Create moment unchecked

Author: daxfohl

cirq-core/cirq/circuits/circuit.py

@@ -1741,10 +1741,12 @@ def _create_from_earliest(self, contents):
                 ckeys[k] = i
             length = max(length, i + 1)
         for i in range(length):
+            curr_ops = []
             if i in moments:
-                self._moments.append(moments[i].with_operations(opses[i]))
-            else:
-                self._moments.append(Moment(opses[i]))
+                curr_ops.extend(moments[i]._operations)
+            if i in opses:
+                curr_ops.extend(opses[i])
+            self._moments.append(Moment._create_unchecked(tuple(curr_ops)))
 
     def __copy__(self) -> 'cirq.Circuit':
         return self.copy()

cirq-core/cirq/circuits/moment.py

@@ -94,7 +94,7 @@ def __init__(self, *contents: 'cirq.OP_TREE') -> None:
 
         # An internal dictionary to support efficient operation access by qubit.
         self._qubit_to_op: Dict['cirq.Qid', 'cirq.Operation'] = {}
-        for op in self.operations:
+        for op in self._operations:
             for q in op.qubits:
                 # Check that operations don't overlap.
                 if q in self._qubit_to_op:
@@ -105,6 +105,14 @@ def __init__(self, *contents: 'cirq.OP_TREE') -> None:
         self._measurement_key_objs: Optional[AbstractSet['cirq.MeasurementKey']] = None
         self._control_keys: Optional[FrozenSet['cirq.MeasurementKey']] = None
 
+    @classmethod
+    def _create_unchecked(cls, operations: Tuple['cirq.Operation']):
+        moment = cls()
+        moment._operations = operations
+        moment._qubit_to_op = {q: op for op in operations for q in op.qubits}
+        moment._qubits = frozenset(moment._qubit_to_op.keys())
+        return moment
+
     @property
     def operations(self) -> Tuple['cirq.Operation', ...]:
         return self._operations