Move wrapper load_qasm_* methods to a submodule (#533)

CHANGELOG.rst

@@ -32,6 +32,7 @@ Changed
   (#531).
 - Renamed the specification schemas (#464).
 - Convert ``LocalJob`` tests into unit-tests. (#526)
+- Move wrapper ``load_qasm_*`` methods to a submodule (#533).
 
 Removed
 -------

qiskit/wrapper/_circuittoolkit.py

@@ -0,0 +1,73 @@
+# -*- coding: utf-8 -*-
+
+# Copyright 2018, IBM.
+#
+# This source code is licensed under the Apache License, Version 2.0 found in
+# the LICENSE.txt file in the root directory of this source tree.
+
+"""
+Utilities regarding the creation of QuantumCircuits from a variety of different
+file formats.
+"""
+
+import os
+from qiskit import QISKitError
+from qiskit.qasm import Qasm
+from qiskit.unroll import Unroller, CircuitBackend
+
+
+def circuit_from_qasm_string(qasm_string, name=None,
+                             basis_gates="id,u0,u1,u2,u3,x,y,z,h,s,sdg,t,tdg,"
+                             "rx,ry,rz,cx,cy,cz,ch,crz,cu1,cu3,swap,ccx,"
+                             "cswap"):
+
+    """Construct a quantum circuit from a qasm representation (string).
+
+    Args:
+        qasm_string (str): a string of qasm, or a filename containing qasm.
+        basis_gates (str): basis gates for the quantum circuit.
+        name (str or None): the name of the quantum circuit after loading
+            qasm text into it. If no name given, assign automatically.
+    Returns:
+        QuantumCircuit: circuit constructed from qasm.
+    Raises:
+        QISKitError: if the string is not valid QASM
+    """
+
+    node_circuit = Qasm(data=qasm_string).parse()
+    unrolled_circuit = Unroller(
+        node_circuit, CircuitBackend(basis_gates.split(",")))
+    circuit_unrolled = unrolled_circuit.execute()
+    if name:
+        circuit_unrolled.name = name
+    return circuit_unrolled
+
+
+def circuit_from_qasm_file(qasm_file, name=None,
+                           basis_gates="id,u0,u1,u2,u3,x,y,z,h,s,sdg,t,tdg,rx,"
+                           "ry,rz,cx,cy,cz,ch,crz,cu1,cu3,swap,ccx,"
+                           "cswap"):
+
+    """Construct a quantum circuit from a qasm representation (file).
+
+    Args:
+        qasm_file (str): a string for the filename including its location.
+        name (str or None): the name of the quantum circuit after
+            loading qasm text into it. If no name is give the name is of
+            the text file.
+        basis_gates (str): basis gates for the quantum circuit.
+    Returns:
+        QuantumCircuit: circuit constructed from qasm.
+    Raises:
+        QISKitError: if the file cannot be read.
+    """
+    if not os.path.exists(qasm_file):
+        raise QISKitError('qasm file "{0}" not found'.format(qasm_file))
+    if not name:
+        name = os.path.splitext(os.path.basename(qasm_file))[0]
+
+    with open(qasm_file) as file:
+        qasm_data = file.read()
+
+    return circuit_from_qasm_string(
+        qasm_data, name=name, basis_gates=basis_gates)

qiskit/wrapper/_wrapper.py

@@ -7,15 +7,13 @@
 
 """Helper module for simplified QISKit usage."""
 
-import os
 import warnings
 import qiskit._compiler
 from qiskit import QISKitError
 from qiskit.backends.ibmq.ibmqprovider import IBMQProvider
 from qiskit.wrapper.defaultqiskitprovider import DefaultQISKitProvider
 from qiskit import QuantumJob
-from qiskit.qasm import Qasm
-from qiskit.unroll import Unroller, CircuitBackend
+from ._circuittoolkit import circuit_from_qasm_file, circuit_from_qasm_string
 
 
 # Default provider used by the rest of the functions on this module. Please
@@ -232,12 +230,7 @@ def load_qasm_string(qasm_string, name=None,
     Raises:
         QISKitError: if the string is not valid QASM
     """
-    node_circuit = Qasm(data=qasm_string).parse()
-    unrolled_circuit = Unroller(node_circuit, CircuitBackend(basis_gates.split(",")))
-    circuit_unrolled = unrolled_circuit.execute()
-    if name:
-        circuit_unrolled.name = name
-    return circuit_unrolled
+    return circuit_from_qasm_string(qasm_string, name, basis_gates)
 
 
 def load_qasm_file(qasm_file, name=None,
@@ -256,12 +249,4 @@ def load_qasm_file(qasm_file, name=None,
     Raises:
         QISKitError: if the file cannot be read.
     """
-    if not os.path.exists(qasm_file):
-        raise QISKitError('qasm file "{0}" not found'.format(qasm_file))
-    if not name:
-        name = os.path.splitext(os.path.basename(qasm_file))[0]
-
-    with open(qasm_file) as file:
-        qasm_data = file.read()
-
-    return load_qasm_string(qasm_data, name=name, basis_gates=basis_gates)
+    return circuit_from_qasm_file(qasm_file, name, basis_gates)