text: # Copyright (c) 2019 PaddlePaddle Authors. All Rights Reserved.
  #
  # Licensed under the Apache License, Version 2.0 (the "License");
  # you may not use this file except in compliance with the License.
  # You may obtain a copy of the License at
  #
  #     http://www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing, software
  # distributed under the License is distributed on an "AS IS" BASIS,
  # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  # See the License for the specific language governing permissions and
  # limitations under the License.
  
  #function:
  #    interface to load data from local files and parse it for samples,
  #    eg: roidb data in pickled files
  
  from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  from __future__ import unicode_literals
  
  import os
  import random
  
  import copy
  import pickle as pkl
  from ..dataset import Dataset
  
  
  class RoiDbSource(Dataset):
      """ interface to load roidb data from files
      """
  
      def __init__(self,
                   anno_file,
                   image_dir=None,
                   samples=-1,
                   is_shuffle=True,
                   load_img=False,
                   cname2cid=None,
                   use_default_label=None,
                   mixup_epoch=-1,
                   with_background=True):
          """ Init
  
          Args:
              fname (str): label file path
              image_dir (str): root dir for images
              samples (int): samples to load, -1 means all
              is_shuffle (bool): whether to shuffle samples
              load_img (bool): whether load data in this class
              cname2cid (dict): the label name to id dictionary
              use_default_label (bool):whether use the default mapping of label to id
              mixup_epoch (int): parse mixup in first n epoch
              with_background (bool): whether load background
                                      as a class
          """
          super(RoiDbSource, self).__init__()
          self._epoch = -1
          assert os.path.isfile(anno_file) or os.path.isdir(anno_file), \
                  'anno_file {} is not a file or a directory'.format(anno_file)
          self._fname = anno_file
          self._image_dir = image_dir if image_dir is not None else ''
          if image_dir is not None:
              assert os.path.isdir(image_dir), \
                      'image_dir {} is not a directory'.format(image_dir)
          self._roidb = None
          self._pos = -1
          self._drained = False
          self._samples = samples
          self._is_shuffle = is_shuffle
          self._load_img = load_img
          self.use_default_label = use_default_label
          self._mixup_epoch = mixup_epoch
          self._with_background = with_background
          self.cname2cid = cname2cid
          self._imid2path = None
  
      def __str__(self):
          return 'RoiDbSource(fname:%s,epoch:%d,size:%d,pos:%d)' \
              % (self._fname, self._epoch, self.size(), self._pos)
  
      def next(self):
          """ load next sample
          """
          if self._epoch < 0:
              self.reset()
          if self._pos >= self._samples:
              self._drained = True
              raise StopIteration('%s no more data' % (str(self)))
          sample = copy.deepcopy(self._roidb[self._pos])
          if self._load_img:
              sample['image'] = self._load_image(sample['im_file'])
          else:
              sample['im_file'] = os.path.join(self._image_dir, sample['im_file'])
  
          if self._epoch < self._mixup_epoch:
              mix_idx = random.randint(1, self._samples - 1)
              mix_pos = (mix_idx + self._pos) % self._samples
              sample['mixup'] = copy.deepcopy(self._roidb[mix_pos])
              if self._load_img:
                  sample['mixup']['image'] = \
                          self._load_image(sample['mixup']['im_file'])
              else:
                  sample['mixup']['im_file'] = \
                          os.path.join(self._image_dir, sample['mixup']['im_file'])
          self._pos += 1
          return sample
  
      def _load(self):
          """ load data from file
          """
          from . import loader
          records, cname2cid = loader.load(self._fname, self._samples,
                                           self._with_background, True,
                                           self.use_default_label, self.cname2cid)
          self.cname2cid = cname2cid
          return records
  
      def _load_image(self, where):
          fn = os.path.join(self._image_dir, where)
          with open(fn, 'rb') as f:
              return f.read()
  
      def reset(self):
          """ implementation of Dataset.reset
          """
          if self._roidb is None:
              self._roidb = self._load()
  
          self._samples = len(self._roidb)
          if self._is_shuffle:
              random.shuffle(self._roidb)
  
          if self._epoch < 0:
              self._epoch = 0
          else:
              self._epoch += 1
  
          self._pos = 0
          self._drained = False
  
      def size(self):
          """ implementation of Dataset.size
          """
          return len(self._roidb)
  
      def drained(self):
          """ implementation of Dataset.drained
          """
          assert self._epoch >= 0, 'The first epoch has not begin!'
          return self._pos >= self.size()
  
      def epoch_id(self):
          """ return epoch id for latest sample
          """
          return self._epoch
  
      def get_imid2path(self):
          """return image id to image path map"""
          if self._imid2path is None:
              self._imid2path = {}
              for record in self._roidb:
                  im_id = record['im_id']
                  im_id = im_id if isinstance(im_id, int) else im_id[0]
                  im_path = os.path.join(self._image_dir, record['im_file'])
                  self._imid2path[im_id] = im_path
          return self._imid2path
  