bool MessageDifferencer::CompareRepeatedRep()

in cdk/extra/protobuf/protobuf-3.19.6/src/google/protobuf/util/message_differencer.cc [1095:1243]
118 lines of code
43 McCabe index (conditional complexity)

bool MessageDifferencer::CompareRepeatedRep(
    const Message& message1, const Message& message2,
    const FieldDescriptor* repeated_field,
    std::vector<SpecificField>* parent_fields) {
  // the input FieldDescriptor is guaranteed to be repeated field.
  GOOGLE_DCHECK(repeated_field->is_repeated());
  const Reflection* reflection1 = message1.GetReflection();
  const Reflection* reflection2 = message2.GetReflection();

  const int count1 = reflection1->FieldSize(message1, repeated_field);
  const int count2 = reflection2->FieldSize(message2, repeated_field);
  const bool treated_as_subset = IsTreatedAsSubset(repeated_field);

  // If the field is not treated as subset and no detailed reports is needed,
  // we do a quick check on the number of the elements to avoid unnecessary
  // comparison.
  if (count1 != count2 && reporter_ == NULL && !treated_as_subset) {
    return false;
  }
  // A match can never be found if message1 has more items than message2.
  if (count1 > count2 && reporter_ == NULL) {
    return false;
  }

  // These two list are used for store the index of the correspondent
  // element in peer repeated field.
  std::vector<int> match_list1;
  std::vector<int> match_list2;

  const MapKeyComparator* key_comparator = GetMapKeyComparator(repeated_field);
  bool smart_list = IsTreatedAsSmartList(repeated_field);
  bool simple_list = key_comparator == nullptr &&
                     !IsTreatedAsSet(repeated_field) &&
                     !IsTreatedAsSmartSet(repeated_field) && !smart_list;

  // For simple lists, we avoid matching repeated field indices, saving the
  // memory allocations that would otherwise be needed for match_list1 and
  // match_list2.
  if (!simple_list) {
    // Try to match indices of the repeated fields. Return false if match fails.
    if (!MatchRepeatedFieldIndices(message1, message2, repeated_field,
                                   key_comparator, *parent_fields, &match_list1,
                                   &match_list2) &&
        reporter_ == nullptr) {
      return false;
    }
  }

  bool fieldDifferent = false;
  SpecificField specific_field;
  specific_field.field = repeated_field;

  // At this point, we have already matched pairs of fields (with the reporting
  // to be done later). Now to check if the paired elements are different.
  int next_unmatched_index = 0;
  for (int i = 0; i < count1; i++) {
    if (simple_list && i >= count2) {
      break;
    }
    if (!simple_list && match_list1[i] == -1) {
      if (smart_list) {
        if (reporter_ == nullptr) return false;
        AddSpecificIndex(&specific_field, message1, repeated_field, i);
        parent_fields->push_back(specific_field);
        reporter_->ReportDeleted(message1, message2, *parent_fields);
        parent_fields->pop_back();
        fieldDifferent = true;
        // Use -2 to mark this element has been reported.
        match_list1[i] = -2;
      }
      continue;
    }
    if (smart_list) {
      for (int j = next_unmatched_index; j < match_list1[i]; ++j) {
        GOOGLE_CHECK_LE(0, j);
        if (reporter_ == nullptr) return false;
        specific_field.index = j;
        AddSpecificNewIndex(&specific_field, message2, repeated_field, j);
        parent_fields->push_back(specific_field);
        reporter_->ReportAdded(message1, message2, *parent_fields);
        parent_fields->pop_back();
        fieldDifferent = true;
        // Use -2 to mark this element has been reported.
        match_list2[j] = -2;
      }
    }
    AddSpecificIndex(&specific_field, message1, repeated_field, i);
    if (simple_list) {
      AddSpecificNewIndex(&specific_field, message2, repeated_field, i);
    } else {
      AddSpecificNewIndex(&specific_field, message2, repeated_field,
                          match_list1[i]);
      next_unmatched_index = match_list1[i] + 1;
    }

    const bool result = CompareFieldValueUsingParentFields(
        message1, message2, repeated_field, i, specific_field.new_index,
        parent_fields);

    // If we have found differences, either report them or terminate if
    // no reporter is present. Note that ReportModified, ReportMoved, and
    // ReportMatched are all mutually exclusive.
    if (!result) {
      if (reporter_ == NULL) return false;
      parent_fields->push_back(specific_field);
      reporter_->ReportModified(message1, message2, *parent_fields);
      parent_fields->pop_back();
      fieldDifferent = true;
    } else if (reporter_ != NULL &&
               specific_field.index != specific_field.new_index &&
               !specific_field.field->is_map() && report_moves_) {
      parent_fields->push_back(specific_field);
      reporter_->ReportMoved(message1, message2, *parent_fields);
      parent_fields->pop_back();
    } else if (report_matches_ && reporter_ != NULL) {
      parent_fields->push_back(specific_field);
      reporter_->ReportMatched(message1, message2, *parent_fields);
      parent_fields->pop_back();
    }
  }

  // Report any remaining additions or deletions.
  for (int i = 0; i < count2; ++i) {
    if (!simple_list && match_list2[i] != -1) continue;
    if (simple_list && i < count1) continue;
    if (!treated_as_subset) {
      fieldDifferent = true;
    }

    if (reporter_ == NULL) continue;
    specific_field.index = i;
    AddSpecificNewIndex(&specific_field, message2, repeated_field, i);
    parent_fields->push_back(specific_field);
    reporter_->ReportAdded(message1, message2, *parent_fields);
    parent_fields->pop_back();
  }

  for (int i = 0; i < count1; ++i) {
    if (!simple_list && match_list1[i] != -1) continue;
    if (simple_list && i < count2) continue;
    assert(reporter_ != NULL);
    AddSpecificIndex(&specific_field, message1, repeated_field, i);
    parent_fields->push_back(specific_field);
    reporter_->ReportDeleted(message1, message2, *parent_fields);
    parent_fields->pop_back();
    fieldDifferent = true;
  }
  return !fieldDifferent;
}