1 files changed, 261 insertions, 0 deletions
diff --git a/lib/sqlalchemy/orm/path_registry.py b/lib/sqlalchemy/orm/path_registry.py
new file mode 100644
index 000000000..3397626b8
--- /dev/null
+++ b/lib/sqlalchemy/orm/path_registry.py
@@ -0,0 +1,261 @@
+# orm/path_registry.py
+# Copyright (C) 2005-2014 the SQLAlchemy authors and contributors <see AUTHORS file>
+#
+# This module is part of SQLAlchemy and is released under
+# the MIT License: http://www.opensource.org/licenses/mit-license.php
+"""Path tracking utilities, representing mapper graph traversals.
+
+"""
+
+from .. import inspection
+from .. import util
+from .. import exc
+from itertools import chain
+from .base import class_mapper
+
+def _unreduce_path(path):
+    return PathRegistry.deserialize(path)
+
+
+_WILDCARD_TOKEN = "*"
+_DEFAULT_TOKEN = "_sa_default"
+
+class PathRegistry(object):
+    """Represent query load paths and registry functions.
+
+    Basically represents structures like:
+
+    (<User mapper>, "orders", <Order mapper>, "items", <Item mapper>)
+
+    These structures are generated by things like
+    query options (joinedload(), subqueryload(), etc.) and are
+    used to compose keys stored in the query._attributes dictionary
+    for various options.
+
+    They are then re-composed at query compile/result row time as
+    the query is formed and as rows are fetched, where they again
+    serve to compose keys to look up options in the context.attributes
+    dictionary, which is copied from query._attributes.
+
+    The path structure has a limited amount of caching, where each
+    "root" ultimately pulls from a fixed registry associated with
+    the first mapper, that also contains elements for each of its
+    property keys.  However paths longer than two elements, which
+    are the exception rather than the rule, are generated on an
+    as-needed basis.
+
+    """
+
+    def __eq__(self, other):
+        return other is not None and \
+            self.path == other.path
+
+    def set(self, attributes, key, value):
+        attributes[(key, self.path)] = value
+
+    def setdefault(self, attributes, key, value):
+        attributes.setdefault((key, self.path), value)
+
+    def get(self, attributes, key, value=None):
+        key = (key, self.path)
+        if key in attributes:
+            return attributes[key]
+        else:
+            return value
+
+    def __len__(self):
+        return len(self.path)
+
+    @property
+    def length(self):
+        return len(self.path)
+
+    def pairs(self):
+        path = self.path
+        for i in range(0, len(path), 2):
+            yield path[i], path[i + 1]
+
+    def contains_mapper(self, mapper):
+        for path_mapper in [
+            self.path[i] for i in range(0, len(self.path), 2)
+        ]:
+            if path_mapper.is_mapper and \
+                path_mapper.isa(mapper):
+                return True
+        else:
+            return False
+
+    def contains(self, attributes, key):
+        return (key, self.path) in attributes
+
+    def __reduce__(self):
+        return _unreduce_path, (self.serialize(), )
+
+    def serialize(self):
+        path = self.path
+        return list(zip(
+            [m.class_ for m in [path[i] for i in range(0, len(path), 2)]],
+            [path[i].key for i in range(1, len(path), 2)] + [None]
+        ))
+
+    @classmethod
+    def deserialize(cls, path):
+        if path is None:
+            return None
+
+        p = tuple(chain(*[(class_mapper(mcls),
+                            class_mapper(mcls).attrs[key]
+                                if key is not None else None)
+                            for mcls, key in path]))
+        if p and p[-1] is None:
+            p = p[0:-1]
+        return cls.coerce(p)
+
+    @classmethod
+    def per_mapper(cls, mapper):
+        return EntityRegistry(
+                cls.root, mapper
+            )
+
+    @classmethod
+    def coerce(cls, raw):
+        return util.reduce(lambda prev, next: prev[next], raw, cls.root)
+
+    def token(self, token):
+        if token.endswith(':' + _WILDCARD_TOKEN):
+            return TokenRegistry(self, token)
+        elif token.endswith(":" + _DEFAULT_TOKEN):
+            return TokenRegistry(self.root, token)
+        else:
+            raise exc.ArgumentError("invalid token: %s" % token)
+
+    def __add__(self, other):
+        return util.reduce(
+                    lambda prev, next: prev[next],
+                    other.path, self)
+
+    def __repr__(self):
+        return "%s(%r)" % (self.__class__.__name__, self.path, )
+
+
+class RootRegistry(PathRegistry):
+    """Root registry, defers to mappers so that
+    paths are maintained per-root-mapper.
+
+    """
+    path = ()
+    has_entity = False
+    def __getitem__(self, entity):
+        return entity._path_registry
+
+PathRegistry.root = RootRegistry()
+
+class TokenRegistry(PathRegistry):
+    def __init__(self, parent, token):
+        self.token = token
+        self.parent = parent
+        self.path = parent.path + (token,)
+
+    has_entity = False
+
+    def __getitem__(self, entity):
+        raise NotImplementedError()
+
+class PropRegistry(PathRegistry):
+    def __init__(self, parent, prop):
+        # restate this path in terms of the
+        # given MapperProperty's parent.
+        insp = inspection.inspect(parent[-1])
+        if not insp.is_aliased_class or insp._use_mapper_path:
+            parent = parent.parent[prop.parent]
+        elif insp.is_aliased_class and insp.with_polymorphic_mappers:
+            if prop.parent is not insp.mapper and \
+                prop.parent in insp.with_polymorphic_mappers:
+                subclass_entity = parent[-1]._entity_for_mapper(prop.parent)
+                parent = parent.parent[subclass_entity]
+
+        self.prop = prop
+        self.parent = parent
+        self.path = parent.path + (prop,)
+
+    @util.memoized_property
+    def has_entity(self):
+        return hasattr(self.prop, "mapper")
+
+    @util.memoized_property
+    def entity(self):
+        return self.prop.mapper
+
+    @util.memoized_property
+    def _wildcard_path_loader_key(self):
+        """Given a path (mapper A, prop X), replace the prop with the wildcard,
+        e.g. (mapper A, 'relationship:.*') or (mapper A, 'column:.*'), then
+        return within the ("loader", path) structure.
+
+        """
+        return ("loader",
+                self.parent.token(
+                    "%s:%s" % (self.prop.strategy_wildcard_key, _WILDCARD_TOKEN)
+                    ).path
+                )
+
+    @util.memoized_property
+    def _default_path_loader_key(self):
+        return ("loader",
+                self.parent.token(
+                    "%s:%s" % (self.prop.strategy_wildcard_key, _DEFAULT_TOKEN)
+                    ).path
+                )
+
+    @util.memoized_property
+    def _loader_key(self):
+        return ("loader", self.path)
+
+    @property
+    def mapper(self):
+        return self.entity
+
+    @property
+    def entity_path(self):
+        return self[self.entity]
+
+    def __getitem__(self, entity):
+        if isinstance(entity, (int, slice)):
+            return self.path[entity]
+        else:
+            return EntityRegistry(
+                self, entity
+            )
+
+class EntityRegistry(PathRegistry, dict):
+    is_aliased_class = False
+    has_entity = True
+
+    def __init__(self, parent, entity):
+        self.key = entity
+        self.parent = parent
+        self.is_aliased_class = entity.is_aliased_class
+        self.entity = entity
+        self.path = parent.path + (entity,)
+        self.entity_path = self
+
+    @property
+    def mapper(self):
+        return inspection.inspect(self.entity).mapper
+
+    def __bool__(self):
+        return True
+    __nonzero__ = __bool__
+
+    def __getitem__(self, entity):
+        if isinstance(entity, (int, slice)):
+            return self.path[entity]
+        else:
+            return dict.__getitem__(self, entity)
+
+    def __missing__(self, key):
+        self[key] = item = PropRegistry(self, key)
+        return item
+
+
+