Quellcode für qiskit.transpiler.passes.utils.convert_conditions_to_if_ops

# This code is part of Qiskit.
# (C) Copyright IBM 2022.
# 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.

"""Replace conditional instructions with equivalent :class:`.IfElseOp` objects."""

from qiskit.converters import dag_to_circuit, circuit_to_dag
from qiskit.circuit import (
from qiskit.dagcircuit import DAGCircuit
from qiskit.transpiler import TransformationPass

[Doku]class ConvertConditionsToIfOps(TransformationPass): """Convert instructions whose ``condition`` attribute is set to a non-``None`` value into the equivalent single-statement :class:`.IfElseBlock`. This is a simple pass aimed at easing the conversion from the old style of using :meth:`.InstructionSet.c_if` into the new style of using more complex conditional logic.""" def _run_inner(self, dag): """Run the pass on one :class:`.DAGCircuit`, mutating it. Returns ``True`` if the circuit was modified and ``False`` if not.""" modified = False for node in dag.op_nodes(): if isinstance(node.op, ControlFlowOp): modified_blocks = False new_dags = [] for block in node.op.blocks: new_dag = circuit_to_dag(block) modified_blocks |= self._run_inner(new_dag) new_dags.append(new_dag) if not modified_blocks: continue dag.substitute_node( node, node.op.replace_blocks(dag_to_circuit(block) for block in new_dags), inplace=True, ) elif getattr(node.op, "condition", None) is None: continue else: target, value = node.op.condition clbits = list(node.cargs) condition_clbits = [target] if isinstance(target, Clbit) else list(target) clbits_set = set(clbits) clbits += [bit for bit in condition_clbits if bit not in clbits_set] block_body = QuantumCircuit(list(node.qargs) + clbits) if isinstance(target, ClassicalRegister): block_body.add_register(target) new_op = node.op.copy() new_op.condition = None block_body._append(CircuitInstruction(new_op, node.qargs, node.cargs)) # Despite only being a node-for-node replacement, control-flow ops contain the # condition bits in their cargs, which requires slightly different handling in the # DAGCircuit methods right now. replacement = DAGCircuit() replacement.add_qubits(block_body.qubits) replacement.add_clbits(block_body.clbits) if isinstance(target, ClassicalRegister): replacement.add_creg(target) replacement.apply_operation_back( IfElseOp((target, value), block_body), block_body.qubits, block_body.clbits ) wire_map = {bit: bit for bit in block_body.qubits + block_body.clbits} dag.substitute_node_with_dag(node, replacement, wire_map, propagate_condition=False) modified = True return modified
[Doku] def run(self, dag): self._run_inner(dag) return dag