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# Authors:
# Pavel Zuna <pzuna@redhat.com>
#
# Copyright (C) 2009 Red Hat
# see file 'COPYING' for use and warranty information
#
# 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 3 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, see <http://www.gnu.org/licenses/>.
"""
Encoding capabilities.
"""
from decimal import Decimal
class EncoderSettings(object):
"""
Container for encoder settings.
"""
encode_to = 'utf-8'
encode_none = False
encode_dict_keys = False
encode_dict_keys_postprocess = True
encode_dict_vals = True
encode_dict_vals_postprocess = True
encode_postprocessor = staticmethod(lambda x: x)
decode_from = 'utf-8'
decode_none = False
decode_dict_keys = False
decode_dict_keys_postprocess = True
decode_dict_vals = True
decode_dict_vals_postprocess = True
decode_dict_vals_table = dict()
decode_dict_vals_table_keygen = staticmethod(lambda x, y: x)
decode_postprocessor = staticmethod(lambda x: x)
class Encoder(object):
"""
Base class implementing encoding of python scalar types to strings
and vise-versa.
"""
encoder_settings = EncoderSettings()
def __init__(self):
# each instance should have its own settings
self.encoder_settings = EncoderSettings()
def _decode_dict_val(self, key, val):
f = self.encoder_settings.decode_dict_vals_table.get(
self.encoder_settings.decode_dict_vals_table_keygen(key, val)
)
if f:
return val
return self.decode(val)
def encode(self, var):
"""
Encode any python built-in python type variable into `self.encode_to`.
Compound types have their individual members encoded.
Returns an encoded copy of 'var'.
"""
if isinstance(var, str):
return var
elif isinstance(var, unicode):
return self.encoder_settings.encode_postprocessor(
var.encode(self.encoder_settings.encode_to)
)
elif isinstance(var, (bool, float, Decimal, int, long)):
return self.encoder_settings.encode_postprocessor(
str(var).encode(self.encoder_settings.encode_to)
)
elif isinstance(var, list):
return [self.encode(m) for m in var]
elif isinstance(var, tuple):
return tuple(self.encode(m) for m in var)
elif isinstance(var, dict):
if self.encoder_settings.encode_dict_keys:
dct = dict()
if not self.encoder_settings.encode_dict_keys_postprocess:
tmp = self.encoder_settings.encode_postprocessor
self.encoder_settings.encode_postprocessor = lambda x: x
for (k, v) in var.iteritems():
dct[self.encode(k)] = v
if not self.encoder_settings.encode_dict_keys_postprocess:
self.encoder_settings.encode_postprocessor = tmp
else:
dct = dict(var)
if self.encoder_settings.encode_dict_vals:
if not self.encoder_settings.encode_dict_vals_postprocess:
tmp = self.encoder_settings.encode_postprocessor
self.encoder_settings.encode_postprocessor = lambda x: x
for (k, v) in dct.iteritems():
dct[k] = self.encode(v)
if not self.encoder_settings.encode_dict_vals_postprocess:
self.encoder_settings.encode_postprocessor = tmp
return dct
elif var is None:
if self.encoder_settings.encode_none:
return self.encoder_settings.encode_postprocessor(
str(var).encode(self.encoder_settings.encode_to)
)
return None
raise TypeError('python built-in type expected, got \'%s\'', type(var))
def decode(self, var):
"""
Decode strings in `self.decode_from` into python strings.
Compound types have their individual members decoded.
Dictionaries can have their values decoded into other types
by looking up keys in `self.decode_dict_vals_table`.
Returns a decoded copy of 'var'.
"""
if isinstance(var, unicode):
return var
elif isinstance(var, str):
return self.encoder_settings.decode_postprocessor(
var.decode(self.encoder_settings.decode_from)
)
elif isinstance(var, (bool, float, Decimal, int, long)):
return var
elif isinstance(var, list):
return [self.decode(m) for m in var]
elif isinstance(var, tuple):
return tuple(self.decode(m) for m in var)
elif isinstance(var, dict):
if self.encoder_settings.decode_dict_keys:
dct = dict()
if not self.encoder_settings.decode_dict_keys_postprocess:
tmp = self.encoder_settings.decode_postprocessor
self.encoder_settings.decode_postprocessor = lambda x: x
for (k, v) in var.iteritems():
dct[self.decode(k)] = v
if not self.encoder_settings.decode_dict_keys_postprocess:
self.encoder_settings.decode_postprocessor = tmp
else:
dct = dict(var)
if self.encoder_settings.decode_dict_vals:
if not self.encoder_settings.decode_dict_vals_postprocess:
tmp = self.encoder_settings.decode_postprocessor
self.encoder_settings.decode_postprocessor = lambda x: x
for (k, v) in dct.iteritems():
dct[k] = self._decode_dict_val(k, v)
if not self.encoder_settings.decode_dict_vals_postprocess:
self.encoder_settings.decode_postprocessor = tmp
return dct
elif var is None:
if self.encoder_settings.decode_none:
return self.encoder_settings.decode_postprocessor(
str(var).decode(self.encoder_settings.decode_from)
)
return None
raise TypeError('python built-in type expected, got \'%s\'', type(var))
## ENCODER METHOD DECORATORS
def encode_args(*outer_args):
def decorate(f):
def new_f(*args, **kwargs):
assert isinstance(args[0], Encoder), \
'first argument not Encoder instance'
new_args = list(args)
for a in outer_args:
if isinstance(a, int):
if a < len(args):
new_args[a] = args[0].encode(args[a])
elif isinstance(a, basestring):
if a in kwargs:
kwargs[a] = args[0].encode(kwargs[a])
else:
raise TypeError(
'encode_args takes a list of ints and basestrings'
)
return f(*new_args, **kwargs)
new_f.func_name = f.func_name
return new_f
return decorate
def decode_retval():
def decorate(f):
def new_f(*args, **kwargs):
assert isinstance(args[0], Encoder), \
'first argument not Encoder instance'
return args[0].decode(f(*args, **kwargs))
new_f.func_name = f.func_name
return new_f
return decorate
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