Unify Query and select() , move all processing to compile phase

Convert Query to do virtually all compile state computation
in the _compile_context() phase, and organize it all
such that a plain select() construct may also be used as the
source of information in order to generate ORM query state.
This makes it such that Query is not needed except for
its additional methods like from_self() which are all to
be deprecated.

The construction of ORM state will occur beyond the
caching boundary when the new execution model is integrated.

future select() gains a working join() and filter_by() method.
as we continue to rebase and merge each commit in the steps,
callcounts continue to bump around.  will have to look at
the final result when it's all in.

References: #5159
References: #4705
References: #4639
References: #4871
References: #5010

Change-Id: I19e05b3424b07114cce6c439b05198ac47f7ac10

1 files changed, 31 insertions, 0 deletions

diff --git a/lib/sqlalchemy/sql/util.py b/lib/sqlalchemy/sql/util.py
index 0a67ff9bf..377aa4fe0 100644
--- a/lib/sqlalchemy/sql/util.py
+++ b/lib/sqlalchemy/sql/util.py
@@ -37,6 +37,7 @@ from .selectable import Join
 from .selectable import ScalarSelect
 from .selectable import SelectBase
 from .selectable import TableClause
+from .traversals import HasCacheKey  # noqa
 from .. import exc
 from .. import util
 
@@ -921,6 +922,14 @@ class ColumnAdapter(ClauseAdapter):
     adapt_clause = traverse
     adapt_list = ClauseAdapter.copy_and_process
 
+    def adapt_check_present(self, col):
+        newcol = self.columns[col]
+
+        if newcol is col and self._corresponding_column(col, True) is None:
+            return None
+
+        return newcol
+
     def _locate_col(self, col):
 
         c = ClauseAdapter.traverse(self, col)
@@ -945,3 +954,25 @@ class ColumnAdapter(ClauseAdapter):
     def __setstate__(self, state):
         self.__dict__.update(state)
         self.columns = util.WeakPopulateDict(self._locate_col)
+
+
+def _entity_namespace_key(entity, key):
+    """Return an entry from an entity_namespace.
+
+
+    Raises :class:`_exc.InvalidRequestError` rather than attribute error
+    on not found.
+
+    """
+
+    ns = entity.entity_namespace
+    try:
+        return getattr(ns, key)
+    except AttributeError as err:
+        util.raise_(
+            exc.InvalidRequestError(
+                'Entity namespace for "%s" has no property "%s"'
+                % (entity, key)
+            ),
+            replace_context=err,
+        )