Class RefreshCache

Lib/_pyrepl/reader.py:220–261

    ## cached metadata to speed up screen refreshes
    @dataclass
    class RefreshCache:
        screen: list[str] = field(default_factory=list)
        screeninfo: list[tuple[int, list[int]]] = field(init=False)
        line_end_offsets: list[int] = field(default_factory=list)
        pos: int = field(init=False)
        cxy: tuple[int, int] = field(init=False)
        dimensions: tuple[int, int] = field(init=False)
        invalidated: bool = False

        def update_cache(self,
                         reader: Reader,
                         screen: list[str],
                         screeninfo: list[tuple[int, list[int]]],
            ) -> None:
            self.screen = screen.copy()
            self.screeninfo = screeninfo.copy()
            self.pos = reader.pos
            self.cxy = reader.cxy
            self.dimensions = reader.console.width, reader.console.height
            self.invalidated = False

        def valid(self, reader: Reader) -> bool:
            if self.invalidated:
                return False
            dimensions = reader.console.width, reader.console.height
            dimensions_changed = dimensions != self.dimensions
            return not dimensions_changed

        def get_cached_location(self, reader: Reader) -> tuple[int, int]:
            if self.invalidated:
                raise ValueError("Cache is invalidated")
            offset = 0
            earliest_common_pos = min(reader.pos, self.pos)
            num_common_lines = len(self.line_end_offsets)
            while num_common_lines > 0:
                offset = self.line_end_offsets[num_common_lines - 1]
                if earliest_common_pos > offset:
                    break
                num_common_lines -= 1
            else:
                offset = 0
            return offset, num_common_lines

    last_refresh_cache: RefreshCache = field(default_factory=RefreshCache)