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# Copyright (C) 2006 Canonical Ltd
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
# TODO: Some kind of command-line display of revision properties:
# perhaps show them in log -v and allow them as options to the commit command.
"""Some functions to enable caching the conversion between unicode to utf8"""
import codecs
_utf8_encode = codecs.getencoder("utf-8")
_utf8_decode = codecs.getdecoder("utf-8")
# Map revisions from and to utf8 encoding
# Whenever we do an encode/decode operation, we save the result, so that
# we don't have to do it again.
_unicode_to_utf8_map = {}
_utf8_to_unicode_map = {}
def encode(unicode_str,
_uni_to_utf8=_unicode_to_utf8_map,
_utf8_to_uni=_utf8_to_unicode_map,
_utf8_encode=_utf8_encode):
"""Take this unicode revision id, and get a unicode version"""
# If the key is in the cache try/KeyError is 50% faster than
# val = dict.get(key), if val is None:
# On jam's machine the difference is
# try/KeyError: 900ms
# if None: 1250ms
# Since these are primarily used when iterating over a knit entry
# *most* of the time the key will already be in the cache, so use the
# fast path
try:
return _uni_to_utf8[unicode_str]
except KeyError:
_uni_to_utf8[unicode_str] = utf8_str = _utf8_encode(unicode_str)[0]
_utf8_to_uni[utf8_str] = unicode_str
return utf8_str
def decode(utf8_str,
_uni_to_utf8=_unicode_to_utf8_map,
_utf8_to_uni=_utf8_to_unicode_map,
_utf8_decode=_utf8_decode):
"""Take a utf8 revision id, and decode it, but cache the result"""
try:
return _utf8_to_uni[utf8_str]
except KeyError:
_utf8_to_uni[utf8_str] = unicode_str = _utf8_decode(utf8_str)[0]
_uni_to_utf8[unicode_str] = utf8_str
return unicode_str
def get_cached_unicode(unicode_str):
"""Return a cached version of the unicode string.
This has a similar idea to that of intern() in that it tries
to return a singleton string. Only it works for unicode strings.
"""
# This might return the same object, or it might return the cached one
# the decode() should just be a hash lookup, because the encode() side
# should add the entry to the maps
return decode(encode(unicode_str))
def clear_encoding_cache():
"""Clear the encoding and decoding caches"""
_unicode_to_utf8_map.clear()
_utf8_to_unicode_map.clear()
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