luatables.py

# Copyright 2017 The TensorFlow 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.
# ==============================================================================

# pylint: disable=line-too-long,g-explicit-length-test
"""A convenience class replicating some lua table syntax with a python dict.

In general, should behave like a dictionary except that we can use dot notation
 to access keys. Users should be careful to only provide keys suitable for
 instance variable names.

Nota bene: do not use the key "keys" since it will collide with the method keys.

Usage example:

>>> t = T(a=5,b='kaw', c=T(v=[],x=33))
>>> t.a
5
>>> t.z = None
>>> print t
T(a=5, z=None, c=T(x=33, v=[]), b='kaw')

>>> t2 = T({'h':'f','x':4})
>>> t2
T(h='f', x=4)
>>> t2['x']
4
"""


class T(object):
  """Class for emulating lua tables."""

  def __init__(self, *args, **kwargs):
    if len(args) > 1 or (len(args) == 1 and len(kwargs) > 0):
      errmsg = '''constructor only allows a single dict as a positional
      argument or keyword arguments'''
      raise ValueError(errmsg)
    if len(args) == 1 and isinstance(args[0], dict):
      self.__dict__.update(args[0])
    else:
      self.__dict__.update(kwargs)

  def __repr__(self):
    fmt = ', '.join('%s=%s' for i in range(len(self.__dict__)))
    kwargstr = fmt % tuple(
        x for tup in self.__dict__.items() for x in [str(tup[0]), repr(tup[1])])
    return 'T(' + kwargstr + ')'

  def __getitem__(self, key):
    return self.__dict__[key]

  def __setitem__(self, key, val):
    self.__dict__[key] = val

  def __delitem__(self, key):
    del self.__dict__[key]

  def __iter__(self):
    return iter(self.__dict__)

  def __len__(self):
    return len(self.__dict__)

  def keys(self):  # Needed for dict(T( ... )) to work.
    return self.__dict__.keys()

  def iteritems(self):
    return self.__dict__.iteritems()