# Licensed to the Apache Software Foundation (ASF) under one
# or more contributor license agreements.  See the NOTICE file
# distributed with this work for additional information
# regarding copyright ownership.  The ASF licenses this file
# to you under the Apache License, Version 2.0 (the
# "License"); you may not use this file except in compliance
# with the License.  You may obtain a copy of the License at
#
#   http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing,
# software distributed under the License is distributed on an
# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
# KIND, either express or implied.  See the License for the
# specific language governing permissions and limitations
# under the License.

from abc import ABC, abstractmethod
from typing import Generic, Optional, TypeVar

T = TypeVar('T')


class RecordIterator(Generic[T], ABC):
    """
    An internal iterator interface which presents a more restrictive API than Iterator
    """

    @abstractmethod
    def next(self) -> Optional[T]:
        """
        Gets the next record from the iterator. Returns null if this iterator has no more elements.
        """

    def return_pos(self) -> int:
        """
        Returns the current position of the file.
        """
