cloudbase-init/cloudbaseinit/utils/template_engine/base_template.py

61 lines
2.1 KiB
Python

# Copyright 2019 Cloudbase Solutions Srl
#
# 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
import re
import six
@six.add_metaclass(abc.ABCMeta)
class BaseTemplateEngine(object):
def __init__(self):
self._template_matcher = re.compile(r"##\s*template:(.*)", re.I)
@abc.abstractmethod
def get_template_type(self):
"""Return the template type for the class loader"""
pass
@abc.abstractmethod
def render(self, data, template):
"""Renders the template according to the data dictionary
The data variable is a dict which contains the key-values
that will be used to render the template.
The template is an encoded string which can contain special
constructions that will be used by the template engine.
The return value will be an encoded string.
"""
def load(self, data):
"""Returns True if the template header matches, False otherwise"""
template_type_matcher = self._template_matcher.match(data.decode())
template_type = template_type_matcher.group(1).lower().strip()
if self.get_template_type() == template_type:
return True
@staticmethod
def remove_template_definition(raw_template):
# Remove the first line, as it contains the template definition
template_split = raw_template.split(b"\n", 1)
if len(template_split) == 2:
# return the template without the header
return template_split[1]
# the template has just one line, return empty encoded string
return b''