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import pickle

from pyflink.datastream.functions import SinkFunction
from pyflink.java_gateway import get_gateway


class DataStreamTestSinkFunction(SinkFunction):
    """
    A util class to collect test DataStream transformation results.
    """

    def __init__(self):
        self.j_data_stream_collect_sink = get_gateway().jvm \
            .org.apache.flink.python.util.DataStreamTestCollectSink()
        super(DataStreamTestSinkFunction, self).__init__(sink_func=self.j_data_stream_collect_sink)

    def get_results(self, is_python_object: bool = False, stringify: bool = True):
        j_results = self.get_java_function().collectAndClear(is_python_object)
        results = list(j_results)
        if not is_python_object:
            return results
        else:
            str_results = []
            for result in results:
                pickled_result = pickle.loads(result)
                if stringify:
                    str_results.append(str(pickled_result))
                else:
                    str_results.append(pickled_result)
            return str_results

    def clear(self):
        if self.j_data_stream_collect_sink is None:
            return
        self.j_data_stream_collect_sink.clear()