Add use_symengine option to qpy.dump

qiskit/qpy/__init__.py

@@ -102,7 +102,7 @@
 serialization format for :class:`~qiskit.circuit.QuantumCircuit` objects in Qiskit. The basic
 file format is as follows:
 
-A QPY file (or memory object) always starts with the following 7
+A QPY file (or memory object) always starts with the following 6
 byte UTF8 string: ``QISKIT`` which is immediately followed by the overall
 file header. The contents of the file header as defined as a C struct are:
 
@@ -116,6 +116,7 @@
         uint64_t num_circuits;
     }
 
+
 All values use network byte order [#f1]_ (big endian) for cross platform
 compatibility.
 
@@ -128,6 +129,58 @@
 by ``num_circuits`` in the file header). There is no padding between the
 circuits in the data.
 
+.. _qpy_version_10:
+
+Version 10
+==========
+
+Version 10 adds support for the ``use_symengine`` flag in ``qpy.dump()``, which allows the use
+of symengine-native serialization and deserialization for objects of type ``ParameterExpression``
+as well as symbolic expressions in Pulse schedule blocks.
+
+For example::
+
+    from qiskit.circuit import QuantumCircuit, Parameter
+    from qiskit import qpy
+
+    theta = Parameter("theta")
+    phi = Parameter("phi")
+    sum_param = theta + phi
+
+    qc = QuantumCircuit(1)
+    qc.rz(sum_param, 0)
+    qc.measure_all()
+
+    with open('bell.qpy', 'wb') as fd:
+        qpy.dump(qc, fd)
+
+    with open('bell.qpy', 'rb') as fd:
+        new_qc = qpy.load(fd)[0]
+
+This is a faster serialization alternative, but not supported in all platforms.
+Please check that your target platform is supported by the symengine library before
+setting this option, as it will be **required** by qpy to deserialize the payload.
+For this reason, the option defaults to False.
+
+As it affects both circuit and block schedule payloads, the option is now stored as part of
+the file header:
+
+FILE_HEADER
+-----------
+
+The contents of FILE_HEADER after V10 are defined as a C struct as:
+
+.. code-block:: c
+
+    struct {
+        uint8_t qpy_version;
+        uint8_t qiskit_major_version;
+        uint8_t qiskit_minor_version;
+        uint8_t qiskit_patch_version;
+        uint64_t num_circuits;
+        _Bool use_symengine;
+    }
+
 
 .. _qpy_version_9:
 

qiskit/qpy/binary_io/circuits.py

@@ -42,12 +42,14 @@
 
 
 def _read_header_v2(file_obj, version, vectors, metadata_deserializer=None):
+
     data = formats.CIRCUIT_HEADER_V2._make(
         struct.unpack(
             formats.CIRCUIT_HEADER_V2_PACK,
             file_obj.read(formats.CIRCUIT_HEADER_V2_SIZE),
         )
     )
+
     name = file_obj.read(data.name_size).decode(common.ENCODE)
     global_phase = value.loads_value(
         data.global_phase_type,
@@ -62,6 +64,7 @@ def _read_header_v2(file_obj, version, vectors, metadata_deserializer=None):
         "num_registers": data.num_registers,
         "num_instructions": data.num_instructions,
     }
+
     metadata_raw = file_obj.read(data.metadata_size)
     metadata = json.loads(metadata_raw, cls=metadata_deserializer)
     return header, name, metadata
@@ -124,7 +127,9 @@ def _read_registers(file_obj, num_registers):
     return registers
 
 
-def _loads_instruction_parameter(type_key, data_bytes, version, vectors, registers, circuit):
+def _loads_instruction_parameter(
+    type_key, data_bytes, version, vectors, registers, circuit, use_symengine
+):
     if type_key == type_keys.Program.CIRCUIT:
         param = common.data_from_binary(data_bytes, read_circuit, version=version)
     elif type_key == type_keys.Container.RANGE:
@@ -139,6 +144,7 @@ def _loads_instruction_parameter(type_key, data_bytes, version, vectors, registe
                 vectors=vectors,
                 registers=registers,
                 circuit=circuit,
+                use_symengine=use_symengine,
             )
         )
     elif type_key == type_keys.Value.INTEGER:
@@ -151,7 +157,13 @@ def _loads_instruction_parameter(type_key, data_bytes, version, vectors, registe
         param = _loads_register_param(data_bytes.decode(common.ENCODE), circuit, registers)
     else:
         param = value.loads_value(
-            type_key, data_bytes, version, vectors, clbits=circuit.clbits, cregs=registers["c"]
+            type_key,
+            data_bytes,
+            version,
+            vectors,
+            clbits=circuit.clbits,
+            cregs=registers["c"],
+            use_symengine=use_symengine,
         )
 
     return param
@@ -165,7 +177,9 @@ def _loads_register_param(data_bytes, circuit, registers):
     return registers["c"][data_bytes]
 
 
-def _read_instruction(file_obj, circuit, registers, custom_operations, version, vectors):
+def _read_instruction(
+    file_obj, circuit, registers, custom_operations, version, vectors, use_symengine
+):
     if version < 5:
         instruction = formats.CIRCUIT_INSTRUCTION._make(
             struct.unpack(
@@ -196,7 +210,12 @@ def _read_instruction(file_obj, circuit, registers, custom_operations, version,
         )
     elif version >= 5 and instruction.conditional_key == type_keys.Condition.EXPRESSION:
         condition = value.read_value(
-            file_obj, version, vectors, clbits=circuit.clbits, cregs=registers["c"]
+            file_obj,
+            version,
+            vectors,
+            clbits=circuit.clbits,
+            cregs=registers["c"],
+            use_symengine=use_symengine,
         )
     if circuit is not None:
         qubit_indices = dict(enumerate(circuit.qubits))
@@ -232,14 +251,14 @@ def _read_instruction(file_obj, circuit, registers, custom_operations, version,
     for _param in range(instruction.num_parameters):
         type_key, data_bytes = common.read_generic_typed_data(file_obj)
         param = _loads_instruction_parameter(
-            type_key, data_bytes, version, vectors, registers, circuit
+            type_key, data_bytes, version, vectors, registers, circuit, use_symengine
         )
         params.append(param)
 
     # Load Gate object
     if gate_name in {"Gate", "Instruction", "ControlledGate"}:
         inst_obj = _parse_custom_operation(
-            custom_operations, gate_name, params, version, vectors, registers
+            custom_operations, gate_name, params, version, vectors, registers, use_symengine
         )
         inst_obj.condition = condition
         if instruction.label_size > 0:
@@ -250,7 +269,7 @@ def _read_instruction(file_obj, circuit, registers, custom_operations, version,
         return None
     elif gate_name in custom_operations:
         inst_obj = _parse_custom_operation(
-            custom_operations, gate_name, params, version, vectors, registers
+            custom_operations, gate_name, params, version, vectors, registers, use_symengine
         )
         inst_obj.condition = condition
         if instruction.label_size > 0:
@@ -317,7 +336,9 @@ def _read_instruction(file_obj, circuit, registers, custom_operations, version,
     return None
 
 
-def _parse_custom_operation(custom_operations, gate_name, params, version, vectors, registers):
+def _parse_custom_operation(
+    custom_operations, gate_name, params, version, vectors, registers, use_symengine
+):
     if version >= 5:
         (
             type_str,
@@ -346,7 +367,7 @@ def _parse_custom_operation(custom_operations, gate_name, params, version, vecto
     if version >= 5 and type_key == type_keys.CircuitInstruction.CONTROLLED_GATE:
         with io.BytesIO(base_gate_raw) as base_gate_obj:
             base_gate = _read_instruction(
-                base_gate_obj, None, registers, custom_operations, version, vectors
+                base_gate_obj, None, registers, custom_operations, version, vectors, use_symengine
             )
         if ctrl_state < 2**num_ctrl_qubits - 1:
             # If open controls, we need to discard the control suffix when setting the name.
@@ -497,7 +518,7 @@ def _dumps_register(register, index_map):
     return b"\x00" + str(index_map["c"][register]).encode(common.ENCODE)
 
 
-def _dumps_instruction_parameter(param, index_map):
+def _dumps_instruction_parameter(param, index_map, use_symengine):
     if isinstance(param, QuantumCircuit):
         type_key = type_keys.Program.CIRCUIT
         data_bytes = common.data_to_binary(param, write_circuit)
@@ -507,7 +528,7 @@ def _dumps_instruction_parameter(param, index_map):
     elif isinstance(param, tuple):
         type_key = type_keys.Container.TUPLE
         data_bytes = common.sequence_to_binary(
-            param, _dumps_instruction_parameter, index_map=index_map
+            param, _dumps_instruction_parameter, index_map=index_map, use_symengine=use_symengine
         )
     elif isinstance(param, int):
         # TODO This uses little endian. This should be fixed in next QPY version.
@@ -521,13 +542,15 @@ def _dumps_instruction_parameter(param, index_map):
         type_key = type_keys.Value.REGISTER
         data_bytes = _dumps_register(param, index_map)
     else:
-        type_key, data_bytes = value.dumps_value(param, index_map=index_map)
+        type_key, data_bytes = value.dumps_value(
+            param, index_map=index_map, use_symengine=use_symengine
+        )
 
     return type_key, data_bytes
 
 
 # pylint: disable=too-many-boolean-expressions
-def _write_instruction(file_obj, instruction, custom_operations, index_map):
+def _write_instruction(file_obj, instruction, custom_operations, index_map, use_symengine):
     gate_class_name = instruction.operation.__class__.__name__
     custom_operations_list = []
     if (
@@ -603,7 +626,7 @@ def _write_instruction(file_obj, instruction, custom_operations, index_map):
         value.write_value(file_obj, op_condition, index_map=index_map)
     else:
         file_obj.write(condition_register)
-    # Encode instruciton args
+    # Encode instruction args
     for qbit in instruction.qubits:
         instruction_arg_raw = struct.pack(
             formats.CIRCUIT_INSTRUCTION_ARG_PACK, b"q", index_map["q"][qbit]
@@ -616,7 +639,7 @@ def _write_instruction(file_obj, instruction, custom_operations, index_map):
         file_obj.write(instruction_arg_raw)
     # Encode instruction params
     for param in instruction_params:
-        type_key, data_bytes = _dumps_instruction_parameter(param, index_map)
+        type_key, data_bytes = _dumps_instruction_parameter(param, index_map, use_symengine)
         common.write_generic_typed_data(file_obj, type_key, data_bytes)
     return custom_operations_list
 
@@ -661,7 +684,7 @@ def _write_elem(buffer, op):
     file_obj.write(synth_data)
 
 
-def _write_custom_operation(file_obj, name, operation, custom_operations):
+def _write_custom_operation(file_obj, name, operation, custom_operations, use_symengine):
     type_key = type_keys.CircuitInstruction.assign(operation)
     has_definition = False
     size = 0
@@ -700,7 +723,11 @@ def _write_custom_operation(file_obj, name, operation, custom_operations):
     else:
         with io.BytesIO() as base_gate_buffer:
             new_custom_instruction = _write_instruction(
-                base_gate_buffer, CircuitInstruction(base_gate, (), ()), custom_operations, {}
+                base_gate_buffer,
+                CircuitInstruction(base_gate, (), ()),
+                custom_operations,
+                {},
+                use_symengine,
             )
             base_gate_raw = base_gate_buffer.getvalue()
     name_raw = name.encode(common.ENCODE)
@@ -915,7 +942,7 @@ def _read_layout(file_obj, circuit):
     circuit._layout = TranspileLayout(initial_layout, input_qubit_mapping, final_layout)
 
 
-def write_circuit(file_obj, circuit, metadata_serializer=None):
+def write_circuit(file_obj, circuit, metadata_serializer=None, use_symengine=False):
     """Write a single QuantumCircuit object in the file like object.
 
     Args:
@@ -925,6 +952,10 @@ def write_circuit(file_obj, circuit, metadata_serializer=None):
             will be passed the :attr:`.QuantumCircuit.metadata` dictionary for
             ``circuit`` and will be used as the ``cls`` kwarg
             on the ``json.dump()`` call to JSON serialize that dictionary.
+        use_symengine (bool): If True, symbolic objects will be serialized using symengine's
+            native mechanism. This is a faster serialization alternative, but not supported in all
+            platforms. Please check that your target platform is supported by the symengine library
+            before setting this option, as it will be required by qpy to deserialize the payload.
     """
     metadata_raw = json.dumps(
         circuit.metadata, separators=(",", ":"), cls=metadata_serializer
@@ -964,7 +995,9 @@ def write_circuit(file_obj, circuit, metadata_serializer=None):
     index_map["q"] = {bit: index for index, bit in enumerate(circuit.qubits)}
     index_map["c"] = {bit: index for index, bit in enumerate(circuit.clbits)}
     for instruction in circuit.data:
-        _write_instruction(instruction_buffer, instruction, custom_operations, index_map)
+        _write_instruction(
+            instruction_buffer, instruction, custom_operations, index_map, use_symengine
+        )
 
     with io.BytesIO() as custom_operations_buffer:
         new_custom_operations = list(custom_operations.keys())
@@ -975,7 +1008,7 @@ def write_circuit(file_obj, circuit, metadata_serializer=None):
                 operation = custom_operations[name]
                 new_custom_operations.extend(
                     _write_custom_operation(
-                        custom_operations_buffer, name, operation, custom_operations
+                        custom_operations_buffer, name, operation, custom_operations, use_symengine
                     )
                 )
 
@@ -990,7 +1023,7 @@ def write_circuit(file_obj, circuit, metadata_serializer=None):
     _write_layout(file_obj, circuit)
 
 
-def read_circuit(file_obj, version, metadata_deserializer=None):
+def read_circuit(file_obj, version, metadata_deserializer=None, use_symengine=False):
     """Read a single QuantumCircuit object from the file like object.
 
     Args:
@@ -1003,7 +1036,11 @@ def read_circuit(file_obj, version, metadata_deserializer=None):
             in the file-like object. If this is not specified the circuit metadata will
             be parsed as JSON with the stdlib ``json.load()`` function using
             the default ``JSONDecoder`` class.
-
+        use_symengine (bool): If True, symbolic objects will be de-serialized using
+            symengine's native mechanism. This is a faster serialization alternative, but not
+            supported in all platforms. Please check that your target platform is supported by
+            the symengine library before setting this option, as it will be required by qpy to
+            deserialize the payload.
     Returns:
         QuantumCircuit: The circuit object from the file.
 
@@ -1023,7 +1060,7 @@ def read_circuit(file_obj, version, metadata_deserializer=None):
     num_clbits = header["num_clbits"]
     num_registers = header["num_registers"]
     num_instructions = header["num_instructions"]
-    # `out_registers` is two "name: registter" maps segregated by type for the rest of QPY, and
+    # `out_registers` is two "name: register" maps segregated by type for the rest of QPY, and
     # `all_registers` is the complete ordered list used to construct the `QuantumCircuit`.
     out_registers = {"q": {}, "c": {}}
     all_registers = []
@@ -1089,7 +1126,9 @@ def read_circuit(file_obj, version, metadata_deserializer=None):
     )
     custom_operations = _read_custom_operations(file_obj, version, vectors)
     for _instruction in range(num_instructions):
-        _read_instruction(file_obj, circ, out_registers, custom_operations, version, vectors)
+        _read_instruction(
+            file_obj, circ, out_registers, custom_operations, version, vectors, use_symengine
+        )
 
     # Read calibrations
     if version >= 5: