Mercurial > hg
view mercurial/pure/base85.py @ 22806:65ccc733d58e
getlogrevs: remove user of baseset.append
A `baseset` has multiple cached results and will get even more in the future.
Making it an object "populated once" like the other smartsets makes it both safer
and simpler. The append method will be removed at some point.
author | Pierre-Yves David <pierre-yves.david@fb.com> |
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date | Tue, 07 Oct 2014 00:04:16 -0700 |
parents | 20a9d823f242 |
children | 9007f697e8ef |
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# base85.py: pure python base85 codec # # Copyright (C) 2009 Brendan Cully <brendan@kublai.com> # # This software may be used and distributed according to the terms of the # GNU General Public License version 2 or any later version. import struct _b85chars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ" \ "abcdefghijklmnopqrstuvwxyz!#$%&()*+-;<=>?@^_`{|}~" _b85chars2 = [(a + b) for a in _b85chars for b in _b85chars] _b85dec = {} def _mkb85dec(): for i, c in enumerate(_b85chars): _b85dec[c] = i def b85encode(text, pad=False): """encode text in base85 format""" l = len(text) r = l % 4 if r: text += '\0' * (4 - r) longs = len(text) >> 2 words = struct.unpack('>%dL' % (longs), text) out = ''.join(_b85chars[(word // 52200625) % 85] + _b85chars2[(word // 7225) % 7225] + _b85chars2[word % 7225] for word in words) if pad: return out # Trim padding olen = l % 4 if olen: olen += 1 olen += l // 4 * 5 return out[:olen] def b85decode(text): """decode base85-encoded text""" if not _b85dec: _mkb85dec() l = len(text) out = [] for i in range(0, len(text), 5): chunk = text[i:i + 5] acc = 0 for j, c in enumerate(chunk): try: acc = acc * 85 + _b85dec[c] except KeyError: raise ValueError('bad base85 character at position %d' % (i + j)) if acc > 4294967295: raise ValueError('Base85 overflow in hunk starting at byte %d' % i) out.append(acc) # Pad final chunk if necessary cl = l % 5 if cl: acc *= 85 ** (5 - cl) if cl > 1: acc += 0xffffff >> (cl - 2) * 8 out[-1] = acc out = struct.pack('>%dL' % (len(out)), *out) if cl: out = out[:-(5 - cl)] return out