import abc
from packaging.specifiers import SpecifierSet
from ..util import get_class_name
from ._tag import TagDefinition
from ._legacy import AsdfExtension
from ._converter import ConverterProxy
from ._compressor import Compressor
[docs]class Extension(abc.ABC):
"""
Abstract base class defining an extension to ASDF.
Implementing classes must provide the `extension_uri`.
Other properties are optional.
"""
@classmethod
def __subclasshook__(cls, C):
if cls is Extension:
return hasattr(C, "extension_uri")
return NotImplemented # pragma: no cover
@abc.abstractproperty
def extension_uri(self):
"""
Get the URI of the extension to the ASDF Standard implemented
by this class. Note that this may not uniquely identify the
class itself.
Returns
-------
str
"""
pass # pragma: no cover
@property
def legacy_class_names(self):
"""
Get the set of fully-qualified class names used by older
versions of this extension. This allows a new-style
implementation of an extension to prevent warnings when a
legacy extension is missing.
Returns
-------
iterable of str
"""
return set()
@property
def asdf_standard_requirement(self):
"""
Get the ASDF Standard version requirement for this extension.
Returns
-------
str or None
If str, PEP 440 version specifier.
If None, support all versions.
"""
return None
@property
def converters(self):
"""
Get the `asdf.extension.Converter` instances for tags
and Python types supported by this extension.
Returns
-------
iterable of asdf.extension.Converter
"""
return []
@property
def tags(self):
"""
Get the YAML tags supported by this extension.
Returns
-------
iterable of str or asdf.extension.TagDefinition
"""
return []
@property
def compressors(self):
"""
Get the `asdf.extension.Compressor` instances for
compression schemes supported by this extension.
Returns
-------
iterable of asdf.extension.Compressor
"""
return []
@property
def yaml_tag_handles(self):
"""
Get a dictionary of custom yaml TAG handles defined by the extension.
The dictionary key indicates the TAG handles to be placed in the YAML header,
the value defines the string for tag replacement.
See https://yaml.org/spec/1.1/#tag%20shorthand/
Example: ``{"!foo!": "tag:nowhere.org:custom/"}``
Returns
-------
dict
"""
return {}
[docs]class ExtensionProxy(Extension, AsdfExtension):
"""
Proxy that wraps an extension, provides default implementations
of optional methods, and carries additional information on the
package that provided the extension.
"""
[docs] @classmethod
def maybe_wrap(self, delegate):
if isinstance(delegate, ExtensionProxy):
return delegate
else:
return ExtensionProxy(delegate)
def __init__(self, delegate, package_name=None, package_version=None):
if not isinstance(delegate, (Extension, AsdfExtension)):
raise TypeError(
"Extension must implement the Extension or AsdfExtension interface"
)
self._delegate = delegate
self._package_name = package_name
self._package_version = package_version
self._class_name = get_class_name(delegate)
self._legacy = isinstance(delegate, AsdfExtension)
# Sort these out up-front so that errors are raised when the extension is loaded
# and not in the middle of the user's session. The extension will fail to load
# and a warning will be emitted, but it won't crash the program.
self._legacy_class_names = set()
for class_name in getattr(self._delegate, "legacy_class_names", []):
if isinstance(class_name, str):
self._legacy_class_names.add(class_name)
else:
raise TypeError("Extension property 'legacy_class_names' must contain str values")
if self._legacy:
self._legacy_class_names.add(self._class_name)
value = getattr(self._delegate, "asdf_standard_requirement", None)
if isinstance(value, str):
self._asdf_standard_requirement = SpecifierSet(value)
elif value is None:
self._asdf_standard_requirement = SpecifierSet()
else:
raise TypeError("Extension property 'asdf_standard_requirement' must be str or None")
self._tags = []
for tag in getattr(self._delegate, "tags", []):
if isinstance(tag, str):
self._tags.append(TagDefinition(tag))
elif isinstance(tag, TagDefinition):
self._tags.append(tag)
else:
raise TypeError("Extension property 'tags' must contain str or asdf.extension.TagDefinition values")
self._yaml_tag_handles = getattr(delegate, "yaml_tag_handles", {})
# Process the converters last, since they expect ExtensionProxy
# properties to already be available.
self._converters = [ConverterProxy(c, self) for c in getattr(self._delegate, "converters", [])]
self._compressors = []
if hasattr(self._delegate, "compressors"):
for compressor in self._delegate.compressors:
if not isinstance(compressor, Compressor):
raise TypeError("Extension property 'compressors' must contain instances of asdf.extension.Compressor")
self._compressors.append(compressor)
@property
def extension_uri(self):
"""
Get the URI of the extension to the ASDF Standard implemented
by this class. Note that this may not uniquely identify the
class itself.
Returns
-------
str or None
"""
return getattr(self._delegate, "extension_uri", None)
@property
def legacy_class_names(self):
"""
Get the set of fully-qualified class names used by older
versions of this extension. This allows a new-style
implementation of an extension to prevent warnings when a
legacy extension is missing.
Returns
-------
set of str
"""
return self._legacy_class_names
@property
def asdf_standard_requirement(self):
"""
Get the extension's ASDF Standard requirement.
Returns
-------
packaging.specifiers.SpecifierSet
"""
return self._asdf_standard_requirement
@property
def converters(self):
"""
Get the extension's converters.
Returns
-------
list of asdf.extension.Converter
"""
return self._converters
@property
def compressors(self):
"""
Get the extension's compressors.
Returns
-------
list of asdf.extension.Compressor
"""
return self._compressors
@property
def tags(self):
"""
Get the YAML tags supported by this extension.
Returns
-------
list of asdf.extension.TagDefinition
"""
return self._tags
@property
def types(self):
"""
Get the legacy extension's ExtensionType subclasses.
Returns
-------
iterable of asdf.type.ExtensionType
"""
return getattr(self._delegate, "types", [])
@property
def tag_mapping(self):
"""
Get the legacy extension's tag-to-schema-URI mapping.
Returns
-------
iterable of tuple or callable
"""
return getattr(self._delegate, "tag_mapping", [])
@property
def url_mapping(self):
"""
Get the legacy extension's schema-URI-to-URL mapping.
Returns
-------
iterable of tuple or callable
"""
return getattr(self._delegate, "url_mapping", [])
@property
def delegate(self):
"""
Get the wrapped extension instance.
Returns
-------
asdf.extension.Extension or asdf.extension.AsdfExtension
"""
return self._delegate
@property
def package_name(self):
"""
Get the name of the Python package that provided this extension.
Returns
-------
str or None
`None` if the extension was added at runtime.
"""
return self._package_name
@property
def package_version(self):
"""
Get the version of the Python package that provided the extension
Returns
-------
str or None
`None` if the extension was added at runtime.
"""
return self._package_version
@property
def class_name(self):
"""
Get the fully qualified class name of the extension.
Returns
-------
str
"""
return self._class_name
@property
def legacy(self):
"""
Get the extension's legacy flag. Subclasses of `asdf.extension.AsdfExtension`
are marked `True`.
Returns
-------
bool
"""
return self._legacy
@property
def yaml_tag_handles(self):
"""
Get a dictionary of custom yaml TAG handles defined by the extension.
The dictionary key indicates the TAG handles to be placed in the YAML header,
the value defines the string for tag replacement.
See https://yaml.org/spec/1.1/#tag%20shorthand/
Example: ``{"!foo!": "tag:nowhere.org:custom/"}``
Returns
-------
dict
"""
return self._yaml_tag_handles
def __eq__(self, other):
if isinstance(other, ExtensionProxy):
return other.delegate is self.delegate
else:
return False
def __hash__(self):
return hash(id(self.delegate))
def __repr__(self):
if self.package_name is None:
package_description = "(none)"
else:
package_description = f"{self.package_name}=={self.package_version}"
if self.extension_uri is None:
uri_description = "(none)"
else:
uri_description = self.extension_uri
return (
f"<ExtensionProxy URI: {uri_description} class: {self.class_name} "
f"package: {package_description} legacy: {self.legacy}>"
)