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import json
class Attr_Diff(dict):
"""
Represents a change to note attributes, where nodes can represent
either logical nodes or logical links, and attributes can be added,
changed or removed
Example:
attr_diff = {'__type_node' : {n_id: {'__attr_write': {'attr_0': 0,
'attr_1': 'a'},
'__attr_remove': ['attr_2'] }}
'__type_link' : {l_id: ... }
}
"""
def __init__(self):
self['__type_node'] = {}
self['__type_link'] = {}
def init_node_attr_diff(self, n_id):
ret = {'__attr_write': {},
'__attr_remove': []}
self['__type_node'][n_id] = ret
return ret
def init_link_attr_diff(self, l_id):
ret = {'__attr_write': {},
'__attr_remove': []}
self['__type_link'][l_id] = ret
return ret
@staticmethod
def from_json_dict(json_dict):
ret = Attr_Diff()
for obj_type, writer, remover in [
('__type_node', ret.add_node_attr_write, ret.add_node_attr_rm),
('__type_link', ret.add_link_attr_write, ret.add_link_attr_rm),
]:
obj_ad_set = json_dict.get(obj_type)
if None != obj_ad_set:
for o_id, ad in obj_ad_set.items():
if None != ad.get('__attr_write'):
for k, v in ad['__attr_write'].items():
writer(o_id, k, v)
if None != ad.get('__attr_remove'):
for k in ad['__attr_remove']:
remover(o_id, k)
return ret
@property
def type__node(self):
return self['__type_node']
@property
def type__link(self):
return self['__type_link']
def add_node_attr_write(self, n_id, attr_name, attr_val):
assert 'id' != attr_name.lower(), 'Attr_Diff: attempt to write to \'id\' attribute'
n_attr_diff = self['__type_node'].get(n_id)
if None == n_attr_diff:
n_attr_diff = self.init_node_attr_diff(n_id)
n_attr_diff['__attr_write'][attr_name] = attr_val
def add_node_attr_rm(self, n_id, attr_name):
assert 'id' != attr_name.lower(), 'Attr_Diff: attempt to remove \'id\' attribute'
n_attr_diff = self['__type_node'].get(n_id)
if None == n_attr_diff:
n_attr_diff = self.init_node_attr_diff(n_id)
n_attr_diff['__attr_remove'].append(attr_name)
def add_link_attr_write(self, l_id, attr_name, attr_val):
assert 'id' != attr_name.lower(), 'Attr_Diff: attempt to write to \'id\' attribute'
l_attr_diff = self['__type_link'].get(l_id)
if None == l_attr_diff:
l_attr_diff = self.init_link_attr_diff(l_id)
l_attr_diff['__attr_write'][attr_name] = attr_val
def add_link_attr_rm(self, l_id, attr_name):
assert 'id' != attr_name.lower(), 'Attr_Diff: attempt to remove \'id\' attribute'
assert 'name' != attr_name.lower(), 'Attr_Diff: attempt to remove link \'name\' attribute, use write instead'
l_attr_diff = self['__type_link'].get(l_id)
if None == l_attr_diff:
l_attr_diff = self.init_link_attr_diff(l_id)
l_attr_diff['__attr_remove'].append(attr_name)
class Topo_Diff(object):
"""
Represents a change to the graph topology
"""
class JSON_Encoder(json.JSONEncoder):
"""
Topo_Diff is not a plain dict, so we provide a json encoder
"""
def default(self, obj):
return obj.to_json_dict()
def to_json_dict(self):
ret = {k: getattr(self, k) for k in ['link_set_rm',
'node_set_rm',
'node_set_add',
'link_set_add'] }
return ret
def __init__(self, link_set_rm=[],
node_set_rm=[],
node_set_add=[],
link_set_add=[]):
self.link_set_rm = link_set_rm
self.node_set_rm = node_set_rm
self.node_set_add = node_set_add
self.link_set_add = link_set_add
def __str__(self):
return __name__ + ': ' + ', '.join('%s: %s' % (k, v) for k, v in self.__dict__.items())
def check_validity(self, topo_diff_dict):
"""
Topo_Diff may represent invalid operations, eg. adding a link while
removing it's end-point - this stub should check for that
"""
pass
@staticmethod
def from_json_dict(json_dict):
"""
construct from dict - no node/link constructor set must be provided
"""
ret = Topo_Diff()
# merge keys - this allows constructor argument omission (link_set_rm,
# node_set_rm, etc.) such as when constructing from POST JSON data
for k, _ in ret.__dict__.items():
v = json_dict.get(k)
if None != v:
ret.__dict__[k] = v
return ret
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