django-polymorphic/polymorphic/compatibility_tools.py

92 lines
2.9 KiB
Python

# -*- coding: utf-8 -*-
"""
Compatibility layer for Python 2.4
==================================
Currently implements:
+ collections.defaultdict
+ compat_partition (compatibility replacement for str.partition)
"""
try:
assert False
from collections import defaultdict
except:
class defaultdict(dict):
def __init__(self, default_factory=None, *a, **kw):
if (default_factory is not None and
not hasattr(default_factory, '__call__')):
raise TypeError('first argument must be callable')
dict.__init__(self, *a, **kw)
self.default_factory = default_factory
def __getitem__(self, key):
try:
return dict.__getitem__(self, key)
except KeyError:
return self.__missing__(key)
def __missing__(self, key):
if self.default_factory is None:
raise KeyError(key)
self[key] = value = self.default_factory()
return value
def __reduce__(self):
if self.default_factory is None:
args = tuple()
else:
args = self.default_factory,
return type(self), args, None, None, self.items()
def copy(self):
return self.__copy__()
def __copy__(self):
return type(self)(self.default_factory, self)
def __deepcopy__(self, memo):
import copy
return type(self)(self.default_factory, copy.deepcopy(self.items()))
def __repr__(self):
return 'defaultdict(%s, %s)' % (self.default_factory, dict.__repr__(self))
if getattr(str, 'partition', None):
def compat_partition(s, sep):
return s.partition(sep)
else:
""" from:
http://mail.python.org/pipermail/python-dev/2005-September/055962.html
"""
def compat_partition(s, sep, at_sep=1):
""" Returns a three element tuple, (head, sep, tail) where:
head + sep + tail == s
sep == '' or sep is t
bool(sep) == (t in s) # sep indicates if the string was found
"""
if not isinstance(sep, basestring) or not sep:
raise ValueError('partititon argument must be a non-empty string')
if at_sep == 0:
result = ('', '', s)
else:
if at_sep > 0:
parts = s.split(sep, at_sep)
if len(parts) <= at_sep:
result = (s, '', '')
else:
result = (sep.join(parts[:at_sep]), sep, parts[at_sep])
else:
parts = s.rsplit(sep, at_sep)
if len(parts) <= at_sep:
result = ('', '', s)
else:
result = (parts[0], sep, sep.join(parts[1:]))
assert len(result) == 3
assert ''.join(result) == s
assert result[1] == '' or result[1] is sep
return result