Add minlen feature to base62.encode() #7
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And there's no performance penalty.
suminb
reviewed
May 19, 2017
| return ord(ch) - ord('a') + 36 | ||
| else: | ||
| try: | ||
| return CHARSET.index(ch) |
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처음엔 문자열 스캔을 없애 성능을 최적화하려고 했었는데, ord() 의 성능이 불투명하기도 하고, 차이가 거의 없을 것 같기도 해서, 차라리 문자열 스캔을 편하게 해버리는 쪽으로 방향을 틀었습니다 ㅎㅎ
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만약 성능이 걱정된다면 다음과 같이 상수 시간으로 접근할 수 있는 자료구조를 만드는 편이 좋을 것 같습니다.
CHARSET_INDEX = {'0': 0, '1': 1, ..., 'A': 10, ..., 'z': 61}
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이흥섭님의 의견:
REVERSE_CHARSET = {v: k for k, v in enumerate(CHARSET)}
suminb
reviewed
May 19, 2017
| @@ -31,22 +31,24 @@ def bytes_to_int(s, byteorder='big', signed=False): | |||
| return sum(ds) | |||
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| def encode(n): | |||
| def encode(n, minlen=0): | |||
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패딩의 길이가 아니라 인코딩 된 문자열의 최소 길이를 지정하는 인자니까 기본값이 1이 되어야 하지 않을까요?
| @@ -15,6 +15,7 @@ | |||
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| def test_basic(): | |||
| assert base62.encode(0) == '0' | |||
| assert base62.encode(0, minlen=5) == '00000' | |||
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이것과 비슷하게 decode() 쪽에도 테스트 케이스를 추가했으면 좋겠습니다. 예를 들면,
assert base62.decode('00000') == 0
| return ord(ch) - ord('a') + 36 | ||
| else: | ||
| try: | ||
| return CHARSET.index(ch) |
There was a problem hiding this comment.
만약 성능이 걱정된다면 다음과 같이 상수 시간으로 접근할 수 있는 자료구조를 만드는 편이 좋을 것 같습니다.
CHARSET_INDEX = {'0': 0, '1': 1, ..., 'A': 10, ..., 'z': 61}
| return ord(ch) - ord('a') + 36 | ||
| else: | ||
| try: | ||
| return CHARSET.index(ch) |
There was a problem hiding this comment.
이흥섭님의 의견:
REVERSE_CHARSET = {v: k for k, v in enumerate(CHARSET)}
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This PR will add minlen feature. In other words, it does zero padding for encode output string.
This implementation (and naming) is copied from the famous and widely used python bitcoin library
pybitcointools :
https://github.com/vbuterin/pybitcointools/blob/a82b00686b51677b047098e8968074a783e054a1/bitcoin/py2specials.py