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# Copyright (C) 2011 - 2017 Satoru SATOH <ssato @ redhat.com> |
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# License: MIT |
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# |
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r"""YAML backend: |
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- Format to support: YAML, http://yaml.org |
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- Requirements: PyYAML (yaml), http://pyyaml.org |
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- Development Status :: 5 - Production/Stable |
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- Limitations: ac_ordered is not effective and just ignored. |
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- Special options: |
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- All keyword options of yaml.safe_load, yaml.load, yaml.safe_dump and |
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yaml.dump should work. |
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- Use 'ac_safe' boolean keyword option if you prefer to call yaml.safe_load |
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and yaml.safe_dump instead of yaml.load and yaml.dump |
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- See also: http://pyyaml.org/wiki/PyYAMLDocumentation |
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Changelog: |
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.. versionchanged:: 0.3 |
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- Changed special keyword option 'ac_safe' from 'safe' to avoid |
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possibility of option conflicts in the future. |
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""" |
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from __future__ import absolute_import |
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import yaml |
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try: |
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from yaml import CSafeLoader as Loader, CSafeDumper as Dumper |
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except ImportError: |
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from yaml import SafeLoader as Loader, SafeDumper as Dumper |
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import anyconfig.backend.base |
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import anyconfig.utils |
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def _setup_loader_and_dumper(container, loader=Loader, dumper=Dumper): |
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""" |
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Force set container (dict, OrderedDict, ...) used to construct python |
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object from yaml node internally. |
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.. note:: |
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It cannot be used with ac_safe keyword option at the same time yet. |
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:param container: Set container used internally |
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""" |
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map_tag = yaml.resolver.BaseResolver.DEFAULT_MAPPING_TAG |
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def construct_mapping(loader, node, deep=False): |
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"""Constructor to construct python object from yaml mapping node. |
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:seealso: :meth:`yaml.BaseConstructor.construct_mapping` |
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""" |
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if not isinstance(node, yaml.MappingNode): |
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msg = "expected a mapping node, but found %s" % node.id |
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raise yaml.constructor.ConstructorError(None, None, msg, |
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node.start_mark) |
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mapping = container() |
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for key_node, value_node in node.value: |
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key = loader.construct_object(key_node, deep=deep) |
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try: |
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hash(key) |
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except TypeError as exc: |
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eargs = ("while constructing a mapping", |
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node.start_mark, |
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"found unacceptable key (%s)" % exc, |
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key_node.start_mark) |
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raise yaml.constructor.ConstructorError(*eargs) |
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value = loader.construct_object(value_node, deep=deep) |
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mapping[key] = value |
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return mapping |
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def container_representer(dumper, data): |
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"""Container representer. |
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""" |
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return dumper.represent_mapping(map_tag, data.items()) |
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loader.add_constructor(map_tag, construct_mapping) |
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dumper.add_representer(container, container_representer) |
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def _yml_fnc(fname, *args, **kwargs): |
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"""An wrapper of yaml.safe_load, yaml.load, yaml.safe_dump and yaml.dump. |
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:param fname: |
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"load" or "dump", not checked but it should be OK. |
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see also :func:`_yml_load` and :func:`_yml_dump` |
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:param args: [stream] for load or [cnf, stream] for dump |
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:param kwargs: keyword args may contain "ac_safe" to load/dump safely |
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""" |
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key = "ac_safe" |
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fnc = getattr(yaml, kwargs.get(key, False) and r"safe_" + fname or fname) |
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kwargs = anyconfig.utils.filter_options([k for k in kwargs.keys() |
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if k != key], kwargs) |
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return fnc(*args, **kwargs) |
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def _yml_load(stream, container, **kwargs): |
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"""An wrapper of yaml.safe_load and yaml.load. |
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:param stream: a file or file-like object to load YAML content |
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:param container: callble to make a container object |
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""" |
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if "ac_safe" in kwargs: # yaml.safe_load does not process Loader opts. |
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kwargs = {} |
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else: |
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maybe_container = kwargs.get("ac_dict", None) |
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loader = kwargs.get("Loader", Loader) |
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dumper = kwargs.get("Dumper", Dumper) |
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if maybe_container is not None and callable(maybe_container): |
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_setup_loader_and_dumper(maybe_container, loader=loader, |
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dumper=dumper) |
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container = maybe_container |
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return container(_yml_fnc("load", stream, **kwargs)) |
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def _yml_dump(cnf, stream, **kwargs): |
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"""An wrapper of yaml.safe_dump and yaml.dump. |
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:param cnf: Mapping object to dump |
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:param stream: a file or file-like object to dump YAML data |
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""" |
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if kwargs.get("ac_safe", False): |
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cnf = anyconfig.dicts.convert_to(cnf) |
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return _yml_fnc("dump", cnf, stream, **kwargs) |
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class Parser(anyconfig.backend.base.FromStreamLoader, |
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anyconfig.backend.base.ToStreamDumper): |
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""" |
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Parser for YAML files. |
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""" |
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_type = "yaml" |
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_extensions = ["yaml", "yml"] |
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_load_opts = ["Loader", "ac_safe"] |
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_dump_opts = ["stream", "ac_safe", "Dumper", "default_style", |
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"default_flow_style", "canonical", "indent", "width", |
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"allow_unicode", "line_break", "encoding", "explicit_start", |
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"explicit_end", "version", "tags"] |
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# _ordered = True # Not yet. |
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load_from_stream = anyconfig.backend.base.to_method(_yml_load) |
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dump_to_stream = anyconfig.backend.base.to_method(_yml_dump) |
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# vim:sw=4:ts=4:et: |
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