"""Operations for implementing attention.

"""

import tensorflow.python.platform

from tensorflow.python.framework import ops

from tensorflow.python.framework import tensor_shape

from tensorflow.python.framework import tensor_util

from tensorflow.python.ops import gen_attention_ops

# pylint: disable=wildcard-import

from tensorflow.python.ops.gen_attention_ops import *

# TODO(bsteiner): Implement the gradient function for extract_glimpse

ops.NoGradient("ExtractGlimpse")

@ops.RegisterShape("ExtractGlimpse")

def _ExtractGlimpseShape(op):

"""Shape function for ExtractGlimpse op."""

input_shape = op.inputs[0].get_shape().with_rank(4)

unused_size_shape = op.inputs[1].get_shape().merge_with(

tensor_shape.vector(2))

offsets_shape = op.inputs[2].get_shape().merge_with(

input_shape[:1].concatenate([2]))

offsets_shape = offsets_shape

size_value = tensor_util.ConstantValue(op.inputs[1])

if size_value is not None:

height = size_value[0]

width = size_value[1]

else:

height = None

width = None

return [tensor_shape.TensorShape(

[input_shape[0], height, width, input_shape[3]])]