Source code for asdf.extension._legacy
import abc
import warnings
from functools import lru_cache
from .. import resolver, types
from ..exceptions import AsdfDeprecationWarning
from ..type_index import AsdfTypeIndex
__all__ = ["AsdfExtension"]
[docs]class AsdfExtension(metaclass=abc.ABCMeta):
"""
Abstract base class defining a (legacy) extension to ASDF.
New code should use `asdf.extension.Extension` instead.
"""
@classmethod
def __subclasshook__(cls, C):
if cls is AsdfExtension:
return hasattr(C, "types") and hasattr(C, "tag_mapping")
return NotImplemented
@property
@abc.abstractmethod
def types(self):
"""
A list of `asdf.CustomType` subclasses that describe how to store
custom objects to and from ASDF.
"""
@property
@abc.abstractmethod
def tag_mapping(self):
"""
A list of 2-tuples or callables mapping YAML tag prefixes to JSON Schema
URL prefixes.
For each entry:
- If a 2-tuple, the first part of the tuple is a YAML tag
prefix to match. The second part is a string, where case
the following are available as Python formatting tokens:
- ``{tag}``: the complete YAML tag.
- ``{tag_suffix}``: the part of the YAML tag after the
matched prefix.
- ``{tag_prefix}``: the matched YAML tag prefix.
- If a callable, it is passed the entire YAML tag must return
the entire JSON schema URL if it matches, otherwise, return `None`.
Note that while JSON Schema URLs uniquely define a JSON
Schema, they do not have to actually exist on an HTTP server
and be fetchable (much like XML namespaces).
For example, to match all YAML tags with the
``tag:nowhere.org:custom` prefix to the
``http://nowhere.org/schemas/custom/`` URL prefix::
return [('tag:nowhere.org:custom/',
'http://nowhere.org/schemas/custom/{tag_suffix}')]
"""
@property
@abc.abstractmethod
def url_mapping(self):
"""
Schema content can be provided using the resource Mapping API.
A list of 2-tuples or callables mapping JSON Schema URLs to
other URLs. This is useful if the JSON Schemas are not
actually fetchable at their corresponding URLs but are on the
local filesystem, or, to save bandwidth, we have a copy of
fetchable schemas on the local filesystem. If neither is
desirable, it may simply be the empty list.
For each entry:
- If a 2-tuple, the first part is a URL prefix to match. The
second part is a string, where the following are available
as Python formatting tokens:
- ``{url}``: The entire JSON schema URL
- ``{url_prefix}``: The matched URL prefix
- ``{url_suffix}``: The part of the URL after the prefix.
- If a callable, it is passed the entire JSON Schema URL and
must return a resolvable URL pointing to the schema content.
If it doesn't match, should return `None`.
For example, to map a remote HTTP URL prefix to files installed
alongside as data alongside Python module::
return [('http://nowhere.org/schemas/custom/1.0.0/',
asdf.util.filepath_to_url(
os.path.join(SCHEMA_PATH, 'stsci.edu')) +
'/{url_suffix}.yaml'
)]
"""
[docs]class AsdfExtensionList:
"""
Manage a set of extensions that are in effect.
"""
def __init__(self, extensions):
from ._extension import ExtensionProxy
extensions = [ExtensionProxy.maybe_wrap(e) for e in extensions]
tag_mapping = []
url_mapping = []
validators = {}
self._type_index = AsdfTypeIndex()
for extension in extensions:
tag_mapping.extend(extension.tag_mapping)
url_mapping.extend(extension.url_mapping)
for typ in extension.types:
self._type_index.add_type(typ, extension)
validators.update(typ.validators)
for sibling in typ.versioned_siblings:
self._type_index.add_type(sibling, extension)
validators.update(sibling.validators)
self._extensions = extensions
self._tag_mapping = resolver.Resolver(tag_mapping, "tag")
self._url_mapping = resolver.Resolver(url_mapping, "url")
self._resolver = resolver.ResolverChain(self._tag_mapping, self._url_mapping)
self._validators = validators
@property
def tag_to_schema_resolver(self):
"""Deprecated. Use `tag_mapping` instead"""
warnings.warn(
"The 'tag_to_schema_resolver' property is deprecated. Use 'tag_mapping' instead.", AsdfDeprecationWarning
)
return self._tag_mapping
@property
def extensions(self):
return self._extensions
@property
def tag_mapping(self):
return self._tag_mapping
@property
def url_mapping(self):
return self._url_mapping
@property
def resolver(self):
return self._resolver
@property
def type_index(self):
return self._type_index
@property
def validators(self):
return self._validators
[docs]def get_cached_asdf_extension_list(extensions):
"""
Get a previously created AsdfExtensionList for the specified
extensions, or create and cache one if necessary. Building
the type index is expensive, so it helps performance to reuse
the index when possible.
Parameters
----------
extensions : list of asdf.extension.AsdfExtension
Returns
-------
asdf.extension.AsdfExtensionList
"""
from ._extension import ExtensionProxy
# The tuple makes the extensions hashable so that we
# can pass them to the lru_cache method. The ExtensionProxy
# overrides __hash__ to return the hashed object id of the wrapped
# extension, so this will method will only return the same
# AsdfExtensionList if the list contains identical extension
# instances in identical order.
extensions = tuple(ExtensionProxy.maybe_wrap(e) for e in extensions)
return _get_cached_asdf_extension_list(extensions)
@lru_cache
def _get_cached_asdf_extension_list(extensions):
return AsdfExtensionList(extensions)
# A kludge in asdf.util.get_class_name allows this class to retain
# its original name, despite being moved from extension.py to
# this file.
[docs]class BuiltinExtension:
"""
This is the "extension" to ASDF that includes all the built-in
tags. Even though it's not really an extension and it's always
available, it's built in the same way as an extension.
"""
@property
def types(self):
return types._all_asdftypes
@property
def tag_mapping(self):
return resolver.DEFAULT_TAG_TO_URL_MAPPING
@property
def url_mapping(self):
return resolver.DEFAULT_URL_MAPPING
class _DefaultExtensions:
@property
def extensions(self):
from ..config import get_config
return [e for e in get_config().extensions if e.legacy]
@property
def extension_list(self):
return get_cached_asdf_extension_list(self.extensions)
@property
def package_metadata(self):
return {
e.class_name: (e.package_name, e.package_version) for e in self.extensions if e.package_name is not None
}
def reset(self):
"""This will be used primarily for testing purposes."""
from ..config import get_config
get_config().reset_extensions()
@property
def resolver(self):
return self.extension_list.resolver
default_extensions = _DefaultExtensions()
[docs]def get_default_resolver():
"""
Get the resolver that includes mappings from all installed extensions.
"""
return default_extensions.resolver