ordered_yaml.py

# Copyright 2018 Amazon.com, Inc. or its affiliates. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License"). You
# may not use this file except in compliance with the License. A copy of
# the License is located at
#
# http://aws.amazon.com/apache2.0/
#
# or in the "license" file accompanying this file. This file 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 yaml
from botocore.compat import OrderedDict


class SafeOrderedLoader(yaml.SafeLoader):
    """ Safely load a yaml file into an OrderedDict."""


class SafeOrderedDumper(yaml.SafeDumper):
    """ Safely dump an OrderedDict as yaml."""


def _ordered_constructor(loader, node):
        loader.flatten_mapping(node)
        return OrderedDict(loader.construct_pairs(node))


SafeOrderedLoader.add_constructor(
                    yaml.resolver.BaseResolver.DEFAULT_MAPPING_TAG,
                    _ordered_constructor)


def _ordered_representer(dumper, data):
        return dumper.represent_mapping(
            yaml.resolver.BaseResolver.DEFAULT_MAPPING_TAG,
            data.items())


SafeOrderedDumper.add_representer(OrderedDict, _ordered_representer)


def ordered_yaml_load(stream):
    """ Load an OrderedDict object from a yaml stream."""
    return yaml.load(stream, SafeOrderedLoader)


def ordered_yaml_dump(to_dump, stream=None):
    """
    Dump an OrderedDict object to yaml.

    :param to_dump: The OrderedDict to dump
    :type to_dump: OrderedDict

    :param stream: The file to dump to
    If not given or if None, only return the value
    :type stream: file
    """
    return yaml.dump(to_dump, stream,
                     SafeOrderedDumper, default_flow_style=False)