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#!/usr/bin/env python3
# -*- coding: utf-8 -*-
#
# Copyright (c) 2017 Cisco and/or its affiliates.
#
# 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.
#
import copy
from netmodel.model.field_names import FieldNames
from netmodel.model.predicate import Predicate, eq, included
from netmodel.util.misc import is_iterable
class Filter(set):
"""
A Filter is a set of Predicate instances
"""
@staticmethod
def from_list(l):
"""
Create a Filter instance by using an input list.
Args:
l: A list of Predicate instances.
"""
f = Filter()
try:
for element in l:
f.add(Predicate(*element))
except Exception as e:
#print("Error in setting Filter from list", e)
return None
return f
@staticmethod
def from_dict(d):
"""
Create a Filter instance by using an input dict.
Args:
d: A dict {key : value} instance where each
key-value pair leads to a Predicate.
'key' could start with the operator to be
used in the predicate, otherwise we use
'=' by default.
"""
f = Filter()
for key, value in d.items():
if key[0] in Predicate.operators.keys():
f.add(Predicate(key[1:], key[0], value))
else:
f.add(Predicate(key, '=', value))
return f
def to_list(self):
"""
Returns:
The list corresponding to this Filter instance.
"""
ret = list()
for predicate in self:
ret.append(predicate.to_list())
return ret
@staticmethod
def from_clause(clause):
"""
NOTE: We can only handle simple clauses formed of AND fields.
"""
raise NotImplementedError
@staticmethod
def from_string(string):
"""
"""
from netmodel.model.sql_parser import SQLParser
p = SQLParser()
ret = p.filter.parseString(string, parseAll=True)
return ret[0] if ret else None
def filter_by(self, predicate):
"""
Update this Filter by adding a Predicate.
Args:
predicate: A Predicate instance.
Returns:
The resulting Filter instance.
"""
assert isinstance(predicate, Predicate),\
"Invalid predicate = %s (%s)" % (predicate, type(predicate))
self.add(predicate)
return self
def unfilter_by(self, *args):
assert len(args) == 1 or len(args) == 3, \
"Invalid expression for filter"
if not self.is_empty():
if len(args) == 1:
# we got a Filter, or a set, or a list, or a tuple or None.
filters = args[0]
if filters != None:
if not isinstance(filters, (set, list, tuple, Filter)):
filters = [filters]
for predicate in set(filters):
self.remove(predicate)
elif len(args) == 3:
# we got three args: (field_name, op, value)
predicate = Predicate(*args)
self.remove(predicate)
assert isinstance(self, Filter),\
"Invalid filters = %s" % (self, type(self))
return self
def add(self, predicate_or_filter):
"""
Adds a predicate or a filter (a set of predicate) -- or a list thereof
-- to the current filter.
"""
if is_iterable(predicate_or_filter):
map(self.add, predicate_or_filter)
return
assert isinstance(predicate_or_filter, Predicate)
set.add(self, predicate_or_filter)
def is_empty(self):
"""
Tests whether this Filter is empty or not.
Returns:
True iif this Filter is empty.
"""
return len(self) == 0
def __str__(self):
"""
Returns:
The '%s' representation of this Filter.
"""
if self.is_empty():
return "<empty filter>"
else:
return " AND ".join([str(pred) for pred in self])
def __repr__(self):
"""
Returns:
The '%r' representation of this Filter.
"""
return '<Filter: %s>' % self
def __key(self):
return tuple([hash(pred) for pred in self])
def __hash__(self):
return hash(self.__key())
def __additem__(self, value):
if not isinstance(value, Predicate):
raise TypeError("Element of class Predicate expected, received %s"\
% value.__class__.__name__)
set.__additem__(self, value)
def copy(self):
return copy.deepcopy(self)
def keys(self):
"""
Returns:
A set of String corresponding to each field name
involved in this Filter.
"""
return set([x.key for x in self])
def has(self, key):
for x in self:
if x.key == key:
return True
return False
def has_op(self, key, op):
for x in self:
if x.key == key and x.op == op:
return True
return False
def has_eq(self, key):
return self.has_op(key, eq)
def get(self, key):
ret = []
for x in self:
if x.key == key:
ret.append(x)
return ret
def delete(self, key):
to_del = []
for x in self:
if x.key == key:
to_del.append(x)
for x in to_del:
self.remove(x)
def get_op(self, key, op):
if isinstance(op, (list, tuple, set)):
for x in self:
if x.key == key and x.op in op:
return x.value
else:
for x in self:
if x.key == key and x.op == op:
return x.value
return None
def get_eq(self, key):
return self.get_op(key, eq)
def set_op(self, key, op, value):
for x in self:
if x.key == key and x.op == op:
x.value = value
return
raise KeyError(key)
def set_eq(self, key, value):
return self.set_op(key, eq, value)
def get_predicates(self, key):
ret = []
for x in self:
if x.key == key:
ret.append(x)
return ret
def match(self, dic, ignore_missing=True):
for predicate in self:
if not predicate.match(dic, ignore_missing):
return False
return True
def filter(self, l):
output = []
for x in l:
if self.match(x):
output.append(x)
return output
def get_field_names(self):
field_names = FieldNames()
for predicate in self:
field_names |= predicate.get_field_names()
return field_names
def grep(self, fun):
return Filter([x for x in self if fun(x)])
def rgrep(self, fun):
return Filter([x for x in self if not fun(x)])
def split(self, fun, true_only = False):
true_filter, false_filter = Filter(), Filter()
for predicate in self:
if fun(predicate):
true_filter.add(predicate)
else:
false_filter.add(predicate)
if true_only:
return true_filter
else:
return (true_filter, false_filter)
def split_fields(self, fields, true_only = False):
return self.split(lambda predicate: predicate.get_key() in fields,
true_only)
def provides_key_field(self, key_fields):
# No support for tuples
for field in key_fields:
if not self.has_op(field, eq) and not self.has_op(field, included):
# Missing key fields in query filters
return False
return True
def rename(self, aliases):
for predicate in self:
predicate.rename(aliases)
return self
def get_field_values(self, field):
"""
This function returns the values that are determined by the filters for
a given field, or None is the filter is not *setting* determined values.
Returns: list : a list of fields
"""
value_list = list()
for predicate in self:
key, op, value = predicate.get_tuple()
if key == field:
extract_tuple = False
elif key == (field, ):
extract_tuple = True
else:
continue
if op == eq:
if extract_tuple:
value = value[0]
value_list.append(value)
elif op == included:
if extract_tuple:
value = [x[0] for x in value]
value_list.extend(value)
else:
continue
return list(set(value_list))
def update_field_value_eq(self, field, value):
for predicate in self:
p_field, p_op, p_value = predicate.get_tuple()
if p_field == field:
predicate.set_op(eq)
predicate.set_value(value)
break # assuming there is a single predicate with field/op
def __and__(self, other):
# Note: we assume the predicates in self and other are already in
# minimal form, eg. not the same fields twice... We could break after
# a predicate with the same key is found btw...
s = self.copy()
for o_predicate in other:
o_key, o_op, o_value = o_predicate.get_tuple()
key_found = False
for predicate in s:
key, op, value = predicate.get_tuple()
if key != o_key:
continue
# We already have a predicate with the same key
key_found = True
if op == eq:
if o_op == eq:
# Similar filters...
if value != o_value:
# ... with different values
return None
else:
# ... with same values
pass
elif o_op == included:
# Inclusion
if value not in o_value:
# no overlap
return None
else:
# We already have the more restrictive predicate...
pass
elif op == included:
if o_op == eq:
if o_value not in value:
return None
else:
# One value overlaps... update the initial predicate
# with the more restrictive one
predicate.set_op(eq)
predicate.set_value(value)
elif o_op == included:
intersection = set(o_value) & set(value)
if not set(o_value) & set(value):
return None
else:
predicate.set_value(tuple(intersection))
# No conflict found, we can add the predicate to s
if not key_found:
s.add(o_predicate)
return s
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