source: utilitiespy/tudelft/utilities/immutablelist/AbstractPermutations.py

from typing import TypeVar
from tudelft.utilities.immutablelist.Permutations import Permutations
from tudelft.utilities.immutablelist.ImmutableList import ImmutableList
from tudelft.utilities.immutablelist.AbstractImmutableList import AbstractImmutableList
from _ctypes import ArgumentError


E = TypeVar('E')
class AbstractPermutations(AbstractImmutableList[ImmutableList[E]], Permutations[E]) :
        '''
        Abstract base class for Permutations. A Permutation is an ordered sublist of
        a list, possibly with repeated elements.
        
        @param <E> type of the elements
        
        '''

        def __init__(self, lst: ImmutableList[E] ,  n:int):
                '''
                all permutations of a given list, drawing n items from the list
                
                @param lst list to be permuted
                @param n    the number of items to draw from the list. Must be between 0
                            and size of list.
                '''
                if n < 0:
                        raise ArgumentError("n<0")
                if lst.size().bit_length() > 31:
                        raise ArgumentError(\
                                "excessive list size detected for starting a permutation"\
                                                        + str(lst.size()))
                # protected, not private vars
                self._drawlist:ImmutableList[E] = lst
                self._drawlistsize:int = lst.size()
                self._drawsize:int = n