48 lines
1.3 KiB
Python
48 lines
1.3 KiB
Python
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# -*- coding: utf-8 -*-
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# Copyright 2017 Mike Fährmann
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#
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License version 2 as
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# published by the Free Software Foundation.
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"""Utility functions"""
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def apply_range(iterable, rangespec):
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"""Return a new iterable containing only the items specified in the given
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integer range
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"""
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try:
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maxval = len(iterable)
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except TypeError:
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maxval = 0
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rset = parse_range(rangespec, maxval)
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return (
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item
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for index, item in enumerate(iterable, 1)
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if index in rset
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)
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def parse_range(rangespec, maxval=0):
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"""Parse an integer range and return the resulting set
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Examples
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parse_range("-2,4,6-8,10-", 12) -> set(1, 2, 4, 6, 7, 8, 10, 11, 12)
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parse_range(" - 3 , 4- 4, 6-2") -> set(1, 2, 3, 4)
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"""
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result = set()
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for group in rangespec.split(","):
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parts = group.split("-", maxsplit=1)
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try:
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if len(parts) == 1:
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result.add(int(parts[0]))
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else:
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beg = int(parts[0]) if parts[0].strip() else 1
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end = int(parts[1]) if parts[1].strip() else maxval
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result.update(range(beg, end+1))
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except ValueError:
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pass
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return result
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