Cache to_camel_case

changes/75.misc.rst

@@ -0,0 +1 @@
+Cache ``to_camel_case``, speeding up building and serialising DIDL objects

didl_lite/utils.py

@@ -1,5 +1,6 @@
 """Utilities."""
 
+import functools
 import re
 
 NAMESPACES = {
@@ -42,6 +43,10 @@ def split_namespace_tag(namespaced_tag: str) -> tuple[str | None, str]:
     return namespace, tag
 
 
+# Cached: called for every attribute set on a DidlObject, with a small closed
+# set of property names. Bounded, as from_xml also passes names read from
+# documents received from other devices.
+@functools.lru_cache(maxsize=256)
 def to_camel_case(name: str) -> str:
     """Get camel case of name."""
     sub1 = re.sub("(.)([A-Z][a-z]+)", r"\1_\2", name)

tests/test_didl_lite.py

@@ -3,7 +3,7 @@
 import pytest
 from defusedxml import ElementTree as ET
 
-from didl_lite import didl_lite
+from didl_lite import didl_lite, utils
 
 NAMESPACES = {
     "didl_lite": "urn:schemas-upnp-org:metadata-1-0/DIDL-Lite/",
@@ -793,3 +793,13 @@ def test_music_track_artist_and_genre(self) -> None:
 
         assert b"<upnp:artist>My Artist</upnp:artist>" in xml
         assert b"<upnp:genre>My Genre</upnp:genre>" in xml
+
+    def test_to_camel_case_is_cached(self) -> None:
+        """Test to_camel_case is cached, and used cached through didl_lite."""
+        assert hasattr(utils.to_camel_case, "cache_info")
+        # didl_lite imports the name; it must be the cached function too.
+        assert didl_lite.to_camel_case is utils.to_camel_case
+
+        hits_before = utils.to_camel_case.cache_info().hits
+        didl_lite.MusicTrack(id="0", parent_id="0", title="Title", restricted="1")
+        assert utils.to_camel_case.cache_info().hits > hits_before