separate StateFn to Factory and BaseClass

qiskit/aqua/operators/converters/pauli_basis_change.py

@@ -27,6 +27,7 @@
 from ..list_ops.list_op import ListOp
 from ..list_ops.composed_op import ComposedOp
 from ..state_fns.state_fn import StateFn
+from ..state_fns.state_fn_base import StateFnBase
 from ..operator_globals import H, S, I
 from .converter_base import ConverterBase
 
@@ -134,7 +135,7 @@ def convert(self, operator: OperatorBase) -> OperatorBase:
         if isinstance(operator, (Pauli, PrimitiveOp)):
             cob_instr_op, dest_pauli_op = self.get_cob_circuit(operator)
             return self._replacement_fn(cob_instr_op, dest_pauli_op)  # type: ignore
-        if isinstance(operator, StateFn) and 'Pauli' in operator.primitive_strings():
+        if isinstance(operator, StateFnBase) and 'Pauli' in operator.primitive_strings():
             # If the StateFn/Meas only contains a Pauli, use it directly.
             if isinstance(operator.primitive, PrimitiveOp):
                 cob_instr_op, dest_pauli_op = self.get_cob_circuit(operator.primitive)

qiskit/aqua/operators/gradients/circuit_gradients/lin_comb.py

@@ -24,6 +24,7 @@
 from qiskit.aqua.operators.operator_globals import Z, I, One, Zero
 from qiskit.aqua.operators.primitive_ops.primitive_op import PrimitiveOp
 from qiskit.aqua.operators.state_fns import StateFn, CircuitStateFn, DictStateFn, VectorStateFn
+from qiskit.aqua.operators.state_fns.state_fn_base import StateFnBase
 from qiskit.circuit import Gate, Instruction, Qubit
 from qiskit.circuit import (QuantumCircuit, QuantumRegister, ParameterVector,
                             ParameterExpression)
@@ -115,14 +116,14 @@ def _prepare_operator(self,
 
         if isinstance(operator, ComposedOp):
             # Get the measurement and the state operator
-            if not isinstance(operator[0], StateFn) or not operator[0].is_measurement:
+            if not isinstance(operator[0], StateFnBase) or not operator[0].is_measurement:
                 raise ValueError("The given operator does not correspond to an expectation value")
-            if not isinstance(operator[-1], StateFn) or operator[-1].is_measurement:
+            if not isinstance(operator[-1], StateFnBase) or operator[-1].is_measurement:
                 raise ValueError("The given operator does not correspond to an expectation value")
             if operator[0].is_measurement:
                 if len(operator.oplist) == 2:
                     state_op = operator[1]
-                    if not isinstance(state_op, StateFn):
+                    if not isinstance(state_op, StateFnBase):
                         raise TypeError('The StateFn representing the quantum state could not be'
                                         'extracted.')
                     if isinstance(params, (ParameterExpression, ParameterVector)) or \
@@ -144,7 +145,7 @@ def _prepare_operator(self,
                 else:
                     state_op = deepcopy(operator)
                     state_op.oplist.pop(0)
-                    if not isinstance(state_op, StateFn):
+                    if not isinstance(state_op, StateFnBase):
                         raise TypeError('The StateFn representing the quantum state could not be'
                                         'extracted.')
 
@@ -169,7 +170,7 @@ def _prepare_operator(self,
                 return operator.traverse(partial(self._prepare_operator, params=params))
         elif isinstance(operator, ListOp):
             return operator.traverse(partial(self._prepare_operator, params=params))
-        elif isinstance(operator, StateFn):
+        elif isinstance(operator, StateFnBase):
             if operator.is_measurement:
                 return operator.traverse(partial(self._prepare_operator, params=params))
             else:
@@ -190,7 +191,7 @@ def _prepare_operator(self,
         return operator
 
     def _gradient_states(self,
-                         state_op: StateFn,
+                         state_op: StateFnBase,
                          meas_op: Optional[OperatorBase] = None,
                          target_params: Optional[
                              Union[ParameterExpression, ParameterVector,
@@ -334,7 +335,7 @@ def _gradient_states(self,
             return op
 
     def _hessian_states(self,
-                        state_op: StateFn,
+                        state_op: StateFnBase,
                         meas_op: Optional[OperatorBase] = None,
                         target_params: Optional[Union[Tuple[ParameterExpression,
                                                             ParameterExpression],

qiskit/aqua/operators/gradients/circuit_gradients/param_shift.py

@@ -23,6 +23,7 @@
 from qiskit.aqua.operators import (OperatorBase, StateFn, Zero, One, CircuitStateFn,
                                    CircuitOp)
 from qiskit.aqua.operators import SummedOp, ListOp, ComposedOp, DictStateFn, VectorStateFn
+from qiskit.aqua.operators.state_fns.state_fn_base import StateFnBase
 from qiskit.aqua.operators.gradients.circuit_gradients.circuit_gradient \
     import CircuitGradient
 from qiskit.aqua.operators.gradients.derivative_base import DerivativeBase
@@ -210,7 +211,7 @@ def _parameter_shift(self,
                 if isinstance(operator, ComposedOp):
                     shifted_op = shift_constant * (pshift_op - mshift_op)
 
-                elif isinstance(operator, StateFn):
+                elif isinstance(operator, StateFnBase):
                     shifted_op = ListOp(
                         [pshift_op, mshift_op],
                         combo_fn=partial(self._prob_combo_fn, shift_constant=shift_constant))

qiskit/aqua/operators/gradients/hessian.py

@@ -17,6 +17,7 @@
 import numpy as np
 from qiskit.aqua.aqua_globals import AquaError
 from qiskit.aqua.operators import Zero, One, CircuitStateFn, StateFn
+from qiskit.aqua.operators.state_fns.state_fn_base import StateFnBase
 from qiskit.aqua.operators.expectations import PauliExpectation
 from qiskit.aqua.operators.gradients.gradient import Gradient
 from qiskit.aqua.operators.gradients.hessian_base import HessianBase
@@ -239,7 +240,7 @@ def is_coeff_c(coeff, c):
 
             return SummedOp([term1, term2])
 
-        elif isinstance(operator, StateFn):
+        elif isinstance(operator, StateFnBase):
             if not operator.is_measurement:
                 from .circuit_gradients import LinComb
                 if isinstance(self.hess_method, LinComb):

qiskit/aqua/operators/state_fns/circuit_state_fn.py

@@ -24,9 +24,10 @@
 from ..operator_base import OperatorBase
 from ..list_ops.summed_op import SummedOp
 from .state_fn import StateFn
+from .state_fn_base import StateFnBase
 
 
-class CircuitStateFn(StateFn):
+class CircuitStateFn(StateFnBase):
     r"""
     A class for state functions and measurements which are defined by the action of a
     QuantumCircuit starting from \|0⟩, and stored using Terra's ``QuantumCircuit`` class.

qiskit/aqua/operators/state_fns/dict_state_fn.py

@@ -23,11 +23,12 @@
 
 from ..operator_base import OperatorBase
 from .state_fn import StateFn
+from .state_fn_base import StateFnBase
 from ..list_ops.list_op import ListOp
 from .vector_state_fn import VectorStateFn
 
 
-class DictStateFn(StateFn):
+class DictStateFn(StateFnBase):
     """ A class for state functions and measurements which are defined by a lookup table,
     stored in a dict.
     """

qiskit/aqua/operators/state_fns/operator_state_fn.py

@@ -19,14 +19,15 @@
 
 from ..operator_base import OperatorBase
 from .state_fn import StateFn
+from .state_fn_base import StateFnBase
 from .vector_state_fn import VectorStateFn
 from ..list_ops.list_op import ListOp
 from ..list_ops.summed_op import SummedOp
 
 
 # pylint: disable=invalid-name
 
-class OperatorStateFn(StateFn):
+class OperatorStateFn(StateFnBase):
     r"""
     A class for state functions and measurements which are defined by a density Operator,
     stored using an ``OperatorBase``.