def test_main_engine_init_defaults():
eng = _main.MainEngine()
eng_list = []
current_engine = eng.next_engine
while not current_engine.is_last_engine:
eng_list.append(current_engine)
current_engine = current_engine.next_engine
assert isinstance(eng_list[-1].next_engine, Simulator)
from projectq.setups.default import default_engines
for engine, expected in zip(eng_list, default_engines()):
assert type(engine) == type(expected)
def __init__(self, backend=None, engine_list=None): """ Initialize the main compiler engine and all compiler engines. Sets 'next_engine'- and 'main_engine'-attributes of all compiler engines and adds the back-end as the last engine. Args: backend (BasicEngine): Backend to send the circuit to. engine_list (list<BasicEngine>): List of engines / backends to use as compiler engines. Example: .. code-block:: python from projectq import MainEngine eng = MainEngine() # will load default setup using Simulator backend Alternatively, one can specify all compiler engines explicitly, e.g., Example: .. code-block:: python from projectq.cengines import TagRemover,AutoReplacer,LocalOptimizer from projectq.backends import Simulator from projectq import MainEngine engines = [AutoReplacer(), TagRemover(), LocalOptimizer(3)] eng = MainEngine(Simulator(), engines) """ BasicEngine.__init__(self) if backend is None: backend = Simulator() else: # Test that backend is BasicEngine object if not isinstance(backend, BasicEngine): raise UnsupportedEngineError( "\nYou supplied a backend which is not supported,\n" + "i.e. not an instance of BasicEngine.\n"+ "Did you forget the brackets to create an instance?\n" + "E.g. MainEngine(backend=Simulator) instead of \n" + " MainEngine(backend=Simulator())") if engine_list is None: try: engine_list = projectq.default_engines() except AttributeError: from projectq.setups.default import default_engines engine_list = default_engines() else: # Test that engine list elements are all BasicEngine objects if not isinstance(engine_list, list): raise UnsupportedEngineError( "\n The engine_list argument is not a list!\n") for current_eng in engine_list: if not isinstance(current_eng, BasicEngine): raise UnsupportedEngineError( "\nYou supplied an unsupported engine in engine_list,\n" + "i.e. not an instance of BasicEngine.\n"+ "Did you forget the brackets to create an instance?\n" + "E.g. MainEngine(engine_list=[AutoReplacer]) instead of \n" + " MainEngine(engine_list=[AutoReplacer()])") engine_list.append(backend) # Test that user did not supply twice the same engine instance num_different_engines = len(set([id(item) for item in engine_list])) if len(engine_list) != num_different_engines: raise UnsupportedEngineError( "\n Error:\n You supplied twice the same engine as backend" + " or item in engine_list. This doesn't work. Create two \n" + " separate instances of a compiler engine if it is needed\n" + " twice.\n") self._qubit_idx = int(0) for i in range(len(engine_list) - 1): engine_list[i].next_engine = engine_list[i + 1] engine_list[i].main_engine = self engine_list[-1].main_engine = self engine_list[-1].is_last_engine = True self.next_engine = engine_list[0] self.main_engine = self self.active_qubits = weakref.WeakSet() self._measurements = dict() self.dirty_qubits = set() # In order to terminate an example code without eng.flush or Measure self._delfun = lambda x: x.flush(deallocate_qubits=True) atexit.register(self._delfun, self)