Updates

ETB-API/venv/lib/python3.12/site-packages/referencing/retrieval.py

@@ -0,0 +1,92 @@
+"""
+Helpers related to (dynamic) resource retrieval.
+"""
+
+from __future__ import annotations
+
+from functools import lru_cache
+from typing import TYPE_CHECKING, Callable
+import json
+
+try:
+    from typing_extensions import TypeVar
+except ImportError:  # pragma: no cover
+    from typing import TypeVar
+
+from referencing import Resource
+
+if TYPE_CHECKING:
+    from referencing.typing import URI, D, Retrieve
+
+#: A serialized document (e.g. a JSON string)
+_T = TypeVar("_T", default=str)
+
+
+def to_cached_resource(
+    cache: Callable[[Retrieve[D]], Retrieve[D]] | None = None,
+    loads: Callable[[_T], D] = json.loads,
+    from_contents: Callable[[D], Resource[D]] = Resource.from_contents,
+) -> Callable[[Callable[[URI], _T]], Retrieve[D]]:
+    """
+    Create a retriever which caches its return values from a simpler callable.
+
+    Takes a function which returns things like serialized JSON (strings) and
+    returns something suitable for passing to `Registry` as a retrieve
+    function.
+
+    This decorator both reduces a small bit of boilerplate for a common case
+    (deserializing JSON from strings and creating `Resource` objects from the
+    result) as well as makes the probable need for caching a bit easier.
+    Retrievers which otherwise do expensive operations (like hitting the
+    network) might otherwise be called repeatedly.
+
+    Examples
+    --------
+
+    .. testcode::
+
+        from referencing import Registry
+        from referencing.typing import URI
+        import referencing.retrieval
+
+
+        @referencing.retrieval.to_cached_resource()
+        def retrieve(uri: URI):
+            print(f"Retrieved {uri}")
+
+            # Normally, go get some expensive JSON from the network, a file ...
+            return '''
+                {
+                    "$schema": "https://json-schema.org/draft/2020-12/schema",
+                    "foo": "bar"
+                }
+            '''
+
+        one = Registry(retrieve=retrieve).get_or_retrieve("urn:example:foo")
+        print(one.value.contents["foo"])
+
+        # Retrieving the same URI again reuses the same value (and thus doesn't
+        # print another retrieval message here)
+        two = Registry(retrieve=retrieve).get_or_retrieve("urn:example:foo")
+        print(two.value.contents["foo"])
+
+    .. testoutput::
+
+        Retrieved urn:example:foo
+        bar
+        bar
+
+    """
+    if cache is None:
+        cache = lru_cache(maxsize=None)
+
+    def decorator(retrieve: Callable[[URI], _T]):
+        @cache
+        def cached_retrieve(uri: URI):
+            response = retrieve(uri)
+            contents = loads(response)
+            return from_contents(contents)
+
+        return cached_retrieve
+
+    return decorator