56 lines
1.7 KiB
Python
56 lines
1.7 KiB
Python
# Copyright 2013 - Mirantis, Inc.
|
|
# Copyright 2015 - StackStorm, Inc.
|
|
#
|
|
# 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 abc
|
|
|
|
|
|
class Evaluator(object):
|
|
"""Expression evaluator interface.
|
|
|
|
Having this interface gives the flexibility to change the actual expression
|
|
language used in Mistral DSL for conditions, output calculation etc.
|
|
"""
|
|
|
|
@classmethod
|
|
@abc.abstractmethod
|
|
def validate(cls, expression):
|
|
"""Parse and validates the expression.
|
|
|
|
:param expression: Expression string
|
|
:return: True if expression is valid
|
|
"""
|
|
pass
|
|
|
|
@classmethod
|
|
@abc.abstractmethod
|
|
def evaluate(cls, expression, context):
|
|
"""Evaluates the expression against the given data context.
|
|
|
|
:param expression: Expression string
|
|
:param context: Data context
|
|
:return: Expression result
|
|
"""
|
|
pass
|
|
|
|
@classmethod
|
|
@abc.abstractmethod
|
|
def is_expression(cls, expression):
|
|
"""Check expression string and decide whether it is expression or not.
|
|
|
|
:param expression: Expression string
|
|
:return: True if string is expression
|
|
"""
|
|
pass
|