Allow creating new gatesets with added gates (#2458)

This will let us create "pre-release" gatesets to deploy server-side support for new gates that are not yet supported by the API.

cirq/google/api/v2/program.py

@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from typing import Type, TYPE_CHECKING
+from typing import TYPE_CHECKING
 
 from cirq import devices, ops
 

cirq/google/serializable_gate_set.py

@@ -13,10 +13,8 @@
 # limitations under the License.
 """Support for serializing and deserializing cirq.api.google.v2 protos."""
 
-from collections import defaultdict
-
-from typing import cast, Dict, Iterable, List, Optional, Tuple, Type, Union, \
-    TYPE_CHECKING
+from typing import (cast, Dict, Iterable, List, Optional, Tuple, Type, Union,
+                    TYPE_CHECKING)
 
 from google.protobuf import json_format
 
@@ -51,12 +49,35 @@ def __init__(self, gate_set_name: str,
                 forms of gates to GateOperations.
         """
         self.gate_set_name = gate_set_name
-        self.serializers = defaultdict(
-            list)  # type: Dict[Type, List[op_serializer.GateOpSerializer]]
+        self.serializers: Dict[Type, List[op_serializer.GateOpSerializer]] = {}
         for s in serializers:
-            self.serializers[s.gate_type].append(s)
+            self.serializers.setdefault(s.gate_type, []).append(s)
         self.deserializers = {d.serialized_gate_id: d for d in deserializers}
 
+    def with_added_gates(
+            self,
+            *,
+            gate_set_name: Optional[str] = None,
+            serializers: Iterable[op_serializer.GateOpSerializer] = (),
+            deserializers: Iterable[op_deserializer.GateOpDeserializer] = (),
+    ) -> 'SerializableGateSet':
+        """Creates a new gateset with additional (de)serializers.
+
+        Args:
+            gate_set_name: Optional new name of the gateset. If not given, use
+                the same name as this gateset.
+            serializers: Serializers to add to those in this gateset.
+            deserializers: Deserializers to add to those in this gateset.
+        """
+        # Iterate over all serializers in this gateset.
+        curr_serializers = (serializer
+                            for serializers in self.serializers.values()
+                            for serializer in serializers)
+        return SerializableGateSet(
+            gate_set_name or self.gate_set_name,
+            serializers=[*curr_serializers, *serializers],
+            deserializers=[*self.deserializers.values(), *deserializers])
+
     def supported_gate_types(self) -> Tuple:
         return tuple(self.serializers.keys())
 

cirq/google/serializable_gate_set_test.py

@@ -17,26 +17,57 @@
 import cirq
 import cirq.google as cg
 
-X_SERIALIZER = cg.GateOpSerializer(gate_type=cirq.XPowGate,
-                                   serialized_gate_id='x_pow',
-                                   args=[
-                                       cg.SerializingArg(
-                                           serialized_name='half_turns',
-                                           serialized_type=float,
-                                           gate_getter='exponent')
-                                   ])
-
-X_DESERIALIZER = cg.GateOpDeserializer(serialized_gate_id='x_pow',
-                                       gate_constructor=cirq.XPowGate,
-                                       args=[
-                                           cg.DeserializingArg(
-                                               serialized_name='half_turns',
-                                               constructor_arg_name='exponent')
-                                       ])
-
-MY_GATE_SET = cg.SerializableGateSet(gate_set_name='my_gate_set',
-                                     serializers=[X_SERIALIZER],
-                                     deserializers=[X_DESERIALIZER])
+X_SERIALIZER = cg.GateOpSerializer(
+    gate_type=cirq.XPowGate,
+    serialized_gate_id='x_pow',
+    args=[
+        cg.SerializingArg(
+            serialized_name='half_turns',
+            serialized_type=float,
+            gate_getter='exponent',
+        )
+    ],
+)
+
+X_DESERIALIZER = cg.GateOpDeserializer(
+    serialized_gate_id='x_pow',
+    gate_constructor=cirq.XPowGate,
+    args=[
+        cg.DeserializingArg(
+            serialized_name='half_turns',
+            constructor_arg_name='exponent',
+        )
+    ],
+)
+
+Y_SERIALIZER = cg.GateOpSerializer(
+    gate_type=cirq.YPowGate,
+    serialized_gate_id='y_pow',
+    args=[
+        cg.SerializingArg(
+            serialized_name='half_turns',
+            serialized_type=float,
+            gate_getter='exponent',
+        )
+    ],
+)
+
+Y_DESERIALIZER = cg.GateOpDeserializer(
+    serialized_gate_id='y_pow',
+    gate_constructor=cirq.XPowGate,
+    args=[
+        cg.DeserializingArg(
+            serialized_name='half_turns',
+            constructor_arg_name='exponent',
+        )
+    ],
+)
+
+MY_GATE_SET = cg.SerializableGateSet(
+    gate_set_name='my_gate_set',
+    serializers=[X_SERIALIZER],
+    deserializers=[X_DESERIALIZER],
+)
 
 
 def test_supported_gate_types():
@@ -338,6 +369,26 @@ def test_multiple_serializers():
     assert gate_set.serialize_op(cirq.X(q0)**0.5).gate.id == 'x_pow'
 
 
+def test_gateset_with_added_gates():
+    x_gateset = cg.SerializableGateSet(
+        gate_set_name='x',
+        serializers=[X_SERIALIZER],
+        deserializers=[X_DESERIALIZER],
+    )
+    xy_gateset = x_gateset.with_added_gates(
+        gate_set_name='xy',
+        serializers=[Y_SERIALIZER],
+        deserializers=[Y_DESERIALIZER],
+    )
+    assert x_gateset.gate_set_name == 'x'
+    assert x_gateset.is_supported_gate(cirq.X)
+    assert not x_gateset.is_supported_gate(cirq.Y)
+
+    assert xy_gateset.gate_set_name == 'xy'
+    assert xy_gateset.is_supported_gate(cirq.X)
+    assert xy_gateset.is_supported_gate(cirq.Y)
+
+
 def test_deserialize_op_invalid_gate():
     proto = {
         'gate': {},