def parse(options):
    """Parse options from string.

    Args:
        options (str): String with options.
                       It should have the form 'arg1=value1,arg2=value2,...'.

    Returns:
        dict: {'arg1': value1, 'arg2': value2, ...}

    """
    kwargs = {}
    if options is not None:
        for parameter in options.split(","):
            if "=" in parameter:
                k, v = parameter.split("=")
                kwargs[k] = v
            else:
                raise ValueError(f"Cannot parse parameter {parameter}.")
    return kwargs


def get(backend_name, options=None):
    options = parse(options)
    if backend_name == "qibo":
        from benchmarks.libraries.qibo import Qibo
        return Qibo(**options)

    elif backend_name == "qiskit":
        from benchmarks.libraries.qiskit import Qiskit
        return Qiskit(**options)
    elif backend_name == "qiskit-gpu":
        from benchmarks.libraries.qiskit import QiskitGpu
        return QiskitGpu(**options)

    elif backend_name == "cirq":
        from benchmarks.libraries.cirq import Cirq
        return Cirq()
    elif backend_name == "qsim":
        from benchmarks.libraries.cirq import QSim
        return QSim(**options)
    elif backend_name == "qsim-gpu":
        from benchmarks.libraries.cirq import QSimGpu
        return QSimGpu(**options)
    elif backend_name == "qsim-cuquantum":
        from benchmarks.libraries.cirq import QSimCuQuantum
        return QSimCuQuantum(**options)
    elif backend_name == "tfq":
        from benchmarks.libraries.cirq import TensorflowQuantum
        return TensorflowQuantum()

    elif backend_name == "qulacs":
        from benchmarks.libraries.qulacs import Qulacs
        return Qulacs()
    elif backend_name == "qulacs-gpu":
        from benchmarks.libraries.qulacs import QulacsGpu
        return QulacsGpu()

    elif backend_name == "qcgpu":
        from benchmarks.libraries.qcgpu import QCGPU
        return QCGPU()

    elif backend_name == "projectq":
        from benchmarks.libraries.projectq import ProjectQ
        return ProjectQ(**options)

    elif backend_name == "hybridq":
        from benchmarks.libraries.hybridq import HybridQ
        return HybridQ(**options)
    elif backend_name == "hybridq-gpu":
        from benchmarks.libraries.hybridq import HybridQGPU
        return HybridQGPU(**options)

    raise KeyError(f"Unknown simulation library {backend_name}.")