# -*- coding: utf-8 -*-

# Copyright 2017 ProjectQ-Framework (www.projectq.ch)

#

# Licensed under the Apache License, Version 2.0 (the "License");

# you may not use this file except in compliance with the License.

# You may obtain a copy of the License at

#

# http://www.apache.org/licenses/LICENSE-2.0

#

# Unless required by applicable law or agreed to in writing, software

# distributed under the License is distributed on an "AS IS" BASIS,

# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

# See the License for the specific language governing permissions and

# limitations under the License.

"""

Tests for projectq.backends._printer.py.

"""

import pytest

from projectq import MainEngine

from projectq.backends import _printer

from projectq.cengines import DummyEngine, InstructionFilter, NotYetMeasuredError

from projectq.meta import LogicalQubitIDTag

from projectq.ops import NOT, Allocate, Command, H, Measure, T

from projectq.types import WeakQubitRef

def test_command_printer_is_available():

inline_cmd_printer = _printer.CommandPrinter()

cmd_printer = _printer.CommandPrinter()

def available_cmd(self, cmd):

return cmd.gate == H

filter = InstructionFilter(available_cmd)

eng = MainEngine(backend=cmd_printer, engine_list=[inline_cmd_printer, filter])

qubit = eng.allocate_qubit()

cmd0 = Command(eng, H, (qubit,))

cmd1 = Command(eng, T, (qubit,))

assert inline_cmd_printer.is_available(cmd0)

assert not inline_cmd_printer.is_available(cmd1)

assert cmd_printer.is_available(cmd0)

assert cmd_printer.is_available(cmd1)

def test_command_printer_accept_input(monkeypatch):

cmd_printer = _printer.CommandPrinter()

eng = MainEngine(backend=cmd_printer, engine_list=[DummyEngine()])

monkeypatch.setattr(_printer, "input", lambda x: 1)

qubit = eng.allocate_qubit()

Measure | qubit

assert int(qubit) == 1

monkeypatch.setattr(_printer, "input", lambda x: 0)

qubit = eng.allocate_qubit()

NOT | qubit

Measure | qubit

assert int(qubit) == 0

def test_command_printer_measure_no_control():

qb1 = WeakQubitRef(engine=None, idx=1)

qb2 = WeakQubitRef(engine=None, idx=2)

printer = _printer.CommandPrinter()

printer.is_last_engine = True

with pytest.raises(ValueError):

printer._print_cmd(Command(engine=None, gate=Measure, qubits=([qb1],), controls=[qb2]))

def test_command_printer_no_input_default_measure():

cmd_printer = _printer.CommandPrinter(accept_input=False)

eng = MainEngine(backend=cmd_printer, engine_list=[DummyEngine()])

qubit = eng.allocate_qubit()

NOT | qubit

Measure | qubit

assert int(qubit) == 0

def test_command_printer_measure_mapped_qubit():

eng = MainEngine(_printer.CommandPrinter(accept_input=False), [])

qb1 = WeakQubitRef(engine=eng, idx=1)

qb2 = WeakQubitRef(engine=eng, idx=2)

cmd0 = Command(engine=eng, gate=Allocate, qubits=([qb1],))

cmd1 = Command(

engine=eng,

gate=Measure,

qubits=([qb1],),

controls=[],

tags=[LogicalQubitIDTag(2)],

)

with pytest.raises(NotYetMeasuredError):

int(qb1)

with pytest.raises(NotYetMeasuredError):

int(qb2)

eng.send([cmd0, cmd1])

eng.flush()

with pytest.raises(NotYetMeasuredError):

int(qb1)

assert int(qb2) == 0