import os
import os.path as osp
import numpy as np
import numpy.random as npr
import torch
import cv2
import scipy.ndimage
from PIL import Image
import copy
import gc
import itertools

def singleton(class_):
    instances = {}
    def getinstance(*args, **kwargs):
        if class_ not in instances:
            instances[class_] = class_(*args, **kwargs)
        return instances[class_]
    return getinstance

@singleton
class get_formatter(object):
    def __init__(self):
        self.formatter = {}

    def register(self, formatf):
        self.formatter[formatf.__name__] = formatf

    def __call__(self, cfg):
        if cfg is None:
            return None
        t = cfg.type
        return self.formatter[t](**cfg.args)

def register():
    def wrapper(class_):
        get_formatter().register(class_)
        return class_
    return wrapper