perf: restore _pst cache with proper invalidation via callbacks and __setattr__

The original cache was dropped to fix staleness, but recomputing the set
union on every call is ~1000x slower. This restores the cache with a
correct invalidation strategy: SetManager fires an on_change callback
after add/remove, and Constants.__setattr__ clears _pst and re-wires
the callback whenever one of the four contributing attrs is replaced
(covering both user mutations and conftest teardown restores).

The conftest manual `CONSTANTS._pst = None` reset is removed — it is
now handled automatically by __setattr__ during collection restore.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: derek73

nameparser/config/__init__.py

@@ -29,7 +29,7 @@
 """
 import re
 import sys
-from collections.abc import Iterable, Iterator, Mapping, Set
+from collections.abc import Callable, Iterable, Iterator, Mapping, Set
 from typing import Any, TypeVar
 
 if sys.version_info >= (3, 11):
@@ -62,8 +62,9 @@ class SetManager(Set):
 
     '''
 
-    def __init__(self, elements: Iterable[str]) -> None:
+    def __init__(self, elements: Iterable[str], on_change: Callable[[], None] | None = None) -> None:
         self.elements = set(elements)
+        self._on_change = on_change
 
     def __call__(self) -> Set[str]:
         return self.elements
@@ -93,6 +94,8 @@ def add_with_encoding(self, s: str, encoding: str | None = None) -> None:
         if isinstance(s, bytes):
             s = s.decode(encoding)
         self.elements.add(lc(s))
+        if self._on_change:
+            self._on_change()
 
     def add(self, *strings: str) -> Self:
         """
@@ -112,7 +115,8 @@ def remove(self, *strings: str) -> Self:
         for s in strings:
             if (lower := lc(s)) in self.elements:
                 self.elements.remove(lower)
-
+        if self._on_change:
+            self._on_change()
         return self
 
 
@@ -146,6 +150,9 @@ def __getattr__(self, attr: str) -> re.Pattern[str]:
         return self.get(attr, EMPTY_REGEX)
 
 
+_PST_ATTRS = frozenset(('prefixes', 'suffix_acronyms', 'suffix_not_acronyms', 'titles'))
+
+
 class Constants:
     """
     An instance of this class hold all of the configuration constants for the parser.
@@ -178,7 +185,7 @@ class Constants:
     conjunctions: SetManager
     capitalization_exceptions: TupleManager[str]
     regexes: RegexTupleManager
-
+    _pst: Set[str] | None
 
     string_format = "{title} {first} {middle} {last} {suffix} ({nickname})"
     """
@@ -262,9 +269,21 @@ def __init__(self,
         self.capitalization_exceptions = TupleManager(capitalization_exceptions)
         self.regexes = RegexTupleManager(regexes)
 
+    def __setattr__(self, name: str, value: object) -> None:
+        if name in _PST_ATTRS:
+            object.__setattr__(self, '_pst', None)
+            if isinstance(value, SetManager):
+                value._on_change = self._invalidate_pst
+        object.__setattr__(self, name, value)
+
+    def _invalidate_pst(self) -> None:
+        self._pst = None
+
     @property
     def suffixes_prefixes_titles(self) -> Set[str]:
-        return self.prefixes | self.suffix_acronyms | self.suffix_not_acronyms | self.titles
+        if not self._pst:
+            self._pst = self.prefixes | self.suffix_acronyms | self.suffix_not_acronyms | self.titles
+        return self._pst
 
     def __repr__(self) -> str:
         return "<Constants() instance>"

tests/conftest.py

@@ -75,6 +75,3 @@ def empty_attribute_default(request: pytest.FixtureRequest) -> Iterator[str | No
         setattr(CONSTANTS, attr, value)
     for attr, value in collection_snapshot.items():
         setattr(CONSTANTS, attr, value)
-    # Invalidate the lazily-built suffixes/prefixes/titles cache so it is
-    # recomputed from the restored collections rather than a mutated one.
-    CONSTANTS._pst = None