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      1 /* Copyright 2017 The TensorFlow Authors. All Rights Reserved.
      2 
      3 Licensed under the Apache License, Version 2.0 (the "License");
      4 you may not use this file except in compliance with the License.
      5 You may obtain a copy of the License at
      6 
      7     http://www.apache.org/licenses/LICENSE-2.0
      8 
      9 Unless required by applicable law or agreed to in writing, software
     10 distributed under the License is distributed on an "AS IS" BASIS,
     11 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     12 See the License for the specific language governing permissions and
     13 limitations under the License.
     14 ==============================================================================*/
     15 #include "tensorflow/python/util/util.h"
     16 
     17 #include "tensorflow/core/lib/strings/strcat.h"
     18 #include "tensorflow/core/platform/logging.h"
     19 
     20 namespace tensorflow {
     21 namespace swig {
     22 
     23 namespace {
     24 
     25 // Type object for collections.Sequence. This is set by RegisterSequenceClass.
     26 PyObject* CollectionsSequenceType = nullptr;
     27 
     28 bool WarnedThatSetIsNotSequence = false;
     29 
     30 // Returns 1 if `o` is considered a sequence for the purposes of Flatten().
     31 // Returns 0 otherwise.
     32 // Returns -1 if an error occurred.
     33 int IsSequenceHelper(PyObject* o) {
     34   if (PyDict_Check(o)) return true;
     35   if (PySet_Check(o) && !WarnedThatSetIsNotSequence) {
     36     LOG(WARNING) << "Sets are not currently considered sequences, "
     37                     "but this may change in the future, "
     38                     "so consider avoiding using them.";
     39     WarnedThatSetIsNotSequence = true;
     40   }
     41   if (CollectionsSequenceType == nullptr) {
     42     PyErr_SetString(
     43         PyExc_RuntimeError,
     44         tensorflow::strings::StrCat(
     45             "collections.Sequence type has not been set. "
     46             "Please call RegisterSequenceClass before using this module")
     47             .c_str());
     48     return -1;
     49   }
     50   int is_instance = PyObject_IsInstance(o, CollectionsSequenceType);
     51   if (is_instance == -1) return -1;
     52   return static_cast<int>(is_instance != 0 && !PyBytes_Check(o) &&
     53 #if PY_MAJOR_VERSION < 3
     54                           !PyString_Check(o) &&
     55 #endif
     56                           !PyUnicode_Check(o));
     57 }
     58 
     59 bool FlattenHelper(PyObject* nested, PyObject* list) {
     60   // if nested is not a sequence, append itself and exit
     61   int is_seq = IsSequenceHelper(nested);
     62   if (is_seq == -1) return false;
     63   if (!is_seq) {
     64     return PyList_Append(list, nested) != -1;
     65   }
     66 
     67   // if nested if dictionary, sort it by key and recurse on each value
     68   if (PyDict_Check(nested)) {
     69     PyObject* keys = PyDict_Keys(nested);
     70     if (PyList_Sort(keys) == -1) return false;
     71     Py_ssize_t size = PyList_Size(keys);
     72     for (Py_ssize_t i = 0; i < size; ++i) {
     73       // We know that key and val will not be deleted because nested owns
     74       // a reference to them and callers of flatten must not modify nested
     75       // while the method is running.
     76       PyObject* key = PyList_GET_ITEM(keys, i);
     77       PyObject* val = PyDict_GetItem(nested, key);
     78       if (Py_EnterRecursiveCall(" in Flatten")) {
     79         Py_DECREF(keys);
     80         return false;
     81       }
     82       FlattenHelper(val, list);
     83       Py_LeaveRecursiveCall();
     84     }
     85     Py_DECREF(keys);
     86     return true;
     87   }
     88 
     89   // iterate and recurse
     90   PyObject* item;
     91   PyObject* iterator = PyObject_GetIter(nested);
     92   while ((item = PyIter_Next(iterator)) != nullptr) {
     93     FlattenHelper(item, list);
     94     Py_DECREF(item);
     95   }
     96   Py_DECREF(iterator);
     97   return true;
     98 }
     99 
    100 }  // anonymous namespace
    101 
    102 void RegisterSequenceClass(PyObject* sequence_class) {
    103   if (!PyType_Check(sequence_class)) {
    104     PyErr_SetString(
    105         PyExc_TypeError,
    106         tensorflow::strings::StrCat(
    107             "Expecting a class definition for `collections.Sequence`. Got ",
    108             Py_TYPE(sequence_class)->tp_name)
    109             .c_str());
    110     return;
    111   }
    112   CollectionsSequenceType = sequence_class;
    113 }
    114 
    115 bool IsSequence(PyObject* o) { return IsSequenceHelper(o) == 1; }
    116 
    117 PyObject* Flatten(PyObject* nested) {
    118   PyObject* list = PyList_New(0);
    119   if (FlattenHelper(nested, list)) {
    120     return list;
    121   } else {
    122     Py_DECREF(list);
    123     return nullptr;
    124   }
    125 }
    126 }  // namespace swig
    127 }  // namespace tensorflow
    128