upstream/mercurial-mirror Files · mercurial/pure/base85.py

scmutil: add a simple key-value file helper...

scmutil: add a simple key-value file helper The purpose of the added class is to serve purposes like save files of shelve or state files of shelve, rebase and histedit. Keys of these files can be alphanumeric and start with letters, while values must not contain newlines. In light of Mercurial's reluctancy to use Python's json module, this tries to provide a reasonable alternative for a non-nested named data. Comparing to current approach of storing state in plain text files, where semantic meaning of lines of text is only determined by their oreder, simple key-value file allows for reordering lines and thus helps handle optional values. Initial use-case I see for this is obs-shelve's shelve files. Later we can possibly migrate state files to this approach. The test is in a new file beause I did not figure out where to put it within existing test suite. If you give me a better idea, I will gladly follow it.

Gregory Szorc - - Load All Authors

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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.

      from __future__ import absolute_import

      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

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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.

				from __future__ import absolute_import

				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