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