3453371f60
Also: - fixed the order tree is traversed in - fixed `evaluate_recursively` variable leak - added couple more tests for uncovered cases - fixed premature db session flush I had to split convey_task_result's transaction into two to give some room for concurrency. As far as I can tell, it should not affect the process since all the crucial data will be reread once again in the second transaction. Anyway, this is a temporary measure and when we switch to MySQL, we should review it once again. Closes-bug: #1339614 Change-Id: I9246931749f13df157d474cf75755462f7336bc7
147 lines
4.3 KiB
Python
147 lines
4.3 KiB
Python
# -*- coding: utf-8 -*-
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#
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# Copyright 2013 - Mirantis, Inc.
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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 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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import abc
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import copy
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import re
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import six
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import yaql
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from mistral.openstack.common import log as logging
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LOG = logging.getLogger(__name__)
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class Evaluator(object):
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"""Expression evaluator interface.
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Having this interface gives the flexibility to change the actual expression
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language used in Mistral DSL for conditions, output calculation etc.
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"""
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@classmethod
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@abc.abstractmethod
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def evaluate(cls, expression, context):
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"""Evaluates the expression against the given data context.
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:param expression: Expression string
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:param context: Data context
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:return: Expression result
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"""
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pass
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@classmethod
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@abc.abstractmethod
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def is_expression(cls, expression):
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"""Check expression string and decide whether it is expression or not.
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:param expression: Expression string
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:return: True if string is expression
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"""
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pass
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class YAQLEvaluator(Evaluator):
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@classmethod
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def evaluate(cls, expression, context):
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LOG.debug("Evaluating YAQL expression [expression='%s', context=%s]"
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% (expression, context))
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return yaql.parse(expression).evaluate(context)
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@classmethod
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def is_expression(cls, s):
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# TODO(rakhmerov): It should be generalized since it may not be YAQL.
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return s and s.startswith('$')
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class InlineYAQLEvaluator(YAQLEvaluator):
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# Put YAQL-specific regexp pattern here.
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# Use form {$.any_symbols_except'}'} to find an expression.
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find_expression_pattern = re.compile("\{\$\.*[^\}]*\}")
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@classmethod
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def evaluate(cls, expression, context):
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if super(InlineYAQLEvaluator, cls).is_expression(expression):
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return super(InlineYAQLEvaluator,
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cls).evaluate(expression, context)
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result = expression
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found_expressions = cls.find_inline_expressions(expression)
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if found_expressions:
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for expr in found_expressions:
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trim_expr = expr.strip("{}")
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evaluated = super(InlineYAQLEvaluator,
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cls).evaluate(trim_expr, context)
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replacement = str(evaluated) if evaluated else expr
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result = result.replace(expr, replacement)
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return result
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@classmethod
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def is_expression(cls, s):
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return s
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@classmethod
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def find_inline_expressions(cls, s):
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return cls.find_expression_pattern.findall(s)
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# TODO(rakhmerov): Make it configurable.
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_EVALUATOR = InlineYAQLEvaluator
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def evaluate(expression, context):
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# Check if the passed value is expression so we don't need to do this
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# every time on a caller side.
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if not isinstance(expression, six.string_types) or \
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not _EVALUATOR.is_expression(expression):
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return expression
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return _EVALUATOR.evaluate(expression, context)
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def _evaluate_item(item, context):
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if isinstance(item, six.string_types):
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try:
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return evaluate(item, context)
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except AttributeError as e:
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LOG.debug("Expression %s is not evaluated, [context=%s]: %s"
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% (item, context, e))
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return item
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else:
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return evaluate_recursively(item, context)
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def evaluate_recursively(data, context):
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data = copy.copy(data)
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if not context:
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return data
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if isinstance(data, dict):
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for key in data:
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data[key] = _evaluate_item(data[key], context)
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elif isinstance(data, list):
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for index, item in enumerate(data):
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data[index] = _evaluate_item(item, context)
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elif isinstance(data, six.string_types):
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return _evaluate_item(data, context)
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return data
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