43 lines
1.1 KiB
Python
43 lines
1.1 KiB
Python
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from contextlib import contextmanager
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import warnings
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__all__ = ["reversed"]
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@contextmanager
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def reversed(G):
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"""A context manager for temporarily reversing a directed graph in place.
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This is a no-op for undirected graphs.
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Parameters
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----------
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G : graph
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A NetworkX graph.
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Warning
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-------
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The reversed context manager is deprecated in favor
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of G.reverse(copy=False). The view allows multiple threads to use the
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same graph without confusion while the context manager does not.
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This context manager is scheduled to be removed in version 3.0.
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"""
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msg = (
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"context manager reversed is deprecated and to be removed in 3.0."
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"Use G.reverse(copy=False) if G.is_directed() else G instead."
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)
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warnings.warn(msg, DeprecationWarning)
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directed = G.is_directed()
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if directed:
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G._pred, G._succ = G._succ, G._pred
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G._adj = G._succ
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try:
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yield
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finally:
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if directed:
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# Reverse the reverse.
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G._pred, G._succ = G._succ, G._pred
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G._adj = G._succ
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