in src/google/appengine/_internal/protorpc/messages.py [0:0]
def find_definition(name, relative_to=None, importer=__import__):
"""Find definition by name in module-space.
The find algorthm will look for definitions by name relative to a message
definition or by fully qualified name. If no definition is found relative
to the relative_to parameter it will do the same search against the container
of relative_to. If relative_to is a nested Message, it will search its
message_definition(). If that message has no message_definition() it will
search its module. If relative_to is a module, it will attempt to look for
the containing module and search relative to it. If the module is a top-level
module, it will look for the a message using a fully qualified name. If
no message is found then, the search fails and DefinitionNotFoundError is
raised.
For example, when looking for any definition 'foo.bar.ADefinition' relative to
an actual message definition abc.xyz.SomeMessage:
find_definition('foo.bar.ADefinition', SomeMessage)
It is like looking for the following fully qualified names:
abc.xyz.SomeMessage. foo.bar.ADefinition
abc.xyz. foo.bar.ADefinition
abc. foo.bar.ADefinition
foo.bar.ADefinition
When resolving the name relative to Message definitions and modules, the
algorithm searches any Messages or sub-modules found in its path.
Non-Message values are not searched.
A name that begins with '.' is considered to be a fully qualified name. The
name is always searched for from the topmost package. For example, assume
two message types:
abc.xyz.SomeMessage
xyz.SomeMessage
Searching for '.xyz.SomeMessage' relative to 'abc' will resolve to
'xyz.SomeMessage' and not 'abc.xyz.SomeMessage'. For this kind of name,
the relative_to parameter is effectively ignored and always set to None.
For more information about package name resolution, please see:
http://code.google.com/apis/protocolbuffers/docs/proto.html#packages
Args:
name: Name of definition to find. May be fully qualified or relative name.
relative_to: Search for definition relative to message definition or module.
None will cause a fully qualified name search.
importer: Import function to use for resolving modules.
Returns:
Enum or Message class definition associated with name.
Raises:
DefinitionNotFoundError if no definition is found in any search path.
"""
if not (relative_to is None or
isinstance(relative_to, types.ModuleType) or
isinstance(relative_to, type) and issubclass(relative_to, Message)):
raise TypeError('relative_to must be None, Message definition or module. '
'Found: %s' % relative_to)
name_path = six.ensure_str(name).split('.')
if not name_path[0]:
relative_to = None
name_path = name_path[1:]
def search_path():
"""Performs a single iteration searching the path from relative_to.
This is the function that searches up the path from a relative object.
fully.qualified.object . relative.or.nested.Definition
---------------------------->
^
|
this part of search --+
Returns:
Message or Enum at the end of name_path, else None.
"""
next = relative_to
for node in name_path:
attribute = getattr(next, node, None)
if attribute is not None:
next = attribute
else:
if next is None or isinstance(next, types.ModuleType):
if next is None:
module_name = node
else:
module_name = '%s.%s' % (next.__name__, node)
try:
fromitem = six.ensure_str(module_name).split('.')[-1]
next = importer(module_name, '', '', [str(fromitem)])
except ImportError:
return None
else:
return None
if (not isinstance(next, types.ModuleType) and
not (isinstance(next, type) and
issubclass(next, (Message, Enum)))):
return None
return next
while True:
found = search_path()
if isinstance(found, type) and issubclass(found, (Enum, Message)):
return found
else:
if relative_to is None:
raise DefinitionNotFoundError('Could not find definition for %s'
% (name,))
else:
if isinstance(relative_to, types.ModuleType):
module_path = six.ensure_str(relative_to.__name__).split('.')[:-1]
if not module_path:
relative_to = None
else:
relative_to = importer(
'.'.join(module_path), '', '', [module_path[-1]])
elif (isinstance(relative_to, type) and
issubclass(relative_to, Message)):
parent = relative_to.message_definition()
if parent is None:
last_module_name = six.ensure_str(
relative_to.__module__).split('.')[-1]
relative_to = importer(
relative_to.__module__, '', '', [last_module_name])
else:
relative_to = parent