#   Copyright (c) 2020 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.

from paddle.common_ops_import import *
import paddle.fluid as fluid

# TODO: define logic functions of a tensor  
__all__ = [
    'equal',
    #            'greater_equal',
    #            'greater_than',
    #            'is_empty',
    #            'isfinite',
    #            'less_equal',
    #            'less_than',
    #            'logical_and',
    #            'logical_not',
    #            'logical_or',
    #            'logical_xor',
    #            'not_equal',
    #            'reduce_all',
    #            'reduce_any',
    #            'allclose',
    #            'elementwise_equal',
    #            'isnan'
]


def equal(x, y, axis=-1, name=None):
    """
    This OP returns the truth value of :math:`x == y`. True if two inputs have the same elements, False otherwise.

    **NOTICE**: The output of this OP has no gradient, and this OP supports broadcasting by :attr:`axis`.

    Args:
        x(Variable): Tensor, data type is float32, float64, int32, int64.
        y(Variable): Tensor, data type is float32, float64, int32, int64.
        axis(int32, optional): If X.dimension != Y.dimension, Y.dimension
            must be a subsequence of x.dimension. And axis is the start 
            dimension index for broadcasting Y onto X. For more detail, 
            please refer to OP:`elementwise_add`.
        name(str, optional): Normally there is no need for user to set this property. 
            For more information, please refer to :ref:`api_guide_Name`.Default: None.

    Returns:
        Variable: output Tensor, data type is bool, value is [False] or [True].

    Examples:
        .. code-block:: python

          import paddle.fluid as fluid
          import paddle
          import numpy as np

          label = fluid.layers.assign(np.array([3, 4], dtype="int32"))
          label_1 = fluid.layers.assign(np.array([1, 2], dtype="int32"))
          limit = fluid.layers.assign(np.array([3, 4], dtype="int32"))
          out1 = paddle.equal(x=label, y=limit) #out1=[True]
          out2 = paddle.equal(x=label_1, y=limit) #out2=[False]

        .. code-block:: python

          import paddle.fluid as fluid
          import paddle
          import numpy as np

          def gen_data():
              return {
                    "x": np.ones((2, 3, 4, 5)).astype('float32'),
                    "y": np.zeros((3, 4)).astype('float32')
                }

          x = fluid.data(name="x", shape=[2,3,4,5], dtype='float32')
          y = fluid.data(name="y", shape=[3,4], dtype='float32')
          out = paddle.equal(x, y, axis=1)
          place = fluid.CPUPlace()
          exe = fluid.Executor(place)

          res = exe.run(feed=gen_data(),
                            fetch_list=[out])
          print(res[0]) #[False]
    """
    helper = LayerHelper("equal_reduce", **locals())
    out = helper.create_variable_for_type_inference(dtype='bool')
    attrs = {}
    attrs['axis'] = axis
    helper.append_op(
        type='equal_reduce',
        inputs={'X': [x],
                'Y': [y]},
        attrs=attrs,
        outputs={'Out': [out]})
    return out