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55 lines
1.6 KiB
55 lines
1.6 KiB
from nd2reader.parser.v3 import V3Parser
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import re
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from nd2reader.exc import InvalidVersionError
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def get_parser(fh):
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"""
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Picks the appropriate parser based on the ND2 version.
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:type fh: file
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:type major_version: int
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:type minor_version: int
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:rtype: a parser object
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"""
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major_version, minor_version = get_version(fh)
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parsers = {(3, None): V3Parser}
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parser = parsers.get((major_version, minor_version)) or parsers.get((major_version, None))
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if not parser:
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raise InvalidVersionError("No parser is available for that version.")
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return parser(fh)
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def get_version(fh):
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"""
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Determines what version the ND2 is.
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:param fh: an open file handle to the ND2
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:type fh: file
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"""
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# the first 16 bytes seem to have no meaning, so we skip them
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fh.seek(16)
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# the next 38 bytes contain the string that we want to parse. Unlike most of the ND2, this is in UTF-8
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data = fh.read(38).decode("utf8")
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return parse_version(data)
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def parse_version(data):
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"""
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Parses a string with the version data in it.
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:param data: the 19th through 54th byte of the ND2, representing the version
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:type data: unicode
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"""
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match = re.search(r"""^ND2 FILE SIGNATURE CHUNK NAME01!Ver(?P<major>\d)\.(?P<minor>\d)$""", data)
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if match:
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# We haven't seen a lot of ND2s but the ones we have seen conform to this
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return int(match.group('major')), int(match.group('minor'))
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raise InvalidVersionError("The version of the ND2 you specified is not supported.")
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