Mercurial > hg
view mercurial/pure/base85.py @ 20610:34bb07e70c68
revset: added filter method to revset classes
This method will replace the creation of lazysets inside the revset methods.
Instead, the classes that handle lazy structures will create them based on
their current order.
author | Lucas Moscovicz <lmoscovicz@fb.com> |
---|---|
date | Thu, 06 Feb 2014 17:18:11 -0800 |
parents | 20a9d823f242 |
children | 9007f697e8ef |
line wrap: on
line source
# 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