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70 lines
2.3 KiB
Python
70 lines
2.3 KiB
Python
"""Generate 10,000 unique examples for the Levenshtein short-circuit tests."""
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import argparse
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from functools import lru_cache
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import json
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import os.path
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from random import choices, randrange
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# This should be in sync with Lib/traceback.py. It's not importing those values
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# because this script is being executed by PYTHON_FOR_REGEN and not by the in-tree
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# build of Python.
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_MOVE_COST = 2
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_CASE_COST = 1
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def _substitution_cost(ch_a, ch_b):
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if ch_a == ch_b:
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return 0
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if ch_a.lower() == ch_b.lower():
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return _CASE_COST
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return _MOVE_COST
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@lru_cache(None)
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def levenshtein(a, b):
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if not a or not b:
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return (len(a) + len(b)) * _MOVE_COST
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option1 = levenshtein(a[:-1], b[:-1]) + _substitution_cost(a[-1], b[-1])
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option2 = levenshtein(a[:-1], b) + _MOVE_COST
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option3 = levenshtein(a, b[:-1]) + _MOVE_COST
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return min(option1, option2, option3)
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def main():
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parser = argparse.ArgumentParser(description=__doc__)
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parser.add_argument('output_path', metavar='FILE', type=str)
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parser.add_argument('--overwrite', dest='overwrite', action='store_const',
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const=True, default=False,
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help='overwrite an existing test file')
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args = parser.parse_args()
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output_path = os.path.realpath(args.output_path)
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if not args.overwrite and os.path.isfile(output_path):
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print(f"{output_path} already exists, skipping regeneration.")
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print(
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"To force, add --overwrite to the invocation of this tool or"
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" delete the existing file."
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)
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return
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examples = set()
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# Create a lot of non-empty examples, which should end up with a Gauss-like
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# distribution for even costs (moves) and odd costs (case substitutions).
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while len(examples) < 9990:
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a = ''.join(choices("abcABC", k=randrange(1, 10)))
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b = ''.join(choices("abcABC", k=randrange(1, 10)))
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expected = levenshtein(a, b)
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examples.add((a, b, expected))
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# Create one empty case each for strings between 0 and 9 in length.
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for i in range(10):
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b = ''.join(choices("abcABC", k=i))
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expected = levenshtein("", b)
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examples.add(("", b, expected))
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with open(output_path, "w") as f:
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json.dump(sorted(examples), f, indent=2)
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if __name__ == "__main__":
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main()
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