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Source code for qiskit.circuit.classicalfunction.classicalfunction

# This code is part of Qiskit.
#
# (C) Copyright IBM 2020.
#
# This code is licensed under the Apache License, Version 2.0. You may
# obtain a copy of this license in the LICENSE.txt file in the root directory
# of this source tree or at http://www.apache.org/licenses/LICENSE-2.0.
#
# Any modifications or derivative works of this code must retain this
# copyright notice, and modified files need to carry a notice indicating
# that they have been altered from the originals.

"""ClassicalFunction class"""

import ast
from typing import Callable, Optional

from tweedledum.classical import simulate  # pylint: disable=import-error
from tweedledum.synthesis import pkrm_synth  # pylint: disable=import-error

from qiskit.circuit import QuantumCircuit, QuantumRegister
from qiskit.exceptions import QiskitError
from .classical_element import ClassicalElement
from .classical_function_visitor import ClassicalFunctionVisitor
from .utils import tweedledum2qiskit


[docs]class ClassicalFunction(ClassicalElement): """Represent a classical function function and its logic network.""" def __init__(self, source, name=None): """Creates a ``ClassicalFunction`` from Python source code in ``source``. The code should be a single function with types. Args: source (str): Python code with type hints. name (str): Optional. Default: "*classicalfunction*". ClassicalFunction name. Raises: QiskitError: If source is not a string. """ if not isinstance(source, str): raise QiskitError("ClassicalFunction needs a source code as a string.") self._ast = ast.parse(source) self._network = None self._scopes = None self._args = None self._truth_table = None super().__init__( name or "*classicalfunction*", num_qubits=sum(qreg.size for qreg in self.qregs), params=[], )
[docs] def compile(self): """Parses and creates the logical circuit""" _classical_function_visitor = ClassicalFunctionVisitor() _classical_function_visitor.visit(self._ast) self._network = _classical_function_visitor._network self._scopes = _classical_function_visitor.scopes self._args = _classical_function_visitor.args self.name = _classical_function_visitor.name
@property def network(self): """Returns the logical network""" if self._network is None: self.compile() return self._network @property def scopes(self): """Returns the scope dict""" if self._scopes is None: self.compile() return self._scopes @property def args(self): """Returns the classicalfunction arguments""" if self._args is None: self.compile() return self._args @property def types(self): """Dumps a list of scopes with their variables and types. Returns: list(dict): A list of scopes as dicts, where key is the variable name and value is its type. """ ret = [] for scope in self.scopes: ret.append({k: v[0] for k, v in scope.items()}) return ret
[docs] def simulate(self, bitstring: str) -> bool: """Evaluate the expression on a bitstring. This evaluation is done classically. Args: bitstring: The bitstring for which to evaluate. Returns: bool: result of the evaluation. """ return simulate(self._network, bitstring)
[docs] def simulate_all(self): """ Returns a truth table. Returns: str: a bitstring with a truth table """ result = [] for position in range(2 ** self._network.num_pis()): sim_result = "".join([str(int(tt[position])) for tt in self.truth_table]) result.append(sim_result) return "".join(reversed(result))
@property def truth_table(self): """Returns (and computes) the truth table""" if self._truth_table is None: self._truth_table = simulate(self._network) return self._truth_table
[docs] def synth( self, registerless: bool = True, synthesizer: Optional[Callable[[ClassicalElement], QuantumCircuit]] = None, ) -> QuantumCircuit: """Synthesis the logic network into a :class:`~qiskit.circuit.QuantumCircuit`. Args: registerless: Default ``True``. If ``False`` uses the parameter names to create registers with those names. Otherwise, creates a circuit with a flat quantum register. synthesizer: Optional. If None tweedledum's pkrm_synth is used. Returns: QuantumCircuit: A circuit implementing the logic network. """ if registerless: qregs = None else: qregs = self.qregs if synthesizer: return synthesizer(self) return tweedledum2qiskit(pkrm_synth(self.truth_table[0]), name=self.name, qregs=qregs)
def _define(self): """The definition of the classical function is its synthesis""" self.definition = self.synth() @property def qregs(self): """The list of qregs used by the classicalfunction""" qregs = [QuantumRegister(1, name=arg) for arg in self.args if self.types[0][arg] == "Int1"] qregs.reverse() if self.types[0]["return"] == "Int1": qregs.append(QuantumRegister(1, name="return")) return qregs