"""This module implements the SwapToCNOTPass."""
from __future__ import annotations
from bqskit.compiler.basepass import BasePass
from bqskit.compiler.passdata import PassData
from bqskit.ir.circuit import Circuit
from bqskit.ir.gates.circuitgate import CircuitGate
from bqskit.ir.gates.constant.cx import CNOTGate
from bqskit.ir.gates.constant.swap import SwapGate
from bqskit.ir.operation import Operation
[docs]
class SwapToCNOTPass(BasePass):
"""
The SwapToCNOTPass class.
This uses a rule to convert Swaps to CNOTs.
"""
[docs]
def __init__(self) -> None:
"""Construct a SwapToCNOTPass."""
circuit = Circuit(2)
circuit.append_gate(CNOTGate(), (1, 0))
circuit.append_gate(CNOTGate(), (0, 1))
circuit.append_gate(CNOTGate(), (1, 0))
self.cg = CircuitGate(circuit)
[docs]
async def run(self, circuit: Circuit, data: PassData) -> None:
"""Perform the pass's operation, see :class:`BasePass` for more."""
# Find all cnots
cnot_points = []
for cycle, op in circuit.operations_with_cycles():
if isinstance(op.gate, SwapGate):
cnot_points.append((cycle, op.location[0]))
# Create new operations
ops = [
Operation(
self.cg,
circuit[p].location,
self.cg._circuit.params,
)
for p in cnot_points
]
# Replace cnots with new ops
circuit.batch_replace(cnot_points, ops)
circuit.unfold_all() # TODO: Replace with batch_unfold