os-ken/ryu/lib/stringify.py
IWASE Yusuke 59ea6a5231 lib: Reduce Pylint warnings
Signed-off-by: IWASE Yusuke <iwase.yusuke0@gmail.com>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
2016-08-19 17:49:01 +09:00

398 lines
13 KiB
Python

# Copyright (C) 2013 Nippon Telegraph and Telephone Corporation.
# Copyright (C) 2013 YAMAMOTO Takashi <yamamoto at valinux co jp>
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
# implied.
# See the License for the specific language governing permissions and
# limitations under the License.
from __future__ import print_function
import base64
import inspect
import six
# Some arguments to __init__ is mangled in order to avoid name conflicts
# with builtin names.
# The standard mangling is to append '_' in order to avoid name clashes
# with reserved keywords.
#
# PEP8:
# Function and method arguments
# If a function argument's name clashes with a reserved keyword,
# it is generally better to append a single trailing underscore
# rather than use an abbreviation or spelling corruption. Thus
# class_ is better than clss. (Perhaps better is to avoid such
# clashes by using a synonym.)
#
# grep __init__ *.py | grep '[^_]_\>' showed that
# 'len', 'property', 'set', 'type'
# A bit more generic way is adopted
_RESERVED_KEYWORD = dir(six.moves.builtins)
_mapdict = lambda f, d: dict([(k, f(v)) for k, v in d.items()])
_mapdict_key = lambda f, d: dict([(f(k), v) for k, v in d.items()])
_mapdict_kv = lambda f, d: dict([(k, f(k, v)) for k, v in d.items()])
class TypeDescr(object):
pass
class AsciiStringType(TypeDescr):
@staticmethod
def encode(v):
# TODO: AsciiStringType data should probably be stored as
# text_type in class data. This isinstance() check exists
# because OFPDescStats violates this.
if six.PY3 and isinstance(v, six.text_type):
return v
return six.text_type(v, 'ascii')
@staticmethod
def decode(v):
if six.PY3:
return v
return v.encode('ascii')
class Utf8StringType(TypeDescr):
@staticmethod
def encode(v):
return six.text_type(v, 'utf-8')
@staticmethod
def decode(v):
return v.encode('utf-8')
class AsciiStringListType(TypeDescr):
@staticmethod
def encode(v):
return [AsciiStringType.encode(x) for x in v]
@staticmethod
def decode(v):
return [AsciiStringType.decode(x) for x in v]
class NXFlowSpecFieldType(TypeDescr):
# ("field_name", 0) <-> ["field_name", 0]
@staticmethod
def encode(v):
if not isinstance(v, tuple):
return v
field, ofs = v
return [field, ofs]
@staticmethod
def decode(v):
if not isinstance(v, list):
return v
field, ofs = v
return field, ofs
_types = {
'ascii': AsciiStringType,
'utf-8': Utf8StringType,
'asciilist': AsciiStringListType,
'nx-flow-spec-field': NXFlowSpecFieldType, # XXX this should not be here
}
class StringifyMixin(object):
_TYPE = {}
"""_TYPE class attribute is used to annotate types of attributes.
This type information is used to find an appropriate conversion for
a JSON style dictionary.
Currently the following types are implemented.
========= =============
Type Description
========= =============
ascii US-ASCII
utf-8 UTF-8
asciilist list of ascii
========= =============
Example::
_TYPE = {
'ascii': [
'hw_addr',
],
'utf-8': [
'name',
]
}
"""
_class_prefixes = []
_class_suffixes = []
def stringify_attrs(self):
"""an override point for sub classes"""
return obj_python_attrs(self)
def __str__(self):
# repr() to escape binaries
return self.__class__.__name__ + '(' + \
','.join("%s=%s" % (k, repr(v)) for k, v in
self.stringify_attrs()) + ')'
__repr__ = __str__ # note: str(list) uses __repr__ for elements
@classmethod
def _is_class(cls, dict_):
# we distinguish a dict like OFPSwitchFeatures.ports
# from OFPxxx classes using heuristics.
# Examples of OFP classes:
# {"OFPMatch": { ... }}
# {"MTIPv6SRC": { ... }}
assert isinstance(dict_, dict)
if len(dict_) != 1:
return False
k = list(dict_.keys())[0]
if not isinstance(k, (bytes, six.text_type)):
return False
for p in cls._class_prefixes:
if k.startswith(p):
return True
for p in cls._class_suffixes:
if k.endswith(p):
return True
return False
@classmethod
def _get_type(cls, k):
if hasattr(cls, '_TYPE'):
for t, attrs in cls._TYPE.items():
if k in attrs:
return _types[t]
return None
@classmethod
def _get_encoder(cls, k, encode_string):
t = cls._get_type(k)
if t:
return t.encode
return cls._get_default_encoder(encode_string)
@classmethod
def _encode_value(cls, k, v, encode_string=base64.b64encode):
return cls._get_encoder(k, encode_string)(v)
@classmethod
def _get_default_encoder(cls, encode_string):
def _encode(v):
if isinstance(v, (bytes, six.text_type)):
if isinstance(v, six.text_type):
v = v.encode('utf-8')
json_value = encode_string(v)
if six.PY3:
json_value = json_value.decode('ascii')
elif isinstance(v, list):
json_value = [_encode(ve) for ve in v]
elif isinstance(v, dict):
json_value = _mapdict(_encode, v)
# while a python dict key can be any hashable object,
# a JSON object key should be a string.
json_value = _mapdict_key(str, json_value)
assert not cls._is_class(json_value)
else:
try:
json_value = v.to_jsondict()
except Exception:
json_value = v
return json_value
return _encode
def to_jsondict(self, encode_string=base64.b64encode):
"""
This method returns a JSON style dict to describe this object.
The returned dict is compatible with json.dumps() and json.loads().
Suppose ClassName object inherits StringifyMixin.
For an object like the following::
ClassName(Param1=100, Param2=200)
this method would produce::
{ "ClassName": {"Param1": 100, "Param2": 200} }
This method takes the following arguments.
.. tabularcolumns:: |l|L|
============= =====================================================
Argument Description
============= =====================================================
encode_string (Optional) specify how to encode attributes which has
python 'str' type.
The default is base64.
This argument is used only for attributes which don't
have explicit type annotations in _TYPE class attribute.
============= =====================================================
"""
dict_ = {}
encode = lambda key, val: self._encode_value(key, val, encode_string)
for k, v in obj_attrs(self):
dict_[k] = encode(k, v)
return {self.__class__.__name__: dict_}
@classmethod
def cls_from_jsondict_key(cls, k):
# find a class with the given name from our class' module.
import sys
mod = sys.modules[cls.__module__]
return getattr(mod, k)
@classmethod
def obj_from_jsondict(cls, jsondict, **additional_args):
assert len(jsondict) == 1
for k, v in jsondict.items():
obj_cls = cls.cls_from_jsondict_key(k)
return obj_cls.from_jsondict(v, **additional_args)
@classmethod
def _get_decoder(cls, k, decode_string):
t = cls._get_type(k)
if t:
return t.decode
return cls._get_default_decoder(decode_string)
@classmethod
def _decode_value(cls, k, json_value, decode_string=base64.b64decode,
**additional_args):
# Note: To avoid passing redundant arguments (e.g. 'datapath' for
# non OFP classes), we omit '**additional_args' here.
return cls._get_decoder(k, decode_string)(json_value)
@classmethod
def _get_default_decoder(cls, decode_string):
def _decode(json_value, **additional_args):
if isinstance(json_value, (bytes, six.text_type)):
v = decode_string(json_value)
elif isinstance(json_value, list):
v = [_decode(jv) for jv in json_value]
elif isinstance(json_value, dict):
if cls._is_class(json_value):
v = cls.obj_from_jsondict(json_value, **additional_args)
else:
v = _mapdict(_decode, json_value)
# XXX: Hack
# try to restore integer keys used by
# OFPSwitchFeatures.ports.
try:
v = _mapdict_key(int, v)
except ValueError:
pass
else:
v = json_value
return v
return _decode
@staticmethod
def _restore_args(dict_):
def restore(k):
if k in _RESERVED_KEYWORD:
return k + '_'
return k
return _mapdict_key(restore, dict_)
@classmethod
def from_jsondict(cls, dict_, decode_string=base64.b64decode,
**additional_args):
"""Create an instance from a JSON style dict.
Instantiate this class with parameters specified by the dict.
This method takes the following arguments.
.. tabularcolumns:: |l|L|
=============== =====================================================
Argument Descrpition
=============== =====================================================
dict\_ A dictionary which describes the parameters.
For example, {"Param1": 100, "Param2": 200}
decode_string (Optional) specify how to decode strings.
The default is base64.
This argument is used only for attributes which don't
have explicit type annotations in _TYPE class
attribute.
additional_args (Optional) Additional kwargs for constructor.
=============== =====================================================
"""
decode = lambda k, x: cls._decode_value(k, x, decode_string,
**additional_args)
kwargs = cls._restore_args(_mapdict_kv(decode, dict_))
try:
return cls(**dict(kwargs, **additional_args))
except TypeError:
# debug
print("CLS %s" % cls)
print("ARG %s" % dict_)
print("KWARG %s" % kwargs)
raise
@classmethod
def set_classes(cls, registered_dict):
cls._class_prefixes.extend([v.__name__ for v in
registered_dict.values()])
def obj_python_attrs(msg_):
"""iterate object attributes for stringify purposes
"""
# a special case for namedtuple which seems widely used in
# ofp parser implementations.
if hasattr(msg_, '_fields'):
for k in msg_._fields:
yield(k, getattr(msg_, k))
return
base = getattr(msg_, '_base_attributes', [])
for k, v in inspect.getmembers(msg_):
if k.startswith('_'):
continue
if callable(v):
continue
if k in base:
continue
if hasattr(msg_.__class__, k):
continue
yield (k, v)
def obj_attrs(msg_):
"""similar to obj_python_attrs() but deals with python reserved keywords
"""
if isinstance(msg_, StringifyMixin):
itr = msg_.stringify_attrs()
else:
# probably called by msg_str_attr
itr = obj_python_attrs(msg_)
for k, v in itr:
if k.endswith('_') and k[:-1] in _RESERVED_KEYWORD:
# XXX currently only StringifyMixin has restoring logic
assert isinstance(msg_, StringifyMixin)
k = k[:-1]
yield (k, v)