Partially move DynamicAnchor.

For now it's JSON Schema specific and out of scope for
the new referencing proposals.

The interface though for Registry still needs to change
to support different anchor behaviors in drafts.

Author: Julian

referencing/_attrs.py

@@ -0,0 +1,24 @@
+from typing import TYPE_CHECKING
+
+if TYPE_CHECKING:
+    from attrs import define, frozen
+else:
+    from attrs import define as _define, frozen as _frozen
+
+    def define(cls):
+        cls.__init_subclass__ = UnsupportedSubclassing.complain
+        return _define(cls)
+
+    def frozen(cls):
+        cls.__init_subclass__ = UnsupportedSubclassing.complain
+        return _frozen(cls)
+
+
+class UnsupportedSubclassing(Exception):
+    @classmethod
+    def complain(this):
+        raise UnsupportedSubclassing(
+            "Subclassing is not part of referencing's public API. "
+            "If no other suitable API exists for what you're trying to do, "
+            "feel free to file an issue asking for one.",
+        )

referencing/_core.py

@@ -1,43 +1,21 @@
 from __future__ import annotations
 
 from collections.abc import Sequence
-from typing import TYPE_CHECKING
 from urllib.parse import unquote, urldefrag, urljoin
 
+from attrs import evolve, field
 from pyrsistent import m, plist, s
 from pyrsistent.typing import PList, PMap, PSet
 
+from referencing._attrs import define, frozen
+from referencing.jsonschema import DynamicAnchor, id_of
 from referencing.typing import Anchor as AnchorType, Schema, Specification
 
 
-class UnsupportedSubclassing(Exception):
-    @classmethod
-    def complain(this):
-        raise UnsupportedSubclassing(
-            "Subclassing is not part of referencing's public API. "
-            "If no other suitable API exists for what you're trying to do, "
-            "feel free to file an issue asking for one.",
-        )
-
-
 class UnidentifiedResource(Exception):
     pass
 
 
-if TYPE_CHECKING:
-    from attrs import define, evolve, field, frozen
-else:
-    from attrs import define as _define, evolve, field, frozen as _frozen
-
-    def define(cls):
-        cls.__init_subclass__ = UnsupportedSubclassing.complain
-        return _define(cls)
-
-    def frozen(cls):
-        cls.__init_subclass__ = UnsupportedSubclassing.complain
-        return _frozen(cls)
-
-
 @frozen
 class Anchor:
 
@@ -49,24 +27,6 @@ def resolve(self, dynamic_scope, uri) -> tuple[Schema, str]:
         return self.resource, uri
 
 
-@frozen
-class DynamicAnchor:
-
-    uri: str
-    name: str
-    resource: Schema
-
-    def resolve(self, dynamic_scope, uri):
-        last = self.resource
-        for resource, anchors in dynamic_scope:
-            anchor = anchors.get(self.name)
-            if isinstance(anchor, DynamicAnchor):
-                last = anchor.resource
-            elif "$ref" not in resource:
-                break
-        return last, id_of(last) or ""  # FIXME: consider when this can be None
-
-
 class OpaqueSpecification:
     """
     A non-specification `Specification` which treats resources opaquely.
@@ -234,9 +194,3 @@ def dynamic_scope(self):
         for uri in self._previous:
             resource, _ = self._registry.resource_at(uri)
             yield resource, self._registry.anchors_at(uri)
-
-
-def id_of(resource) -> str | None:
-    if resource is True or resource is False:
-        return None
-    return resource.get("$id")

referencing/jsonschema.py

@@ -4,10 +4,8 @@
 
 from __future__ import annotations
 
-from typing import TYPE_CHECKING
-
-if TYPE_CHECKING:
-    from referencing.typing import ObjectSchema
+from referencing._attrs import frozen
+from referencing.typing import Schema
 
 
 class Draft202012:
@@ -16,7 +14,7 @@ class Draft202012:
     _SUBRESOURCE_ITEMS = {"allOf"}
     _SUBRESOURCE_VALUES = {"$defs", "properties"}
 
-    def subresources_of(self, resource: ObjectSchema):
+    def subresources_of(self, resource):
         for each in self._SUBRESOURCE:
             if each in resource:
                 yield resource[each]
@@ -28,13 +26,31 @@ def subresources_of(self, resource: ObjectSchema):
                 yield from resource[each].values()
 
 
+@frozen
+class DynamicAnchor:
+
+    uri: str
+    name: str
+    resource: Schema
+
+    def resolve(self, dynamic_scope, uri):
+        last = self.resource
+        for resource, anchors in dynamic_scope:
+            anchor = anchors.get(self.name)
+            if isinstance(anchor, DynamicAnchor):
+                last = anchor.resource
+            elif "$ref" not in resource:
+                break
+        return last, id_of(last) or ""  # FIXME: consider when this can be None
+
+
 class Draft201909:
 
     _SUBRESOURCE = {"not"}
     _SUBRESOURCE_ITEMS = {"allOf"}
     _SUBRESOURCE_VALUES = {"$defs", "properties"}
 
-    def subresources_of(self, resource: ObjectSchema):
+    def subresources_of(self, resource):
         for each in self._SUBRESOURCE:
             if each in resource:
                 yield resource[each]
@@ -52,3 +68,9 @@ def subresources_of(self, resource: ObjectSchema):
             yield from items
         else:
             yield items
+
+
+def id_of(resource) -> str | None:
+    if resource is True or resource is False:
+        return None
+    return resource.get("$id")