Replace _PhasedFSimConverter in cirq_google with new transformer primitives

cirq-google/cirq_google/calibration/engine_simulator.py

@@ -487,38 +487,21 @@ def _create_step_result(
         raise NotImplementedError()
 
 
-class _PhasedFSimConverter(cirq.PointOptimizer):
-    def __init__(self, simulator: PhasedFSimEngineSimulator) -> None:
-        super().__init__()
-        self._simulator = simulator
-
-    def optimization_at(
-        self, circuit: cirq.Circuit, index: int, op: cirq.Operation
-    ) -> Optional[cirq.PointOptimizationSummary]:
-
-        if isinstance(op.gate, (cirq.MeasurementGate, cirq.SingleQubitGate, cirq.WaitGate)):
-            new_op = op
-        else:
-            if op.gate is None:
-                raise IncompatibleMomentError(f'Operation {op} has a missing gate')
-            translated = self._simulator.gates_translator(op.gate)
-            if translated is None:
-                raise IncompatibleMomentError(
-                    f'Moment contains non-single qubit operation ' f'{op} with unsupported gate'
-                )
-
-            a, b = op.qubits
-            new_op = self._simulator.create_gate_with_drift(a, b, translated).on(a, b)
-
-        return cirq.PointOptimizationSummary(
-            clear_span=1, clear_qubits=op.qubits, new_operations=new_op
-        )
-
-
 def _convert_to_circuit_with_drift(
     simulator: PhasedFSimEngineSimulator, circuit: cirq.AbstractCircuit
 ) -> cirq.Circuit:
-    circuit_with_drift = cirq.Circuit(circuit)
-    converter = _PhasedFSimConverter(simulator)
-    converter.optimize_circuit(circuit_with_drift)
-    return circuit_with_drift
+    def map_func(op: cirq.Operation, _) -> cirq.Operation:
+        if isinstance(op.gate, (cirq.MeasurementGate, cirq.SingleQubitGate, cirq.WaitGate)):
+            return op
+        if op.gate is None:
+            raise IncompatibleMomentError(f'Operation {op} has a missing gate')
+        translated = simulator.gates_translator(op.gate)
+        if translated is None:
+            raise IncompatibleMomentError(
+                f'Moment contains non-single qubit operation ' f'{op} with unsupported gate'
+            )
+
+        a, b = op.qubits
+        return simulator.create_gate_with_drift(a, b, translated).on(a, b)
+
+    return cirq.map_operations(circuit, map_func)