terminal.py 文件源码

def cursor_left(self, n=1):
        """ESCnD CUB (Cursor Back)"""
        # Commented out to save CPU (and the others below too)
        #logging.debug('cursor_left(%s)' % n)
        n = int(n)
        # This logic takes care of double-width unicode characters
        if self.double_width_left:
            self.double_width_left = False
            return
        self.cursorX = max(0, self.cursorX - n) # Ensures positive value
        try:
            char = self.screen[self.cursorY][self.cursorX]
        except IndexError: # Cursor is past the right-edge of the screen; ignore
            char = u' ' # This is a safe default/fallback
        if unicodedata.east_asian_width(char) == 'W':
            # This lets us skip the next call (get called 2x for 2x width)
            self.double_width_left = True
        try:
            for callback in self.callbacks[CALLBACK_CURSOR_POS].values():
                callback()
        except TypeError:
            pass