# 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.
"Circuit operation representing a ``continue`` from a loop."
from typing import Optional
from qiskit.circuit.instruction import Instruction
from .builder import InstructionPlaceholder, InstructionResources
[documentos]class ContinueLoopOp(Instruction):
"""A circuit operation which, when encountered, moves to the next iteration of
the nearest enclosing loop.
.. note::
Can be inserted only within the body of a loop op, and must span the full
width of that block.
**Circuit symbol:**
.. parsed-literal::
┌─────────────────┐
q_0: ┤0 ├
│ │
q_1: ┤1 ├
│ continue_loop │
q_2: ┤2 ├
│ │
c_0: ╡0 ╞
└─────────────────┘
"""
def __init__(self, num_qubits: int, num_clbits: int, label: Optional[str] = None):
super().__init__("continue_loop", num_qubits, num_clbits, [], label=label)
class ContinueLoopPlaceholder(InstructionPlaceholder):
"""A placeholder instruction for use in control-flow context managers, when the number of qubits
and clbits is not yet known.
.. warning::
This is an internal interface and no part of it should be relied upon outside of Qiskit
Terra.
"""
def __init__(self, *, label: Optional[str] = None):
super().__init__("continue_loop", 0, 0, [], label=label)
def concrete_instruction(self, qubits, clbits):
return (
self._copy_mutable_properties(
ContinueLoopOp(len(qubits), len(clbits), label=self.label)
),
InstructionResources(qubits=tuple(qubits), clbits=tuple(clbits)),
)
def placeholder_resources(self):
return InstructionResources()