo)
 from django.db.models.sql.datastructures import EmptyResultSet, Empty, MultiJoin
 from django.db.models.sql.expressions import SQLEvaluator
 from django.db.models.sql.where import (WhereNode, Constraint, EverythingNode,
diff --git a/django/db/models/sql/subqueries.py b/django/db/models/sql/subqueries.py
index 937505b9b0..c6995c6abb 100644
--- a/django/db/models/sql/subqueries.py
+++ b/django/db/models/sql/subqueries.py
@@ -3,6 +3,7 @@ Query subclasses which provide extra functionality beyond simple data retrieval.
 """
 
 from django.core.exceptions import FieldError
+from django.db.models.constants import LOOKUP_SEP
 from django.db.models.fields import DateField, FieldDoesNotExist
 from django.db.models.sql.constants import *
 from django.db.models.sql.datastructures import Date