Source code for iamsystem.stopwords.simple

""" Basic stopwords implementation. """
from typing import Iterable
from typing import Optional
from typing import Set

from iamsystem.stopwords.api import SimpleStopwords
from iamsystem.tokenization.api import TokenT


class Stopwords(SimpleStopwords[TokenT]):
    """A simple implementation of :class:`~iamsystem.IStopwords` protocol."""

    def __init__(self, stopwords: Optional[Iterable[str]] = None):
        """Create a Stopword instance to store stopwords.

        :param stopwords: a set of stopwords. Default to None.
        """
        self._stopwords: Set[str] = set()
        if stopwords is not None:
            self._stopwords.update(stopwords)

    @property
    def stopwords(self):
        """Get the set of stopwords."""
        return self._stopwords

    def is_stopword(self, word: str) -> bool:
        """True if, after lowercasing, the word belongs to the stopwords set"""
        word = word.lower()
        return word.isspace() or word in self._stopwords

    def add(self, words: Iterable[str]) -> None:
        """Add stopwords.

        :param words: a list of string.
        :return: None
        """
        for word in words:
            self._stopwords.add(word)


class NoStopwords(SimpleStopwords[TokenT]):
    """Utility class. Class to use when no stopwords are used."""

    def is_token_a_stopword(self, token: TokenT) -> bool:
        """Return False."""
        return False

    def is_stopword(self, word: str) -> bool:
        """Return False."""
        return False