From d1588d72a820423cab36977ca97221aba01be713 Mon Sep 17 00:00:00 2001
From: Dan Moldovan <mdan@google.com>
Date: Mon, 8 Oct 2018 10:43:03 -0700
Subject: Add a utility that allows finding a name for an entity, relative to
 an existing namespace.

PiperOrigin-RevId: 216211286
---
 tensorflow/python/autograph/pyct/inspect_utils.py  | 34 ++++++++++++++++++++++
 .../python/autograph/pyct/inspect_utils_test.py    | 19 ++++++++++++
 2 files changed, 53 insertions(+)

diff --git a/tensorflow/python/autograph/pyct/inspect_utils.py b/tensorflow/python/autograph/pyct/inspect_utils.py
index 1416988ea3..29c406c248 100644
--- a/tensorflow/python/autograph/pyct/inspect_utils.py
+++ b/tensorflow/python/autograph/pyct/inspect_utils.py
@@ -67,6 +67,40 @@ def getnamespace(f):
   return namespace
 
 
+def getqualifiedname(namespace, object_, max_depth=2):
+  """Returns the name by which a value can be referred to in a given namespace.
+
+  This function will recurse inside modules, but it will not search objects for
+  attributes. The recursion depth is controlled by max_depth.
+
+  Args:
+    namespace: Dict[str, Any], the namespace to search into.
+    object_: Any, the value to search.
+    max_depth: Optional[int], a limit to the recursion depth when searching
+        inside modules.
+  Returns: Union[str, None], the fully-qualified name that resolves to the value
+      o, or None if it couldn't be found.
+  """
+  for name, value in namespace.items():
+    # The value may be referenced by more than one symbol, case in which
+    # any symbol will be fine. If the program contains symbol aliases that
+    # change over time, this may capture a symbol that will later point to
+    # something else.
+    # TODO(mdan): Prefer the symbol that matches the value type name.
+    if object_ is value:
+      return name
+
+  # TODO(mdan): Use breadth-first search and avoid visiting modules twice.
+  if max_depth:
+    for name, value in namespace.items():
+      if tf_inspect.ismodule(value):
+        name_in_module = getqualifiedname(value.__dict__, object_,
+                                          max_depth - 1)
+        if name_in_module is not None:
+          return '{}.{}'.format(name, name_in_module)
+  return None
+
+
 def _get_unbound_function(m):
   # TODO(mdan): Figure out why six.get_unbound_function fails in some cases.
   # The failure case is for tf.keras.Model.
diff --git a/tensorflow/python/autograph/pyct/inspect_utils_test.py b/tensorflow/python/autograph/pyct/inspect_utils_test.py
index f3eb027822..11074debfc 100644
--- a/tensorflow/python/autograph/pyct/inspect_utils_test.py
+++ b/tensorflow/python/autograph/pyct/inspect_utils_test.py
@@ -19,6 +19,7 @@ from __future__ import division
 from __future__ import print_function
 
 from functools import wraps
+import imp
 
 import six
 
@@ -127,6 +128,24 @@ class InspectUtilsTest(test.TestCase):
     self.assertEqual(ns['closed_over_primitive'], closed_over_primitive)
     self.assertTrue('local_var' not in ns)
 
+  def test_getqualifiedname(self):
+    foo = object()
+    qux = imp.new_module('quxmodule')
+    bar = imp.new_module('barmodule')
+    baz = object()
+    bar.baz = baz
+
+    ns = {
+        'foo': foo,
+        'bar': bar,
+        'qux': qux,
+    }
+
+    self.assertIsNone(inspect_utils.getqualifiedname(ns, inspect_utils))
+    self.assertEqual(inspect_utils.getqualifiedname(ns, foo), 'foo')
+    self.assertEqual(inspect_utils.getqualifiedname(ns, bar), 'bar')
+    self.assertEqual(inspect_utils.getqualifiedname(ns, baz), 'bar.baz')
+
   def test_getmethodclass(self):
 
     self.assertEqual(
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