From 6be7e462a5d7c0688ca486555d069134e60c77a2 Mon Sep 17 00:00:00 2001
From: James Mitchell <jdm3@st-andrews.ac.uk>
Date: Tue, 17 Jun 2025 14:34:57 +0100
Subject: [PATCH] Add __call__ to CxxWrapper

---
 .../detail/cxx_wrapper.py                     | 53 ++++++++++++++-----
 tests/test_sims.py                            |  6 +++
 2 files changed, 47 insertions(+), 12 deletions(-)

diff --git a/src/libsemigroups_pybind11/detail/cxx_wrapper.py b/src/libsemigroups_pybind11/detail/cxx_wrapper.py
index b38a4e1a3..e9d590900 100644
--- a/src/libsemigroups_pybind11/detail/cxx_wrapper.py
+++ b/src/libsemigroups_pybind11/detail/cxx_wrapper.py
@@ -66,13 +66,21 @@ def __init__(
         optional_kwargs=(),
         **kwargs,
     ) -> None:
-        if len(args) == 1 and len(kwargs) == 0 and type(args[0]) in self._all_wrapped_cxx_types:
+        if (
+            len(args) == 1
+            and len(kwargs) == 0
+            and type(args[0]) in self._all_wrapped_cxx_types
+        ):
             # Copy constructor like construction directly from cxx object
             self._cxx_obj = args[0]
             self.py_template_params = self.py_template_params_from_cxx_obj()
             return
 
-        if not len(required_kwargs) <= len(kwargs) <= len(required_kwargs) + len(optional_kwargs):
+        if (
+            not len(required_kwargs)
+            <= len(kwargs)
+            <= len(required_kwargs) + len(optional_kwargs)
+        ):
             raise TypeError(
                 f"expected between {len(required_kwargs)} and "
                 f"{len(required_kwargs) + len(optional_kwargs)} "
@@ -111,7 +119,9 @@ def __getattr__(self: Self, name: str):
             def cxx_fn_wrapper(*args) -> Any:
                 if len(args) == 1 and isinstance(args[0], list):
                     args = args[0]
-                    return getattr(self._cxx_obj, name)([to_cxx(x) for x in args])
+                    return getattr(self._cxx_obj, name)(
+                        [to_cxx(x) for x in args]
+                    )
                 return getattr(self._cxx_obj, name)(*(to_cxx(x) for x in args))
 
             return cxx_fn_wrapper
@@ -126,14 +136,27 @@ def __copy__(self: Self) -> Self:
         if self._cxx_obj is not None:
             if hasattr(self._cxx_obj, "__copy__"):
                 return to_py(self._cxx_obj.__copy__())
-            raise NotImplementedError(f"{type(self._cxx_obj)} has no member named __copy__")
+            raise NotImplementedError(
+                f"{type(self._cxx_obj)} has no member named __copy__"
+            )
         raise NameError("_cxx_obj has not been defined")
 
-    def __eq__(self: Self, that) -> bool:
+    def __eq__(self: Self, that: Self) -> bool:
         if self._cxx_obj is not None:
             if hasattr(self._cxx_obj, "__eq__"):
                 return self._cxx_obj.__eq__(that._cxx_obj)
-            raise NotImplementedError(f"{type(self._cxx_obj)} has no member named __eq__")
+            raise NotImplementedError(
+                f"{type(self._cxx_obj)} has no member named __eq__"
+            )
+        raise NameError("_cxx_obj has not been defined")
+
+    def __call__(self: Self, *args) -> Any:
+        if self._cxx_obj is not None:
+            if callable(self._cxx_obj):
+                return self._cxx_obj.__call__(*args)
+            raise NotImplementedError(
+                f"{type(self._cxx_obj)} has no member named __call__"
+            )
         raise NameError("_cxx_obj has not been defined")
 
     def py_template_params_from_cxx_obj(self: Self) -> tuple:
@@ -152,9 +175,9 @@ def init_cxx_obj(self: Self, *args) -> None:
         defined.
         """
         assert self.py_template_params is not None
-        self._cxx_obj = self._py_template_params_to_cxx_type[self.py_template_params](
-            *(to_cxx(x) for x in args)
-        )
+        self._cxx_obj = self._py_template_params_to_cxx_type[
+            self.py_template_params
+        ](*(to_cxx(x) for x in args))
 
 
 # TODO proper annotations
@@ -170,13 +193,17 @@ def cxx_mem_fn_wrapper(self, *args):
         # TODO move the first if-clause into to_cxx?
         if len(args) == 1 and isinstance(args[0], list):
             args = [[to_cxx(x) for x in args[0]]]
-        result = getattr(to_cxx(self), cxx_mem_fn.__name__)(*(to_cxx(x) for x in args))
+        result = getattr(to_cxx(self), cxx_mem_fn.__name__)(
+            *(to_cxx(x) for x in args)
+        )
         if result is to_cxx(self):
             return self
         if type(result) in _CXX_WRAPPED_TYPE_TO_PY_TYPE:
             cached_val = f"_cached_return_value_{cxx_mem_fn.__name__}"
             # TODO use args too in cached_val?
-            if hasattr(self, cached_val) and result is to_cxx(getattr(self, cached_val)):
+            if hasattr(self, cached_val) and result is to_cxx(
+                getattr(self, cached_val)
+            ):
                 return getattr(self, cached_val)
             result = _CXX_WRAPPED_TYPE_TO_PY_TYPE[type(result)](result)
             setattr(self, cached_val, result)
@@ -210,7 +237,9 @@ def copy_cxx_mem_fns(cxx_class: pybind11_type, py_class: CxxWrapper) -> None:
     that call the cxx member function on the _cxx_obj.
     """
     for py_meth_name in dir(cxx_class):
-        if (not py_meth_name.startswith("_")) and py_meth_name not in dir(py_class):
+        if (not py_meth_name.startswith("_")) and py_meth_name not in dir(
+            py_class
+        ):
             setattr(
                 py_class,
                 py_meth_name,
diff --git a/tests/test_sims.py b/tests/test_sims.py
index 8f0bfad34..141b7bed4 100644
--- a/tests/test_sims.py
+++ b/tests/test_sims.py
@@ -597,6 +597,12 @@ def test_sims_refiner_faithful_return_policy():
     assert srf.init([[0, 1], [0]]) is srf
 
 
+def test_sims_refiner_faithful_call():
+    srf = SimsRefinerFaithful()
+    wg = WordGraph(2, [[0, 1]])
+    assert srf(wg)
+
+
 def test_sims_refiner_ideals_return_policy():
     sri = SimsRefinerIdeals()
     assert sri.presentation() is sri.presentation()