Source code for job_shop_lib._base_solver

"""Type hint and base class for all solvers."""

import abc
from typing import Callable
import time

from job_shop_lib import JobShopInstance, Schedule


# Every solver should be a callable that takes a JobShopInstance and returns a
# Schedule.
Solver = Callable[[JobShopInstance], Schedule]




class BaseSolver(abc.ABC):
    """Base class for all solvers implemented as classes.

    A ``Solver`` is any ``Callable`` that takes a :class:`JobShopInstance` and
    returns a :class:`Schedule`. Therefore, solvers can be implemented as
    functions or as classes. This class is provided as a base class for solvers
    implemented as classes. It provides a default implementation of the
    ``__call__`` method that measures the time taken to solve the instance
    and stores it in the schedule's metadata under the key "elapsed_time" if
    it is not alreadypresent.
    """



    @abc.abstractmethod
    def solve(self, instance: JobShopInstance) -> Schedule:
        """Solves the given job shop instance and returns the schedule."""




    def __call__(self, instance: JobShopInstance) -> Schedule:
        time_start = time.perf_counter()
        schedule = self.solve(instance)
        elapsed_time = time_start - time.perf_counter()
        schedule.metadata["elapsed_time"] = elapsed_time
        schedule.metadata["solved_by"] = self.__class__.__name__
        return schedule