# Written by Shigeki Karita, 2019
# Published under Apache 2.0  (http://www.apache.org/licenses/LICENSE-2.0)
# Adapted by Florian Lux, 2021


import torch


class PositionwiseFeedForward(torch.nn.Module):
    """
    Args:
        idim (int): Input dimenstion.
        hidden_units (int): The number of hidden units.
        dropout_rate (float): Dropout rate.

    """

    def __init__(self, idim, hidden_units, dropout_rate, activation=torch.nn.ReLU()):
        super(PositionwiseFeedForward, self).__init__()
        self.w_1 = torch.nn.Linear(idim, hidden_units)
        self.w_2 = torch.nn.Linear(hidden_units, idim)
        self.dropout = torch.nn.Dropout(dropout_rate)
        self.activation = activation

    def forward(self, x):
        return self.w_2(self.dropout(self.activation(self.w_1(x))))