Function IsSequenceHelper

tensorflow/python/util/util.cc:293–313

Returns 1 if `o` is considered a sequence for the purposes of Flatten(). Returns 0 otherwise. Returns -1 if an error occurred.

// Returns 0 otherwise.
// Returns -1 if an error occurred.
int IsSequenceHelper(PyObject* o) {
  // We treat dicts and other mappings as special cases of sequences.
  if (IsMappingHelper(o)) return true;
  if (IsMappingViewHelper(o)) return true;
  if (IsAttrsHelper(o)) return true;
  if (PySet_Check(o) && !WarnedThatSetIsNotSequence) {
    LOG(WARNING) << "Sets are not currently considered sequences, "
                    "but this may change in the future, "
                    "so consider avoiding using them.";
    WarnedThatSetIsNotSequence = true;
  }
  static auto* const check_cache = new CachedTypeCheck([](PyObject* to_check) {
    int is_instance = IsInstanceOfRegisteredType(to_check, "Sequence");

    // Don't cache a failed is_instance check.
    if (is_instance == -1) return -1;

    return static_cast<int>(is_instance != 0 && !IsString(to_check));
  });
  return check_cache->CachedLookup(o);
}

// ValueIterator interface
class ValueIterator {