Move apply_gate to its own file

Author: Takishima

projectq/libs/qasm/_parse_qasm_qiskit.py

@@ -18,34 +18,11 @@
 from qiskit.circuit import QuantumCircuit, ClassicalRegister, Clbit
 
 from ._qiskit_conv import gates_conv_table
+from ._utils import apply_gate, OpaqueGate
 
 # ==============================================================================
 
 
-def apply_gate(gate, qubits):
-    """
-    Apply a gate to some qubits while separating control and target qubits.
-
-
-    Args:
-        gate (BasicGate): Instance of a ProjectQ gate
-        qubits (list): List of ProjectQ qubits the gate applies to.
-    """
-    if isinstance(gate, ControlledGate):
-        ctrls = qubits[:gate._n]
-        qubits = qubits[gate._n:]
-        if isinstance(gate._gate, SwapGate):
-            assert len(qubits) == 2
-            gate | (ctrls, qubits[0], qubits[1])
-        else:
-            gate | (ctrls, qubits)
-    elif isinstance(gate, SwapGate):
-        assert len(qubits) == 2
-        gate | (qubits[0], qubits[1])
-    else:
-        gate | qubits
-
-
 def apply_op(eng, gate, qubits, bits, bits_map):
     """
     Apply a qiskit operation.
@@ -73,6 +50,7 @@ def apply_op(eng, gate, qubits, bits, bits_map):
     else:
         if gate.name not in gates_conv_table:
             if not gate._definition:
+                # TODO: This will silently discard opaque gates...
                 return
 
             gate_args = {gate._definition.qregs[0].name: qubits}

projectq/libs/qasm/_utils.py

@@ -0,0 +1,74 @@
+#   Copyright 2020 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.
+"""Some helper utilities."""
+
+from projectq.ops import ControlledGate, SwapGate, BasicGate
+
+# ==============================================================================
+
+
+class OpaqueGate(BasicGate):
+    def __init__(self, name, params):
+        """
+        Constructor
+
+        Args:
+            name (str): Name/type of gat
+            params (list,tuple): Parameter for the gate (may be empty)
+        """
+
+        super().__init__()
+        self.name = name
+        self.params = params
+
+    def __str__(self):
+        """
+        String conversion.
+        """
+        # TODO: This is a bit crude...
+        if self.params:
+            return 'Opaque({})({})'.format(self.name, ','.join(self.params))
+        return 'Opaque({})'.format(self.name)
+
+
+# ==============================================================================
+
+
+def apply_gate(gate, qubits):
+    """
+    Apply a gate to some qubits while separating control and target qubits.
+
+
+    Args:
+        gate (BasicGate): Instance of a ProjectQ gate
+        qubits (list): List of ProjectQ qubits the gate applies to.
+    """
+    # pylint: disable = protected-access,pointless-statement
+
+    if isinstance(gate, ControlledGate):
+        ctrls = qubits[:gate._n]
+        qubits = qubits[gate._n:]
+        if isinstance(gate._gate, SwapGate):
+            assert len(qubits) == 2
+            gate | (ctrls, qubits[0], qubits[1])
+        else:
+            gate | (ctrls, qubits)
+    elif isinstance(gate, SwapGate):
+        assert len(qubits) == 2
+        gate | (qubits[0], qubits[1])
+    else:
+        gate | qubits
+
+
+# ==============================================================================

projectq/libs/qasm/_utils_test.py

@@ -0,0 +1,68 @@
+#   Copyright 2020 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.libs.qasm._utils.py."""
+
+import pytest
+
+from projectq.types import WeakQubitRef
+from projectq.cengines import DummyEngine
+from projectq.ops import (X, Y, Z, T, Tdagger, S, Sdagger, H, Ph, R, Rx, Ry, Rz,
+                          U2, U3, Swap, Toffoli, Barrier, C)
+from ._utils import apply_gate, OpaqueGate
+
+# ==============================================================================
+
+
+def test_opaque_gate():
+    gate = OpaqueGate('my_gate', None)
+    assert gate.name == 'my_gate'
+    assert not gate.params
+    assert str(gate) == 'Opaque(my_gate)'
+
+    gate = OpaqueGate('my_gate', ('lambda', 'alpha'))
+    assert gate.name == 'my_gate'
+    assert gate.params == ('lambda', 'alpha')
+
+    assert str(gate) == 'Opaque(my_gate)(lambda,alpha)'
+
+
+# ==============================================================================
+
+
+@pytest.mark.parametrize(
+    'gate, n_qubits', (list(
+        map(lambda x:
+            (x, 1), [
+                X, Y, Z, S, Sdagger, T, Tdagger, H, Barrier,
+                Ph(1.12),
+                Rx(1.12),
+                Ry(1.12),
+                Rz(1.12),
+                R(1.12),
+                U2(1.12, 1.12),
+                U3(1.12, 1.12, 1.12),
+            ])) + list(map(lambda x:
+                           (x, 2), [C(X), C(Y), C(Z), Swap, Barrier])) +
+                       list(map(lambda x:
+                                (x, 3), [Toffoli, C(Swap), Barrier])) +
+                       list(map(lambda x: (x, 10), [Barrier]))),
+    ids=str)
+def test_apply_gate(gate, n_qubits):
+    backend = DummyEngine()
+    backend.is_last_engine = True
+
+    gate.engine = backend
+    qubits = [WeakQubitRef(backend, idx) for idx in range(n_qubits)]
+
+    apply_gate(gate, qubits)