Method _match_length_from_index

data_compression/lz77.py:183–210

Calculate the longest possible match of text and window characters from text_index in text and window_index in window. Args: text: _description_ window: sliding window text_index: index of character in text window_index: index of chara

(
        self, text: str, window: str, text_index: int, window_index: int
    )

        return Token(offset, length, text[length])

    def _match_length_from_index(
        self, text: str, window: str, text_index: int, window_index: int
    ) -> int:
        """Calculate the longest possible match of text and window characters from
        text_index in text and window_index in window.

        Args:
            text: _description_
            window: sliding window
            text_index: index of character in text
            window_index: index of character in sliding window

        Returns:
            The maximum match between text and window, from given indexes.

        Tests:
            >>> lz77_compressor = LZ77Compressor(13, 6)
            >>> lz77_compressor._match_length_from_index("rarrad", "adabrar", 0, 4)
            5
            >>> lz77_compressor._match_length_from_index("adabrarrarrad",
            ...     "cabrac", 0, 1)
            1
        """
        if not text or text[text_index] != window[window_index]:
            return 0
        return 1 + self._match_length_from_index(
            text, window + text[text_index], text_index + 1, window_index + 1
        )


if __name__ == "__main__":