mapped_struct.py 文件源码

def map_file(cls, fileobj, offset = 0, size = None):
        # If no size is given, it's the whole file by default
        if size is None:
            fileobj.seek(0, os.SEEK_END)
            size = fileobj.tell() - offset

        # Read the footer
        fileobj.seek(offset + size - cls._Footer.size)
        values_pos, = cls._Footer.unpack(fileobj.read(cls._Footer.size))
        fileobj.seek(offset)

        # Map everything
        id_mapper = cls.IdMapper.map_file(fileobj, offset, size = values_pos)
        value_array = cls.ValueArray.map_file(fileobj, offset + values_pos, 
            size = size - cls._Footer.size - values_pos)
        return cls(value_array, id_mapper)