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# Copyright (c) 2009, Jay Loden, Giampaolo Rodola'. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
"""Module which provides compatibility with older Python versions."""
__all__ = ["PY3", "int", "long", "xrange", "exec_", "callable",
"namedtuple", "property", "defaultdict"]
import sys
# --- python 2/3 compatibility layer
PY3 = sys.version_info >= (3,)
try:
import __builtin__
except ImportError:
import builtins as __builtin__ # py3
if PY3:
int = int
long = int
xrange = range
exec_ = getattr(__builtin__, "exec")
print_ = getattr(__builtin__, "print")
else:
int = int
long = long
xrange = xrange
def exec_(code, globs=None, locs=None):
if globs is None:
frame = _sys._getframe(1)
globs = frame.f_globals
if locs is None:
locs = frame.f_locals
del frame
elif locs is None:
locs = globs
exec("""exec code in globs, locs""")
def print_(s):
sys.stdout.write(s + '\n')
sys.stdout.flush()
# removed in 3.0, reintroduced in 3.2
try:
callable = callable
except Exception:
def callable(obj):
for klass in type(obj).__mro__:
if "__call__" in klass.__dict__:
return True
return False
# --- stdlib additions
try:
from collections import namedtuple
except ImportError:
from operator import itemgetter as _itemgetter
from keyword import iskeyword as _iskeyword
import sys as _sys
def namedtuple(typename, field_names, verbose=False, rename=False):
"""A collections.namedtuple implementation written in Python
to support Python versions < 2.6.
Taken from: http://code.activestate.com/recipes/500261/
"""
# Parse and validate the field names. Validation serves two
# purposes, generating informative error messages and preventing
# template injection attacks.
if isinstance(field_names, basestring):
# names separated by whitespace and/or commas
field_names = field_names.replace(',', ' ').split()
field_names = tuple(map(str, field_names))
if rename:
names = list(field_names)
seen = set()
for i, name in enumerate(names):
if (not min(c.isalnum() or c=='_' for c in name) or _iskeyword(name)
or not name or name[0].isdigit() or name.startswith('_')
or name in seen):
names[i] = '_%d' % i
seen.add(name)
field_names = tuple(names)
for name in (typename,) + field_names:
if not min(c.isalnum() or c=='_' for c in name):
raise ValueError('Type names and field names can only contain ' \
'alphanumeric characters and underscores: %r'
% name)
if _iskeyword(name):
raise ValueError('Type names and field names cannot be a keyword: %r' \
% name)
if name[0].isdigit():
raise ValueError('Type names and field names cannot start with a ' \
'number: %r' % name)
seen_names = set()
for name in field_names:
if name.startswith('_') and not rename:
raise ValueError('Field names cannot start with an underscore: %r'
% name)
if name in seen_names:
raise ValueError('Encountered duplicate field name: %r' % name)
seen_names.add(name)
# Create and fill-in the class template
numfields = len(field_names)
# tuple repr without parens or quotes
argtxt = repr(field_names).replace("'", "")[1:-1]
reprtxt = ', '.join('%s=%%r' % name for name in field_names)
template = '''class %(typename)s(tuple):
'%(typename)s(%(argtxt)s)' \n
__slots__ = () \n
_fields = %(field_names)r \n
def __new__(_cls, %(argtxt)s):
return _tuple.__new__(_cls, (%(argtxt)s)) \n
@classmethod
def _make(cls, iterable, new=tuple.__new__, len=len):
'Make a new %(typename)s object from a sequence or iterable'
result = new(cls, iterable)
if len(result) != %(numfields)d:
raise TypeError('Expected %(numfields)d arguments, got %%d' %% len(result))
return result \n
def __repr__(self):
return '%(typename)s(%(reprtxt)s)' %% self \n
def _asdict(self):
'Return a new dict which maps field names to their values'
return dict(zip(self._fields, self)) \n
def _replace(_self, **kwds):
'Return a new %(typename)s object replacing specified fields with new values'
result = _self._make(map(kwds.pop, %(field_names)r, _self))
if kwds:
raise ValueError('Got unexpected field names: %%r' %% kwds.keys())
return result \n
def __getnewargs__(self):
return tuple(self) \n\n''' % locals()
for i, name in enumerate(field_names):
template += ' %s = _property(_itemgetter(%d))\n' % (name, i)
if verbose:
sys.stdout.write(template + '\n')
sys.stdout.flush()
# Execute the template string in a temporary namespace
namespace = dict(_itemgetter=_itemgetter, __name__='namedtuple_%s' % typename,
_property=property, _tuple=tuple)
try:
exec_(template, namespace)
except SyntaxError:
e = sys.exc_info()[1]
raise SyntaxError(e.message + ':\n' + template)
result = namespace[typename]
# For pickling to work, the __module__ variable needs to be set
# to the frame where the named tuple is created. Bypass this
# step in enviroments where sys._getframe is not defined (Jython
# for example) or sys._getframe is not defined for arguments
# greater than 0 (IronPython).
try:
result.__module__ = _sys._getframe(1).f_globals.get('__name__', '__main__')
except (AttributeError, ValueError):
pass
return result
# hack to support property.setter/deleter on python < 2.6
# http://docs.python.org/library/functions.html?highlight=property#property
if hasattr(property, 'setter'):
property = property
else:
class property(__builtin__.property):
__metaclass__ = type
def __init__(self, fget, *args, **kwargs):
super(property, self).__init__(fget, *args, **kwargs)
self.__doc__ = fget.__doc__
def getter(self, method):
return property(method, self.fset, self.fdel)
def setter(self, method):
return property(self.fget, method, self.fdel)
def deleter(self, method):
return property(self.fget, self.fset, method)
# py 2.5 collections.defauldict
# Taken from:
# http://code.activestate.com/recipes/523034-emulate-collectionsdefaultdict/
# credits: Jason Kirtland
try:
from collections import defaultdict
except ImportError:
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))
# py 2.5 functools.wraps
try:
from functools import wraps
except ImportError:
def wraps(original):
def inner(fn):
# see functools.WRAPPER_ASSIGNMENTS
for attribute in ['__module__',
'__name__',
'__doc__'
]:
setattr(fn, attribute, getattr(original, attribute))
# see functools.WRAPPER_UPDATES
for attribute in ['__dict__',
]:
if hasattr(fn, attribute):
getattr(fn, attribute).update(getattr(original, attribute))
else:
setattr(fn, attribute,
getattr(original, attribute).copy())
return fn
return inner
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