begin migration to jschon

Author: whitequark

amaranth/lib/meta.py

@@ -1,7 +1,20 @@
+import jschon
 from abc import abstractmethod, ABCMeta
 
 
-__all__ = ["Annotation"]
+__all__ = ["InvalidSchema", "InvalidAnnotation", "Annotation"]
+
+
+def _create_catalog():
+    return jschon.create_catalog('2020-12')
+
+
+class InvalidSchema(Exception):
+    """Exception raised when an annotation with a non-conformant schema is defined."""
+
+
+class InvalidAnnotation(Exception):
+    """Exception raised when an annotation."""
 
 
 class Annotation(metaclass=ABCMeta):
@@ -14,7 +27,8 @@ class Annotation(metaclass=ABCMeta):
 
     #: :class:`dict`: Schema of this annotation, expressed in the `JSON Schema`_ language.
     #:
-    #: Subclasses of :class:`Annotation` must implement this class attribute.
+    #: Subclasses of :class:`Annotation` must implement this class attribute. If the value of
+    #: the attribute is not a valid Amaranth annotation JSON Schema, :exc:`InvalidSchema` is raised.
     schema = {}
 
     def __init_subclass__(cls, **kwargs):
@@ -27,14 +41,8 @@ def __init_subclass__(cls, **kwargs):
         if "$id" not in cls.schema:
             raise ValueError(f"'$id' keyword is missing from Annotation schema: {cls.schema}")
 
-        try:
-            import jsonschema
-            jsonschema.Draft202012Validator.check_schema(cls.schema)
-        except ImportError:
-            # Amaranth was installed in some weird way and doesn't have jsonschema installed,
-            # despite it being a mandatory dependency. The schema will eventually get checked
-            # by the CI, so ignore the error here.
-            pass # :nocov:
+        schema_validity = jschon.JSONSchema(cls.schema, catalog=_create_catalog()).validate()
+        # TODO
 
     @property
     @abstractmethod
@@ -74,11 +82,11 @@ def validate(cls, instance):
 
         Raises
         ------
-        :exc:`jsonschema.exceptions.ValidationError`
+        :exc:`InvalidAnnotation`
             If :py:`instance` doesn't comply with :attr:`Annotation.schema`.
         """
-        import jsonschema
-        jsonschema.validate(instance, schema=cls.schema)
+        validity = JSONSchema(cls.schema, catalog=_create_catalog()).evaluate(instance)
+        # TODO
 
     def __repr__(self):
-        return f"<{type(self).__module__}.{type(self).__qualname__} for {self.origin!r}>"
+        return f"<{type(self).__module__}.{type(self).__qualname__} for {self.origin!r}>"

docs/conf.py

@@ -27,7 +27,6 @@
 
 intersphinx_mapping = {
     "python": ("https://docs.python.org/3", None),
-    "jsonschema": (f"https://python-jsonschema.readthedocs.io/en/v{package_version('jsonschema')}/", None),
 }
 
 todo_include_todos = True

pyproject.toml

@@ -15,7 +15,7 @@ license = {file = "LICENSE.txt"}
 requires-python = "~=3.8"
 dependencies = [
   "importlib_resources; python_version<'3.9'", # for amaranth._toolchain.yosys
-  "jsonschema~=4.20.0", # for amaranth.lib.meta
+  "jschon~=0.11.1", # for amaranth.lib.meta
   "pyvcd>=0.2.2,<0.5", # for amaranth.sim.pysim
   "Jinja2~=3.0", # for amaranth.build
 ]