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import re |
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from abc import abstractmethod |
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from dataclasses import field |
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from typing import Any, Dict, Generator, List, Optional |
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from .artifact import Artifact |
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from .dataclass import NonPositionalField |
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from .stream import MultiStream, Stream |
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class Operator(Artifact): |
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pass |
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class OperatorError(Exception): |
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def __init__(self, exception: Exception, operators: List[Operator]): |
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super().__init__( |
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"This error was raised by the following operators: " |
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+ ",\n".join([str(operator) for operator in operators]) |
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+ "." |
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) |
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self.exception = exception |
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self.operators = operators |
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@classmethod |
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def from_operator_error(cls, exception: Exception, operator: Operator): |
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return cls(exception.exception, [*exception.operators, operator]) |
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@classmethod |
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def from_exception(cls, exception: Exception, operator: Operator): |
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return cls(exception, [operator]) |
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class StreamingOperator(Artifact): |
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"""Base class for all stream operators in the streaming model. |
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Stream operators are a key component of the streaming model and are responsible for processing continuous data streams. |
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They perform operations such as transformations, aggregations, joins, windowing and more on these streams. |
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There are several types of stream operators, including source operators, processing operators, etc. |
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As a `StreamingOperator`, this class is responsible for performing operations on a stream, and must be implemented by all other specific types of stream operators in the system. |
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When called, a `StreamingOperator` must return a MultiStream. |
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As a subclass of `Artifact`, every `StreamingOperator` can be saved in a catalog for further usage or reference. |
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""" |
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@abstractmethod |
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def __call__(self, streams: Optional[MultiStream] = None) -> MultiStream: |
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"""Abstract method that performs operations on the stream. |
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Args: |
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streams (Optional[MultiStream]): The input MultiStream, which can be None. |
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Returns: |
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MultiStream: The output MultiStream resulting from the operations performed on the input. |
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""" |
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class SideEffectOperator(StreamingOperator): |
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"""Base class for operators that does not affect the stream.""" |
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def __call__(self, streams: Optional[MultiStream] = None) -> MultiStream: |
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self.process() |
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return streams |
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@abstractmethod |
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def process() -> None: |
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pass |
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class SourceOperator(StreamingOperator): |
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"""A class representing a source operator in the streaming system. |
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A source operator is responsible for generating the data stream from some source, such as a database or a file. |
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This is the starting point of a stream processing pipeline. |
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The `SourceOperator` class is a type of `SourceOperator`, which is a special type of `StreamingOperator` |
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that generates an output stream but does not take any input streams. |
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When called, a `SourceOperator` invokes its `process` method, which should be implemented by all subclasses |
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to generate the required `MultiStream`. |
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""" |
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caching: bool = NonPositionalField(default=None) |
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def __call__(self, multi_stream: Optional[MultiStream] = None) -> MultiStream: |
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multi_stream = self.process() |
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if self.caching is not None: |
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multi_stream.set_caching(self.caching) |
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return multi_stream |
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@abstractmethod |
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def process(self) -> MultiStream: |
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pass |
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class StreamInitializerOperator(SourceOperator): |
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"""A class representing a stream initializer operator in the streaming system. |
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A stream initializer operator is a special type of `SourceOperator` that is capable of taking parameters during the stream generation process. This can be useful in situations where the stream generation process needs to be customized or configured based on certain parameters. |
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When called, a `StreamInitializerOperator` invokes its `process` method, passing any supplied arguments and keyword arguments. The `process` method should be implemented by all subclasses to generate the required `MultiStream` based on the given arguments and keyword arguments. |
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""" |
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caching: bool = NonPositionalField(default=None) |
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def __call__(self, *args, **kwargs) -> MultiStream: |
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multi_stream = self.process(*args, **kwargs) |
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if self.caching is not None: |
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multi_stream.set_caching(self.caching) |
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return self.process(*args, **kwargs) |
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@abstractmethod |
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def process(self, *args, **kwargs) -> MultiStream: |
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pass |
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class MultiStreamOperator(StreamingOperator): |
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"""A class representing a multi-stream operator in the streaming system. |
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A multi-stream operator is a type of `StreamingOperator` that operates on an entire MultiStream object at once. It takes a `MultiStream` as input and produces a `MultiStream` as output. The `process` method should be implemented by subclasses to define the specific operations to be performed on the input `MultiStream`. |
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""" |
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caching: bool = NonPositionalField(default=None) |
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def __call__(self, multi_stream: Optional[MultiStream] = None) -> MultiStream: |
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self.before_process_multi_stream() |
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result = self._process_multi_stream(multi_stream) |
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if self.caching is not None: |
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result.set_caching(self.caching) |
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return result |
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def before_process_multi_stream(self): |
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pass |
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def _process_multi_stream( |
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self, multi_stream: Optional[MultiStream] = None |
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) -> MultiStream: |
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result = self.process(multi_stream) |
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assert isinstance( |
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result, MultiStream |
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), "MultiStreamOperator must return a MultiStream" |
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return result |
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@abstractmethod |
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def process(self, multi_stream: MultiStream) -> MultiStream: |
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pass |
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def process_instance(self, instance, stream_name="tmp"): |
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multi_stream = {stream_name: [instance]} |
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processed_multi_stream = self(multi_stream) |
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return next(iter(processed_multi_stream[stream_name])) |
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class SingleStreamOperator(MultiStreamOperator): |
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"""A class representing a single-stream operator in the streaming system. |
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A single-stream operator is a type of `MultiStreamOperator` that operates on individual |
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`Stream` objects within a `MultiStream`. It iterates through each `Stream` in the `MultiStream` |
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and applies the `process` method. |
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The `process` method should be implemented by subclasses to define the specific operations |
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to be performed on each `Stream`. |
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""" |
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apply_to_streams: List[str] = NonPositionalField( |
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default=None |
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) |
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dont_apply_to_streams: List[str] = NonPositionalField(default_factory=None) |
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def _process_multi_stream(self, multi_stream: MultiStream) -> MultiStream: |
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result = {} |
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for stream_name, stream in multi_stream.items(): |
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if self._is_should_be_processed(stream_name): |
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stream = self._process_single_stream(stream, stream_name) |
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else: |
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stream = stream |
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assert isinstance( |
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stream, Stream |
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), "SingleStreamOperator must return a Stream" |
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result[stream_name] = stream |
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return MultiStream(result) |
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def _process_single_stream( |
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self, stream: Stream, stream_name: Optional[str] = None |
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) -> Stream: |
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return Stream( |
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self._process_stream, |
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gen_kwargs={"stream": stream, "stream_name": stream_name}, |
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) |
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def _is_should_be_processed(self, stream_name): |
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if ( |
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self.apply_to_streams is not None |
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and self.dont_apply_to_streams is not None |
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and stream_name in self.apply_to_streams |
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and stream_name in self.dont_apply_to_streams |
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): |
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raise ValueError( |
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f"Stream '{stream_name}' can be in either apply_to_streams or dont_apply_to_streams not both." |
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) |
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return ( |
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self.apply_to_streams is None or stream_name in self.apply_to_streams |
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) and ( |
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self.dont_apply_to_streams is None |
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or stream_name not in self.dont_apply_to_streams |
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) |
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def _process_stream( |
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self, stream: Stream, stream_name: Optional[str] = None |
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) -> Generator: |
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yield from self.process(stream, stream_name) |
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@abstractmethod |
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def process(self, stream: Stream, stream_name: Optional[str] = None) -> Generator: |
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pass |
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def process_instance(self, instance, stream_name="tmp"): |
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processed_stream = self._process_single_stream([instance], stream_name) |
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return next(iter(processed_stream)) |
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class PagedStreamOperator(SingleStreamOperator): |
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"""A class representing a paged-stream operator in the streaming system. |
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A paged-stream operator is a type of `SingleStreamOperator` that operates on a page of instances |
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in a `Stream` at a time, where a page is a subset of instances. |
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The `process` method should be implemented by subclasses to define the specific operations |
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to be performed on each page. |
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Args: |
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page_size (int): The size of each page in the stream. Defaults to 1000. |
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""" |
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page_size: int = 1000 |
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def _process_stream( |
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self, stream: Stream, stream_name: Optional[str] = None |
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) -> Generator: |
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page = [] |
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for instance in stream: |
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page.append(instance) |
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if len(page) >= self.page_size: |
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yield from self.process(page, stream_name) |
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page = [] |
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yield from self._process_page(page, stream_name) |
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def _process_page( |
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self, page: List[Dict], stream_name: Optional[str] = None |
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) -> Generator: |
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yield from self.process(page, stream_name) |
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@abstractmethod |
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def process(self, page: List[Dict], stream_name: Optional[str] = None) -> Generator: |
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pass |
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def process_instance(self, instance, stream_name="tmp"): |
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processed_stream = self._process_page([instance], stream_name) |
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return next(iter(processed_stream)) |
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class SingleStreamReducer(StreamingOperator): |
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"""A class representing a single-stream reducer in the streaming system. |
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A single-stream reducer is a type of `StreamingOperator` that operates on individual `Stream` objects within a `MultiStream` and reduces each `Stream` to a single output value. The `process` method should be implemented by subclasses to define the specific reduction operation to be performed on each `Stream`. |
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""" |
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def __call__(self, multi_stream: Optional[MultiStream] = None) -> Dict[str, Any]: |
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result = {} |
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for stream_name, stream in multi_stream.items(): |
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stream = self.process(stream) |
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result[stream_name] = stream |
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return result |
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@abstractmethod |
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def process(self, stream: Stream) -> Stream: |
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pass |
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class StreamInstanceOperator(SingleStreamOperator): |
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"""A class representing a stream instance operator in the streaming system. |
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A stream instance operator is a type of `SingleStreamOperator` that operates on individual instances within a `Stream`. It iterates through each instance in the `Stream` and applies the `process` method. The `process` method should be implemented by subclasses to define the specific operations to be performed on each instance. |
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""" |
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def _process_stream( |
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self, stream: Stream, stream_name: Optional[str] = None |
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) -> Generator: |
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try: |
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_index = None |
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for _index, instance in enumerate(stream): |
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yield self._process_instance(instance, stream_name) |
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except Exception as e: |
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if _index is None: |
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raise e |
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else: |
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raise ValueError( |
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f"Error processing instance '{_index}' from stream '{stream_name}' in {self.__class__.__name__} due to: {e}" |
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) from e |
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def _process_instance( |
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self, instance: Dict[str, Any], stream_name: Optional[str] = None |
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) -> Dict[str, Any]: |
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return self.process(instance, stream_name) |
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@abstractmethod |
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def process( |
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self, instance: Dict[str, Any], stream_name: Optional[str] = None |
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) -> Dict[str, Any]: |
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pass |
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def process_instance(self, instance, stream_name="tmp"): |
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return self._process_instance(instance, stream_name) |
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class StreamInstanceOperatorValidator(StreamInstanceOperator): |
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"""A class representing a stream instance operator validator in the streaming system. |
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A stream instance operator validator is a type of `StreamInstanceOperator` that includes a validation step. It operates on individual instances within a `Stream` and validates the result of processing each instance. |
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""" |
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@abstractmethod |
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def validate(self, instance): |
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pass |
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def _process_stream( |
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self, stream: Stream, stream_name: Optional[str] = None |
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) -> Generator: |
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iterator = iter(stream) |
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try: |
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first_instance = next(iterator) |
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except StopIteration as e: |
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raise StopIteration(f"Stream '{stream_name}' is empty") from e |
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result = self._process_instance(first_instance, stream_name) |
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self.validate(result) |
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yield result |
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yield from ( |
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self._process_instance(instance, stream_name) for instance in iterator |
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) |
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class InstanceOperator(Artifact): |
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"""A class representing an instance operator in the streaming system. |
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An instance operator is a type of `Artifact` that operates on a single instance (represented as a dict) at a time. It takes an instance as input and produces a transformed instance as output. |
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""" |
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def __call__(self, data: dict) -> dict: |
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return self.process(data) |
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@abstractmethod |
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def process(self, data: dict) -> dict: |
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pass |
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class BaseFieldOperator(Artifact): |
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"""A class representing a field operator in the streaming system. |
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A field operator is a type of `Artifact` that operates on a single field within an instance. It takes an instance and a field name as input, processes the field, and updates the field in the instance with the processed value. |
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""" |
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def __call__(self, data: Dict[str, Any], field: str) -> dict: |
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value = self.process(data[field]) |
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data[field] = value |
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return data |
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@abstractmethod |
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def process(self, value: Any) -> Any: |
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pass |
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class InstanceOperatorWithMultiStreamAccess(StreamingOperator): |
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"""A class representing an instance operator with global access in the streaming system. |
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An instance operator with global access is a type of `StreamingOperator` that operates on individual instances within a `Stream` and can also access other streams. |
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It uses the `accessible_streams` attribute to determine which other streams it has access to. |
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In order to make this efficient and to avoid qudratic complexity, it caches the accessible streams by default. |
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""" |
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def __call__(self, multi_stream: Optional[MultiStream] = None) -> MultiStream: |
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result = {} |
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for stream_name, stream in multi_stream.items(): |
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stream = Stream( |
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self.generator, |
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gen_kwargs={"stream": stream, "multi_stream": multi_stream}, |
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) |
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result[stream_name] = stream |
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return MultiStream(result) |
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def generator(self, stream, multi_stream): |
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yield from (self.process(instance, multi_stream) for instance in stream) |
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@abstractmethod |
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def process(self, instance: dict, multi_stream: MultiStream) -> dict: |
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pass |
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class SequentialOperator(MultiStreamOperator): |
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"""A class representing a sequential operator in the streaming system. |
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A sequential operator is a type of `MultiStreamOperator` that applies a sequence of other operators to a |
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`MultiStream`. It maintains a list of `StreamingOperator`s and applies them in order to the `MultiStream`. |
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""" |
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max_steps = None |
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steps: List[StreamingOperator] = field(default_factory=list) |
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def num_steps(self) -> int: |
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return len(self.steps) |
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def set_max_steps(self, max_steps): |
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assert ( |
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max_steps <= self.num_steps() |
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), f"Max steps requested ({max_steps}) is larger than defined steps {self.num_steps()}" |
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assert max_steps >= 1, f"Max steps requested ({max_steps}) is less than 1" |
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self.max_steps = max_steps |
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def get_last_step_description(self): |
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last_step = ( |
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self.max_steps - 1 if self.max_steps is not None else len(self.steps) - 1 |
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) |
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description = str(self.steps[last_step]) |
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return re.sub(r"\w+=None, ", "", description) |
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def _get_max_steps(self): |
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return self.max_steps if self.max_steps is not None else len(self.steps) |
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def process(self, multi_stream: Optional[MultiStream] = None) -> MultiStream: |
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for operator in self.steps[0 : self._get_max_steps()]: |
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multi_stream = operator(multi_stream) |
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return multi_stream |
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class SourceSequentialOperator(SequentialOperator): |
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"""A class representing a source sequential operator in the streaming system. |
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A source sequential operator is a type of `SequentialOperator` that starts with a source operator. |
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The first operator in its list of steps is a `SourceOperator`, which generates the initial `MultiStream` |
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that the other operators then process. |
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""" |
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def __call__(self) -> MultiStream: |
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return super().__call__() |
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def process(self, multi_stream: Optional[MultiStream] = None) -> MultiStream: |
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assert ( |
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self.num_steps() > 0 |
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), "Calling process on a SourceSequentialOperator without any steps" |
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multi_stream = self.steps[0]() |
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for operator in self.steps[1 : self._get_max_steps()]: |
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multi_stream = operator(multi_stream) |
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return multi_stream |
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class SequentialOperatorInitilizer(SequentialOperator): |
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"""A class representing a sequential operator initializer in the streaming system. |
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A sequential operator initializer is a type of `SequntialOperator` that starts with a stream initializer operator. The first operator in its list of steps is a `StreamInitializerOperator`, which generates the initial `MultiStream` based on the provided arguments and keyword arguments. |
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""" |
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def __call__(self, *args, **kwargs) -> MultiStream: |
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return self.process(*args, **kwargs) |
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def process(self, *args, **kwargs) -> MultiStream: |
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assert ( |
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self.num_steps() > 0 |
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), "Calling process on a SequentialOperatorInitilizer without any steps" |
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assert isinstance( |
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self.steps[0], StreamInitializerOperator |
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), "The first step in a SequentialOperatorInitilizer must be a StreamInitializerOperator" |
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multi_stream = self.steps[0](*args, **kwargs) |
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for operator in self.steps[1 : self._get_max_steps()]: |
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multi_stream = operator(multi_stream) |
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return multi_stream |
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