Add new methods for getting predicates from python passes

pytket/binders/passes.cpp

@@ -268,6 +268,32 @@ PYBIND11_MODULE(passes, m) {
             return py::cast(serialise(base_pass));
           },
           ":return: A JSON serializable dictionary representation of the Pass.")
+      .def(
+          "get_pre_conditions",
+          [](const BasePass &base_pass) {
+            std::vector<PredicatePtr> pre_conditions;
+            for (const std::pair<
+                     const std::type_index, std::shared_ptr<tket::Predicate>>
+                     &p : base_pass.get_conditions().first) {
+              pre_conditions.push_back(p.second);
+            }
+            return pre_conditions;
+          },
+          "Returns the pre condition Predicates for the given pass."
+          "\n:return: A list of Predicate")
+      .def(
+          "get_post_conditions",
+          [](const BasePass &base_pass) {
+            std::vector<PredicatePtr> post_conditions;
+            for (const std::pair<
+                     const std::type_index, std::shared_ptr<tket::Predicate>> &
+                     p : base_pass.get_conditions().second.specific_postcons_) {
+              post_conditions.push_back(p.second);
+            }
+            return post_conditions;
+          },
+          "Returns the post condition Predicates for the given pass."
+          "\n:return: A list of Predicate")
       .def_static(
           "from_dict",
           [](const py::dict &base_pass_dict,

pytket/binders/predicates.cpp

@@ -83,7 +83,7 @@ PYBIND11_MODULE(predicates, m) {
           "implies", &Predicate::implies,
           ":return: True if predicate implies another one, else False",
           py::arg("other"))
-      .def("__str__", [](const Predicate &) { return "<tket::Predicate>"; })
+      .def("__str__", &Predicate::to_string)
       .def("__repr__", &Predicate::to_string)
       .def(
           "to_dict",

pytket/docs/changelog.rst

@@ -1,6 +1,13 @@
 Changelog
 =========
 
+Unreleased
+----------
+
+Features:
+
+* Add `BasePass.get_pre_conditions()` and `BasePass.get_post_conditions()`.
+
 1.35.0 (November 2024)
 ----------------------
 

pytket/pytket/_tket/passes.pyi

@@ -54,6 +54,16 @@ class BasePass:
         :param after_apply: Invoked after a pass is applied. The CompilationUnit and a summary of the pass configuration are passed into the callback.
         :return: True if pass modified the circuit, else False
         """
+    def get_post_conditions(self) -> list[pytket._tket.predicates.Predicate]:
+        """
+        Returns the post condition Predicates for the given pass.
+        :return: A list of Predicate
+        """
+    def get_pre_conditions(self) -> list[pytket._tket.predicates.Predicate]:
+        """
+        Returns the pre condition Predicates for the given pass.
+        :return: A list of Predicate
+        """
     def to_dict(self) -> typing.Any:
         """
         :return: A JSON serializable dictionary representation of the Pass.

pytket/tests/predicates_test.py

@@ -1107,6 +1107,19 @@ def test_auto_rebase_deprecation(recwarn: Any) -> None:
     assert "deprecated" in str(w.message)
 
 
+def test_get_pre_conditions() -> None:
+    pre_cons = GreedyPauliSimp().get_pre_conditions()
+    gate_set = pre_cons[0].gate_set
+    assert OpType.CX in gate_set
+    assert OpType.Measure in gate_set
+
+
+def test_get_post_conditions() -> None:
+    gate_set = {OpType.CX, OpType.Rz, OpType.H, OpType.Reset, OpType.Measure}
+    post_cons = AutoRebase(gate_set).get_post_conditions()
+    assert post_cons[0].gate_set == gate_set
+
+
 if __name__ == "__main__":
     test_predicate_generation()
     test_compilation_unit_generation()