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"""API for converting notebooks between versions."""
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# Copyright (c) IPython Development Team.
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# Distributed under the terms of the Modified BSD License.
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from .reader import get_version, versions
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def convert(nb, to_version):
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"""Convert a notebook node object to a specific version. Assumes that
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all the versions starting from 1 to the latest major X are implemented.
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In other words, there should never be a case where v1 v2 v3 v5 exist without
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a v4. Also assumes that all conversions can be made in one step increments
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between major versions and ignores minor revisions.
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Parameters
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----------
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nb : NotebookNode
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to_version : int
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Major revision to convert the notebook to. Can either be an upgrade or
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a downgrade.
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"""
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# Get input notebook version.
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(version, version_minor) = get_version(nb)
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# Check if destination is current version, if so return contents
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if version == to_version:
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return nb
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# If the version exist, try to convert to it one step at a time.
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elif to_version in versions:
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# Get the the version that this recursion will convert to as a step
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# closer to the final revision. Make sure the newer of the conversion
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# functions is used to perform the conversion.
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if to_version > version:
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step_version = version + 1
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convert_function = versions[step_version].upgrade
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else:
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step_version = version - 1
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convert_function = versions[version].downgrade
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# Convert and make sure version changed during conversion.
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converted = convert_function(nb)
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if converted.get('nbformat', 1) == version:
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raise ValueError("Cannot convert notebook from v%d to v%d. Operation" \
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"failed silently." % (version, step_version))
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# Recursively convert until target version is reached.
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return convert(converted, to_version)
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else:
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raise ValueError("Cannot convert notebook to v%d because that " \
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"version doesn't exist" % (to_version))
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