mirror of
https://github.com/rjNemo/design-patterns
synced 2026-06-06 10:36:39 +00:00
64 lines
2 KiB
Python
64 lines
2 KiB
Python
from __future__ import annotations
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from typing import Iterator, Iterable, List, Any
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class WordCollection(Iterable):
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"""
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Concrete Collections provide one or several methods for retrieving fresh
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iterator instances, compatible with the collection class.
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"""
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def __init__(self, collection: List[Any] = []) -> None:
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self._collection = collection
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def __iter__(self) -> AlphabeticalOrderIterator:
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"""
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The __iter__() method returns the iterator object itself, by default we
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return the iterator in ascending order.
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"""
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return AlphabeticalOrderIterator(self._collection)
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def get_reverse_iterator(self) -> AlphabeticalOrderIterator:
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return AlphabeticalOrderIterator(self._collection, reverse=True)
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def add_item(self, item: Any) -> None:
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self._collection.append(item)
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class AlphabeticalOrderIterator(Iterator):
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"""
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Concrete Iterators implement various traversal algorithms. These classes
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store the current traversal position at all times.
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"""
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"""
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`_position` attribute stores the current traversal position. An iterator may
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have a lot of other fields for storing iteration state, especially when it
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is supposed to work with a particular kind of collection.
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"""
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_position: int = None
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"""
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This attribute indicates the traversal direction.
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"""
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_reverse: bool = False
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def __init__(self, collection: WordCollection, reverse: bool = False) -> None:
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self._collection = collection
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self._reverse = reverse
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self._position = -1 if reverse else 0
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def __next__(self):
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"""
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The __next__() method must return the next item in the sequence. On
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reaching the end, and in subsequent calls, it must raise StopIteration.
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"""
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try:
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value = self._collection[self._position]
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self._position += -1 if self._reverse else 1
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except IndexError:
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raise StopIteration()
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return value
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