|
| 1 | +import jschon |
| 2 | +import pprint |
| 3 | +import warnings |
| 4 | +from abc import abstractmethod, ABCMeta |
| 5 | + |
| 6 | + |
| 7 | +__all__ = ["InvalidSchema", "InvalidAnnotation", "Annotation"] |
| 8 | + |
| 9 | + |
| 10 | +class InvalidSchema(Exception): |
| 11 | + """Exception raised when a subclass of :class:`Annotation` is defined with a non-conformant |
| 12 | + :data:`~Annotation.schema`.""" |
| 13 | + |
| 14 | + |
| 15 | +class InvalidAnnotation(Exception): |
| 16 | + """Exception raised by :meth:`Annotation.validate` when the JSON representation of |
| 17 | + an annotation does not conform to its schema.""" |
| 18 | + |
| 19 | + |
| 20 | +class Annotation(metaclass=ABCMeta): |
| 21 | + """Interface annotation. |
| 22 | +
|
| 23 | + Annotations are containers for metadata that can be retrieved from an interface object using |
| 24 | + the :meth:`Signature.annotations <.wiring.Signature.annotations>` method. |
| 25 | +
|
| 26 | + Annotations have a JSON representation whose structure is defined by the `JSON Schema`_ |
| 27 | + language. |
| 28 | + """ |
| 29 | + |
| 30 | + #: :class:`dict`: Schema of this annotation, expressed in the `JSON Schema`_ language. |
| 31 | + #: |
| 32 | + #: Subclasses of :class:`Annotation` must define this class attribute. |
| 33 | + schema = {} |
| 34 | + |
| 35 | + @classmethod |
| 36 | + def __jschon_schema(cls): |
| 37 | + catalog = jschon.create_catalog("2020-12") |
| 38 | + return jschon.JSONSchema(cls.schema, catalog=catalog) |
| 39 | + |
| 40 | + def __init_subclass__(cls, **kwargs): |
| 41 | + """ |
| 42 | + Defining a subclass of :class:`Annotation` causes its :data:`schema` to be validated. |
| 43 | +
|
| 44 | + Raises |
| 45 | + ------ |
| 46 | + :exc:`InvalidSchema` |
| 47 | + If :data:`schema` doesn't conform to the `2020-12` draft of `JSON Schema`_. |
| 48 | + :exc:`InvalidSchema` |
| 49 | + If :data:`schema` doesn't have a `"$id" keyword`_ at its root. This requirement is |
| 50 | + specific to :class:`Annotation` schemas. |
| 51 | + """ |
| 52 | + super().__init_subclass__(**kwargs) |
| 53 | + |
| 54 | + if not isinstance(cls.schema, dict): |
| 55 | + raise TypeError(f"Annotation schema must be a dict, not {cls.schema!r}") |
| 56 | + |
| 57 | + if "$id" not in cls.schema: |
| 58 | + raise InvalidSchema(f"'$id' keyword is missing from Annotation schema: {cls.schema}") |
| 59 | + |
| 60 | + try: |
| 61 | + # TODO: Remove this. Ignore a deprecation warning from jschon's rfc3986 dependency. |
| 62 | + with warnings.catch_warnings(): |
| 63 | + warnings.filterwarnings("ignore", category=DeprecationWarning) |
| 64 | + result = cls.__jschon_schema().validate() |
| 65 | + except jschon.JSONSchemaError as e: |
| 66 | + raise InvalidSchema(e) from e |
| 67 | + |
| 68 | + if not result.valid: |
| 69 | + raise InvalidSchema("Invalid Annotation schema:\n" + |
| 70 | + pprint.pformat(result.output("basic")["errors"], |
| 71 | + sort_dicts=False)) |
| 72 | + |
| 73 | + @property |
| 74 | + @abstractmethod |
| 75 | + def origin(self): |
| 76 | + """Python object described by this :class:`Annotation` instance. |
| 77 | +
|
| 78 | + Subclasses of :class:`Annotation` must implement this property. |
| 79 | + """ |
| 80 | + pass # :nocov: |
| 81 | + |
| 82 | + @abstractmethod |
| 83 | + def as_json(self): |
| 84 | + """Convert to a JSON representation. |
| 85 | +
|
| 86 | + Subclasses of :class:`Annotation` must implement this method. |
| 87 | +
|
| 88 | + JSON representation returned by this method must adhere to :data:`schema` and pass |
| 89 | + validation by :meth:`validate`. |
| 90 | +
|
| 91 | + Returns |
| 92 | + ------- |
| 93 | + :class:`dict` |
| 94 | + JSON representation of this annotation, expressed in Python primitive types |
| 95 | + (:class:`dict`, :class:`list`, :class:`str`, :class:`int`, :class:`bool`). |
| 96 | + """ |
| 97 | + pass # :nocov: |
| 98 | + |
| 99 | + @classmethod |
| 100 | + def validate(cls, instance): |
| 101 | + """Validate a JSON representation against :attr:`schema`. |
| 102 | +
|
| 103 | + Arguments |
| 104 | + --------- |
| 105 | + instance : :class:`dict` |
| 106 | + JSON representation to validate, either previously returned by :meth:`as_json` |
| 107 | + or retrieved from an external source. |
| 108 | +
|
| 109 | + Raises |
| 110 | + ------ |
| 111 | + :exc:`InvalidAnnotation` |
| 112 | + If :py:`instance` doesn't conform to :attr:`schema`. |
| 113 | + """ |
| 114 | + # TODO: Remove this. Ignore a deprecation warning from jschon's rfc3986 dependency. |
| 115 | + with warnings.catch_warnings(): |
| 116 | + warnings.filterwarnings("ignore", category=DeprecationWarning) |
| 117 | + result = cls.__jschon_schema().evaluate(jschon.JSON(instance)) |
| 118 | + |
| 119 | + if not result.valid: |
| 120 | + raise InvalidAnnotation("Invalid instance:\n" + |
| 121 | + pprint.pformat(result.output("basic")["errors"], |
| 122 | + sort_dicts=False)) |
| 123 | + |
| 124 | + def __repr__(self): |
| 125 | + return f"<{type(self).__module__}.{type(self).__qualname__} for {self.origin!r}>" |
| 126 | + |
| 127 | + |
| 128 | +# For internal use only; we may consider exporting this function in the future. |
| 129 | +def _extract_schemas(package, *, base_uri, path="schema/"): |
| 130 | + import json |
| 131 | + import pathlib |
| 132 | + from importlib.metadata import distribution |
| 133 | + |
| 134 | + entry_points = distribution(package).entry_points |
| 135 | + for entry_point in entry_points.select(group="amaranth.lib.meta"): |
| 136 | + schema = entry_point.load().schema |
| 137 | + relative_path = entry_point.name # v0.5/component.json |
| 138 | + schema_filename = pathlib.Path(path) / relative_path |
| 139 | + assert schema["$id"] == f"{base_uri}/{relative_path}", \ |
| 140 | + f"Schema $id {schema['$id']} must be {base_uri}/{relative_path}" |
| 141 | + |
| 142 | + schema_filename.parent.mkdir(parents=True, exist_ok=True) |
| 143 | + with open(pathlib.Path(path) / relative_path, "wt") as schema_file: |
| 144 | + json.dump(schema, schema_file, indent=2) |
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