[WIP] Encapsulate instruction in args in "Instruction" class

qiskit/circuit/__init__.py

@@ -177,6 +177,7 @@
    Clbit
    AncillaRegister
    AncillaQubit
+   Operation
 
 Gates and Instructions
 ----------------------
@@ -212,6 +213,7 @@
    random.random_circuit
 """
 from .quantumcircuit import QuantumCircuit
+from .operation import Operation
 from .classicalregister import ClassicalRegister, Clbit
 from .quantumregister import QuantumRegister, Qubit, AncillaRegister, AncillaQubit
 from .gate import Gate

qiskit/circuit/operation.py

@@ -0,0 +1,81 @@
+# This code is part of Qiskit.
+#
+# (C) Copyright IBM 2021.
+#
+# This code is licensed under the Apache License, Version 2.0. You may
+# obtain a copy of this license in the LICENSE.txt file in the root directory
+# of this source tree or at http://www.apache.org/licenses/LICENSE-2.0.
+#
+# Any modifications or derivative works of this code must retain this
+# copyright notice, and modified files need to carry a notice indicating
+# that they have been altered from the originals.
+
+"""
+Operation object
+"""
+
+from collections.abc import Sequence
+
+
+class Operation(Sequence):
+    """Class representation of a circuit operation
+
+    An operation is an instruction with it's operands.
+    """
+
+    __slots__ = ("instruction", "qargs", "cargs")
+
+    def __init__(self, instruction, qargs=None, cargs=None):
+        """Initialize a new instruction object
+
+        Args:
+            instruction (qiskit.circuit.Instruction): The instruction object for
+                the operation
+            qargs (list): A list of :class:`~qiskit.circuit.Qubit` objects that
+                the instruction runs on
+            cargs (list): A list of :class:`~qiskit.circuit.Clbit` objects that
+                the instruction runs on
+        """
+        self.instruction = instruction
+        if qargs is None:
+            self.qargs = []
+        else:
+            self.qargs = qargs
+        if cargs is None:
+            self.cargs = []
+        else:
+            self.cargs = cargs
+
+    def __len__(self):
+        return 3
+
+    def __getitem__(self, index):
+        if index == 0:
+            return self.instruction
+        if index == 1:
+            return self.qargs
+        if index == 2:
+            return self.cargs
+        if isinstance(index, slice):
+            out_items = (self.instruction, self.qargs, self.cargs)
+            return out_items.__getitem__(index)
+        raise IndexError("Index %s is out of range" % index)
+
+    def __eq__(self, other):
+        if isinstance(other, tuple):
+            if other[0] == self.instruction and other[1] == self.qargs and other[2] == self.cargs:
+                return True
+            return False
+        elif isinstance(other, Operation):
+            if (
+                self.instruction == other.instruction
+                and self.qargs == other.qargs
+                and self.cargs == other.cargs
+            ):
+                return True
+            return False
+        else:
+            return False
+
+    def __repr__(self):
+        return repr((self.instruction, self.qargs, self.cargs))

qiskit/circuit/quantumcircuit.py

@@ -40,6 +40,7 @@
 from qiskit.circuit.instruction import Instruction
 from qiskit.circuit.gate import Gate
 from qiskit.circuit.parameter import Parameter
+from qiskit.circuit.operation import Operation
 from qiskit.qasm.qasm import Qasm
 from qiskit.qasm.exceptions import QasmError
 from qiskit.circuit.exceptions import CircuitError
@@ -1195,8 +1196,8 @@ def _append(
         self._check_cargs(cargs)
 
         # add the instruction onto the given wires
-        instruction_context = instruction, qargs, cargs
-        self._data.append(instruction_context)
+        operation = Operation(instruction, qargs, cargs)
+        self._data.append(operation)
 
         self._update_parameter_table(instruction)
 
@@ -1811,6 +1812,7 @@ def depth(self, filter_function: Optional[callable] = lambda x: not x[0]._direct
                 # Add to the stacks of the qubits and
                 # cbits used in the gate.
                 reg_ints.append(bit_indices[reg])
+
                 if (instr, qargs, cargs) in filter(filter_function, self._data):
                     levels.append(op_stack[reg_ints[ind]] + 1)
                 else:

qiskit/circuit/quantumcircuitdata.py

@@ -17,6 +17,7 @@
 
 from qiskit.circuit.exceptions import CircuitError
 from qiskit.circuit.instruction import Instruction
+from qiskit.circuit.operation import Operation
 
 
 class QuantumCircuitData(MutableSequence):
@@ -54,12 +55,14 @@ def __setitem__(self, key, value):
         self._circuit._check_qargs(qargs)
         self._circuit._check_cargs(cargs)
 
-        self._circuit._data[key] = (instruction, qargs, cargs)
+        self._circuit._data[key] = Operation(instruction, qargs, cargs)
 
         self._circuit._update_parameter_table(instruction)
 
     def insert(self, index, value):
         self._circuit._data.insert(index, None)
+        if isinstance(value, tuple):
+            self[index] = Operation(*value)
         self[index] = value
 
     def __delitem__(self, i):